TreeView: Track model indexes during selection

As we keep track of the previous user-selected row,
it can happen that that row is no longer part of the
TreeModelAdaptor items if the user collapses it or
any of its ancestors (collapsing a node doesn't update
the current selection). This will result on the row
index pointing to the wrong entry in the model (or a
completely invalid one).

Instead, we now track the selection with QModelIndexes
making it more robust to branch expansion and collapse
in the view. We'll still need to account for model changes
which means that, in the future, we should invalidate
the previous user-selected item.

Change-Id: I54ba2582e65515eef95d5f8ad755a8c68568d7ad
Task-number: QTBUG-46891
Reviewed-by: Caroline Chao <caroline.chao@theqtcompany.com>

1 files changed, 33 insertions, 25 deletions

diff --git a/src/controls/TreeView.qml b/src/controls/TreeView.qml
index 84c30edd..c97930f3 100644
--- a/src/controls/TreeView.qml
+++ b/src/controls/TreeView.qml
@@ -118,10 +118,11 @@ BasicTableView {
         // the flickable from eating our mouse press events
         preventStealing: !Settings.hasTouchScreen
 
-        property int clickedRow: -1
-        property int pressedRow: -1
+        property var clickedIndex: undefined
+        property var pressedIndex: undefined
         property int pressedColumn: -1
         readonly property alias currentRow: root.__currentRow
+        readonly property alias currentIndex: root.currentIndex
 
         // Handle vertical scrolling whem dragging mouse outside boundaries
         property int autoScroll: 0 // 0 -> do nothing; 1 -> increment; 2 -> decrement
@@ -132,7 +133,7 @@ BasicTableView {
             interval: 20
             repeat: true
             onTriggered: {
-                var oldPressedRow = mouseArea.pressedRow
+                var oldPressedIndex = mouseArea.pressedIndex
                 var row
                 if (mouseArea.autoScroll === 1) {
                     __listView.incrementCurrentIndexBlocking();
@@ -144,28 +145,33 @@ BasicTableView {
                     row = __listView.indexAt(0, __listView.contentY)
                 }
 
-                if (row !== oldPressedRow) {
-                    mouseArea.pressedRow = row
+                var index = modelAdaptor.mapRowToModelIndex(row)
+                if (index !== oldPressedIndex) {
+                    mouseArea.pressedIndex = index
                     var modifiers = mouseArea.shiftPressed ? Qt.ShiftModifier : Qt.NoModifier
-                    mouseArea.mouseSelect(row, modifiers, true /* drag */)
+                    mouseArea.mouseSelect(index, modifiers, true /* drag */)
                 }
             }
         }
 
-        function mouseSelect(row, modifiers, drag) {
+        function mouseSelect(modelIndex, modifiers, drag) {
             if (!selection) {
                 maybeWarnAboutSelectionMode()
                 return
             }
 
             if (selectionMode) {
-                var modelIndex = modelAdaptor.mapRowToModelIndex(row)
                 selection.setCurrentIndex(modelIndex, ItemSelectionModel.NoUpdate)
                 if (selectionMode === SelectionMode.SingleSelection) {
                     selection.select(modelIndex, ItemSelectionModel.ClearAndSelect)
                 } else {
-                    var itemSelection = clickedRow === row ? modelIndex
-                                        : modelAdaptor.selectionForRowRange(clickedRow, row)
+                    var selectRowRange = (drag && (selectionMode === SelectionMode.MultiSelection
+                                                   || (selectionMode === SelectionMode.ExtendedSelection
+                                                       && modifiers & Qt.ControlModifier)))
+                                         || modifiers & Qt.ShiftModifier
+                    var itemSelection = !selectRowRange || clickedIndex === modelIndex ? modelIndex
+                                        : modelAdaptor.selectionForRowRange(clickedIndex, modelIndex)
+
                     if (selectionMode === SelectionMode.MultiSelection
                         || selectionMode === SelectionMode.ExtendedSelection && modifiers & Qt.ControlModifier) {
                         if (drag)
@@ -175,7 +181,7 @@ BasicTableView {
                     } else if (modifiers & Qt.ShiftModifier) {
                         selection.select(itemSelection, ItemSelectionModel.SelectCurrent)
                     } else {
-                        clickedRow = row // Needed only when drag is true
+                        clickedIndex = modelIndex // Needed only when drag is true
                         selection.select(modelIndex, ItemSelectionModel.ClearAndSelect)
                     }
                 }
@@ -185,9 +191,9 @@ BasicTableView {
         function keySelect(keyModifiers) {
             if (selectionMode) {
                 if (!keyModifiers)
-                    clickedRow = currentRow
+                    clickedIndex = currentIndex
                 if (!(keyModifiers & Qt.ControlModifier))
-                    mouseSelect(currentRow, keyModifiers, keyModifiers & Qt.ShiftModifier)
+                    mouseSelect(currentIndex, keyModifiers, keyModifiers & Qt.ShiftModifier)
             }
         }
 
@@ -227,22 +233,23 @@ BasicTableView {
         }
 
         onPressed: {
-            pressedRow = __listView.indexAt(0, mouseY + __listView.contentY)
+            var pressedRow = __listView.indexAt(0, mouseY + __listView.contentY)
+            pressedIndex = modelAdaptor.mapRowToModelIndex(pressedRow)
             pressedColumn = __listView.columnAt(mouseX)
             __listView.forceActiveFocus()
             if (pressedRow > -1 && !Settings.hasTouchScreen
                 && !branchDecorationContains(mouse.x, mouse.y)) {
                 __listView.currentIndex = pressedRow
-                if (clickedRow === -1)
-                    clickedRow = pressedRow
-                mouseSelect(pressedRow, mouse.modifiers, false)
+                if (!clickedIndex)
+                    clickedIndex = pressedIndex
+                mouseSelect(pressedIndex, mouse.modifiers, false)
                 if (!mouse.modifiers)
-                    clickedRow = pressedRow
+                    clickedIndex = pressedIndex
             }
         }
 
         onReleased: {
-            pressedRow = -1
+            pressedIndex = undefined
             pressedColumn = -1
             autoScroll = 0
         }
@@ -261,23 +268,24 @@ BasicTableView {
             }
 
             if (pressed && containsMouse) {
-                var oldPressedRow = pressedRow
-                pressedRow = __listView.indexAt(0, mouseY + __listView.contentY)
+                var oldPressedIndex = pressedIndex
+                var pressedRow = __listView.indexAt(0, mouseY + __listView.contentY)
+                pressedIndex = modelAdaptor.mapRowToModelIndex(pressedRow)
                 pressedColumn = __listView.columnAt(mouseX)
-                if (pressedRow > -1 && oldPressedRow !== pressedRow) {
+                if (pressedRow > -1 && oldPressedIndex !== pressedIndex) {
                     __listView.currentIndex = pressedRow
-                    mouseSelect(pressedRow, mouse.modifiers, true /* drag */)
+                    mouseSelect(pressedIndex, mouse.modifiers, true /* drag */)
                 }
             }
         }
 
         onExited: {
-            pressedRow = -1
+            pressedIndex = undefined
             pressedColumn = -1
         }
 
         onCanceled: {
-            pressedRow = -1
+            pressedIndex = undefined
             pressedColumn = -1
             autoScroll = 0
         }