Windows: shared code for CalcWindowMinSize().

+ Don't apply WindowMinSize during auto-fit of child windows (not exercised yet).

imgui.cpp

@@ -5646,6 +5646,24 @@ static ImGuiWindow* CreateNewWindow(const char* name, ImGuiWindowFlags flags)
     return window;
 }
 
+static inline ImVec2 CalcWindowMinSize(ImGuiWindow* window)
+{
+    // Popups, menus and childs bypass style.WindowMinSize by default, but we give then a non-zero minimum size to facilitate understanding problematic cases (e.g. empty popups)
+    ImGuiContext& g = *GImGui;
+    ImVec2 size_min;
+    if (window->Flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_ChildMenu | ImGuiWindowFlags_ChildWindow))
+    {
+        size_min = ImVec2(4.0f, 4.0f);
+    }
+    else
+    {
+        ImGuiWindow* window_for_height = window;
+        size_min = g.Style.WindowMinSize;
+        size_min.y = ImMax(size_min.y, window_for_height->TitleBarHeight() + window_for_height->MenuBarHeight() + ImMax(0.0f, g.Style.WindowRounding - 1.0f)); // Reduce artifacts with very small windows
+    }
+    return size_min;
+}
+
 static ImVec2 CalcWindowSizeAfterConstraint(ImGuiWindow* window, const ImVec2& size_desired)
 {
     ImGuiContext& g = *GImGui;
@@ -5671,14 +5689,8 @@ static ImVec2 CalcWindowSizeAfterConstraint(ImGuiWindow* window, const ImVec2& s
     }
 
     // Minimum size
-    if (!(window->Flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_AlwaysAutoResize)))
-    {
-        ImGuiWindow* window_for_height = window;
-        new_size = ImMax(new_size, g.Style.WindowMinSize);
-        const float minimum_height = window_for_height->TitleBarHeight() + window_for_height->MenuBarHeight() + ImMax(0.0f, g.Style.WindowRounding - 1.0f);
-        new_size.y = ImMax(new_size.y, minimum_height); // Reduce artifacts with very small windows
-    }
-    return new_size;
+    ImVec2 size_min = CalcWindowMinSize(window);
+    return ImMax(new_size, size_min);
 }
 
 static void CalcWindowContentSizes(ImGuiWindow* window, ImVec2* content_size_current, ImVec2* content_size_ideal)
@@ -5717,12 +5729,7 @@ static ImVec2 CalcWindowAutoFitSize(ImGuiWindow* window, const ImVec2& size_cont
     else
     {
         // Maximum window size is determined by the viewport size or monitor size
-        const bool is_popup = (window->Flags & ImGuiWindowFlags_Popup) != 0;
-        const bool is_menu = (window->Flags & ImGuiWindowFlags_ChildMenu) != 0;
-        ImVec2 size_min = style.WindowMinSize;
-        if (is_popup || is_menu) // Popups and menus bypass style.WindowMinSize by default, but we give then a non-zero minimum size to facilitate understanding problematic cases (e.g. empty popups)
-            size_min = ImMin(size_min, ImVec2(4.0f, 4.0f));
-
+        ImVec2 size_min = CalcWindowMinSize(window);
         ImVec2 avail_size = ImGui::GetMainViewport()->WorkSize;
         ImVec2 size_auto_fit = ImClamp(size_desired, size_min, ImMax(size_min, avail_size - style.DisplaySafeAreaPadding * 2.0f));