QQuickTreeView: be able to expand rows that are not yet visible in the viewHEADmaster

If the app expands a row in TreeView, that row will for a brief moment
be expanded in the proxy model, but not in the view, until the
view is polished. For that reason, when determining if a row can be
expanded or not, we should check the state of the proxy model, and
not the view.

Note: if the application needs the state of the view to reflect the
state of the proxy model immediataly after a call to expand,
forcePolish() is always possible.

Task-number: QTBUG-91374
Change-Id: Ibda8d90e2dc2077a6f24090566ce3ba20a734c29
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

2 files changed, 37 insertions, 10 deletions

diff --git a/src/qquicktreeview.cpp b/src/qquicktreeview.cpp
index c2bd912..01010e0 100644
--- a/src/qquicktreeview.cpp
+++ b/src/qquicktreeview.cpp
@@ -647,40 +647,44 @@ QQuickTreeView::~QQuickTreeView()
 
 bool QQuickTreeView::isExpanded(int row) const
 {
-    if (row < 0 || row >= rows())
+    Q_D(const QQuickTreeView);
+    if (row < 0 || row >= d->m_proxyModel.rowCount())
         return false;
 
-    return d_func()->m_proxyModel.isExpanded(row);
+    return d->m_proxyModel.isExpanded(row);
 }
 
 bool QQuickTreeView::hasChildren(int row) const
 {
-    if (row < 0 || row >= rows())
+    Q_D(const QQuickTreeView);
+    if (row < 0 || row >= d->m_proxyModel.rowCount())
         return false;
 
-    return d_func()->m_proxyModel.hasChildren(row);
+    return d->m_proxyModel.hasChildren(row);
 }
 
 bool QQuickTreeView::hasSiblings(int row) const
 {
-    if (row < 0 || row >= rows())
+    Q_D(const QQuickTreeView);
+    if (row < 0 || row >= d->m_proxyModel.rowCount())
         return false;
 
-    return d_func()->m_proxyModel.hasSiblings(row);
+    return d->m_proxyModel.hasSiblings(row);
 }
 
 int QQuickTreeView::depth(int row) const
 {
-    if (row < 0 || row >= rows())
+    Q_D(const QQuickTreeView);
+    if (row < 0 || row >= d->m_proxyModel.rowCount())
         return -1;
 
-    return d_func()->m_proxyModel.depthAtRow(row);
+    return d->m_proxyModel.depthAtRow(row);
 }
 
 void QQuickTreeView::expand(int row)
 {
     Q_D(QQuickTreeView);
-    if (row < 0 || row >= rows())
+    if (row < 0 || row >= d->m_proxyModel.rowCount())
         return;
 
     if (d->m_proxyModel.isExpanded(row))
@@ -714,7 +718,7 @@ void QQuickTreeView::toggleModelIndexExpanded(const QModelIndex &modelIndex)
 void QQuickTreeView::collapse(int row)
 {
     Q_D(QQuickTreeView);
-    if (row < 0 || row >= rows())
+    if (row < 0 || row >= d->m_proxyModel.rowCount())
         return;
 
     if (!d->m_proxyModel.isExpanded(row))
diff --git a/tests/auto/tst_treeview.cpp b/tests/auto/tst_treeview.cpp
index 413b2b3..b8f1713 100644
--- a/tests/auto/tst_treeview.cpp
+++ b/tests/auto/tst_treeview.cpp
@@ -74,6 +74,7 @@ private slots:
     void showTreeView();
     void expandAndCollapseRoot();
     void expandAndCollapseChildren();
+    void expandChildPendingToBeVisible();
     void attachedPropertiesRoot();
     void attachedPropertiesChildren();
     void emptyModel();
@@ -167,6 +168,28 @@ void tst_treeview::expandAndCollapseChildren()
     QCOMPARE(treeView->rows(), 1);
 }
 
+void tst_treeview::expandChildPendingToBeVisible()
+{
+    // Check that if we expand a row r1, and that row has a child r2 that can
+    // be expanded, we can continue to expand c2 immediately, even if r1 is
+    // still pending to be shown as expanded in the view.
+    LOAD_TREEVIEW("normaltreeview.qml");
+    QMetaObject::invokeMethod(treeView, "expand", Q_ARG(int, 0));
+    // The view has not yet been updated at this point to show
+    // the newly expanded children, so it still has only one row.
+    QCOMPARE(treeView->rows(), 1);
+    // ...but we still expand row 5, which is a child that has children
+    // in the proxy model
+    QMetaObject::invokeMethod(treeView, "expand", Q_ARG(int, 4));
+    QCOMPARE(treeView->rows(), 1);
+
+    WAIT_UNTIL_POLISHED;
+
+    // Now the view have updated to show
+    // all the rows that has been expanded.
+    QCOMPARE(treeView->rows(), 9);
+}
+
 void tst_treeview::attachedPropertiesRoot()
 {
     LOAD_TREEVIEW("normaltreeview.qml");