imgui/imgui_internal.h

// dear imgui, v1.54 WIP
// (internals)

// You may use this file to debug, understand or extend ImGui features but we don't provide any guarantee of forward compatibility!
// Set:
//   #define IMGUI_DEFINE_MATH_OPERATORS
// To implement maths operators for ImVec2 (disabled by default to not collide with using IM_VEC2_CLASS_EXTRA along with your own math types+operators)

#pragma once

#ifndef IMGUI_VERSION
#error Must include imgui.h before imgui_internal.h
#endif

#include <stdio.h>      // FILE*
#include <math.h>       // sqrtf, fabsf, fmodf, powf, floorf, ceilf, cosf, sinf
#include <limits.h>     // INT_MIN, INT_MAX

#ifdef _MSC_VER
#pragma warning (push)
#pragma warning (disable: 4251) // class 'xxx' needs to have dll-interface to be used by clients of struct 'xxx' // when IMGUI_API is set to__declspec(dllexport)
#endif

#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-function"        // for stb_textedit.h
#pragma clang diagnostic ignored "-Wmissing-prototypes"     // for stb_textedit.h
#pragma clang diagnostic ignored "-Wold-style-cast"
#endif

//-----------------------------------------------------------------------------
// Forward Declarations
//-----------------------------------------------------------------------------

struct ImRect;
struct ImGuiColMod;
struct ImGuiStyleMod;
struct ImGuiGroupData;
struct ImGuiMenuColumns;
struct ImGuiDrawContext;
struct ImGuiTextEditState;
struct ImGuiPopupRef;
struct ImGuiWindow;
struct ImGuiWindowSettings;

typedef int ImGuiLayoutType;        // enum: horizontal or vertical             // enum ImGuiLayoutType_
typedef int ImGuiButtonFlags;       // flags: for ButtonEx(), ButtonBehavior()  // enum ImGuiButtonFlags_
typedef int ImGuiItemFlags;         // flags: for PushItemFlag()                // enum ImGuiItemFlags_
typedef int ImGuiItemStatusFlags;   // flags: storage for DC.LastItemXXX        // enum ImGuiItemStatusFlags_
typedef int ImGuiNavHighlightFlags; // flags: for RenderNavHighlight()          // enum ImGuiNavHighlightFlags_
typedef int ImGuiNavDirSourceFlags; // flags: for GetNavInputAmount2d()         // enum ImGuiNavDirSourceFlags_
typedef int ImGuiSeparatorFlags;    // flags: for Separator() - internal        // enum ImGuiSeparatorFlags_
typedef int ImGuiSliderFlags;       // flags: for SliderBehavior()              // enum ImGuiSliderFlags_

//-------------------------------------------------------------------------
// STB libraries
//-------------------------------------------------------------------------

namespace ImGuiStb
{

#undef STB_TEXTEDIT_STRING
#undef STB_TEXTEDIT_CHARTYPE
#define STB_TEXTEDIT_STRING             ImGuiTextEditState
#define STB_TEXTEDIT_CHARTYPE           ImWchar
#define STB_TEXTEDIT_GETWIDTH_NEWLINE   -1.0f
#include "stb_textedit.h"

} // namespace ImGuiStb

//-----------------------------------------------------------------------------
// Context
//-----------------------------------------------------------------------------

#ifndef GImGui
extern IMGUI_API ImGuiContext* GImGui;  // Current implicit ImGui context pointer
#endif

//-----------------------------------------------------------------------------
// Helpers
//-----------------------------------------------------------------------------

#define IM_PI           3.14159265358979323846f

// Helpers: UTF-8 <> wchar
IMGUI_API int           ImTextStrToUtf8(char* buf, int buf_size, const ImWchar* in_text, const ImWchar* in_text_end);      // return output UTF-8 bytes count
IMGUI_API int           ImTextCharFromUtf8(unsigned int* out_char, const char* in_text, const char* in_text_end);          // return input UTF-8 bytes count
IMGUI_API int           ImTextStrFromUtf8(ImWchar* buf, int buf_size, const char* in_text, const char* in_text_end, const char** in_remaining = NULL);   // return input UTF-8 bytes count
IMGUI_API int           ImTextCountCharsFromUtf8(const char* in_text, const char* in_text_end);                            // return number of UTF-8 code-points (NOT bytes count)
IMGUI_API int           ImTextCountUtf8BytesFromStr(const ImWchar* in_text, const ImWchar* in_text_end);                   // return number of bytes to express string as UTF-8 code-points

// Helpers: Misc
IMGUI_API ImU32         ImHash(const void* data, int data_size, ImU32 seed = 0);    // Pass data_size==0 for zero-terminated strings
IMGUI_API void*         ImFileLoadToMemory(const char* filename, const char* file_open_mode, int* out_file_size = NULL, int padding_bytes = 0);
IMGUI_API FILE*         ImFileOpen(const char* filename, const char* file_open_mode);
static inline bool      ImCharIsSpace(int c)            { return c == ' ' || c == '\t' || c == 0x3000; }
static inline bool      ImIsPowerOfTwo(int v)           { return v != 0 && (v & (v - 1)) == 0; }
static inline int       ImUpperPowerOfTwo(int v)        { v--; v |= v >> 1; v |= v >> 2; v |= v >> 4; v |= v >> 8; v |= v >> 16; v++; return v; }

// Helpers: Geometry
IMGUI_API ImVec2        ImLineClosestPoint(const ImVec2& a, const ImVec2& b, const ImVec2& p);
IMGUI_API bool          ImTriangleContainsPoint(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& p);
IMGUI_API ImVec2        ImTriangleClosestPoint(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& p);
IMGUI_API void          ImTriangleBarycentricCoords(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& p, float& out_u, float& out_v, float& out_w);

// Helpers: String
IMGUI_API int           ImStricmp(const char* str1, const char* str2);
IMGUI_API int           ImStrnicmp(const char* str1, const char* str2, size_t count);
IMGUI_API void          ImStrncpy(char* dst, const char* src, size_t count);
IMGUI_API char*         ImStrdup(const char* str);
IMGUI_API char*         ImStrchrRange(const char* str_begin, const char* str_end, char c);
IMGUI_API int           ImStrlenW(const ImWchar* str);
IMGUI_API const ImWchar*ImStrbolW(const ImWchar* buf_mid_line, const ImWchar* buf_begin); // Find beginning-of-line
IMGUI_API const char*   ImStristr(const char* haystack, const char* haystack_end, const char* needle, const char* needle_end);
IMGUI_API int           ImFormatString(char* buf, size_t buf_size, const char* fmt, ...) IM_FMTARGS(3);
IMGUI_API int           ImFormatStringV(char* buf, size_t buf_size, const char* fmt, va_list args) IM_FMTLIST(3);

// Helpers: Math
// We are keeping those not leaking to the user by default, in the case the user has implicit cast operators between ImVec2 and its own types (when IM_VEC2_CLASS_EXTRA is defined)
#ifdef IMGUI_DEFINE_MATH_OPERATORS
static inline ImVec2 operator*(const ImVec2& lhs, const float rhs)              { return ImVec2(lhs.x*rhs, lhs.y*rhs); }
static inline ImVec2 operator/(const ImVec2& lhs, const float rhs)              { return ImVec2(lhs.x/rhs, lhs.y/rhs); }
static inline ImVec2 operator+(const ImVec2& lhs, const ImVec2& rhs)            { return ImVec2(lhs.x+rhs.x, lhs.y+rhs.y); }
static inline ImVec2 operator-(const ImVec2& lhs, const ImVec2& rhs)            { return ImVec2(lhs.x-rhs.x, lhs.y-rhs.y); }
static inline ImVec2 operator*(const ImVec2& lhs, const ImVec2& rhs)            { return ImVec2(lhs.x*rhs.x, lhs.y*rhs.y); }
static inline ImVec2 operator/(const ImVec2& lhs, const ImVec2& rhs)            { return ImVec2(lhs.x/rhs.x, lhs.y/rhs.y); }
static inline ImVec2& operator+=(ImVec2& lhs, const ImVec2& rhs)                { lhs.x += rhs.x; lhs.y += rhs.y; return lhs; }
static inline ImVec2& operator-=(ImVec2& lhs, const ImVec2& rhs)                { lhs.x -= rhs.x; lhs.y -= rhs.y; return lhs; }
static inline ImVec2& operator*=(ImVec2& lhs, const float rhs)                  { lhs.x *= rhs; lhs.y *= rhs; return lhs; }
static inline ImVec2& operator/=(ImVec2& lhs, const float rhs)                  { lhs.x /= rhs; lhs.y /= rhs; return lhs; }
static inline ImVec4 operator+(const ImVec4& lhs, const ImVec4& rhs)            { return ImVec4(lhs.x+rhs.x, lhs.y+rhs.y, lhs.z+rhs.z, lhs.w+rhs.w); }
static inline ImVec4 operator-(const ImVec4& lhs, const ImVec4& rhs)            { return ImVec4(lhs.x-rhs.x, lhs.y-rhs.y, lhs.z-rhs.z, lhs.w-rhs.w); }
static inline ImVec4 operator*(const ImVec4& lhs, const ImVec4& rhs)            { return ImVec4(lhs.x*rhs.x, lhs.y*rhs.y, lhs.z*rhs.z, lhs.w*rhs.w); }
#endif

static inline int    ImMin(int lhs, int rhs)                                    { return lhs < rhs ? lhs : rhs; }
static inline int    ImMax(int lhs, int rhs)                                    { return lhs >= rhs ? lhs : rhs; }
static inline float  ImMin(float lhs, float rhs)                                { return lhs < rhs ? lhs : rhs; }
static inline float  ImMax(float lhs, float rhs)                                { return lhs >= rhs ? lhs : rhs; }
static inline ImVec2 ImMin(const ImVec2& lhs, const ImVec2& rhs)                { return ImVec2(lhs.x < rhs.x ? lhs.x : rhs.x, lhs.y < rhs.y ? lhs.y : rhs.y); }
static inline ImVec2 ImMax(const ImVec2& lhs, const ImVec2& rhs)                { return ImVec2(lhs.x >= rhs.x ? lhs.x : rhs.x, lhs.y >= rhs.y ? lhs.y : rhs.y); }
static inline int    ImClamp(int v, int mn, int mx)                             { return (v < mn) ? mn : (v > mx) ? mx : v; }
static inline float  ImClamp(float v, float mn, float mx)                       { return (v < mn) ? mn : (v > mx) ? mx : v; }
static inline ImVec2 ImClamp(const ImVec2& f, const ImVec2& mn, ImVec2 mx)      { return ImVec2(ImClamp(f.x,mn.x,mx.x), ImClamp(f.y,mn.y,mx.y)); }
static inline float  ImSaturate(float f)                                        { return (f < 0.0f) ? 0.0f : (f > 1.0f) ? 1.0f : f; }
static inline void   ImSwap(int& a, int& b)                                     { int tmp = a; a = b; b = tmp; }
static inline void   ImSwap(float& a, float& b)                                 { float tmp = a; a = b; b = tmp; }
static inline int    ImLerp(int a, int b, float t)                              { return (int)(a + (b - a) * t); }
static inline float  ImLerp(float a, float b, float t)                          { return a + (b - a) * t; }
static inline ImVec2 ImLerp(const ImVec2& a, const ImVec2& b, float t)          { return ImVec2(a.x + (b.x - a.x) * t, a.y + (b.y - a.y) * t); }
static inline ImVec2 ImLerp(const ImVec2& a, const ImVec2& b, const ImVec2& t)  { return ImVec2(a.x + (b.x - a.x) * t.x, a.y + (b.y - a.y) * t.y); }
static inline ImVec4 ImLerp(const ImVec4& a, const ImVec4& b, float t)          { return ImVec4(a.x + (b.x - a.x) * t, a.y + (b.y - a.y) * t, a.z + (b.z - a.z) * t, a.w + (b.w - a.w) * t); }
static inline float  ImLengthSqr(const ImVec2& lhs)                             { return lhs.x*lhs.x + lhs.y*lhs.y; }
static inline float  ImLengthSqr(const ImVec4& lhs)                             { return lhs.x*lhs.x + lhs.y*lhs.y + lhs.z*lhs.z + lhs.w*lhs.w; }
static inline float  ImInvLength(const ImVec2& lhs, float fail_value)           { float d = lhs.x*lhs.x + lhs.y*lhs.y; if (d > 0.0f) return 1.0f / sqrtf(d); return fail_value; }
static inline float  ImFloor(float f)                                           { return (float)(int)f; }
static inline ImVec2 ImFloor(const ImVec2& v)                                   { return ImVec2((float)(int)v.x, (float)(int)v.y); }
static inline float  ImDot(const ImVec2& a, const ImVec2& b)                    { return a.x * b.x + a.y * b.y; }
static inline ImVec2 ImRotate(const ImVec2& v, float cos_a, float sin_a)        { return ImVec2(v.x * cos_a - v.y * sin_a, v.x * sin_a + v.y * cos_a); }
static inline float  ImLinearSweep(float current, float target, float speed)    { if (current < target) return ImMin(current + speed, target); if (current > target) return ImMax(current - speed, target); return current; }
static inline ImVec2 ImMul(const ImVec2& lhs, const ImVec2& rhs)                { return ImVec2(lhs.x * rhs.x, lhs.y * rhs.y); }

// We call C++ constructor on own allocated memory via the placement "new(ptr) Type()" syntax.
// Defining a custom placement new() with a dummy parameter allows us to bypass including <new> which on some platforms complains when user has disabled exceptions.
struct ImNewPlacementDummy {};
inline void* operator   new(size_t, ImNewPlacementDummy, void* ptr) { return ptr; }
inline void  operator   delete(void*, ImNewPlacementDummy, void*)   {} // This is only required so we can use the symetrical new()
#define IM_PLACEMENT_NEW(_PTR)              new(ImNewPlacementDummy(), _PTR)
#define IM_NEW(_TYPE)                       new(ImNewPlacementDummy(), ImGui::MemAlloc(sizeof(_TYPE))) _TYPE
template <typename T> void IM_DELETE(T*& p) { if (p) { p->~T(); ImGui::MemFree(p); p = NULL; } }

//-----------------------------------------------------------------------------
// Types
//-----------------------------------------------------------------------------

enum ImGuiButtonFlags_
{
    ImGuiButtonFlags_Repeat                 = 1 << 0,   // hold to repeat
    ImGuiButtonFlags_PressedOnClickRelease  = 1 << 1,   // return true on click + release on same item [DEFAULT if no PressedOn* flag is set]
    ImGuiButtonFlags_PressedOnClick         = 1 << 2,   // return true on click (default requires click+release)
    ImGuiButtonFlags_PressedOnRelease       = 1 << 3,   // return true on release (default requires click+release)
    ImGuiButtonFlags_PressedOnDoubleClick   = 1 << 4,   // return true on double-click (default requires click+release)
    ImGuiButtonFlags_FlattenChildren        = 1 << 5,   // allow interactions even if a child window is overlapping
    ImGuiButtonFlags_AllowItemOverlap       = 1 << 6,   // require previous frame HoveredId to either match id or be null before being usable, use along with SetItemAllowOverlap()
    ImGuiButtonFlags_DontClosePopups        = 1 << 7,   // disable automatically closing parent popup on press // [UNUSED]
    ImGuiButtonFlags_Disabled               = 1 << 8,   // disable interactions
    ImGuiButtonFlags_AlignTextBaseLine      = 1 << 9,   // vertically align button to match text baseline - ButtonEx() only // FIXME: Should be removed and handled by SmallButton(), not possible currently because of DC.CursorPosPrevLine
    ImGuiButtonFlags_NoKeyModifiers         = 1 << 10,  // disable interaction if a key modifier is held
    ImGuiButtonFlags_NoHoldingActiveID      = 1 << 11,  // don't set ActiveId while holding the mouse (ImGuiButtonFlags_PressedOnClick only)
    ImGuiButtonFlags_PressedOnDragDropHold  = 1 << 12,  // press when held into while we are drag and dropping another item (used by e.g. tree nodes, collapsing headers)
    ImGuiButtonFlags_NoNavFocus             = 1 << 13   // don't override navigation focus when activated
};

enum ImGuiSliderFlags_
{
    ImGuiSliderFlags_Vertical               = 1 << 0
};

enum ImGuiColumnsFlags_
{
    // Default: 0
    ImGuiColumnsFlags_NoBorder              = 1 << 0,   // Disable column dividers
    ImGuiColumnsFlags_NoResize              = 1 << 1,   // Disable resizing columns when clicking on the dividers
    ImGuiColumnsFlags_NoPreserveWidths      = 1 << 2,   // Disable column width preservation when adjusting columns
    ImGuiColumnsFlags_NoForceWithinWindow   = 1 << 3,   // Disable forcing columns to fit within window
    ImGuiColumnsFlags_GrowParentContentsSize= 1 << 4    // (WIP) Restore pre-1.51 behavior of extending the parent window contents size but _without affecting the columns width at all_. Will eventually remove.
};

enum ImGuiSelectableFlagsPrivate_
{
    // NB: need to be in sync with last value of ImGuiSelectableFlags_
    ImGuiSelectableFlags_Menu               = 1 << 3,   // -> PressedOnClick
    ImGuiSelectableFlags_MenuItem           = 1 << 4,   // -> PressedOnRelease
    ImGuiSelectableFlags_Disabled           = 1 << 5,
    ImGuiSelectableFlags_DrawFillAvailWidth = 1 << 6
};

enum ImGuiSeparatorFlags_
{
    ImGuiSeparatorFlags_Horizontal          = 1 << 0,   // Axis default to current layout type, so generally Horizontal unless e.g. in a menu bar
    ImGuiSeparatorFlags_Vertical            = 1 << 1
};

// Storage for LastItem data
enum ImGuiItemStatusFlags_
{
    ImGuiItemStatusFlags_HoveredRect        = 1 << 0,
    ImGuiItemStatusFlags_HasDisplayRect     = 1 << 1
};

// FIXME: this is in development, not exposed/functional as a generic feature yet.
enum ImGuiLayoutType_
{
    ImGuiLayoutType_Vertical,
    ImGuiLayoutType_Horizontal
};

enum ImGuiAxis
{
    ImGuiAxis_None = -1,
    ImGuiAxis_X = 0,
    ImGuiAxis_Y = 1
};

enum ImGuiPlotType
{
    ImGuiPlotType_Lines,
    ImGuiPlotType_Histogram
};

enum ImGuiDataType
{
    ImGuiDataType_Int,
    ImGuiDataType_Float,
    ImGuiDataType_Float2
};

enum ImGuiDir
{
    ImGuiDir_None    = -1,
    ImGuiDir_Left    = 0,
    ImGuiDir_Right   = 1,
    ImGuiDir_Up      = 2,
    ImGuiDir_Down    = 3,
    ImGuiDir_Count_
};

enum ImGuiInputSource
{
    ImGuiInputSource_None = 0,
    ImGuiInputSource_Mouse,
    ImGuiInputSource_Nav,
    ImGuiInputSource_NavKeyboard,   // Only used occasionally for storage, not tested/handled by most code
    ImGuiInputSource_NavGamepad,    // "
    ImGuiInputSource_Count_,
};

// FIXME-NAV: Clarify/expose various repeat delay/rate
enum ImGuiInputReadMode
{
    ImGuiInputReadMode_Down,
    ImGuiInputReadMode_Pressed,
    ImGuiInputReadMode_Released,
    ImGuiInputReadMode_Repeat,
    ImGuiInputReadMode_RepeatSlow,
    ImGuiInputReadMode_RepeatFast
};

enum ImGuiNavHighlightFlags_
{
    ImGuiNavHighlightFlags_TypeDefault  = 1 << 0,
    ImGuiNavHighlightFlags_TypeThin     = 1 << 1,
    ImGuiNavHighlightFlags_AlwaysDraw   = 1 << 2,
    ImGuiNavHighlightFlags_NoRounding   = 1 << 3
};

enum ImGuiNavDirSourceFlags_
{
    ImGuiNavDirSourceFlags_Keyboard     = 1 << 0,
    ImGuiNavDirSourceFlags_PadDPad      = 1 << 1,
    ImGuiNavDirSourceFlags_PadLStick    = 1 << 2
};

enum ImGuiNavForward
{
    ImGuiNavForward_None,
    ImGuiNavForward_ForwardQueued,
    ImGuiNavForward_ForwardActive
};

// 2D axis aligned bounding-box
// NB: we can't rely on ImVec2 math operators being available here
struct IMGUI_API ImRect
{
    ImVec2      Min;    // Upper-left
    ImVec2      Max;    // Lower-right

    ImRect()                                        : Min(FLT_MAX,FLT_MAX), Max(-FLT_MAX,-FLT_MAX)  {}
    ImRect(const ImVec2& min, const ImVec2& max)    : Min(min), Max(max)                            {}
    ImRect(const ImVec4& v)                         : Min(v.x, v.y), Max(v.z, v.w)                  {}
    ImRect(float x1, float y1, float x2, float y2)  : Min(x1, y1), Max(x2, y2)                      {}

    ImVec2      GetCenter() const                   { return ImVec2((Min.x + Max.x) * 0.5f, (Min.y + Max.y) * 0.5f); }
    ImVec2      GetSize() const                     { return ImVec2(Max.x - Min.x, Max.y - Min.y); }
    float       GetWidth() const                    { return Max.x - Min.x; }
    float       GetHeight() const                   { return Max.y - Min.y; }
    ImVec2      GetTL() const                       { return Min; }                   // Top-left
    ImVec2      GetTR() const                       { return ImVec2(Max.x, Min.y); }  // Top-right
    ImVec2      GetBL() const                       { return ImVec2(Min.x, Max.y); }  // Bottom-left
    ImVec2      GetBR() const                       { return Max; }                   // Bottom-right
    bool        Contains(const ImVec2& p) const     { return p.x     >= Min.x && p.y     >= Min.y && p.x     <  Max.x && p.y     <  Max.y; }
    bool        Contains(const ImRect& r) const     { return r.Min.x >= Min.x && r.Min.y >= Min.y && r.Max.x <= Max.x && r.Max.y <= Max.y; }
    bool        Overlaps(const ImRect& r) const     { return r.Min.y <  Max.y && r.Max.y >  Min.y && r.Min.x <  Max.x && r.Max.x >  Min.x; }
    void        Add(const ImVec2& p)                { if (Min.x > p.x)     Min.x = p.x;     if (Min.y > p.y)     Min.y = p.y;     if (Max.x < p.x)     Max.x = p.x;     if (Max.y < p.y)     Max.y = p.y; }
    void        Add(const ImRect& r)                { if (Min.x > r.Min.x) Min.x = r.Min.x; if (Min.y > r.Min.y) Min.y = r.Min.y; if (Max.x < r.Max.x) Max.x = r.Max.x; if (Max.y < r.Max.y) Max.y = r.Max.y; }
    void        Expand(const float amount)          { Min.x -= amount;   Min.y -= amount;   Max.x += amount;   Max.y += amount; }
    void        Expand(const ImVec2& amount)        { Min.x -= amount.x; Min.y -= amount.y; Max.x += amount.x; Max.y += amount.y; }
    void        Translate(const ImVec2& v)          { Min.x += v.x; Min.y += v.y; Max.x += v.x; Max.y += v.y; }
    void        ClipWith(const ImRect& r)           { Min = ImMax(Min, r.Min); Max = ImMin(Max, r.Max); }                   // Simple version, may lead to an inverted rectangle, which is fine for Contains/Overlaps test but not for display.
    void        ClipWithFull(const ImRect& r)       { Min = ImClamp(Min, r.Min, r.Max); Max = ImClamp(Max, r.Min, r.Max); } // Full version, ensure both points are fully clipped.
    void        Floor()                             { Min.x = (float)(int)Min.x; Min.y = (float)(int)Min.y; Max.x = (float)(int)Max.x; Max.y = (float)(int)Max.y; }
    void        FixInverted()                       { if (Min.x > Max.x) ImSwap(Min.x, Max.x); if (Min.y > Max.y) ImSwap(Min.y, Max.y); }
    bool        IsInverted() const                  { return Min.x > Max.x || Min.y > Max.y; }
    bool        IsFinite() const                    { return Min.x != FLT_MAX; }
};

// Stacked color modifier, backup of modified data so we can restore it
struct ImGuiColMod
{
    ImGuiCol    Col;
    ImVec4      BackupValue;
};

// Stacked style modifier, backup of modified data so we can restore it. Data type inferred from the variable.
struct ImGuiStyleMod
{
    ImGuiStyleVar   VarIdx;
    union           { int BackupInt[2]; float BackupFloat[2]; };
    ImGuiStyleMod(ImGuiStyleVar idx, int v)     { VarIdx = idx; BackupInt[0] = v; }
    ImGuiStyleMod(ImGuiStyleVar idx, float v)   { VarIdx = idx; BackupFloat[0] = v; }
    ImGuiStyleMod(ImGuiStyleVar idx, ImVec2 v)  { VarIdx = idx; BackupFloat[0] = v.x; BackupFloat[1] = v.y; }
};

// Stacked data for BeginGroup()/EndGroup()
struct ImGuiGroupData
{
    ImVec2      BackupCursorPos;
    ImVec2      BackupCursorMaxPos;
    float       BackupIndentX;
    float       BackupGroupOffsetX;
    float       BackupCurrentLineHeight;
    float       BackupCurrentLineTextBaseOffset;
    float       BackupLogLinePosY;
    bool        BackupActiveIdIsAlive;
    bool        AdvanceCursor;
};

// Simple column measurement currently used for MenuItem() only. This is very short-sighted/throw-away code and NOT a generic helper.
struct IMGUI_API ImGuiMenuColumns
{
    int         Count;
    float       Spacing;
    float       Width, NextWidth;
    float       Pos[4], NextWidths[4];

    ImGuiMenuColumns();
    void        Update(int count, float spacing, bool clear);
    float       DeclColumns(float w0, float w1, float w2);
    float       CalcExtraSpace(float avail_w);
};

// Internal state of the currently focused/edited text input box
struct IMGUI_API ImGuiTextEditState
{
    ImGuiID             Id;                         // widget id owning the text state
    ImVector<ImWchar>   Text;                       // edit buffer, we need to persist but can't guarantee the persistence of the user-provided buffer. so we copy into own buffer.
    ImVector<char>      InitialText;                // backup of end-user buffer at the time of focus (in UTF-8, unaltered)
    ImVector<char>      TempTextBuffer;
    int                 CurLenA, CurLenW;           // we need to maintain our buffer length in both UTF-8 and wchar format.
    int                 BufSizeA;                   // end-user buffer size
    float               ScrollX;
    ImGuiStb::STB_TexteditState   StbState;
    float               CursorAnim;
    bool                CursorFollow;
    bool                SelectedAllMouseLock;

    ImGuiTextEditState()                            { memset(this, 0, sizeof(*this)); }
    void                CursorAnimReset()           { CursorAnim = -0.30f; }                                   // After a user-input the cursor stays on for a while without blinking
    void                CursorClamp()               { StbState.cursor = ImMin(StbState.cursor, CurLenW); StbState.select_start = ImMin(StbState.select_start, CurLenW); StbState.select_end = ImMin(StbState.select_end, CurLenW); }
    bool                HasSelection() const        { return StbState.select_start != StbState.select_end; }
    void                ClearSelection()            { StbState.select_start = StbState.select_end = StbState.cursor; }
    void                SelectAll()                 { StbState.select_start = 0; StbState.cursor = StbState.select_end = CurLenW; StbState.has_preferred_x = false; }
    void                OnKeyPressed(int key);
};

// Data saved in imgui.ini file
struct ImGuiWindowSettings
{
    char*       Name;
    ImGuiID     Id;
    ImVec2      Pos;
    ImVec2      Size;
    bool        Collapsed;

    ImGuiWindowSettings() { Name = NULL; Id = 0; Pos = Size = ImVec2(0,0); Collapsed = false; }
};

struct ImGuiSettingsHandler
{
    const char* TypeName;   // Short description stored in .ini file. Disallowed characters: '[' ']'  
    ImGuiID     TypeHash;   // == ImHash(TypeName, 0, 0)
    void*       (*ReadOpenFn)(ImGuiContext* ctx, ImGuiSettingsHandler* handler, const char* name);
    void        (*ReadLineFn)(ImGuiContext* ctx, ImGuiSettingsHandler* handler, void* entry, const char* line);
    void        (*WriteAllFn)(ImGuiContext* ctx, ImGuiSettingsHandler* handler, ImGuiTextBuffer* out_buf);
    void*       UserData;

    ImGuiSettingsHandler() { memset(this, 0, sizeof(*this)); }
};

// Storage for current popup stack
struct ImGuiPopupRef
{
    ImGuiID             PopupId;        // Set on OpenPopup()
    ImGuiWindow*        Window;         // Resolved on BeginPopup() - may stay unresolved if user never calls OpenPopup()
    ImGuiWindow*        ParentWindow;   // Set on OpenPopup()
    int                 OpenFrameCount; // Set on OpenPopup()
    ImGuiID             OpenParentId;   // Set on OpenPopup(), we need this to differenciate multiple menu sets from each others (e.g. inside menu bar vs loose menu items)
    ImVec2              OpenPopupPos;   // Set on OpenPopup(), preferred popup position (typically == OpenMousePos when using mouse)
    ImVec2              OpenMousePos;   // Set on OpenPopup(), copy of mouse position at the time of opening popup
};

struct ImGuiColumnData
{
    float               OffsetNorm;         // Column start offset, normalized 0.0 (far left) -> 1.0 (far right)
    float               OffsetNormBeforeResize;
    ImGuiColumnsFlags   Flags;              // Not exposed
    ImRect              ClipRect;

    ImGuiColumnData()   { OffsetNorm = OffsetNormBeforeResize = 0.0f; Flags = 0; }
};

struct ImGuiColumnsSet
{
    ImGuiID             ID;
    ImGuiColumnsFlags   Flags;
    bool                IsFirstFrame;
    bool                IsBeingResized;
    int                 Current;
    int                 Count;
    float               MinX, MaxX;
    float               StartPosY;
    float               StartMaxPosX;       // Backup of CursorMaxPos
    float               CellMinY, CellMaxY;
    ImVector<ImGuiColumnData> Columns;

    ImGuiColumnsSet()   { Clear(); }
    void Clear()
    {
        ID = 0;
        Flags = 0;
        IsFirstFrame = false;
        IsBeingResized = false;
        Current = 0;
        Count = 1;
        MinX = MaxX = 0.0f;
        StartPosY = 0.0f;
        StartMaxPosX = 0.0f;
        CellMinY = CellMaxY = 0.0f;
        Columns.clear();
    }
};

struct IMGUI_API ImDrawListSharedData
{
    ImVec2          TexUvWhitePixel;            // UV of white pixel in the atlas
    ImFont*         Font;                       // Current/default font (optional, for simplified AddText overload)
    float           FontSize;                   // Current/default font size (optional, for simplified AddText overload)
    float           CurveTessellationTol;
    ImVec4          ClipRectFullscreen;         // Value for PushClipRectFullscreen()

    // Const data
    // FIXME: Bake rounded corners fill/borders in atlas
    ImVec2          CircleVtx12[12];

    ImDrawListSharedData();
};

struct ImDrawDataBuilder
{
    ImVector<ImDrawList*>   Layers[2];           // Global layers for: regular, tooltip

    void Clear()            { for (int n = 0; n < IM_ARRAYSIZE(Layers); n++) Layers[n].resize(0); }
    void ClearFreeMemory()  { for (int n = 0; n < IM_ARRAYSIZE(Layers); n++) Layers[n].clear(); }
    IMGUI_API void FlattenIntoSingleLayer();
};

struct ImGuiNavMoveResult
{
    ImGuiID       ID;           // Best candidate
    ImGuiID       ParentID;     // Best candidate window->IDStack.back() - to compare context
    ImGuiWindow*  Window;       // Best candidate window
    float         DistBox;      // Best candidate box distance to current NavId
    float         DistCenter;   // Best candidate center distance to current NavId
    float         DistAxial;
    ImRect        RectRel;      // Best candidate bounding box in window relative space

    ImGuiNavMoveResult() { Clear(); }
    void Clear()         { ID = ParentID = 0; Window = NULL; DistBox = DistCenter = DistAxial = FLT_MAX; RectRel = ImRect(); }
};

// Storage for SetNexWindow** functions
struct ImGuiNextWindowData
{
    ImGuiCond               PosCond;
    ImGuiCond               SizeCond;
    ImGuiCond               ContentSizeCond;
    ImGuiCond               CollapsedCond;
    ImGuiCond               SizeConstraintCond;
    ImGuiCond               FocusCond;
    ImGuiCond               BgAlphaCond;
    ImVec2                  PosVal;
    ImVec2                  PosPivotVal;
    ImVec2                  SizeVal;
    ImVec2                  ContentSizeVal;
    bool                    CollapsedVal;
    ImRect                  SizeConstraintRect;                 // Valid if 'SetNextWindowSizeConstraint' is true
    ImGuiSizeCallback       SizeCallback;
    void*                   SizeCallbackUserData;
    float                   BgAlphaVal;

    ImGuiNextWindowData()
    {
        PosCond = SizeCond = ContentSizeCond = CollapsedCond = SizeConstraintCond = FocusCond = BgAlphaCond = 0;
        PosVal = PosPivotVal = SizeVal = ImVec2(0.0f, 0.0f);
        ContentSizeVal = ImVec2(0.0f, 0.0f);
        CollapsedVal = false;
        SizeConstraintRect = ImRect();
        SizeCallback = NULL;
        SizeCallbackUserData = NULL;
        BgAlphaVal = FLT_MAX;
    }

    void    Clear()
    {
        PosCond = SizeCond = ContentSizeCond = CollapsedCond = SizeConstraintCond = FocusCond = BgAlphaCond = 0;
    }
};

// Main state for ImGui
struct ImGuiContext
{
    bool                    Initialized;
    ImGuiIO                 IO;
    ImGuiStyle              Style;
    ImFont*                 Font;                               // (Shortcut) == FontStack.empty() ? IO.Font : FontStack.back()
    float                   FontSize;                           // (Shortcut) == FontBaseSize * g.CurrentWindow->FontWindowScale == window->FontSize(). Text height for current window.
    float                   FontBaseSize;                       // (Shortcut) == IO.FontGlobalScale * Font->Scale * Font->FontSize. Base text height.
    ImDrawListSharedData    DrawListSharedData;

    float                   Time;
    int                     FrameCount;
    int                     FrameCountEnded;
    int                     FrameCountRendered;
    ImVector<ImGuiWindow*>  Windows;
    ImVector<ImGuiWindow*>  WindowsSortBuffer;
    ImVector<ImGuiWindow*>  CurrentWindowStack;
    ImGuiStorage            WindowsById;
    int                     WindowsActiveCount;
    ImGuiWindow*            CurrentWindow;                      // Being drawn into
    ImGuiWindow*            HoveredWindow;                      // Will catch mouse inputs
    ImGuiWindow*            HoveredRootWindow;                  // Will catch mouse inputs (for focus/move only)
    ImGuiID                 HoveredId;                          // Hovered widget
    bool                    HoveredIdAllowOverlap;
    ImGuiID                 HoveredIdPreviousFrame;
    float                   HoveredIdTimer;
    ImGuiID                 ActiveId;                           // Active widget
    ImGuiID                 ActiveIdPreviousFrame;
    float                   ActiveIdTimer;
    bool                    ActiveIdIsAlive;                    // Active widget has been seen this frame
    bool                    ActiveIdIsJustActivated;            // Set at the time of activation for one frame
    bool                    ActiveIdAllowOverlap;               // Active widget allows another widget to steal active id (generally for overlapping widgets, but not always)
    int                     ActiveIdAllowNavDirFlags;           // Active widget allows using directional navigation (e.g. can activate a button and move away from it)
    ImVec2                  ActiveIdClickOffset;                // Clicked offset from upper-left corner, if applicable (currently only set by ButtonBehavior)
    ImGuiWindow*            ActiveIdWindow;
    ImGuiInputSource        ActiveIdSource;                     // Activating with mouse or nav (gamepad/keyboard)
    ImGuiWindow*            MovingWindow;                       // Track the window we clicked on (in order to preserve focus). The actually window that is moved is generally MovingWindow->RootWindow.
    ImVector<ImGuiColMod>   ColorModifiers;                     // Stack for PushStyleColor()/PopStyleColor()
    ImVector<ImGuiStyleMod> StyleModifiers;                     // Stack for PushStyleVar()/PopStyleVar()
    ImVector<ImFont*>       FontStack;                          // Stack for PushFont()/PopFont()
    ImVector<ImGuiPopupRef> OpenPopupStack;                     // Which popups are open (persistent)
    ImVector<ImGuiPopupRef> CurrentPopupStack;                  // Which level of BeginPopup() we are in (reset every frame)
    ImGuiNextWindowData     NextWindowData;                     // Storage for SetNextWindow** functions
    bool                    NextTreeNodeOpenVal;                // Storage for SetNextTreeNode** functions
    ImGuiCond               NextTreeNodeOpenCond;

    // Navigation data (for gamepad/keyboard)
    ImGuiWindow*            NavWindow;                          // Focused window for navigation. Could be called 'FocusWindow'
    ImGuiID                 NavId;                              // Focused item for navigation
    ImGuiID                 NavActivateId;                      // ~~ (g.ActiveId == 0) && IsNavInputPressed(ImGuiNavInput_Activate) ? NavId : 0, also set when calling ActivateItem()
    ImGuiID                 NavActivateDownId;                  // ~~ IsNavInputDown(ImGuiNavInput_Activate) ? NavId : 0
    ImGuiID                 NavActivatePressedId;               // ~~ IsNavInputPressed(ImGuiNavInput_Activate) ? NavId : 0
    ImGuiID                 NavInputId;                         // ~~ IsNavInputPressed(ImGuiNavInput_Input) ? NavId : 0
    ImGuiID                 NavJustTabbedId;                    // Just tabbed to this id.
    ImGuiID                 NavNextActivateId;                  // Set by ActivateItem(), queued until next frame
    ImGuiID                 NavJustMovedToId;                   // Just navigated to this id (result of a successfully MoveRequest)
    ImRect                  NavScoringRectScreen;               // Rectangle used for scoring, in screen space. Based of window->DC.NavRefRectRel[], modified for directional navigation scoring.
    int                     NavScoringCount;                    // Metrics for debugging
    ImGuiWindow*            NavWindowingTarget;                 // When selecting a window (holding Menu+FocusPrev/Next, or equivalent of CTRL-TAB) this window is temporarily displayed front-most. 
    float                   NavWindowingHighlightTimer;
    float                   NavWindowingHighlightAlpha;
    bool                    NavWindowingToggleLayer;
    ImGuiInputSource        NavWindowingInputSource;            // Gamepad or keyboard mode
    int                     NavLayer;                           // Layer we are navigating on. For now the system is hard-coded for 0=main contents and 1=menu/title bar, may expose layers later.
    int                     NavIdTabCounter;                    // == NavWindow->DC.FocusIdxTabCounter at time of NavId processing
    bool                    NavIdIsAlive;                       // Nav widget has been seen this frame ~~ NavRefRectRel is valid
    bool                    NavMousePosDirty;                   // When set we will update mouse position if (NavFlags & ImGuiNavFlags_MoveMouse) if set (NB: this not enabled by default)
    bool                    NavDisableHighlight;                // When user starts using mouse, we hide gamepad/keyboard highlight (nb: but they are still available, which is why NavDisableHighlight isn't always != NavDisableMouseHover)
    bool                    NavDisableMouseHover;               // When user starts using gamepad/keyboard, we hide mouse hovering highlight until mouse is touched again.
    bool                    NavAnyRequest;                      // ~~ NavMoveRequest || NavInitRequest
    bool                    NavInitRequest;                     // Init request for appearing window to select first item
    bool                    NavInitRequestFromMove;
    ImGuiID                 NavInitResultId;
    ImRect                  NavInitResultRectRel;
    bool                    NavMoveFromClampedRefRect;          // Set by manual scrolling, if we scroll to a point where NavId isn't visible we reset navigation from visible items
    bool                    NavMoveRequest;                     // Move request for this frame
    ImGuiNavForward         NavMoveRequestForward;              // None / ForwardQueued / ForwardActive (this is used to navigate sibling parent menus from a child menu)
    ImGuiDir                NavMoveDir, NavMoveDirLast;         // Direction of the move request (left/right/up/down), direction of the previous move request
    ImGuiNavMoveResult      NavMoveResultLocal;                 // Best move request candidate within NavWindow
    ImGuiNavMoveResult      NavMoveResultOther;                 // Best move request candidate within NavWindow's flattened hierarchy (when using the NavFlattened flag)

    // Render
    ImDrawData              DrawData;                           // Main ImDrawData instance to pass render information to the user
    ImDrawDataBuilder       DrawDataBuilder;
    float                   ModalWindowDarkeningRatio;
    ImDrawList              OverlayDrawList;                    // Optional software render of mouse cursors, if io.MouseDrawCursor is set + a few debug overlays
    ImGuiMouseCursor        MouseCursor;

    // Drag and Drop
    bool                    DragDropActive;
    ImGuiDragDropFlags      DragDropSourceFlags;
    int                     DragDropMouseButton;
    ImGuiPayload            DragDropPayload;
    ImRect                  DragDropTargetRect;
    ImGuiID                 DragDropTargetId;
    float                   DragDropAcceptIdCurrRectSurface;
    ImGuiID                 DragDropAcceptIdCurr;               // Target item id (set at the time of accepting the payload)
    ImGuiID                 DragDropAcceptIdPrev;               // Target item id from previous frame (we need to store this to allow for overlapping drag and drop targets)
    int                     DragDropAcceptFrameCount;           // Last time a target expressed a desire to accept the source
    ImVector<unsigned char> DragDropPayloadBufHeap;             // We don't expose the ImVector<> directly
    unsigned char           DragDropPayloadBufLocal[8];

    // Widget state
    ImGuiTextEditState      InputTextState;
    ImFont                  InputTextPasswordFont;
    ImGuiID                 ScalarAsInputTextId;                // Temporary text input when CTRL+clicking on a slider, etc.
    ImGuiColorEditFlags     ColorEditOptions;                   // Store user options for color edit widgets
    ImVec4                  ColorPickerRef;
    float                   DragCurrentValue;                   // Currently dragged value, always float, not rounded by end-user precision settings
    ImVec2                  DragLastMouseDelta;
    float                   DragSpeedDefaultRatio;              // If speed == 0.0f, uses (max-min) * DragSpeedDefaultRatio
    float                   DragSpeedScaleSlow;
    float                   DragSpeedScaleFast;
    ImVec2                  ScrollbarClickDeltaToGrabCenter;    // Distance between mouse and center of grab box, normalized in parent space. Use storage?
    int                     TooltipOverrideCount;
    ImVector<char>          PrivateClipboard;                   // If no custom clipboard handler is defined
    ImVec2                  OsImePosRequest, OsImePosSet;       // Cursor position request & last passed to the OS Input Method Editor

    // Settings
    float                          SettingsDirtyTimer;          // Save .ini Settings on disk when time reaches zero
    ImVector<ImGuiWindowSettings>  SettingsWindows;             // .ini settings for ImGuiWindow
    ImVector<ImGuiSettingsHandler> SettingsHandlers;            // List of .ini settings handlers

    // Logging
    bool                    LogEnabled;
    FILE*                   LogFile;                            // If != NULL log to stdout/ file
    ImGuiTextBuffer*        LogClipboard;                       // Else log to clipboard. This is pointer so our GImGui static constructor doesn't call heap allocators.
    int                     LogStartDepth;
    int                     LogAutoExpandMaxDepth;

    // Misc
    float                   FramerateSecPerFrame[120];          // calculate estimate of framerate for user
    int                     FramerateSecPerFrameIdx;
    float                   FramerateSecPerFrameAccum;
    int                     WantCaptureMouseNextFrame;          // explicit capture via CaptureInputs() sets those flags
    int                     WantCaptureKeyboardNextFrame;
    int                     WantTextInputNextFrame;
    char                    TempBuffer[1024*3+1];               // temporary text buffer

    ImGuiContext() : OverlayDrawList(NULL)
    {
        Initialized = false;
        Font = NULL;
        FontSize = FontBaseSize = 0.0f;

        Time = 0.0f;
        FrameCount = 0;
        FrameCountEnded = FrameCountRendered = -1;
        WindowsActiveCount = 0;
        CurrentWindow = NULL;
        HoveredWindow = NULL;
        HoveredRootWindow = NULL;
        HoveredId = 0;
        HoveredIdAllowOverlap = false;
        HoveredIdPreviousFrame = 0;
        HoveredIdTimer = 0.0f;
        ActiveId = 0;
        ActiveIdPreviousFrame = 0;
        ActiveIdTimer = 0.0f;
        ActiveIdIsAlive = false;
        ActiveIdIsJustActivated = false;
        ActiveIdAllowOverlap = false;
        ActiveIdAllowNavDirFlags = 0;
        ActiveIdClickOffset = ImVec2(-1,-1);
        ActiveIdWindow = NULL;
        ActiveIdSource = ImGuiInputSource_None;
        MovingWindow = NULL;
        NextTreeNodeOpenVal = false;
        NextTreeNodeOpenCond = 0;

        NavWindow = NULL;
        NavId = NavActivateId = NavActivateDownId = NavActivatePressedId = NavInputId = 0;
        NavJustTabbedId = NavJustMovedToId = NavNextActivateId = 0;
        NavScoringRectScreen = ImRect();
        NavScoringCount = 0;
        NavWindowingTarget = NULL;
        NavWindowingHighlightTimer = NavWindowingHighlightAlpha = 0.0f;
        NavWindowingToggleLayer = false;
        NavWindowingInputSource = ImGuiInputSource_None;
        NavLayer = 0;
        NavIdTabCounter = INT_MAX;
        NavIdIsAlive = false;
        NavMousePosDirty = false;
        NavDisableHighlight = true;
        NavDisableMouseHover = false;
        NavAnyRequest = false;
        NavInitRequest = false;
        NavInitRequestFromMove = false;
        NavInitResultId = 0;
        NavMoveFromClampedRefRect = false;
        NavMoveRequest = false;
        NavMoveRequestForward = ImGuiNavForward_None;
        NavMoveDir = NavMoveDirLast = ImGuiDir_None;

        ModalWindowDarkeningRatio = 0.0f;
        OverlayDrawList._Data = &DrawListSharedData;
        OverlayDrawList._OwnerName = "##Overlay"; // Give it a name for debugging
        MouseCursor = ImGuiMouseCursor_Arrow;

        DragDropActive = false;
        DragDropSourceFlags = 0;
        DragDropMouseButton = -1;
        DragDropTargetId = 0;
        DragDropAcceptIdCurrRectSurface = 0.0f;
        DragDropAcceptIdPrev = DragDropAcceptIdCurr = 0;
        DragDropAcceptFrameCount = -1;
        memset(DragDropPayloadBufLocal, 0, sizeof(DragDropPayloadBufLocal));

        ScalarAsInputTextId = 0;
        ColorEditOptions = ImGuiColorEditFlags__OptionsDefault;
        DragCurrentValue = 0.0f;
        DragLastMouseDelta = ImVec2(0.0f, 0.0f);
        DragSpeedDefaultRatio = 1.0f / 100.0f;
        DragSpeedScaleSlow = 1.0f / 100.0f;
        DragSpeedScaleFast = 10.0f;
        ScrollbarClickDeltaToGrabCenter = ImVec2(0.0f, 0.0f);
        TooltipOverrideCount = 0;
        OsImePosRequest = OsImePosSet = ImVec2(-1.0f, -1.0f);

        SettingsDirtyTimer = 0.0f;

        LogEnabled = false;
        LogFile = NULL;
        LogClipboard = NULL;
        LogStartDepth = 0;
        LogAutoExpandMaxDepth = 2;

        memset(FramerateSecPerFrame, 0, sizeof(FramerateSecPerFrame));
        FramerateSecPerFrameIdx = 0;
        FramerateSecPerFrameAccum = 0.0f;
        WantCaptureMouseNextFrame = WantCaptureKeyboardNextFrame = WantTextInputNextFrame = -1;
        memset(TempBuffer, 0, sizeof(TempBuffer));
    }
};

// Transient per-window flags, reset at the beginning of the frame. For child window, inherited from parent on first Begin().
// This is going to be exposed in imgui.h when stabilized enough.
enum ImGuiItemFlags_
{
    ImGuiItemFlags_AllowKeyboardFocus           = 1 << 0,  // true
    ImGuiItemFlags_ButtonRepeat                 = 1 << 1,  // false    // Button() will return true multiple times based on io.KeyRepeatDelay and io.KeyRepeatRate settings.
    ImGuiItemFlags_Disabled                     = 1 << 2,  // false    // FIXME-WIP: Disable interactions but doesn't affect visuals. Should be: grey out and disable interactions with widgets that affect data + view widgets (WIP) 
    ImGuiItemFlags_NoNav                        = 1 << 3,  // false
    ImGuiItemFlags_NoNavDefaultFocus            = 1 << 4,  // false
    ImGuiItemFlags_SelectableDontClosePopup     = 1 << 5,  // false    // MenuItem/Selectable() automatically closes current Popup window
    ImGuiItemFlags_Default_                     = ImGuiItemFlags_AllowKeyboardFocus
};

// Transient per-window data, reset at the beginning of the frame
// FIXME: That's theory, in practice the delimitation between ImGuiWindow and ImGuiDrawContext is quite tenuous and could be reconsidered.
struct IMGUI_API ImGuiDrawContext
{
    ImVec2                  CursorPos;
    ImVec2                  CursorPosPrevLine;
    ImVec2                  CursorStartPos;
    ImVec2                  CursorMaxPos;           // Used to implicitly calculate the size of our contents, always growing during the frame. Turned into window->SizeContents at the beginning of next frame
    float                   CurrentLineHeight;
    float                   CurrentLineTextBaseOffset;
    float                   PrevLineHeight;
    float                   PrevLineTextBaseOffset;
    float                   LogLinePosY;
    int                     TreeDepth;
    ImU32                   TreeDepthMayCloseOnPop; // Store a copy of !g.NavIdIsAlive for TreeDepth 0..31
    ImGuiID                 LastItemId;
    ImGuiItemStatusFlags    LastItemStatusFlags;
    ImRect                  LastItemRect;           // Interaction rect
    ImRect                  LastItemDisplayRect;    // End-user display rect (only valid if LastItemStatusFlags & ImGuiItemStatusFlags_HasDisplayRect)
    bool                    NavHideHighlightOneFrame;
    bool                    NavHasScroll;           // Set when scrolling can be used (ScrollMax > 0.0f)
    int                     NavLayerCurrent;        // Current layer, 0..31 (we currently only use 0..1)
    int                     NavLayerCurrentMask;    // = (1 << NavLayerCurrent) used by ItemAdd prior to clipping.
    int                     NavLayerActiveMask;     // Which layer have been written to (result from previous frame)
    int                     NavLayerActiveMaskNext; // Which layer have been written to (buffer for current frame)
    bool                    MenuBarAppending;       // FIXME: Remove this
    float                   MenuBarOffsetX;
    ImVector<ImGuiWindow*>  ChildWindows;
    ImGuiStorage*           StateStorage;
    ImGuiLayoutType         LayoutType;
    ImGuiLayoutType         ParentLayoutType;       // Layout type of parent window at the time of Begin()

    // We store the current settings outside of the vectors to increase memory locality (reduce cache misses). The vectors are rarely modified. Also it allows us to not heap allocate for short-lived windows which are not using those settings.
    ImGuiItemFlags          ItemFlags;              // == ItemFlagsStack.back() [empty == ImGuiItemFlags_Default]
    float                   ItemWidth;              // == ItemWidthStack.back(). 0.0: default, >0.0: width in pixels, <0.0: align xx pixels to the right of window
    float                   TextWrapPos;            // == TextWrapPosStack.back() [empty == -1.0f]
    ImVector<ImGuiItemFlags>ItemFlagsStack;
    ImVector<float>         ItemWidthStack;
    ImVector<float>         TextWrapPosStack;
    ImVector<ImGuiGroupData>GroupStack;
    int                     StackSizesBackup[6];    // Store size of various stacks for asserting

    float                   IndentX;                // Indentation / start position from left of window (increased by TreePush/TreePop, etc.)
    float                   GroupOffsetX;
    float                   ColumnsOffsetX;         // Offset to the current column (if ColumnsCurrent > 0). FIXME: This and the above should be a stack to allow use cases like Tree->Column->Tree. Need revamp columns API.
    ImGuiColumnsSet*        ColumnsSet;             // Current columns set

    ImGuiDrawContext()
    {
        CursorPos = CursorPosPrevLine = CursorStartPos = CursorMaxPos = ImVec2(0.0f, 0.0f);
        CurrentLineHeight = PrevLineHeight = 0.0f;
        CurrentLineTextBaseOffset = PrevLineTextBaseOffset = 0.0f;
        LogLinePosY = -1.0f;
        TreeDepth = 0;
        TreeDepthMayCloseOnPop = 0x00;
        LastItemId = 0;
        LastItemStatusFlags = 0;
        LastItemRect = LastItemDisplayRect = ImRect();
        NavHideHighlightOneFrame = false;
        NavHasScroll = false;
        NavLayerActiveMask = NavLayerActiveMaskNext = 0x00;
        NavLayerCurrent = 0;
        NavLayerCurrentMask = 1 << 0;
        MenuBarAppending = false;
        MenuBarOffsetX = 0.0f;
        StateStorage = NULL;
        LayoutType = ParentLayoutType = ImGuiLayoutType_Vertical;
        ItemWidth = 0.0f;
        ItemFlags = ImGuiItemFlags_Default_;
        TextWrapPos = -1.0f;
        memset(StackSizesBackup, 0, sizeof(StackSizesBackup));

        IndentX = 0.0f;
        GroupOffsetX = 0.0f;
        ColumnsOffsetX = 0.0f;
        ColumnsSet = NULL;
    }
};

// Windows data
struct IMGUI_API ImGuiWindow
{
    char*                   Name;
    ImGuiID                 ID;                                 // == ImHash(Name)
    ImGuiWindowFlags        Flags;                              // See enum ImGuiWindowFlags_
    ImVec2                  PosFloat;
    ImVec2                  Pos;                                // Position rounded-up to nearest pixel
    ImVec2                  Size;                               // Current size (==SizeFull or collapsed title bar size)
    ImVec2                  SizeFull;                           // Size when non collapsed
    ImVec2                  SizeFullAtLastBegin;                // Copy of SizeFull at the end of Begin. This is the reference value we'll use on the next frame to decide if we need scrollbars.
    ImVec2                  SizeContents;                       // Size of contents (== extents reach of the drawing cursor) from previous frame. Include decoration, window title, border, menu, etc.
    ImVec2                  SizeContentsExplicit;               // Size of contents explicitly set by the user via SetNextWindowContentSize()
    ImRect                  ContentsRegionRect;                 // Maximum visible content position in window coordinates. ~~ (SizeContentsExplicit ? SizeContentsExplicit : Size - ScrollbarSizes) - CursorStartPos, per axis
    ImVec2                  WindowPadding;                      // Window padding at the time of begin.
    float                   WindowRounding;                     // Window rounding at the time of begin.
    float                   WindowBorderSize;                   // Window border size at the time of begin.
    ImGuiID                 MoveId;                             // == window->GetID("#MOVE")
    ImGuiID                 ChildId;                            // Id of corresponding item in parent window (for child windows)
    ImVec2                  Scroll;
    ImVec2                  ScrollTarget;                       // target scroll position. stored as cursor position with scrolling canceled out, so the highest point is always 0.0f. (FLT_MAX for no change)
    ImVec2                  ScrollTargetCenterRatio;            // 0.0f = scroll so that target position is at top, 0.5f = scroll so that target position is centered
    bool                    ScrollbarX, ScrollbarY;
    ImVec2                  ScrollbarSizes;
    bool                    Active;                             // Set to true on Begin(), unless Collapsed
    bool                    WasActive;
    bool                    WriteAccessed;                      // Set to true when any widget access the current window
    bool                    Collapsed;                          // Set when collapsing window to become only title-bar
    bool                    CollapseToggleWanted;
    bool                    SkipItems;                          // Set when items can safely be all clipped (e.g. window not visible or collapsed)
    bool                    Appearing;                          // Set during the frame where the window is appearing (or re-appearing)
    bool                    CloseButton;                        // Set when the window has a close button (p_open != NULL)
    int                     BeginOrderWithinParent;             // Order within immediate parent window, if we are a child window. Otherwise 0.
    int                     BeginOrderWithinContext;            // Order within entire imgui context. This is mostly used for debugging submission order related issues.
    int                     BeginCount;                         // Number of Begin() during the current frame (generally 0 or 1, 1+ if appending via multiple Begin/End pairs)
    ImGuiID                 PopupId;                            // ID in the popup stack when this window is used as a popup/menu (because we use generic Name/ID for recycling)
    int                     AutoFitFramesX, AutoFitFramesY;
    bool                    AutoFitOnlyGrows;
    int                     AutoFitChildAxises;
    ImGuiDir                AutoPosLastDirection;
    int                     HiddenFrames;
    ImGuiCond               SetWindowPosAllowFlags;             // store condition flags for next SetWindowPos() call.
    ImGuiCond               SetWindowSizeAllowFlags;            // store condition flags for next SetWindowSize() call.
    ImGuiCond               SetWindowCollapsedAllowFlags;       // store condition flags for next SetWindowCollapsed() call.
    ImVec2                  SetWindowPosVal;                    // store window position when using a non-zero Pivot (position set needs to be processed when we know the window size)
    ImVec2                  SetWindowPosPivot;                  // store window pivot for positioning. ImVec2(0,0) when positioning from top-left corner; ImVec2(0.5f,0.5f) for centering; ImVec2(1,1) for bottom right.

    ImGuiDrawContext        DC;                                 // Temporary per-window data, reset at the beginning of the frame
    ImVector<ImGuiID>       IDStack;                            // ID stack. ID are hashes seeded with the value at the top of the stack
    ImRect                  ClipRect;                           // = DrawList->clip_rect_stack.back(). Scissoring / clipping rectangle. x1, y1, x2, y2.
    ImRect                  WindowRectClipped;                  // = WindowRect just after setup in Begin(). == window->Rect() for root window.
    ImRect                  InnerRect;
    int                     LastFrameActive;
    float                   ItemWidthDefault;
    ImGuiMenuColumns        MenuColumns;                        // Simplified columns storage for menu items
    ImGuiStorage            StateStorage;
    ImVector<ImGuiColumnsSet> ColumnsStorage;
    float                   FontWindowScale;                    // Scale multiplier per-window
    ImDrawList*             DrawList;
    ImGuiWindow*            ParentWindow;                       // If we are a child _or_ popup window, this is pointing to our parent. Otherwise NULL.
    ImGuiWindow*            RootWindow;                         // Generally point to ourself. If we are a child window, this is pointing to the first non-child parent window.
    ImGuiWindow*            RootNonPopupWindow;                 // Generally point to ourself. Used to display TitleBgActive color and for selecting which window to use for NavWindowing

    ImGuiWindow*            NavRootWindow;                      // Generally point to ourself. If we are a child window with the NavFlattened flag, point to a parent window. 
    ImGuiWindow*            NavLastChildNavWindow;              // When going to the menu bar, we remember the child window we came from. (This could probably be made implicit if we kept g.Windows sorted by last focused including child window.)
    ImGuiID                 NavLastIds[2];                      // Last known NavId for this window, per layer (0/1)
    ImRect                  NavRectRel[2];                      // Reference rectangle, in window relative space

    // Navigation / Focus
    // FIXME-NAV: Merge all this with the new Nav system, at least the request variables should be moved to ImGuiContext
    int                     FocusIdxAllCounter;                 // Start at -1 and increase as assigned via FocusItemRegister()
    int                     FocusIdxTabCounter;                 // (same, but only count widgets which you can Tab through)
    int                     FocusIdxAllRequestCurrent;          // Item being requested for focus
    int                     FocusIdxTabRequestCurrent;          // Tab-able item being requested for focus
    int                     FocusIdxAllRequestNext;             // Item being requested for focus, for next update (relies on layout to be stable between the frame pressing TAB and the next frame)
    int                     FocusIdxTabRequestNext;             // "

public:
    ImGuiWindow(ImGuiContext* context, const char* name);
    ~ImGuiWindow();

    ImGuiID     GetID(const char* str, const char* str_end = NULL);
    ImGuiID     GetID(const void* ptr);
    ImGuiID     GetIDNoKeepAlive(const char* str, const char* str_end = NULL);
    ImGuiID     GetIDFromRectangle(const ImRect& r_abs);

    // We don't use g.FontSize because the window may be != g.CurrentWidow.
    ImRect      Rect() const                            { return ImRect(Pos.x, Pos.y, Pos.x+Size.x, Pos.y+Size.y); }
    float       CalcFontSize() const                    { return GImGui->FontBaseSize * FontWindowScale; }
    float       TitleBarHeight() const                  { return (Flags & ImGuiWindowFlags_NoTitleBar) ? 0.0f : CalcFontSize() + GImGui->Style.FramePadding.y * 2.0f; }
    ImRect      TitleBarRect() const                    { return ImRect(Pos, ImVec2(Pos.x + SizeFull.x, Pos.y + TitleBarHeight())); }
    float       MenuBarHeight() const                   { return (Flags & ImGuiWindowFlags_MenuBar) ? CalcFontSize() + GImGui->Style.FramePadding.y * 2.0f : 0.0f; }
    ImRect      MenuBarRect() const                     { float y1 = Pos.y + TitleBarHeight(); return ImRect(Pos.x, y1, Pos.x + SizeFull.x, y1 + MenuBarHeight()); }
};

// Backup and restore just enough data to be able to use IsItemHovered() on item A after another B in the same window has overwritten the data.  
struct ImGuiItemHoveredDataBackup
{
    ImGuiID                 LastItemId;
    ImGuiItemStatusFlags    LastItemStatusFlags;
    ImRect                  LastItemRect;
    ImRect                  LastItemDisplayRect;

    ImGuiItemHoveredDataBackup() { Backup(); }
    void Backup()        { ImGuiWindow* window = GImGui->CurrentWindow; LastItemId = window->DC.LastItemId; LastItemStatusFlags = window->DC.LastItemStatusFlags; LastItemRect = window->DC.LastItemRect; LastItemDisplayRect = window->DC.LastItemDisplayRect; }
    void Restore() const { ImGuiWindow* window = GImGui->CurrentWindow; window->DC.LastItemId = LastItemId; window->DC.LastItemStatusFlags = LastItemStatusFlags; window->DC.LastItemRect = LastItemRect; window->DC.LastItemDisplayRect = LastItemDisplayRect; }
};

//-----------------------------------------------------------------------------
// Internal API
// No guarantee of forward compatibility here.
//-----------------------------------------------------------------------------

namespace ImGui
{
    // We should always have a CurrentWindow in the stack (there is an implicit "Debug" window)
    // If this ever crash because g.CurrentWindow is NULL it means that either
    // - ImGui::NewFrame() has never been called, which is illegal.
    // - You are calling ImGui functions after ImGui::Render() and before the next ImGui::NewFrame(), which is also illegal.
    inline    ImGuiWindow*  GetCurrentWindowRead()      { ImGuiContext& g = *GImGui; return g.CurrentWindow; }
    inline    ImGuiWindow*  GetCurrentWindow()          { ImGuiContext& g = *GImGui; g.CurrentWindow->WriteAccessed = true; return g.CurrentWindow; }
    IMGUI_API ImGuiWindow*  FindWindowByName(const char* name);
    IMGUI_API void          FocusWindow(ImGuiWindow* window);
    IMGUI_API void          BringWindowToFront(ImGuiWindow* window);
    IMGUI_API void          BringWindowToBack(ImGuiWindow* window);
    IMGUI_API bool          IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent);
    IMGUI_API bool          IsWindowNavFocusable(ImGuiWindow* window);

    IMGUI_API void          Initialize();

    IMGUI_API void                  MarkIniSettingsDirty();
    IMGUI_API ImGuiSettingsHandler* FindSettingsHandler(const char* type_name);
    IMGUI_API ImGuiWindowSettings*  FindWindowSettings(ImGuiID id);

    IMGUI_API void          SetActiveID(ImGuiID id, ImGuiWindow* window);
    IMGUI_API ImGuiID       GetActiveID();
    IMGUI_API void          SetFocusID(ImGuiID id, ImGuiWindow* window);
    IMGUI_API void          ClearActiveID();
    IMGUI_API void          SetHoveredID(ImGuiID id);
    IMGUI_API ImGuiID       GetHoveredID();
    IMGUI_API void          KeepAliveID(ImGuiID id);

    IMGUI_API void          ItemSize(const ImVec2& size, float text_offset_y = 0.0f);
    IMGUI_API void          ItemSize(const ImRect& bb, float text_offset_y = 0.0f);
    IMGUI_API bool          ItemAdd(const ImRect& bb, ImGuiID id, const ImRect* nav_bb = NULL);
    IMGUI_API bool          ItemHoverable(const ImRect& bb, ImGuiID id);
    IMGUI_API bool          IsClippedEx(const ImRect& bb, ImGuiID id, bool clip_even_when_logged);
    IMGUI_API bool          FocusableItemRegister(ImGuiWindow* window, ImGuiID id, bool tab_stop = true);      // Return true if focus is requested
    IMGUI_API void          FocusableItemUnregister(ImGuiWindow* window);
    IMGUI_API ImVec2        CalcItemSize(ImVec2 size, float default_x, float default_y);
    IMGUI_API float         CalcWrapWidthForPos(const ImVec2& pos, float wrap_pos_x);
    IMGUI_API void          PushMultiItemsWidths(int components, float width_full = 0.0f);
    IMGUI_API void          PushItemFlag(ImGuiItemFlags option, bool enabled);
    IMGUI_API void          PopItemFlag();

    IMGUI_API void          SetCurrentFont(ImFont* font);

    IMGUI_API void          OpenPopupEx(ImGuiID id);
    IMGUI_API void          ClosePopup(ImGuiID id);
    IMGUI_API void          ClosePopupsOverWindow(ImGuiWindow* ref_window);
    IMGUI_API bool          IsPopupOpen(ImGuiID id);
    IMGUI_API bool          BeginPopupEx(ImGuiID id, ImGuiWindowFlags extra_flags);
    IMGUI_API void          BeginTooltipEx(ImGuiWindowFlags extra_flags, bool override_previous_tooltip = true);

    IMGUI_API void          NavInitWindow(ImGuiWindow* window, bool force_reinit);
    IMGUI_API void          ActivateItem(ImGuiID id);   // Remotely activate a button, checkbox, tree node etc. given its unique ID. activation is queued and processed on the next frame when the item is encountered again.

    IMGUI_API float         GetNavInputAmount(ImGuiNavInput n, ImGuiInputReadMode mode);
    IMGUI_API ImVec2        GetNavInputAmount2d(ImGuiNavDirSourceFlags dir_sources, ImGuiInputReadMode mode, float slow_factor = 0.0f, float fast_factor = 0.0f);
    IMGUI_API int           CalcTypematicPressedRepeatAmount(float t, float t_prev, float repeat_delay, float repeat_rate);

    IMGUI_API void          Scrollbar(ImGuiLayoutType direction);
    IMGUI_API void          VerticalSeparator();        // Vertical separator, for menu bars (use current line height). not exposed because it is misleading what it doesn't have an effect on regular layout.
    IMGUI_API bool          SplitterBehavior(ImGuiID id, const ImRect& bb, ImGuiAxis axis, float* size1, float* size2, float min_size1, float min_size2, float hover_extend = 0.0f);

    IMGUI_API bool          BeginDragDropTargetCustom(const ImRect& bb, ImGuiID id);
    IMGUI_API void          ClearDragDrop();
    IMGUI_API bool          IsDragDropPayloadBeingAccepted();

    // FIXME-WIP: New Columns API
    IMGUI_API void          BeginColumns(const char* str_id, int count, ImGuiColumnsFlags flags = 0); // setup number of columns. use an identifier to distinguish multiple column sets. close with EndColumns().
    IMGUI_API void          EndColumns();                                                             // close columns
    IMGUI_API void          PushColumnClipRect(int column_index = -1);

    // NB: All position are in absolute pixels coordinates (never using window coordinates internally)
    // AVOID USING OUTSIDE OF IMGUI.CPP! NOT FOR PUBLIC CONSUMPTION. THOSE FUNCTIONS ARE A MESS. THEIR SIGNATURE AND BEHAVIOR WILL CHANGE, THEY NEED TO BE REFACTORED INTO SOMETHING DECENT.
    IMGUI_API void          RenderText(ImVec2 pos, const char* text, const char* text_end = NULL, bool hide_text_after_hash = true);
    IMGUI_API void          RenderTextWrapped(ImVec2 pos, const char* text, const char* text_end, float wrap_width);
    IMGUI_API void          RenderTextClipped(const ImVec2& pos_min, const ImVec2& pos_max, const char* text, const char* text_end, const ImVec2* text_size_if_known, const ImVec2& align = ImVec2(0,0), const ImRect* clip_rect = NULL);
    IMGUI_API void          RenderFrame(ImVec2 p_min, ImVec2 p_max, ImU32 fill_col, bool border = true, float rounding = 0.0f);
    IMGUI_API void          RenderFrameBorder(ImVec2 p_min, ImVec2 p_max, float rounding = 0.0f);
    IMGUI_API void          RenderColorRectWithAlphaCheckerboard(ImVec2 p_min, ImVec2 p_max, ImU32 fill_col, float grid_step, ImVec2 grid_off, float rounding = 0.0f, int rounding_corners_flags = ~0);
    IMGUI_API void          RenderTriangle(ImVec2 pos, ImGuiDir dir, float scale = 1.0f);
    IMGUI_API void          RenderBullet(ImVec2 pos);
    IMGUI_API void          RenderCheckMark(ImVec2 pos, ImU32 col, float sz);
    IMGUI_API void          RenderNavHighlight(const ImRect& bb, ImGuiID id, ImGuiNavHighlightFlags flags = ImGuiNavHighlightFlags_TypeDefault); // Navigation highlight
    IMGUI_API void          RenderRectFilledRangeH(ImDrawList* draw_list, const ImRect& rect, ImU32 col, float x_start_norm, float x_end_norm, float rounding);
    IMGUI_API const char*   FindRenderedTextEnd(const char* text, const char* text_end = NULL); // Find the optional ## from which we stop displaying text.

    IMGUI_API bool          ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool* out_held, ImGuiButtonFlags flags = 0);
    IMGUI_API bool          ButtonEx(const char* label, const ImVec2& size_arg = ImVec2(0,0), ImGuiButtonFlags flags = 0);
    IMGUI_API bool          CloseButton(ImGuiID id, const ImVec2& pos, float radius);
    IMGUI_API bool          ArrowButton(ImGuiID id, ImGuiDir dir, ImVec2 padding, ImGuiButtonFlags flags = 0);

    IMGUI_API bool          SliderBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v_min, float v_max, float power, int decimal_precision, ImGuiSliderFlags flags = 0);
    IMGUI_API bool          SliderFloatN(const char* label, float* v, int components, float v_min, float v_max, const char* display_format, float power);
    IMGUI_API bool          SliderIntN(const char* label, int* v, int components, int v_min, int v_max, const char* display_format);

    IMGUI_API bool          DragBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v_speed, float v_min, float v_max, int decimal_precision, float power);
    IMGUI_API bool          DragFloatN(const char* label, float* v, int components, float v_speed, float v_min, float v_max, const char* display_format, float power);
    IMGUI_API bool          DragIntN(const char* label, int* v, int components, float v_speed, int v_min, int v_max, const char* display_format);

    IMGUI_API bool          InputTextEx(const char* label, char* buf, int buf_size, const ImVec2& size_arg, ImGuiInputTextFlags flags, ImGuiTextEditCallback callback = NULL, void* user_data = NULL);
    IMGUI_API bool          InputFloatN(const char* label, float* v, int components, int decimal_precision, ImGuiInputTextFlags extra_flags);
    IMGUI_API bool          InputIntN(const char* label, int* v, int components, ImGuiInputTextFlags extra_flags);
    IMGUI_API bool          InputScalarEx(const char* label, ImGuiDataType data_type, void* data_ptr, void* step_ptr, void* step_fast_ptr, const char* scalar_format, ImGuiInputTextFlags extra_flags);
    IMGUI_API bool          InputScalarAsWidgetReplacement(const ImRect& aabb, const char* label, ImGuiDataType data_type, void* data_ptr, ImGuiID id, int decimal_precision);

    IMGUI_API void          ColorTooltip(const char* text, const float* col, ImGuiColorEditFlags flags);
    IMGUI_API void          ColorEditOptionsPopup(const float* col, ImGuiColorEditFlags flags);

    IMGUI_API bool          TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* label, const char* label_end = NULL);
    IMGUI_API bool          TreeNodeBehaviorIsOpen(ImGuiID id, ImGuiTreeNodeFlags flags = 0);                     // Consume previous SetNextTreeNodeOpened() data, if any. May return true when logging
    IMGUI_API void          TreePushRawID(ImGuiID id);

    IMGUI_API void          PlotEx(ImGuiPlotType plot_type, const char* label, float (*values_getter)(void* data, int idx), void* data, int values_count, int values_offset, const char* overlay_text, float scale_min, float scale_max, ImVec2 graph_size);

    IMGUI_API int           ParseFormatPrecision(const char* fmt, int default_value);
    IMGUI_API float         RoundScalar(float value, int decimal_precision);

    // Shade functions
    IMGUI_API void          ShadeVertsLinearColorGradientKeepAlpha(ImDrawVert* vert_start, ImDrawVert* vert_end, ImVec2 gradient_p0, ImVec2 gradient_p1, ImU32 col0, ImU32 col1);
    IMGUI_API void          ShadeVertsLinearAlphaGradientForLeftToRightText(ImDrawVert* vert_start, ImDrawVert* vert_end, float gradient_p0_x, float gradient_p1_x);
    IMGUI_API void          ShadeVertsLinearUV(ImDrawVert* vert_start, ImDrawVert* vert_end, const ImVec2& a, const ImVec2& b, const ImVec2& uv_a, const ImVec2& uv_b, bool clamp);

} // namespace ImGui

// ImFontAtlas internals
IMGUI_API bool              ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas);
IMGUI_API void              ImFontAtlasBuildRegisterDefaultCustomRects(ImFontAtlas* atlas);
IMGUI_API void              ImFontAtlasBuildSetupFont(ImFontAtlas* atlas, ImFont* font, ImFontConfig* font_config, float ascent, float descent); 
IMGUI_API void              ImFontAtlasBuildPackCustomRects(ImFontAtlas* atlas, void* spc);
IMGUI_API void              ImFontAtlasBuildFinish(ImFontAtlas* atlas);
IMGUI_API void              ImFontAtlasBuildMultiplyCalcLookupTable(unsigned char out_table[256], float in_multiply_factor);
IMGUI_API void              ImFontAtlasBuildMultiplyRectAlpha8(const unsigned char table[256], unsigned char* pixels, int x, int y, int w, int h, int stride);

#ifdef __clang__
#pragma clang diagnostic pop
#endif

#ifdef _MSC_VER
#pragma warning (pop)
#endif