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>

3 files changed, 57 insertions, 11 deletions

diff --git a/tests/auto/controls/data/tst_treeview.qml b/tests/auto/controls/data/tst_treeview.qml
index 9db58f14..6e17e318 100644
--- a/tests/auto/controls/data/tst_treeview.qml
+++ b/tests/auto/controls/data/tst_treeview.qml
@@ -785,5 +785,34 @@ Item {
             compare(treeIndex.column, modelIndex.column)
             compare(treeIndex.internalId, modelIndex.internalId)
         }
+
+        function test_QTBUG_46891_selection_collapse_parent()
+        {
+            var component = Qt.createComponent("treeview/treeview_1.qml")
+            compare(component.status, Component.Ready)
+            var tree = component.createObject(container);
+            verify(tree !== null, "tree created is null")
+            var model = tree.model
+            model.removeRows(1, 9)
+            model.removeRows(1, 9, model.index(0, 0))
+            waitForRendering(tree)
+
+            var selectionModel = Qt.createQmlObject(testCase.instance_selectionModel, container, '')
+            selectionModel.model = tree.model
+            tree.selection = selectionModel
+            tree.selectionMode = SelectionMode.ExtendedSelection
+
+            var parentItem = tree.model.index(0, 0)
+            tree.expand(parentItem)
+            verify(tree.isExpanded(parentItem))
+
+            wait(100)
+            mouseClick(tree, semiIndent + 50, 20 + 100, Qt.LeftButton)
+            verify(selectionModel.isSelected(tree.currentIndex))
+
+            tree.collapse(parentItem)
+            mouseClick(tree, semiIndent + 50, 20 + 50, Qt.LeftButton)
+            verify(selectionModel.isSelected(parentItem))
+        }
     }
 }
diff --git a/tests/auto/qquicktreemodeladaptor/tst_qquicktreemodeladaptor.cpp b/tests/auto/qquicktreemodeladaptor/tst_qquicktreemodeladaptor.cpp
index 503b9e6f..b484665d 100644
--- a/tests/auto/qquicktreemodeladaptor/tst_qquicktreemodeladaptor.cpp
+++ b/tests/auto/qquicktreemodeladaptor/tst_qquicktreemodeladaptor.cpp
@@ -1138,7 +1138,8 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
 
     for (int i = 0; i < ModelRowCount; i += ModelRowCountLoopStep) {
         // Single row selection
-        const QItemSelection &sel = tma.selectionForRowRange(i, i);
+        const QModelIndex &idx = model.index(i, 0);
+        const QItemSelection &sel = tma.selectionForRowRange(idx, idx);
         QCOMPARE(sel.count(), 1);
         const QItemSelectionRange &range = sel.first();
         QCOMPARE(QModelIndex(range.topLeft()), model.index(i, 0));
@@ -1147,7 +1148,9 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
 
     for (int i = 0; i < ModelRowCount - ModelRowCountLoopStep; i += ModelRowCountLoopStep) {
         // Single range selection
-        const QItemSelection &sel = tma.selectionForRowRange(i, i + ModelRowCountLoopStep);
+        const QModelIndex &from = model.index(i, 0);
+        const QModelIndex &to = model.index(i + ModelRowCountLoopStep, 0);
+        const QItemSelection &sel = tma.selectionForRowRange(from, to);
         QCOMPARE(sel.count(), 1);
         const QItemSelectionRange &range = sel.first();
         QCOMPARE(QModelIndex(range.topLeft()), model.index(i, 0));
@@ -1155,7 +1158,9 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
     }
 
     {   // Select all, no branch expanded
-        const QItemSelection &sel = tma.selectionForRowRange(0, ModelRowCount - 1);
+        const QModelIndex &from = model.index(0, 0);
+        const QModelIndex &to = model.index(ModelRowCount - 1, 0);
+        const QItemSelection &sel = tma.selectionForRowRange(from, to);
         QCOMPARE(sel.count(), 1);
         const QItemSelectionRange &range = sel.first();
         QCOMPARE(QModelIndex(range.topLeft()), model.index(0, 0));
@@ -1167,7 +1172,9 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
     tma.expand(parent);
 
     {   // 1st item expanded, select first 5 rows
-        const QItemSelection &sel = tma.selectionForRowRange(0, 4);
+        const QModelIndex &from = tma.mapRowToModelIndex(0);
+        const QModelIndex &to = tma.mapRowToModelIndex(4);
+        const QItemSelection &sel = tma.selectionForRowRange(from, to);
         QCOMPARE(sel.count(), 2);
         // We don't know in which order the selection ranges are
         // being added, so we iterate and try to find what we expect.
@@ -1182,7 +1189,9 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
     }
 
     {   // 1st item expanded, select first 5 top-level items
-        const QItemSelection &sel = tma.selectionForRowRange(0, 4 + ModelRowCount);
+        const QModelIndex &from = tma.mapRowToModelIndex(0);
+        const QModelIndex &to = tma.mapRowToModelIndex(4 + ModelRowCount);
+        const QItemSelection &sel = tma.selectionForRowRange(from, to);
         QCOMPARE(sel.count(), 2);
         // We don't know in which order the selection ranges are
         // being added, so we iterate and try to find what we expect.
@@ -1201,7 +1210,9 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
     tma.expand(parent2);
 
     {   // 1st two items expanded, select first 5 top-level items
-        const QItemSelection &sel = tma.selectionForRowRange(0, 4 + 2 * ModelRowCount);
+        const QModelIndex &from = tma.mapRowToModelIndex(0);
+        const QModelIndex &to = tma.mapRowToModelIndex(4 + 2 * ModelRowCount);
+        const QItemSelection &sel = tma.selectionForRowRange(from, to);
         QCOMPARE(sel.count(), 3);
         // We don't know in which order the selection ranges are
         // being added, so we iterate and try to find what we expect.
@@ -1222,7 +1233,9 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
     tma.expand(parent3);
 
     {   // 1st two items, and 1st child of 1st item expanded, select first 5 rows
-        const QItemSelection &sel = tma.selectionForRowRange(0, 4);
+        const QModelIndex &from = tma.mapRowToModelIndex(0);
+        const QModelIndex &to = tma.mapRowToModelIndex(4);
+        const QItemSelection &sel = tma.selectionForRowRange(from, to);
         QCOMPARE(sel.count(), 3);
         // We don't know in which order the selection ranges are
         // being added, so we iterate and try to find what we expect.
@@ -1239,7 +1252,9 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
     }
 
     {   // 1st two items, and 1st child of 1st item expanded, select all
-        const QItemSelection &sel = tma.selectionForRowRange(0, 4 * ModelRowCount - 1);
+        const QModelIndex &from = tma.mapRowToModelIndex(0);
+        const QModelIndex &to = tma.mapRowToModelIndex(4 * ModelRowCount - 1);
+        const QItemSelection &sel = tma.selectionForRowRange(from, to);
         QCOMPARE(sel.count(), 4);
         // We don't know in which order the selection ranges are
         // being added, so we iterate and try to find what we expect.
@@ -1258,7 +1273,9 @@ void tst_QQuickTreeModelAdaptor::selectionForRowRange()
     }
 
     {   // 1st two items, and 1st child of 1st item expanded, select rows across branches
-        const QItemSelection &sel = tma.selectionForRowRange(8, 23);
+        const QModelIndex &from = tma.mapRowToModelIndex(8);
+        const QModelIndex &to = tma.mapRowToModelIndex(23);
+        const QItemSelection &sel = tma.selectionForRowRange(from, to);
         QCOMPARE(sel.count(), 4);
         // We don't know in which order the selection ranges are
         // being added, so we iterate and try to find what we expect.
diff --git a/tests/auto/shared/testmodel.h b/tests/auto/shared/testmodel.h
index 0bc06757..00e74129 100644
--- a/tests/auto/shared/testmodel.h
+++ b/tests/auto/shared/testmodel.h
@@ -124,7 +124,7 @@ public:
         return false;
     }
 
-    Q_INVOKABLE QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const
+    QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const
     {
         if (row < 0 || column < 0 || (level(parent) > levels) || column >= cols)
             return QModelIndex();
@@ -199,7 +199,7 @@ public:
         emit layoutChanged(parents);
     }
 
-    bool removeRows(int row, int count, const QModelIndex &parent)
+    Q_INVOKABLE bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex())
     {
         beginRemoveRows(parent, row, row + count - 1);
         Node *n = (Node *)parent.internalPointer();