Drag and Drop: Fixed drop target highlight on items temporarily pushing a widened clip rect. (#7049, #4281, #3272)

docs/CHANGELOG.txt

@@ -44,6 +44,9 @@ Breaking changes:
 
 Other changes:
 
+- Drag and Drop: Fixed drop target highlight on items temporarily pushing a widened clip rect
+  (namely Selectables and Treenodes using SpanAllColumn flag) so the highlight properly covers
+  all columns. (#7049, #4281, #3272)
 - Misc: Fixed text functions fast-path for handling "%s" and "%.*s" to handle null pointers gracefully,
   like most printf implementations. (#7016, #3466, #6846) [@codefrog2002]
 - Misc: Renamed some defines in imstb_textedit.h to avoid conflicts when using unity/jumbo builds

imgui.cpp

@@ -12778,13 +12778,14 @@ bool ImGui::BeginDragDropTargetCustom(const ImRect& bb, ImGuiID id)
 
     IM_ASSERT(g.DragDropWithinTarget == false);
     g.DragDropTargetRect = bb;
+    g.DragDropTargetClipRect = window->ClipRect; // May want to be overriden by user depending on use case?
     g.DragDropTargetId = id;
     g.DragDropWithinTarget = true;
     return true;
 }
 
 // We don't use BeginDragDropTargetCustom() and duplicate its code because:
-// 1) we use LastItemRectHoveredRect which handles items that push a temporarily clip rectangle in their code. Calling BeginDragDropTargetCustom(LastItemRect) would not handle them.
+// 1) we use LastItemData's ImGuiItemStatusFlags_HoveredRect which handles items that push a temporarily clip rectangle in their code. Calling BeginDragDropTargetCustom(LastItemRect) would not handle them.
 // 2) and it's faster. as this code may be very frequently called, we want to early out as fast as we can.
 // Also note how the HoveredWindow test is positioned differently in both functions (in both functions we optimize for the cheapest early out case)
 bool ImGui::BeginDragDropTarget()
@@ -12812,6 +12813,7 @@ bool ImGui::BeginDragDropTarget()
 
     IM_ASSERT(g.DragDropWithinTarget == false);
     g.DragDropTargetRect = display_rect;
+    g.DragDropTargetClipRect = (g.LastItemData.StatusFlags & ImGuiItemStatusFlags_HasClipRect) ? g.LastItemData.ClipRect : window->ClipRect;
     g.DragDropTargetId = id;
     g.DragDropWithinTarget = true;
     return true;
@@ -12849,7 +12851,7 @@ const ImGuiPayload* ImGui::AcceptDragDropPayload(const char* type, ImGuiDragDrop
     payload.Preview = was_accepted_previously;
     flags |= (g.DragDropSourceFlags & ImGuiDragDropFlags_AcceptNoDrawDefaultRect); // Source can also inhibit the preview (useful for external sources that live for 1 frame)
     if (!(flags & ImGuiDragDropFlags_AcceptNoDrawDefaultRect) && payload.Preview)
-        RenderDragDropTargetRect(r);
+        RenderDragDropTargetRect(r, g.DragDropTargetClipRect);
 
     g.DragDropAcceptFrameCount = g.FrameCount;
     payload.Delivery = was_accepted_previously && !IsMouseDown(g.DragDropMouseButton); // For extern drag sources affecting OS window focus, it's easier to just test !IsMouseDown() instead of IsMouseReleased()
@@ -12861,12 +12863,12 @@ const ImGuiPayload* ImGui::AcceptDragDropPayload(const char* type, ImGuiDragDrop
 }
 
 // FIXME-STYLE FIXME-DRAGDROP: Settle on a proper default visuals for drop target.
-void ImGui::RenderDragDropTargetRect(const ImRect& bb)
+void ImGui::RenderDragDropTargetRect(const ImRect& bb, const ImRect& item_clip_rect)
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
     ImRect bb_display = bb;
-    bb_display.ClipWith(window->ClipRect); // Clip THEN expand so we have a way to visualize that target is not entirely visible.
+    bb_display.ClipWith(item_clip_rect); // Clip THEN expand so we have a way to visualize that target is not entirely visible.
     bb_display.Expand(3.5f);
     bool push_clip_rect = !window->ClipRect.Contains(bb_display);
     if (push_clip_rect)

imgui_internal.h

@@ -837,6 +837,7 @@ enum ImGuiItemStatusFlags_
     ImGuiItemStatusFlags_HoveredWindow      = 1 << 7,   // Override the HoveredWindow test to allow cross-window hover testing.
     ImGuiItemStatusFlags_FocusedByTabbing   = 1 << 8,   // Set when the Focusable item just got focused by Tabbing (FIXME: to be removed soon)
     ImGuiItemStatusFlags_Visible            = 1 << 9,   // [WIP] Set when item is overlapping the current clipping rectangle (Used internally. Please don't use yet: API/system will change as we refactor Itemadd()).
+    ImGuiItemStatusFlags_HasClipRect        = 1 << 10,  // g.LastItemData.ClipRect is valid
 
     // Additional status + semantic for ImGuiTestEngine
 #ifdef IMGUI_ENABLE_TEST_ENGINE
@@ -1221,7 +1222,9 @@ struct ImGuiLastItemData
     ImGuiItemStatusFlags    StatusFlags;        // See ImGuiItemStatusFlags_
     ImRect                  Rect;               // Full rectangle
     ImRect                  NavRect;            // Navigation scoring rectangle (not displayed)
-    ImRect                  DisplayRect;        // Display rectangle (only if ImGuiItemStatusFlags_HasDisplayRect is set)
+    // Rarely used fields are not explicitly cleared, only valid when the corresponding ImGuiItemStatusFlags is set.
+    ImRect                  DisplayRect;        // Display rectangle (ONLY VALID IF ImGuiItemStatusFlags_HasDisplayRect is set)
+    ImRect                  ClipRect;           // Clip rectangle at the time of submitting item (ONLY VALID IF ImGuiItemStatusFlags_HasClipRect is set)
 
     ImGuiLastItemData()     { memset(this, 0, sizeof(*this)); }
 };
@@ -2038,6 +2041,7 @@ struct ImGuiContext
     int                     DragDropMouseButton;
     ImGuiPayload            DragDropPayload;
     ImRect                  DragDropTargetRect;                 // Store rectangle of current target candidate (we favor small targets when overlapping)
+    ImRect                  DragDropTargetClipRect;             // Store ClipRect at the time of item's drawing
     ImGuiID                 DragDropTargetId;
     ImGuiDragDropFlags      DragDropAcceptFlags;
     float                   DragDropAcceptIdCurrRectSurface;    // Target item surface (we resolve overlapping targets by prioritizing the smaller surface)
@@ -3168,7 +3172,7 @@ namespace ImGui
     IMGUI_API bool          BeginDragDropTargetCustom(const ImRect& bb, ImGuiID id);
     IMGUI_API void          ClearDragDrop();
     IMGUI_API bool          IsDragDropPayloadBeingAccepted();
-    IMGUI_API void          RenderDragDropTargetRect(const ImRect& bb);
+    IMGUI_API void          RenderDragDropTargetRect(const ImRect& bb, const ImRect& item_clip_rect);
 
     // Typing-Select API
     IMGUI_API ImGuiTypingSelectRequest* GetTypingSelectRequest(ImGuiTypingSelectFlags flags = ImGuiTypingSelectFlags_None);

imgui_widgets.cpp

@@ -6232,7 +6232,11 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
     }
 
     if (span_all_columns)
+    {
         TablePushBackgroundChannel();
+        g.LastItemData.StatusFlags |= ImGuiItemStatusFlags_HasClipRect;
+        g.LastItemData.ClipRect = window->ClipRect;
+    }
 
     ImGuiButtonFlags button_flags = ImGuiTreeNodeFlags_None;
     if ((flags & ImGuiTreeNodeFlags_AllowOverlap) || (g.LastItemData.InFlags & ImGuiItemFlags_AllowOverlap))
@@ -6562,10 +6566,15 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
 
     // FIXME: We can standardize the behavior of those two, we could also keep the fast path of override ClipRect + full push on render only,
     // which would be advantageous since most selectable are not selected.
-    if (span_all_columns && window->DC.CurrentColumns)
-        PushColumnsBackground();
-    else if (span_all_columns && g.CurrentTable)
-        TablePushBackgroundChannel();
+    if (span_all_columns)
+    {
+        if (g.CurrentTable)
+            TablePushBackgroundChannel();
+        else if (window->DC.CurrentColumns)
+            PushColumnsBackground();
+        g.LastItemData.StatusFlags |= ImGuiItemStatusFlags_HasClipRect;
+        g.LastItemData.ClipRect = window->ClipRect;
+    }
 
     // We use NoHoldingActiveID on menus so user can click and _hold_ on a menu then drag to browse child entries
     ImGuiButtonFlags button_flags = 0;
@@ -6616,10 +6625,13 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
     if (g.NavId == id)
         RenderNavHighlight(bb, id, ImGuiNavHighlightFlags_TypeThin | ImGuiNavHighlightFlags_NoRounding);
 
-    if (span_all_columns && window->DC.CurrentColumns)
-        PopColumnsBackground();
-    else if (span_all_columns && g.CurrentTable)
-        TablePopBackgroundChannel();
+    if (span_all_columns)
+    {
+        if (g.CurrentTable)
+            TablePopBackgroundChannel();
+        else if (window->DC.CurrentColumns)
+            PopColumnsBackground();
+    }
 
     RenderTextClipped(text_min, text_max, label, NULL, &label_size, style.SelectableTextAlign, &bb);