QQuickWidget: Clamp texture size

Copy the behavior from QQuickRhiItem, which handles this correctly.
The older QQuickWidget seems to lack that logic for some reason.

Also add a qWarning to make it clear what is happening, because
clamping the texture size may cause unexpected results in the
visual output.

Pick-to: 6.6 6.5
Fixes: QTBUG-123636
Change-Id: I08d4ac23f709c85dc975c030fd198127d7eb4d23
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
(cherry picked from commit 431da3b90556e0ffceaff4aea878c480818cdd69)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit c07953df95adb0d99098b88857c150be1c191d96)

1 files changed, 11 insertions, 1 deletions

diff --git a/src/quickwidgets/qquickwidget.cpp b/src/quickwidgets/qquickwidget.cpp
index b99838f337..5efcfc7812 100644
--- a/src/quickwidgets/qquickwidget.cpp
+++ b/src/quickwidgets/qquickwidget.cpp
@@ -1123,7 +1123,17 @@ void QQuickWidget::createFramebufferObject()
     else
         samples = 0;
 
-    const QSize fboSize = size() * devicePixelRatio();
+    const int minTexSize = d->rhi->resourceLimit(QRhi::TextureSizeMin);
+    const int maxTexSize = d->rhi->resourceLimit(QRhi::TextureSizeMax);
+
+    QSize fboSize = size() * devicePixelRatio();
+    if (fboSize.width() > maxTexSize || fboSize.height() > maxTexSize) {
+        qWarning("QQuickWidget: Requested backing texture size is %dx%d, but the maximum texture size for the 3D API implementation is %dx%d",
+                 fboSize.width(), fboSize.height(),
+                 maxTexSize, maxTexSize);
+    }
+    fboSize.setWidth(qMin(maxTexSize, qMax(minTexSize, fboSize.width())));
+    fboSize.setHeight(qMin(maxTexSize, qMax(minTexSize, fboSize.height())));
 
     // Could be a simple hide - show, in which case the previous texture is just fine.
     if (!d->outputTexture) {