Add auto-panning when mouse goes outside the editor while dragging stuff

imnodes.cpp

@@ -252,6 +252,33 @@ inline bool RectangleOverlapsLink(
     return false;
 }
 
+// [SECTION] coordinate space conversion helpers
+
+inline ImVec2 ScreenSpaceToGridSpace(const ImNodesEditorContext& editor, const ImVec2& v)
+{
+    return v - GImNodes->CanvasOriginScreenSpace - editor.Panning;
+}
+
+inline ImVec2 GridSpaceToScreenSpace(const ImNodesEditorContext& editor, const ImVec2& v)
+{
+    return v + GImNodes->CanvasOriginScreenSpace + editor.Panning;
+}
+
+inline ImVec2 GridSpaceToEditorSpace(const ImNodesEditorContext& editor, const ImVec2& v)
+{
+    return v + editor.Panning;
+}
+
+inline ImVec2 EditorSpaceToGridSpace(const ImNodesEditorContext& editor, const ImVec2& v)
+{
+    return v - editor.Panning;
+}
+
+inline ImVec2 EditorSpaceToScreenSpace(const ImVec2& v)
+{
+    return GImNodes->CanvasOriginScreenSpace + v;
+}
+
 // [SECTION] draw list helper
 
 void ImDrawListGrowChannels(ImDrawList* draw_list, const int num_channels)
@@ -664,7 +691,7 @@ void BeginCanvasInteraction(ImNodesEditorContext& editor)
         else if (GImNodes->LeftMouseClicked)
         {
             editor.ClickInteraction.Type = ImNodesClickInteractionType_BoxSelection;
-            editor.ClickInteraction.BoxSelector.Rect.Min = GImNodes->MousePos;
+            editor.ClickInteraction.BoxSelector.Rect.Min = ScreenSpaceToGridSpace(editor, GImNodes->MousePos);
         }
     }
 }
@@ -743,7 +770,7 @@ void TranslateSelectedNodes(ImNodesEditorContext& editor)
             ImNodeData& node = editor.Nodes.Pool[node_idx];
             if (node.Draggable)
             {
-                node.Origin += io.MouseDelta;
+                node.Origin += io.MouseDelta - editor.AutoPanningDelta;
             }
         }
     }
@@ -835,8 +862,11 @@ void ClickInteractionUpdate(ImNodesEditorContext& editor)
     {
     case ImNodesClickInteractionType_BoxSelection:
     {
-        ImRect& box_rect = editor.ClickInteraction.BoxSelector.Rect;
-        box_rect.Max = GImNodes->MousePos;
+        editor.ClickInteraction.BoxSelector.Rect.Max = ScreenSpaceToGridSpace(editor, GImNodes->MousePos);
+
+        ImRect box_rect = editor.ClickInteraction.BoxSelector.Rect;
+        box_rect.Min = GridSpaceToScreenSpace(editor, box_rect.Min);
+        box_rect.Max = GridSpaceToScreenSpace(editor, box_rect.Max);
 
         BoxSelectorUpdateSelection(editor, box_rect);
 
@@ -1225,31 +1255,6 @@ ImOptionalIndex ResolveHoveredLink(
 
 // [SECTION] render helpers
 
-inline ImVec2 ScreenSpaceToGridSpace(const ImNodesEditorContext& editor, const ImVec2& v)
-{
-    return v - GImNodes->CanvasOriginScreenSpace - editor.Panning;
-}
-
-inline ImVec2 GridSpaceToScreenSpace(const ImNodesEditorContext& editor, const ImVec2& v)
-{
-    return v + GImNodes->CanvasOriginScreenSpace + editor.Panning;
-}
-
-inline ImVec2 GridSpaceToEditorSpace(const ImNodesEditorContext& editor, const ImVec2& v)
-{
-    return v + editor.Panning;
-}
-
-inline ImVec2 EditorSpaceToGridSpace(const ImNodesEditorContext& editor, const ImVec2& v)
-{
-    return v - editor.Panning;
-}
-
-inline ImVec2 EditorSpaceToScreenSpace(const ImVec2& v)
-{
-    return GImNodes->CanvasOriginScreenSpace + v;
-}
-
 inline ImRect GetItemRect() { return ImRect(ImGui::GetItemRectMin(), ImGui::GetItemRectMax()); }
 
 inline ImVec2 GetNodeTitleBarOrigin(const ImNodeData& node)
@@ -1926,7 +1931,7 @@ ImNodesIO::LinkDetachWithModifierClick::LinkDetachWithModifierClick() : Modifier
 
 ImNodesIO::ImNodesIO()
     : EmulateThreeButtonMouse(), LinkDetachWithModifierClick(),
-      AltMouseButton(ImGuiMouseButton_Middle)
+      AltMouseButton(ImGuiMouseButton_Middle), AutoPanningSpeed(1000.0f)
 {
 }
 
@@ -2125,6 +2130,7 @@ void BeginNodeEditor()
     // Reset state from previous pass
 
     ImNodesEditorContext& editor = EditorContextGet();
+    editor.AutoPanningDelta = ImVec2(0, 0);
     ObjectPoolReset(editor.Nodes);
     ObjectPoolReset(editor.Pins);
     ObjectPoolReset(editor.Links);
@@ -2283,6 +2289,21 @@ void EndNodeEditor()
             BeginCanvasInteraction(editor);
         }
 
+        bool shouldAutoPan =
+            editor.ClickInteraction.Type == ImNodesClickInteractionType_BoxSelection ||
+            editor.ClickInteraction.Type == ImNodesClickInteractionType_LinkCreation ||
+            editor.ClickInteraction.Type == ImNodesClickInteractionType_Node;
+        if (shouldAutoPan && !MouseInCanvas())
+        {
+            ImVec2 mouse = ImGui::GetMousePos();
+            ImVec2 center = GImNodes->CanvasRectScreenSpace.GetCenter();
+            ImVec2 direction = (center - mouse);
+            direction = direction * ImInvLength(direction, 0.0);
+
+            editor.AutoPanningDelta = direction * ImGui::GetIO().DeltaTime * GImNodes->Io.AutoPanningSpeed;
+            editor.Panning += editor.AutoPanningDelta;
+        }
+
         ClickInteractionUpdate(editor);
     }
 

imnodes.h

@@ -125,6 +125,9 @@ struct ImNodesIO
     // Set based on ImGuiMouseButton values
     int AltMouseButton;
 
+    // Panning speed when dragging an element and mouse is outside the main editor view.
+    float AutoPanningSpeed;
+
     ImNodesIO();
 };
 

imnodes_internal.h

@@ -215,7 +215,7 @@ struct ImClickInteractionState
 
     struct
     {
-        ImRect Rect;
+        ImRect Rect; // Coordinates in grid space
     } BoxSelector;
 
     ImClickInteractionState() : Type(ImNodesClickInteractionType_None) {}
@@ -252,6 +252,7 @@ struct ImNodesEditorContext
 
     // ui related fields
     ImVec2 Panning;
+    ImVec2 AutoPanningDelta;
 
     ImVector<int> SelectedNodeIndices;
     ImVector<int> SelectedLinkIndices;