Windows: Fixed altering FramePadding mid-frame not correctly affecting logic responsible for honoring io.ConfigWindowsMoveFromTitleBarOnly. (#7576, #899)

Latching TitleBarHeight, MenuBarHeight in window.

docs/CHANGELOG.txt

@@ -43,6 +43,9 @@ Breaking changes:
 
 Other changes:
 
+- Windows: fixed altering FramePadding mid-frame not correctly affecting logic
+  responsible for honoring io.ConfigWindowsMoveFromTitleBarOnly. (#7576, #899)
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.7 (Released 2024-05-27)

imgui.cpp

@@ -5777,7 +5777,7 @@ static inline ImVec2 CalcWindowMinSize(ImGuiWindow* window)
 
     // Reduce artifacts with very small windows
     ImGuiWindow* window_for_height = window;
-    size_min.y = ImMax(size_min.y, window_for_height->TitleBarHeight() + window_for_height->MenuBarHeight() + ImMax(0.0f, g.Style.WindowRounding - 1.0f));
+    size_min.y = ImMax(size_min.y, window_for_height->TitleBarHeight + window_for_height->MenuBarHeight + ImMax(0.0f, g.Style.WindowRounding - 1.0f));
     return size_min;
 }
 
@@ -5988,7 +5988,7 @@ static int ImGui::UpdateWindowManualResize(ImGuiWindow* window, const ImVec2& si
     ImRect clamp_rect = visibility_rect;
     const bool window_move_from_title_bar = g.IO.ConfigWindowsMoveFromTitleBarOnly && !(window->Flags & ImGuiWindowFlags_NoTitleBar);
     if (window_move_from_title_bar)
-        clamp_rect.Min.y -= window->TitleBarHeight();
+        clamp_rect.Min.y -= window->TitleBarHeight;
 
     ImVec2 pos_target(FLT_MAX, FLT_MAX);
     ImVec2 size_target(FLT_MAX, FLT_MAX);
@@ -6187,7 +6187,7 @@ static inline void ClampWindowPos(ImGuiWindow* window, const ImRect& visibility_
     ImGuiContext& g = *GImGui;
     ImVec2 size_for_clamping = window->Size;
     if (g.IO.ConfigWindowsMoveFromTitleBarOnly && !(window->Flags & ImGuiWindowFlags_NoTitleBar))
-        size_for_clamping.y = window->TitleBarHeight();
+        size_for_clamping.y = window->TitleBarHeight;
     window->Pos = ImClamp(window->Pos, visibility_rect.Min - size_for_clamping, visibility_rect.Max);
 }
 
@@ -6223,7 +6223,7 @@ static void ImGui::RenderWindowOuterBorders(ImGuiWindow* window)
     }
     if (g.Style.FrameBorderSize > 0 && !(window->Flags & ImGuiWindowFlags_NoTitleBar))
     {
-        float y = window->Pos.y + window->TitleBarHeight() - 1;
+        float y = window->Pos.y + window->TitleBarHeight - 1;
         window->DrawList->AddLine(ImVec2(window->Pos.x + border_size, y), ImVec2(window->Pos.x + window->Size.x - border_size, y), border_col, g.Style.FrameBorderSize);
     }
 }
@@ -6268,7 +6268,7 @@ void ImGui::RenderWindowDecorations(ImGuiWindow* window, const ImRect& title_bar
             }
             if (override_alpha)
                 bg_col = (bg_col & ~IM_COL32_A_MASK) | (IM_F32_TO_INT8_SAT(alpha) << IM_COL32_A_SHIFT);
-            window->DrawList->AddRectFilled(window->Pos + ImVec2(0, window->TitleBarHeight()), window->Pos + window->Size, bg_col, window_rounding, (flags & ImGuiWindowFlags_NoTitleBar) ? 0 : ImDrawFlags_RoundCornersBottom);
+            window->DrawList->AddRectFilled(window->Pos + ImVec2(0, window->TitleBarHeight), window->Pos + window->Size, bg_col, window_rounding, (flags & ImGuiWindowFlags_NoTitleBar) ? 0 : ImDrawFlags_RoundCornersBottom);
         }
 
         // Title bar
@@ -6730,6 +6730,8 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         // Lock menu offset so size calculation can use it as menu-bar windows need a minimum size.
         window->DC.MenuBarOffset.x = ImMax(ImMax(window->WindowPadding.x, style.ItemSpacing.x), g.NextWindowData.MenuBarOffsetMinVal.x);
         window->DC.MenuBarOffset.y = g.NextWindowData.MenuBarOffsetMinVal.y;
+        window->TitleBarHeight = (flags & ImGuiWindowFlags_NoTitleBar) ? 0.0f : g.FontSize + g.Style.FramePadding.y * 2.0f;
+        window->MenuBarHeight = (flags & ImGuiWindowFlags_MenuBar) ? window->DC.MenuBarOffset.y + g.FontSize + g.Style.FramePadding.y * 2.0f : 0.0f;
 
         // Depending on condition we use previous or current window size to compare against contents size to decide if a scrollbar should be visible.
         // Those flags will be altered further down in the function depending on more conditions.
@@ -6770,7 +6772,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         const ImVec2 scrollbar_sizes_from_last_frame = window->ScrollbarSizes;
         window->DecoOuterSizeX1 = 0.0f;
         window->DecoOuterSizeX2 = 0.0f;
-        window->DecoOuterSizeY1 = window->TitleBarHeight() + window->MenuBarHeight();
+        window->DecoOuterSizeY1 = window->TitleBarHeight + window->MenuBarHeight;
         window->DecoOuterSizeY2 = 0.0f;
         window->ScrollbarSizes = ImVec2(0.0f, 0.0f);
 

imgui_internal.h

@@ -2507,6 +2507,7 @@ struct IMGUI_API ImGuiWindow
     ImVec2                  WindowPadding;                      // Window padding at the time of Begin().
     float                   WindowRounding;                     // Window rounding at the time of Begin(). May be clamped lower to avoid rendering artifacts with title bar, menu bar etc.
     float                   WindowBorderSize;                   // Window border size at the time of Begin().
+    float                   TitleBarHeight, MenuBarHeight;
     float                   DecoOuterSizeX1, DecoOuterSizeY1;   // Left/Up offsets. Sum of non-scrolling outer decorations (X1 generally == 0.0f. Y1 generally = TitleBarHeight + MenuBarHeight). Locked during Begin().
     float                   DecoOuterSizeX2, DecoOuterSizeY2;   // Right/Down offsets (X2 generally == ScrollbarSize.x, Y2 == ScrollbarSizes.y).
     float                   DecoInnerSizeX1, DecoInnerSizeY1;   // Applied AFTER/OVER InnerRect. Specialized for Tables as they use specialized form of clipping and frozen rows/columns are inside InnerRect (and not part of regular decoration sizes).
@@ -2608,10 +2609,8 @@ public:
     // We don't use g.FontSize because the window may be != g.CurrentWindow.
     ImRect      Rect() const            { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
     float       CalcFontSize() const    { ImGuiContext& g = *Ctx; float scale = g.FontBaseSize * FontWindowScale; if (ParentWindow) scale *= ParentWindow->FontWindowScale; return scale; }
-    float       TitleBarHeight() const  { ImGuiContext& g = *Ctx; return (Flags & ImGuiWindowFlags_NoTitleBar) ? 0.0f : CalcFontSize() + g.Style.FramePadding.y * 2.0f; }
-    ImRect      TitleBarRect() const    { return ImRect(Pos, ImVec2(Pos.x + SizeFull.x, Pos.y + TitleBarHeight())); }
-    float       MenuBarHeight() const   { ImGuiContext& g = *Ctx; return (Flags & ImGuiWindowFlags_MenuBar) ? DC.MenuBarOffset.y + CalcFontSize() + g.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()); }
+    ImRect      TitleBarRect() const    { return ImRect(Pos, ImVec2(Pos.x + SizeFull.x, Pos.y + TitleBarHeight)); }
+    ImRect      MenuBarRect() const     { float y1 = Pos.y + TitleBarHeight; return ImRect(Pos.x, y1, Pos.x + SizeFull.x, y1 + MenuBarHeight); }
 };
 
 //-----------------------------------------------------------------------------

imgui_widgets.cpp

@@ -7519,7 +7519,7 @@ bool ImGui::BeginMenuEx(const char* label, const char* icon, bool enabled)
         // Menu inside an horizontal menu bar
         // Selectable extend their highlight by half ItemSpacing in each direction.
         // For ChildMenu, the popup position will be overwritten by the call to FindBestWindowPosForPopup() in Begin()
-        popup_pos = ImVec2(pos.x - 1.0f - IM_TRUNC(style.ItemSpacing.x * 0.5f), pos.y - style.FramePadding.y + window->MenuBarHeight());
+        popup_pos = ImVec2(pos.x - 1.0f - IM_TRUNC(style.ItemSpacing.x * 0.5f), pos.y - style.FramePadding.y + window->MenuBarHeight);
         window->DC.CursorPos.x += IM_TRUNC(style.ItemSpacing.x * 0.5f);
         PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(style.ItemSpacing.x * 2.0f, style.ItemSpacing.y));
         float w = label_size.x;