Drag and Drop: tweaked BeginDragDropSource() to remove indent. Added debug log.

imgui.cpp

@@ -13096,6 +13096,8 @@ bool ImGui::IsDragDropActive()
 void ImGui::ClearDragDrop()
 {
     ImGuiContext& g = *GImGui;
+    if (g.DragDropActive)
+        IMGUI_DEBUG_LOG_ACTIVEID("[dragdrop] ClearDragDrop()\n");
     g.DragDropActive = false;
     g.DragDropPayload.Clear();
     g.DragDropAcceptFlags = ImGuiDragDropFlags_None;
@@ -13134,7 +13136,7 @@ bool ImGui::BeginDragDropSource(ImGuiDragDropFlags flags)
     bool source_drag_active = false;
     ImGuiID source_id = 0;
     ImGuiID source_parent_id = 0;
-    if (!(flags & ImGuiDragDropFlags_SourceExtern))
+    if ((flags & ImGuiDragDropFlags_SourceExtern) == 0)
     {
         source_id = g.LastItemData.ID;
         if (source_id != 0)
@@ -13196,43 +13198,44 @@ bool ImGui::BeginDragDropSource(ImGuiDragDropFlags flags)
     }
 
     IM_ASSERT(g.DragDropWithinTarget == false); // Can't nest BeginDragDropSource() and BeginDragDropTarget()
-    if (source_drag_active)
-    {
-        if (!g.DragDropActive)
-        {
-            IM_ASSERT(source_id != 0);
-            ClearDragDrop();
-            ImGuiPayload& payload = g.DragDropPayload;
-            payload.SourceId = source_id;
-            payload.SourceParentId = source_parent_id;
-            g.DragDropActive = true;
-            g.DragDropSourceFlags = flags;
-            g.DragDropMouseButton = mouse_button;
-            if (payload.SourceId == g.ActiveId)
-                g.ActiveIdNoClearOnFocusLoss = true;
-        }
-        g.DragDropSourceFrameCount = g.FrameCount;
-        g.DragDropWithinSource = true;
+    if (!source_drag_active)
+        return false;
 
-        if (!(flags & ImGuiDragDropFlags_SourceNoPreviewTooltip))
-        {
-            // Target can request the Source to not display its tooltip (we use a dedicated flag to make this request explicit)
-            // We unfortunately can't just modify the source flags and skip the call to BeginTooltip, as caller may be emitting contents.
-            bool ret;
-            if (g.DragDropAcceptIdPrev && (g.DragDropAcceptFlags & ImGuiDragDropFlags_AcceptNoPreviewTooltip))
-                ret = BeginTooltipHidden();
-            else
-                ret = BeginTooltip();
-            IM_ASSERT(ret); // FIXME-NEWBEGIN: If this ever becomes false, we need to Begin("##Hidden", NULL, ImGuiWindowFlags_NoSavedSettings) + SetWindowHiddendAndSkipItemsForCurrentFrame().
-            IM_UNUSED(ret);
-        }
+    // Activate drag and drop
+    if (!g.DragDropActive)
+    {
+        IM_ASSERT(source_id != 0);
+        ClearDragDrop();
+        IMGUI_DEBUG_LOG_ACTIVEID("[dragdrop] BeginDragDropSource() DragDropActive = true, source_id = %08X\n", source_id);
+        ImGuiPayload& payload = g.DragDropPayload;
+        payload.SourceId = source_id;
+        payload.SourceParentId = source_parent_id;
+        g.DragDropActive = true;
+        g.DragDropSourceFlags = flags;
+        g.DragDropMouseButton = mouse_button;
+        if (payload.SourceId == g.ActiveId)
+            g.ActiveIdNoClearOnFocusLoss = true;
+    }
+    g.DragDropSourceFrameCount = g.FrameCount;
+    g.DragDropWithinSource = true;
+
+    if (!(flags & ImGuiDragDropFlags_SourceNoPreviewTooltip))
+    {
+        // Target can request the Source to not display its tooltip (we use a dedicated flag to make this request explicit)
+        // We unfortunately can't just modify the source flags and skip the call to BeginTooltip, as caller may be emitting contents.
+        bool ret;
+        if (g.DragDropAcceptIdPrev && (g.DragDropAcceptFlags & ImGuiDragDropFlags_AcceptNoPreviewTooltip))
+            ret = BeginTooltipHidden();
+        else
+            ret = BeginTooltip();
+        IM_ASSERT(ret); // FIXME-NEWBEGIN: If this ever becomes false, we need to Begin("##Hidden", NULL, ImGuiWindowFlags_NoSavedSettings) + SetWindowHiddendAndSkipItemsForCurrentFrame().
+        IM_UNUSED(ret);
+    }
 
-        if (!(flags & ImGuiDragDropFlags_SourceNoDisableHover) && !(flags & ImGuiDragDropFlags_SourceExtern))
-            g.LastItemData.StatusFlags &= ~ImGuiItemStatusFlags_HoveredRect;
+    if (!(flags & ImGuiDragDropFlags_SourceNoDisableHover) && !(flags & ImGuiDragDropFlags_SourceExtern))
+        g.LastItemData.StatusFlags &= ~ImGuiItemStatusFlags_HoveredRect;
 
-        return true;
-    }
-    return false;
+    return true;
 }
 
 void ImGui::EndDragDropSource()