Internals: wrapped used of g.TempBuffer into ImFormatStringToTempBuffer/ImFormatStringToTempBufferV helpers.

This leaves us room for growing the buffer if needed, and gives us a resizable buffer available for other work.

imgui.cpp

@@ -1704,6 +1704,25 @@ int ImFormatStringV(char* buf, size_t buf_size, const char* fmt, va_list args)
 }
 #endif // #ifdef IMGUI_DISABLE_DEFAULT_FORMAT_FUNCTIONS
 
+void ImFormatStringToTempBuffer(const char** out_buf, const char** out_buf_end, const char* fmt, ...)
+{
+    ImGuiContext& g = *GImGui;
+    va_list args;
+    va_start(args, fmt);
+    int buf_len = ImFormatStringV(g.TempBuffer.Data, g.TempBuffer.Size, fmt, args);
+    *out_buf = g.TempBuffer.Data;
+    if (out_buf_end) { *out_buf_end = g.TempBuffer.Data + buf_len; }
+    va_end(args);
+}
+
+void ImFormatStringToTempBufferV(const char** out_buf, const char** out_buf_end, const char* fmt, va_list args)
+{
+    ImGuiContext& g = *GImGui;
+    int buf_len = ImFormatStringV(g.TempBuffer.Data, g.TempBuffer.Size, fmt, args);
+    *out_buf = g.TempBuffer.Data;
+    if (out_buf_end) { *out_buf_end = g.TempBuffer.Data + buf_len; }
+}
+
 // CRC32 needs a 1KB lookup table (not cache friendly)
 // Although the code to generate the table is simple and shorter than the table itself, using a const table allows us to easily:
 // - avoid an unnecessary branch/memory tap, - keep the ImHashXXX functions usable by static constructors, - make it thread-safe.
@@ -4482,6 +4501,7 @@ void ImGui::Initialize()
     // Create default viewport
     ImGuiViewportP* viewport = IM_NEW(ImGuiViewportP)();
     g.Viewports.push_back(viewport);
+    g.TempBuffer.resize(1024 * 3 + 1, 0);
 
 #ifdef IMGUI_HAS_DOCK
 #endif
@@ -5178,15 +5198,16 @@ bool ImGui::BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, b
     SetNextWindowSize(size);
 
     // Build up name. If you need to append to a same child from multiple location in the ID stack, use BeginChild(ImGuiID id) with a stable value.
+    const char* temp_window_name;
     if (name)
-        ImFormatString(g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer), "%s/%s_%08X", parent_window->Name, name, id);
+        ImFormatStringToTempBuffer(&temp_window_name, NULL, "%s/%s_%08X", parent_window->Name, name, id);
     else
-        ImFormatString(g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer), "%s/%08X", parent_window->Name, id);
+        ImFormatStringToTempBuffer(&temp_window_name, NULL, "%s/%08X", parent_window->Name, id);
 
     const float backup_border_size = g.Style.ChildBorderSize;
     if (!border)
         g.Style.ChildBorderSize = 0.0f;
-    bool ret = Begin(g.TempBuffer, NULL, flags);
+    bool ret = Begin(temp_window_name, NULL, flags);
     g.Style.ChildBorderSize = backup_border_size;
 
     ImGuiWindow* child_window = g.CurrentWindow;
@@ -13219,8 +13240,8 @@ void ImGui::ShowStackToolWindow(bool* p_open)
     if (tool->CopyToClipboardOnCtrlC && IsKeyDown(ImGuiKey_ModCtrl) && IsKeyPressed(ImGuiKey_C))
     {
         tool->CopyToClipboardLastTime = (float)g.Time;
-        char* p = g.TempBuffer;
+        char* p = g.TempBuffer.Data;
-        char* p_end = p + IM_ARRAYSIZE(g.TempBuffer);
+        char* p_end = p + g.TempBuffer.Size;
         for (int stack_n = 0; stack_n < tool->Results.Size && p + 3 < p_end; stack_n++)
         {
             *p++ = '/';
@@ -13234,7 +13255,7 @@ void ImGui::ShowStackToolWindow(bool* p_open)
             }
         }
         *p = '\0';
-        SetClipboardText(g.TempBuffer);
+        SetClipboardText(g.TempBuffer.Data);
     }
 
     // Display decorated stack
@@ -13252,8 +13273,8 @@ void ImGui::ShowStackToolWindow(bool* p_open)
             TableNextColumn();
             Text("0x%08X", (n > 0) ? tool->Results[n - 1].ID : 0);
             TableNextColumn();
-            StackToolFormatLevelInfo(tool, n, true, g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer));
+            StackToolFormatLevelInfo(tool, n, true, g.TempBuffer.Data, g.TempBuffer.Size);
-            TextUnformatted(g.TempBuffer);
+            TextUnformatted(g.TempBuffer.Data);
             TableNextColumn();
             Text("0x%08X", info->ID);
             if (n == tool->Results.Size - 1)

imgui_internal.h

@@ -331,6 +331,8 @@ static inline bool      ImCharIsBlankW(unsigned int c)  { return c == ' ' || c =
 // Helpers: Formatting
 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);
+IMGUI_API void          ImFormatStringToTempBuffer(const char** out_buf, const char** out_buf_end, const char* fmt, ...) IM_FMTARGS(3);
+IMGUI_API void          ImFormatStringToTempBufferV(const char** out_buf, const char** out_buf_end, const char* fmt, va_list args) IM_FMTLIST(3);
 IMGUI_API const char*   ImParseFormatFindStart(const char* format);
 IMGUI_API const char*   ImParseFormatFindEnd(const char* format);
 IMGUI_API const char*   ImParseFormatTrimDecorations(const char* format, char* buf, size_t buf_size);
@@ -1809,7 +1811,7 @@ struct ImGuiContext
     int                     WantCaptureMouseNextFrame;          // Explicit capture override via SetNextFrameWantCaptureMouse()/SetNextFrameWantCaptureKeyboard(). Default to -1.
     int                     WantCaptureKeyboardNextFrame;       // "
     int                     WantTextInputNextFrame;
-    char                    TempBuffer[1024 * 3 + 1];           // Temporary text buffer
+    ImVector<char>          TempBuffer;                         // Temporary text buffer
 
     ImGuiContext(ImFontAtlas* shared_font_atlas)
     {
@@ -1958,7 +1960,6 @@ struct ImGuiContext
         FramerateSecPerFrameIdx = FramerateSecPerFrameCount = 0;
         FramerateSecPerFrameAccum = 0.0f;
         WantCaptureMouseNextFrame = WantCaptureKeyboardNextFrame = WantTextInputNextFrame = -1;
-        memset(TempBuffer, 0, sizeof(TempBuffer));
     }
 };
 

imgui_widgets.cpp

@@ -276,9 +276,9 @@ void ImGui::TextV(const char* fmt, va_list args)
         return;
 
     // FIXME-OPT: Handle the %s shortcut?
-    ImGuiContext& g = *GImGui;
+    const char* text, *text_end;
-    const char* text_end = g.TempBuffer + ImFormatStringV(g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer), fmt, args);
+    ImFormatStringToTempBufferV(&text, &text_end, fmt, args);
-    TextEx(g.TempBuffer, text_end, ImGuiTextFlags_NoWidthForLargeClippedText);
+    TextEx(text, text_end, ImGuiTextFlags_NoWidthForLargeClippedText);
 }
 
 void ImGui::TextColored(const ImVec4& col, const char* fmt, ...)
@@ -359,8 +359,8 @@ void ImGui::LabelTextV(const char* label, const char* fmt, va_list args)
     const ImGuiStyle& style = g.Style;
     const float w = CalcItemWidth();
 
-    const char* value_text_begin = &g.TempBuffer[0];
+    const char* value_text_begin, *value_text_end;
-    const char* value_text_end = value_text_begin + ImFormatStringV(g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer), fmt, args);
+    ImFormatStringToTempBufferV(&value_text_begin, &value_text_end, fmt, args);
     const ImVec2 value_size = CalcTextSize(value_text_begin, value_text_end, false);
     const ImVec2 label_size = CalcTextSize(label, NULL, true);
 
@@ -395,8 +395,8 @@ void ImGui::BulletTextV(const char* fmt, va_list args)
     ImGuiContext& g = *GImGui;
     const ImGuiStyle& style = g.Style;
 
-    const char* text_begin = g.TempBuffer;
+    const char* text_begin, *text_end;
-    const char* text_end = text_begin + ImFormatStringV(g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer), fmt, args);
+    ImFormatStringToTempBufferV(&text_begin, &text_end, fmt, args);
     const ImVec2 label_size = CalcTextSize(text_begin, text_end, false);
     const ImVec2 total_size = ImVec2(g.FontSize + (label_size.x > 0.0f ? (label_size.x + style.FramePadding.x * 2) : 0.0f), label_size.y);  // Empty text doesn't add padding
     ImVec2 pos = window->DC.CursorPos;
@@ -1910,9 +1910,9 @@ static const char* PatchFormatStringFloatToInt(const char* fmt)
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
         if (fmt_start == fmt && fmt_end[0] == 0)
             return "%d";
-        ImGuiContext& g = *GImGui;
+        const char* tmp_format;
-        ImFormatString(g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer), "%.*s%%d%s", (int)(fmt_start - fmt), fmt, fmt_end); // Honor leading and trailing decorations, but lose alignment/precision.
+        ImFormatStringToTempBuffer(&tmp_format, NULL, "%.*s%%d%s", (int)(fmt_start - fmt), fmt, fmt_end); // Honor leading and trailing decorations, but lose alignment/precision.
-        return g.TempBuffer;
+        return tmp_format;
 #else
         IM_ASSERT(0 && "DragInt(): Invalid format string!"); // Old versions used a default parameter of "%.0f", please replace with e.g. "%d"
 #endif
@@ -5835,9 +5835,9 @@ bool ImGui::TreeNodeExV(const char* str_id, ImGuiTreeNodeFlags flags, const char
     if (window->SkipItems)
         return false;
 
-    ImGuiContext& g = *GImGui;
+    const char* label, *label_end;
-    const char* label_end = g.TempBuffer + ImFormatStringV(g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer), fmt, args);
+    ImFormatStringToTempBufferV(&label, &label_end, fmt, args);
-    return TreeNodeBehavior(window->GetID(str_id), flags, g.TempBuffer, label_end);
+    return TreeNodeBehavior(window->GetID(str_id), flags, label, label_end);
 }
 
 bool ImGui::TreeNodeExV(const void* ptr_id, ImGuiTreeNodeFlags flags, const char* fmt, va_list args)
@@ -5846,9 +5846,9 @@ bool ImGui::TreeNodeExV(const void* ptr_id, ImGuiTreeNodeFlags flags, const char
     if (window->SkipItems)
         return false;
 
-    ImGuiContext& g = *GImGui;
+    const char* label, *label_end;
-    const char* label_end = g.TempBuffer + ImFormatStringV(g.TempBuffer, IM_ARRAYSIZE(g.TempBuffer), fmt, args);
+    ImFormatStringToTempBufferV(&label, &label_end, fmt, args);
-    return TreeNodeBehavior(window->GetID(ptr_id), flags, g.TempBuffer, label_end);
+    return TreeNodeBehavior(window->GetID(ptr_id), flags, label, label_end);
 }
 
 bool ImGui::TreeNodeBehaviorIsOpen(ImGuiID id, ImGuiTreeNodeFlags flags)