QTableView: Make sure to repaint all needed cells during resizing

Don't try to update the scrollarea geometry while resizing a row or
column since this may lead in flickering and artifacts, esp when the
scroll mode is scrollPerItems. Instead do the calculation only when the
resize is finished.

Fixes: QTBUG-72870
Fixes: QTBUG-82595
Change-Id: Id6903c00485b3be6ed54bd5f9bcafdda6da21598
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 14 insertions, 8 deletions

diff --git a/src/widgets/itemviews/qtableview.cpp b/src/widgets/itemviews/qtableview.cpp
index 81fceba8dc..a8da6530a4 100644
--- a/src/widgets/itemviews/qtableview.cpp
+++ b/src/widgets/itemviews/qtableview.cpp
@@ -2939,14 +2939,17 @@ void QTableView::timerEvent(QTimerEvent *event)
     Q_D(QTableView);
 
     if (event->timerId() == d->columnResizeTimerID) {
-        updateGeometries();
-        killTimer(d->columnResizeTimerID);
-        d->columnResizeTimerID = 0;
+        const int oldScrollMax = horizontalScrollBar()->maximum();
+        if (horizontalHeader()->d_func()->state != QHeaderViewPrivate::ResizeSection) {
+            updateGeometries();
+            killTimer(d->columnResizeTimerID);
+            d->columnResizeTimerID = 0;
+        }
 
         QRect rect;
         int viewportHeight = d->viewport->height();
         int viewportWidth = d->viewport->width();
-        if (d->hasSpans()) {
+        if (d->hasSpans() || horizontalScrollBar()->value() == oldScrollMax) {
             rect = QRect(0, 0, viewportWidth, viewportHeight);
         } else {
             for (int i = d->columnsToUpdate.size()-1; i >= 0; --i) {
@@ -2964,14 +2967,17 @@ void QTableView::timerEvent(QTimerEvent *event)
     }
 
     if (event->timerId() == d->rowResizeTimerID) {
-        updateGeometries();
-        killTimer(d->rowResizeTimerID);
-        d->rowResizeTimerID = 0;
+        const int oldScrollMax = verticalScrollBar()->maximum();
+        if (verticalHeader()->d_func()->state != QHeaderViewPrivate::ResizeSection) {
+            updateGeometries();
+            killTimer(d->rowResizeTimerID);
+            d->rowResizeTimerID = 0;
+        }
 
         int viewportHeight = d->viewport->height();
         int viewportWidth = d->viewport->width();
         int top;
-        if (d->hasSpans()) {
+        if (d->hasSpans() || verticalScrollBar()->value() == oldScrollMax) {
             top = 0;
         } else {
             top = viewportHeight;