Fonts: fixed an issue where using PushFont() from the implicit/fallback "Debug" window when its recorded state is collapsed would incorrectly early out. (#9210, #8865)

Amend 0e769c5, ca31693, d8da97f, 1bf41a0.

docs/CHANGELOG.txt

@@ -78,6 +78,9 @@ Breaking Changes:
     has already been rendered. (#9162) [@ocornut, @cyfewlp]
   - Removed ImFontConfig::PixelSnapV added in 1.92 which turns out is unnecessary
     (and misdocumented). Post-rescale GlyphOffset is always rounded.
+  - Fixed an issue where using PushFont() from the implicit/fallback "Debug" window when
+    its recorded state is collapsed would incorrectly early out. This would break e.g. using
+    direct draw-list calls such as GetForegroundDrawList() with current font. (#9210, #8865)
  - Popups: changed compile-time 'ImGuiPopupFlags popup_flags = 1' default value to be '= 0' for
    BeginPopupContextItem(), BeginPopupContextWindow(), BeginPopupContextVoid(), OpenPopupOnItemClick().
    The default value has same meaning before and after. (#9157, #9146)

imgui.cpp

@@ -4566,13 +4566,13 @@ static void SetCurrentWindow(ImGuiWindow* window)
     g.CurrentDpiScale = 1.0f; // FIXME-DPI: WIP this is modified in docking
     if (window)
     {
-        bool backup_skip_items = window->SkipItems;
-        window->SkipItems = false;
         if (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasTextures)
         {
             ImGuiViewport* viewport = window->Viewport;
             g.FontRasterizerDensity = (viewport->FramebufferScale.x != 0.0f) ? viewport->FramebufferScale.x : g.IO.DisplayFramebufferScale.x; // == SetFontRasterizerDensity()
         }
+        const bool backup_skip_items = window->SkipItems;
+        window->SkipItems = false;
         ImGui::UpdateCurrentFontSize(0.0f);
         window->SkipItems = backup_skip_items;
         ImGui::NavUpdateCurrentWindowIsScrollPushableX();
@@ -9000,16 +9000,6 @@ void ImGui::UpdateCurrentFontSize(float restore_font_size_after_scaling)
 
     g.Style.FontSizeBase = g.FontSizeBase;
 
-    // Early out to avoid hidden window keeping bakes referenced and out of GC reach.
-    // However this would leave a pretty subtle and damning error surface area if g.FontBaked was mismatching.
-    // FIXME: perhaps g.FontSize should be updated?
-    if (window != NULL && window->SkipItems)
-    {
-        ImGuiTable* table = g.CurrentTable;
-        if (table == NULL || (table->CurrentColumn != -1 && table->Columns[table->CurrentColumn].IsSkipItems == false)) // See 8465#issuecomment-2951509561 and #8865. Ideally the SkipItems=true in tables would be amended with extra data.
-            return;
-    }
-
     // Restoring is pretty much only used by PopFont()
     float final_size = (restore_font_size_after_scaling > 0.0f) ? restore_font_size_after_scaling : 0.0f;
     if (final_size == 0.0f)
@@ -9039,10 +9029,24 @@ void ImGui::UpdateCurrentFontSize(float restore_font_size_after_scaling)
     final_size = ImClamp(final_size, 1.0f, IMGUI_FONT_SIZE_MAX);
     if (g.Font != NULL && (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasTextures))
         g.Font->CurrentRasterizerDensity = g.FontRasterizerDensity;
+
     g.FontSize = final_size;
+    g.DrawListSharedData.FontSize = g.FontSize;
+
+    // Early out to avoid hidden window keeping bakes referenced and out of GC reach.
+    // - However this leave a pretty subtle and damning error surface area if g.FontBaked was mismatching.
+    //   Probably needs to be reevaluated into e.g. setting g.FontBaked = nullptr to mark it as dirty.
+    // - Note that 'PushFont(); Begin(); End(); PopFont()' from within any collapsed window is not compromised, because Begin() calls SetCurrentWindow()->...->UpdateCurrentSize()
+    if (window != NULL && window->SkipItems)
+    {
+        ImGuiTable* table = g.CurrentTable;
+        const bool allow_early_out = table == NULL || (table->CurrentColumn != -1 && table->Columns[table->CurrentColumn].IsSkipItems == false); // See 8465#issuecomment-2951509561 and #8865. Ideally the SkipItems=true in tables would be amended with extra data.
+        if (allow_early_out)
+            return;
+    }
+
     g.FontBaked = (g.Font != NULL && window != NULL) ? g.Font->GetFontBaked(final_size) : NULL;
     g.FontBakedScale = (g.Font != NULL && window != NULL) ? (g.FontSize / g.FontBaked->Size) : 0.0f;
-    g.DrawListSharedData.FontSize = g.FontSize;
     g.DrawListSharedData.FontScale = g.FontBakedScale;
 }