Added ImGuiDragDropFlags_AcceptNoPreviewTooltip flag to disable drag source tooltip from the target site (#143)

CHANGELOG.txt

@@ -47,6 +47,7 @@ Other Changes:
  - TreeNode: Fixed nodes with ImGuiTreeNodeFlags_Leaf flag always returning true which was meaningless.
  - ColorEdit3, ColorEdit4, ColorButton: Added ImGuiColorEditFlags_NoDragDrop flag to disable ColorEditX as drag target and ColorButton as drag source. (#1826) 
  - BeginDragDropSource(): Offset tooltip position so it is off the mouse cursor, but also closer to it than regular tooltips, and not clamped by viewport. (#1739)
+ - BeginDragDropTarget(): Added ImGuiDragDropFlags_AcceptNoPreviewTooltip flag to request hiding the drag source tooltip from the target site. (#143)
  - BeginCombo(), BeginMainMenuBar(), BeginChildFrame(): Temporary style modification are restored at the end of BeginXXX instead of EndXXX, to not affect tooltips and child windows.
  - Examples: GLFW: Made it possible to Shutdown/Init the backend again (by reseting the time storage properly). (#1827) [@ice1000]
  - Internals: PushItemFlag() flags are inherited by BeginChild().

TODO.txt

@@ -215,11 +215,13 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - filters: handle wildcards (with implicit leading/trailing *), regexps
  - filters: fuzzy matches (may use code at blog.forrestthewoods.com/4cffeed33fdb)
 
- - drag and drop: allow drag target to alter tooltip / and or disable tooltip.
+ - drag and drop: allow drag target to alter tooltip.
  - drag and drop: add demo. (#143, #479)
+ - drag and drop: have some way to know when a drag begin from BeginDragDropSource() pov
  - drag and drop: allow using with other mouse buttons (where activeid won't be set). (#1637)
  - drag and drop: test with reordering nodes (in a list, or a tree node). (#143)
  - drag and drop: test integrating with os drag and drop.
+ - drag and drop: make payload optional? (#143)
  - node/graph editor (#306)
  - pie menus patterns (#434)
  - markup: simple markup language for color change? (#902)

imgui.cpp

@@ -13145,6 +13145,7 @@ void ImGui::ClearDragDrop()
     ImGuiContext& g = *GImGui;
     g.DragDropActive = false;
     g.DragDropPayload.Clear();
+    g.DragDropAcceptFlags = 0;
     g.DragDropAcceptIdCurr = g.DragDropAcceptIdPrev = 0;
     g.DragDropAcceptIdCurrRectSurface = FLT_MAX;
     g.DragDropAcceptFrameCount = -1;
@@ -13239,6 +13240,15 @@ bool ImGui::BeginDragDropSource(ImGuiDragDropFlags flags)
             SetNextWindowPos(tooltip_pos);
             PushStyleColor(ImGuiCol_PopupBg, GetStyleColorVec4(ImGuiCol_PopupBg) * ImVec4(1.0f, 1.0f, 1.0f, 0.6f));
             BeginTooltip();
+
+            // 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. 
+            if (g.DragDropActive && g.DragDropAcceptIdPrev && (g.DragDropAcceptFlags & ImGuiDragDropFlags_AcceptNoPreviewTooltip))
+            {
+                ImGuiWindow* tooltip_window = g.CurrentWindow;
+                tooltip_window->SkipItems = true;
+                tooltip_window->HiddenFrames = 1;
+            }
         }
 
         if (!(flags & ImGuiDragDropFlags_SourceNoDisableHover) && !(flags & ImGuiDragDropFlags_SourceExtern))
@@ -13379,6 +13389,7 @@ const ImGuiPayload* ImGui::AcceptDragDropPayload(const char* type, ImGuiDragDrop
     float r_surface = r.GetWidth() * r.GetHeight();
     if (r_surface < g.DragDropAcceptIdCurrRectSurface)
     {
+        g.DragDropAcceptFlags = flags;
         g.DragDropAcceptIdCurr = g.DragDropTargetId;
         g.DragDropAcceptIdCurrRectSurface = r_surface;
     }

imgui.h

@@ -717,6 +717,7 @@ enum ImGuiDragDropFlags_
     // AcceptDragDropPayload() flags
     ImGuiDragDropFlags_AcceptBeforeDelivery         = 1 << 10,  // AcceptDragDropPayload() will returns true even before the mouse button is released. You can then call IsDelivery() to test if the payload needs to be delivered.
     ImGuiDragDropFlags_AcceptNoDrawDefaultRect      = 1 << 11,  // Do not draw the default highlight rectangle when hovering over target.
+    ImGuiDragDropFlags_AcceptNoPreviewTooltip       = 1 << 12,  // Request hiding the BeginDragDropSource tooltip from the BeginDragDropTarget site.
     ImGuiDragDropFlags_AcceptPeekOnly               = ImGuiDragDropFlags_AcceptBeforeDelivery | ImGuiDragDropFlags_AcceptNoDrawDefaultRect  // For peeking ahead and inspecting the payload before delivery.
 };
 

imgui_internal.h

@@ -688,7 +688,8 @@ struct ImGuiContext
     ImGuiPayload            DragDropPayload;
     ImRect                  DragDropTargetRect;
     ImGuiID                 DragDropTargetId;
-    float                   DragDropAcceptIdCurrRectSurface;
+    ImGuiDragDropFlags      DragDropAcceptFlags;
+    float                   DragDropAcceptIdCurrRectSurface;    // Target item surface (we resolve overlapping targets by prioritizing the smaller surface)
     ImGuiID                 DragDropAcceptIdCurr;               // Target item id (set at the time of accepting the payload)
     ImGuiID                 DragDropAcceptIdPrev;               // Target item id from previous frame (we need to store this to allow for overlapping drag and drop targets)
     int                     DragDropAcceptFrameCount;           // Last time a target expressed a desire to accept the source
@@ -799,6 +800,7 @@ struct ImGuiContext
         DragDropSourceFlags = 0;
         DragDropMouseButton = -1;
         DragDropTargetId = 0;
+        DragDropAcceptFlags = 0;
         DragDropAcceptIdCurrRectSurface = 0.0f;
         DragDropAcceptIdPrev = DragDropAcceptIdCurr = 0;
         DragDropAcceptFrameCount = -1;