Begin: Shuffled some code, _should_ have no side-effect. Clear NextWindowData in one call and more consistently. (merged from viewport branch to minimize branch drift).

imgui.cpp

@@ -5742,14 +5742,12 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         {
             SetWindowPos(window, g.NextWindowData.PosVal, g.NextWindowData.PosCond);
         }
-        g.NextWindowData.PosCond = 0;
     }
     if (g.NextWindowData.SizeCond)
     {
         window_size_x_set_by_api = (window->SetWindowSizeAllowFlags & g.NextWindowData.SizeCond) != 0 && (g.NextWindowData.SizeVal.x > 0.0f);
         window_size_y_set_by_api = (window->SetWindowSizeAllowFlags & g.NextWindowData.SizeCond) != 0 && (g.NextWindowData.SizeVal.y > 0.0f);
         SetWindowSize(window, g.NextWindowData.SizeVal, g.NextWindowData.SizeCond);
-        g.NextWindowData.SizeCond = 0;
     }
     if (g.NextWindowData.ContentSizeCond)
     {
@@ -5757,22 +5755,15 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         window->SizeContentsExplicit = g.NextWindowData.ContentSizeVal;
         if (window->SizeContentsExplicit.y != 0.0f)
             window->SizeContentsExplicit.y += window->TitleBarHeight() + window->MenuBarHeight();
-        g.NextWindowData.ContentSizeCond = 0;
     }
     else if (first_begin_of_the_frame)
     {
         window->SizeContentsExplicit = ImVec2(0.0f, 0.0f);
     }
     if (g.NextWindowData.CollapsedCond)
-    {
         SetWindowCollapsed(window, g.NextWindowData.CollapsedVal, g.NextWindowData.CollapsedCond);
-        g.NextWindowData.CollapsedCond = 0;
-    }
     if (g.NextWindowData.FocusCond)
-    {
+        FocusWindow(window);
-        SetWindowFocus();
-        g.NextWindowData.FocusCond = 0;
-    }
     if (window->Appearing)
         SetWindowConditionAllowFlags(window, ImGuiCond_Appearing, false);
 
@@ -5799,8 +5790,35 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         window->LastFrameActive = current_frame;
         window->IDStack.resize(1);
 
-        // Lock window rounding, border size and rounding so that altering the border sizes for children doesn't have side-effects.
+        // UPDATE CONTENTS SIZE, UPDATE HIDDEN STATUS
-        window->WindowRounding = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildRounding : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupRounding : style.WindowRounding;
+
+        // Update contents size from last frame for auto-fitting (or use explicit size)
+        window->SizeContents = CalcSizeContents(window);
+        if (window->HiddenFrames > 0)
+            window->HiddenFrames--;
+
+        // Hide new windows for one frame until they calculate their size
+        if (window_just_created && (!window_size_x_set_by_api || !window_size_y_set_by_api))
+            window->HiddenFrames = 1;
+
+        // Hide popup/tooltip window when re-opening while we measure size (because we recycle the windows)
+        // We reset Size/SizeContents for reappearing popups/tooltips early in this function, so further code won't be tempted to use the old size.
+        if (window_just_activated_by_user && (flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) != 0)
+        {
+            window->HiddenFrames = 1;
+            if (flags & ImGuiWindowFlags_AlwaysAutoResize)
+            {
+                if (!window_size_x_set_by_api)
+                    window->Size.x = window->SizeFull.x = 0.f;
+                if (!window_size_y_set_by_api)
+                    window->Size.y = window->SizeFull.y = 0.f;
+                window->SizeContents = ImVec2(0.f, 0.f);
+            }
+        }
+
+        SetCurrentWindow(window);
+
+        // Lock border size and padding for the frame (so that altering them doesn't cause inconsistencies)
         window->WindowBorderSize = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildBorderSize : ((flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupBorderSize : style.WindowBorderSize;
         window->WindowPadding = style.WindowPadding;
         if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & (ImGuiWindowFlags_AlwaysUseWindowPadding | ImGuiWindowFlags_Popup)) && window->WindowBorderSize == 0.0f)
@@ -5828,29 +5846,6 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
 
         // SIZE
 
-        // Update contents size from last frame for auto-fitting (unless explicitly specified)
-        window->SizeContents = CalcSizeContents(window);
-
-        // Hide popup/tooltip window when re-opening while we measure size (because we recycle the windows)
-        if (window->HiddenFrames > 0)
-            window->HiddenFrames--;
-        if (window_just_activated_by_user && (flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) != 0)
-        {
-            window->HiddenFrames = 1;
-            if (flags & ImGuiWindowFlags_AlwaysAutoResize)
-            {
-                if (!window_size_x_set_by_api)
-                    window->Size.x = window->SizeFull.x = 0.f;
-                if (!window_size_y_set_by_api)
-                    window->Size.y = window->SizeFull.y = 0.f;
-                window->SizeContents = ImVec2(0.f, 0.f);
-            }
-        }
-
-        // Hide new windows for one frame until they calculate their size
-        if (window_just_created && (!window_size_x_set_by_api || !window_size_y_set_by_api))
-            window->HiddenFrames = 1;
-
         // Calculate auto-fit size, handle automatic resize
         const ImVec2 size_auto_fit = CalcSizeAutoFit(window, window->SizeContents);
         ImVec2 size_full_modified(FLT_MAX, FLT_MAX);
@@ -5934,6 +5929,9 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         }
         window->Pos = ImFloor(window->Pos);
 
+        // Lock window rounding for the frame (so that altering them doesn't cause inconsistencies)
+        window->WindowRounding = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildRounding : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupRounding : style.WindowRounding;
+
         // Prepare for focus requests
         window->FocusIdxAllRequestCurrent = (window->FocusIdxAllRequestNext == INT_MAX || window->FocusIdxAllCounter == -1) ? INT_MAX : (window->FocusIdxAllRequestNext + (window->FocusIdxAllCounter+1)) % (window->FocusIdxAllCounter+1);
         window->FocusIdxTabRequestCurrent = (window->FocusIdxTabRequestNext == INT_MAX || window->FocusIdxTabCounter == -1) ? INT_MAX : (window->FocusIdxTabRequestNext + (window->FocusIdxTabCounter+1)) % (window->FocusIdxTabCounter+1);
@@ -6225,7 +6223,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         window->WriteAccessed = false;
 
     window->BeginCount++;
-    g.NextWindowData.SizeConstraintCond = 0;
+    g.NextWindowData.Clear();
 
     // Child window can be out of sight and have "negative" clip windows.
     // Mark them as collapsed so commands are skipped earlier (we can't manually collapse them because they have no title bar).