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Internals: Scroll related, comments & shallow tweaks.

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This commit is contained in:
ocornut 2020-09-03 16:11:01 +02:00
parent b73305be11
commit 8db94cd992
2 changed files with 36 additions and 30 deletions
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58
imgui.cpp
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@ -7368,16 +7368,16 @@ static ImVec2 CalcNextScrollFromScrollTargetAndClamp(ImGuiWindow* window)
ImVec2 scroll = window->Scroll; ImVec2 scroll = window->Scroll;
if (window->ScrollTarget.x < FLT_MAX) if (window->ScrollTarget.x < FLT_MAX)
{ {
float cr_x = window->ScrollTargetCenterRatio.x; float center_x_ratio = window->ScrollTargetCenterRatio.x;
float target_x = window->ScrollTarget.x; float scroll_target_x = window->ScrollTarget.x;
scroll.x = target_x - cr_x * (window->SizeFull.x - window->ScrollbarSizes.x); scroll.x = scroll_target_x - center_x_ratio * (window->SizeFull.x - window->ScrollbarSizes.x);
} }
if (window->ScrollTarget.y < FLT_MAX) if (window->ScrollTarget.y < FLT_MAX)
{ {
float decoration_up_height = window->TitleBarHeight() + window->MenuBarHeight(); float decoration_up_height = window->TitleBarHeight() + window->MenuBarHeight();
float cr_y = window->ScrollTargetCenterRatio.y; float center_y_ratio = window->ScrollTargetCenterRatio.y;
float target_y = window->ScrollTarget.y; float scroll_target_y = window->ScrollTarget.y;
scroll.y = target_y - cr_y * (window->SizeFull.y - window->ScrollbarSizes.y - decoration_up_height); scroll.y = scroll_target_y - center_y_ratio * (window->SizeFull.y - window->ScrollbarSizes.y - decoration_up_height);
} }
scroll.x = IM_FLOOR(ImMax(scroll.x, 0.0f)); scroll.x = IM_FLOOR(ImMax(scroll.x, 0.0f));
scroll.y = IM_FLOOR(ImMax(scroll.y, 0.0f)); scroll.y = IM_FLOOR(ImMax(scroll.y, 0.0f));
@ -7443,38 +7443,44 @@ float ImGui::GetScrollMaxY()
return window->ScrollMax.y; return window->ScrollMax.y;
} }
void ImGui::SetScrollX(float scroll_x) void ImGui::SetScrollX(ImGuiWindow* window, float scroll_x)
{ {
ImGuiWindow* window = GetCurrentWindow();
window->ScrollTarget.x = scroll_x; window->ScrollTarget.x = scroll_x;
window->ScrollTargetCenterRatio.x = 0.0f; window->ScrollTargetCenterRatio.x = 0.0f;
} }
void ImGui::SetScrollY(float scroll_y) void ImGui::SetScrollY(ImGuiWindow* window, float scroll_y)
{ {
ImGuiWindow* window = GetCurrentWindow();
window->ScrollTarget.y = scroll_y; window->ScrollTarget.y = scroll_y;
window->ScrollTargetCenterRatio.y = 0.0f; window->ScrollTargetCenterRatio.y = 0.0f;
} }
void ImGui::SetScrollX(ImGuiWindow* window, float new_scroll_x) void ImGui::SetScrollX(float scroll_x)
{ {
window->ScrollTarget.x = new_scroll_x; ImGuiContext& g = *GImGui;
window->ScrollTargetCenterRatio.x = 0.0f; SetScrollX(g.CurrentWindow, scroll_x);
} }
void ImGui::SetScrollY(ImGuiWindow* window, float new_scroll_y) void ImGui::SetScrollY(float scroll_y)
{ {
window->ScrollTarget.y = new_scroll_y; ImGuiContext& g = *GImGui;
window->ScrollTargetCenterRatio.y = 0.0f; SetScrollY(g.CurrentWindow, scroll_y);
} }
// Note that a local position will vary depending on initial scroll value // Note that a local position will vary depending on initial scroll value,
// We store a target position so centering can occur on the next frame when we are guaranteed to have a known window size // This is a little bit confusing so bear with us:
// - local_pos = (absolution_pos - window->Pos)
// - So local_x/local_y are 0.0f for a position at the upper-left corner of a window,
// and generally local_x/local_y are >(padding+decoration) && <(size-padding-decoration) when in the visible area.
// - They mostly exists because of legacy API.
// Following the rules above, when trying to work with scrolling code, consider that:
// - SetScrollFromPosY(0.0f) == SetScrollY(0.0f + scroll.y) == has no effect!
// - SetScrollFromPosY(-scroll.y) == SetScrollY(-scroll.y + scroll.y) == SetScrollY(0.0f) == reset scroll. Of course writing SetScrollY(0.0f) directly then makes more sense
// We store a target position so centering and clamping can occur on the next frame when we are guaranteed to have a known window size
void ImGui::SetScrollFromPosX(ImGuiWindow* window, float local_x, float center_x_ratio) void ImGui::SetScrollFromPosX(ImGuiWindow* window, float local_x, float center_x_ratio)
{ {
IM_ASSERT(center_x_ratio >= 0.0f && center_x_ratio <= 1.0f); IM_ASSERT(center_x_ratio >= 0.0f && center_x_ratio <= 1.0f);
window->ScrollTarget.x = IM_FLOOR(local_x + window->Scroll.x); window->ScrollTarget.x = IM_FLOOR(local_x + window->Scroll.x); // Convert local position to scroll offset
window->ScrollTargetCenterRatio.x = center_x_ratio; window->ScrollTargetCenterRatio.x = center_x_ratio;
} }
@ -7482,7 +7488,7 @@ void ImGui::SetScrollFromPosY(ImGuiWindow* window, float local_y, float center_y
{ {
IM_ASSERT(center_y_ratio >= 0.0f && center_y_ratio <= 1.0f); IM_ASSERT(center_y_ratio >= 0.0f && center_y_ratio <= 1.0f);
local_y -= window->TitleBarHeight() + window->MenuBarHeight(); // FIXME: Would be nice to have a more standardized access to our scrollable/client rect local_y -= window->TitleBarHeight() + window->MenuBarHeight(); // FIXME: Would be nice to have a more standardized access to our scrollable/client rect
window->ScrollTarget.y = IM_FLOOR(local_y + window->Scroll.y); window->ScrollTarget.y = IM_FLOOR(local_y + window->Scroll.y); // Convert local position to scroll offset
window->ScrollTargetCenterRatio.y = center_y_ratio; window->ScrollTargetCenterRatio.y = center_y_ratio;
} }
@ -7517,15 +7523,15 @@ void ImGui::SetScrollHereX(float center_x_ratio)
ImGuiContext& g = *GImGui; ImGuiContext& g = *GImGui;
ImGuiWindow* window = g.CurrentWindow; ImGuiWindow* window = g.CurrentWindow;
float spacing_x = g.Style.ItemSpacing.x; float spacing_x = g.Style.ItemSpacing.x;
float target_x = ImLerp(window->DC.LastItemRect.Min.x - spacing_x, window->DC.LastItemRect.Max.x + spacing_x, center_x_ratio); float target_pos_x = ImLerp(window->DC.LastItemRect.Min.x - spacing_x, window->DC.LastItemRect.Max.x + spacing_x, center_x_ratio);
// Tweak: snap on edges when aiming at an item very close to the edge // Tweak: snap on edges when aiming at an item very close to the edge
const float snap_x_threshold = ImMax(0.0f, window->WindowPadding.x - spacing_x); const float snap_x_threshold = ImMax(0.0f, window->WindowPadding.x - spacing_x);
const float snap_x_min = window->DC.CursorStartPos.x - window->WindowPadding.x; const float snap_x_min = window->DC.CursorStartPos.x - window->WindowPadding.x;
const float snap_x_max = window->DC.CursorStartPos.x + window->ContentSize.x + window->WindowPadding.x; const float snap_x_max = window->DC.CursorStartPos.x + window->ContentSize.x + window->WindowPadding.x;
target_x = CalcScrollSnap(target_x, snap_x_min, snap_x_max, snap_x_threshold, center_x_ratio); target_pos_x = CalcScrollSnap(target_pos_x, snap_x_min, snap_x_max, snap_x_threshold, center_x_ratio);
SetScrollFromPosX(window, target_x - window->Pos.x, center_x_ratio); SetScrollFromPosX(window, target_pos_x - window->Pos.x, center_x_ratio); // Convert from absolute to local pos
} }
// center_y_ratio: 0.0f top of last item, 0.5f vertical center of last item, 1.0f bottom of last item. // center_y_ratio: 0.0f top of last item, 0.5f vertical center of last item, 1.0f bottom of last item.
@ -7534,15 +7540,15 @@ void ImGui::SetScrollHereY(float center_y_ratio)
ImGuiContext& g = *GImGui; ImGuiContext& g = *GImGui;
ImGuiWindow* window = g.CurrentWindow; ImGuiWindow* window = g.CurrentWindow;
float spacing_y = g.Style.ItemSpacing.y; float spacing_y = g.Style.ItemSpacing.y;
float target_y = ImLerp(window->DC.CursorPosPrevLine.y - spacing_y, window->DC.CursorPosPrevLine.y + window->DC.PrevLineSize.y + spacing_y, center_y_ratio); float target_pos_y = ImLerp(window->DC.CursorPosPrevLine.y - spacing_y, window->DC.CursorPosPrevLine.y + window->DC.PrevLineSize.y + spacing_y, center_y_ratio);
// Tweak: snap on edges when aiming at an item very close to the edge // Tweak: snap on edges when aiming at an item very close to the edge
const float snap_y_threshold = ImMax(0.0f, window->WindowPadding.y - spacing_y); const float snap_y_threshold = ImMax(0.0f, window->WindowPadding.y - spacing_y);
const float snap_y_min = window->DC.CursorStartPos.y - window->WindowPadding.y; const float snap_y_min = window->DC.CursorStartPos.y - window->WindowPadding.y;
const float snap_y_max = window->DC.CursorStartPos.y + window->ContentSize.y + window->WindowPadding.y; const float snap_y_max = window->DC.CursorStartPos.y + window->ContentSize.y + window->WindowPadding.y;
target_y = CalcScrollSnap(target_y, snap_y_min, snap_y_max, snap_y_threshold, center_y_ratio); target_pos_y = CalcScrollSnap(target_pos_y, snap_y_min, snap_y_max, snap_y_threshold, center_y_ratio);
SetScrollFromPosY(window, target_y - window->Pos.y, center_y_ratio); SetScrollFromPosY(window, target_pos_y - window->Pos.y, center_y_ratio); // Convert from absolute to local pos
} }
//----------------------------------------------------------------------------- //-----------------------------------------------------------------------------

8
imgui_internal.h
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@ -1826,10 +1826,10 @@ namespace ImGui
// Scrolling // Scrolling
IMGUI_API void SetNextWindowScroll(const ImVec2& scroll); // Use -1.0f on one axis to leave as-is IMGUI_API void SetNextWindowScroll(const ImVec2& scroll); // Use -1.0f on one axis to leave as-is
IMGUI_API void SetScrollX(ImGuiWindow* window, float new_scroll_x); IMGUI_API void SetScrollX(ImGuiWindow* window, float scroll_x);
IMGUI_API void SetScrollY(ImGuiWindow* window, float new_scroll_y); IMGUI_API void SetScrollY(ImGuiWindow* window, float scroll_y);
IMGUI_API void SetScrollFromPosX(ImGuiWindow* window, float local_x, float center_x_ratio = 0.5f); IMGUI_API void SetScrollFromPosX(ImGuiWindow* window, float local_x, float center_x_ratio);
IMGUI_API void SetScrollFromPosY(ImGuiWindow* window, float local_y, float center_y_ratio = 0.5f); IMGUI_API void SetScrollFromPosY(ImGuiWindow* window, float local_y, float center_y_ratio);
IMGUI_API ImVec2 ScrollToBringRectIntoView(ImGuiWindow* window, const ImRect& item_rect); IMGUI_API ImVec2 ScrollToBringRectIntoView(ImGuiWindow* window, const ImRect& item_rect);
// Basic Accessors // Basic Accessors