Fix glitch in AssetsView when dragging files onto it

Moved the DropArea from the AssetDelegate into the AssetsView, so that
moving the cursor through the delegates no longer denies and then
permits dragging. This glitch happened because the DropArea was inside
the delegate, while the TreeView also has rowSpacing, which are areas
that do not belong to the delegates, and for which you don't normally
have drag & drop support.

Task-number: QDS-8232
Change-Id: If49a384f25bb870105448156f436e048479e880c
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

share/qtcreator/qmldesigner/itemLibraryQmlSources/AssetDelegate.qml

@@ -12,7 +12,7 @@ TreeViewDelegate {
     required property Item assetsRoot
 
     property bool hasChildWithDropHover: false
-    property bool isHoveringDrop: false
+    property bool isHighlighted: false
     readonly property string suffix: model.fileName.substr(-4)
     readonly property bool isFont: root.suffix === ".ttf" || root.suffix === ".otf"
     readonly property bool isEffect: root.suffix === ".qep"
@@ -74,7 +74,7 @@ TreeViewDelegate {
         id: bg
 
         color: {
-            if (root.__isDirectory && (root.isHoveringDrop || root.hasChildWithDropHover))
+            if (root.__isDirectory && (root.isHighlighted || root.hasChildWithDropHover))
                 return StudioTheme.Values.themeInteraction
 
             if (!root.__isDirectory && root.assetsView.selectedAssets[root.__itemPath])
@@ -120,40 +120,6 @@ TreeViewDelegate {
         }
     }
 
-    DropArea {
-        id: treeDropArea
-
-        enabled: true
-        anchors.fill: parent
-
-        onEntered: (drag) => {
-            root.assetsRoot.updateDropExtFiles(drag)
-            root.isHoveringDrop = drag.accepted && root.assetsRoot.dropSimpleExtFiles.length > 0
-            if (root.isHoveringDrop)
-                root.assetsView.startDropHoverOver(root.__currentRow)
-        }
-
-        onDropped: (drag) => {
-            root.isHoveringDrop = false
-            root.assetsView.endDropHover(root.__currentRow)
-
-            let dirPath = root.__isDirectory
-                       ? model.filePath
-                       : assetsModel.parentDirPath(model.filePath);
-
-            rootView.emitExtFilesDrop(root.assetsRoot.dropSimpleExtFiles,
-                                      root.assetsRoot.dropComplexExtFiles,
-                                      dirPath)
-        }
-
-        onExited: {
-            if (root.isHoveringDrop) {
-                root.isHoveringDrop = false
-                root.assetsView.endDropHover(root.__currentRow)
-            }
-        }
-    }
-
     MouseArea {
         id: mouseArea
 
@@ -247,6 +213,14 @@ TreeViewDelegate {
         }
     } // MouseArea
 
+    function getDirPath()
+    {
+        if (root.__isDirectory)
+            return model.filePath
+        else
+            return assetsModel.parentDirPath(model.filePath)
+    }
+
     function __openContextMenuForCurrentRow()
     {
         let modelIndex = assetsModel.indexForPath(model.filePath)

share/qtcreator/qmldesigner/itemLibraryQmlSources/AssetsView.qml

@@ -250,8 +250,12 @@ TreeView {
     function startDropHoverOver(row)
     {
         let index = root.__modelIndex(row)
-        if (assetsModel.isDirectory(index))
+        if (assetsModel.isDirectory(index)) {
+            let item = root.__getDelegateItemForIndex(index)
+            if (item)
+                item.isHighlighted = true
             return
+        }
 
         let parentItem = root.__getDelegateParentForIndex(index)
         if (parentItem)
@@ -261,8 +265,12 @@ TreeView {
     function endDropHover(row)
     {
         let index = root.__modelIndex(row)
-        if (assetsModel.isDirectory(index))
+        if (assetsModel.isDirectory(index)) {
+            let item = root.__getDelegateItemForIndex(index)
+            if (item)
+                item.isHighlighted = false
             return
+        }
 
         let parentItem = root.__getDelegateParentForIndex(index)
         if (parentItem)
@@ -292,6 +300,12 @@ TreeView {
         return root.itemAtCell(parentCell)
     }
 
+    function __getDelegateItemForIndex(index)
+    {
+        let cell = root.cellAtIndex(index)
+        return root.itemAtCell(cell)
+    }
+
     function __modelIndex(row)
     {
         // The modelIndex() function exists since 6.3. In Qt 6.3, this modelIndex() function was a
@@ -303,6 +317,76 @@ TreeView {
             return root.modelIndex(row, 0)
     }
 
+    DropArea {
+        id: dropArea
+        enabled: true
+        anchors.fill: parent
+
+        property bool __isHoveringDrop: false
+        property int __rowHoveringOver: -1
+
+        function __rowAndItem(drag)
+        {
+            let pos = dropArea.mapToItem(root, drag.x, drag.y)
+            let cell = root.cellAtPos(pos.x, pos.y, true)
+            let item = root.itemAtCell(cell)
+
+            return [cell.y, item]
+        }
+
+        onEntered: (drag) => {
+            root.assetsRoot.updateDropExtFiles(drag)
+
+            let [row, item] = dropArea.__rowAndItem(drag)
+            dropArea.__isHoveringDrop = drag.accepted && root.assetsRoot.dropSimpleExtFiles.length > 0
+
+            if (item && dropArea.__isHoveringDrop)
+                root.startDropHoverOver(row)
+
+            dropArea.__rowHoveringOver = row
+        }
+
+        onDropped: (drag) => {
+            let [row, item] = dropArea.__rowAndItem(drag)
+
+            if (item) {
+               root.endDropHover(row)
+
+               let dirPath = item.getDirPath()
+
+               rootView.emitExtFilesDrop(root.assetsRoot.dropSimpleExtFiles,
+                                         root.assetsRoot.dropComplexExtFiles,
+                                         dirPath)
+            }
+
+            dropArea.__isHoveringDrop = false
+            dropArea.__rowHoveringOver = -1
+        }
+
+        onPositionChanged: (drag) => {
+            let [row, item] = dropArea.__rowAndItem(drag)
+
+            if (dropArea.__rowHoveringOver !== row && dropArea.__rowHoveringOver > -1) {
+                root.endDropHover(dropArea.__rowHoveringOver)
+
+                if (item)
+                    root.startDropHoverOver(row)
+            }
+
+            dropArea.__rowHoveringOver = row
+        }
+
+        onExited: {
+            if (!dropArea.__isHoveringDrop || dropArea.__rowHoveringOver === -1)
+                return
+
+            root.endDropHover(dropArea.__rowHoveringOver)
+
+            dropArea.__isHoveringDrop = false
+            dropArea.__rowHoveringOver = -1
+        }
+    }
+
     delegate: AssetDelegate {
         assetsView: root
         assetsRoot: root.assetsRoot