Fix hidpi support for opengl window grabbing

Now set the QImage devicePixelRatio so the content is correct on all
screens.

Task-number: QTBUG-53795
Change-Id: If94edf901da1285afe9bb847b8973d568a2b7082
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

3 files changed, 3 insertions, 0 deletions

diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index ec874f6ff0..64f920e417 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -423,6 +423,7 @@ void QSGGuiThreadRenderLoop::renderWindow(QQuickWindow *window)
     if (data.grabOnly) {
         bool alpha = window->format().alphaBufferSize() > 0 && window->color().alpha() != 255;
         grabContent = qt_gl_read_framebuffer(window->size() * window->effectiveDevicePixelRatio(), alpha, alpha);
+        grabContent.setDevicePixelRatio(window->effectiveDevicePixelRatio());
         data.grabOnly = false;
     }
 
diff --git a/src/quick/scenegraph/qsgthreadedrenderloop.cpp b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
index 4543782d5b..41347cf868 100644
--- a/src/quick/scenegraph/qsgthreadedrenderloop.cpp
+++ b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
@@ -432,6 +432,7 @@ bool QSGRenderThread::event(QEvent *e)
             qCDebug(QSG_LOG_RENDERLOOP) << QSG_RT_PAD << "- grabbing result";
             bool alpha = ce->window->format().alphaBufferSize() > 0 && ce->window->color().alpha() != 255;
             *ce->image = qt_gl_read_framebuffer(windowSize * ce->window->effectiveDevicePixelRatio(), alpha, alpha);
+            ce->image->setDevicePixelRatio(ce->window->effectiveDevicePixelRatio());
         }
         qCDebug(QSG_LOG_RENDERLOOP) << QSG_RT_PAD << "- waking gui to handle result";
         waitCondition.wakeOne();
diff --git a/src/quick/scenegraph/qsgwindowsrenderloop.cpp b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
index 13388c0841..209715fff6 100644
--- a/src/quick/scenegraph/qsgwindowsrenderloop.cpp
+++ b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
@@ -326,6 +326,7 @@ QImage QSGWindowsRenderLoop::grab(QQuickWindow *window)
 
     bool alpha = window->format().alphaBufferSize() > 0 && window->color().alpha() != 255;
     QImage image = qt_gl_read_framebuffer(window->size() * window->effectiveDevicePixelRatio(), alpha, alpha);
+    image.setDevicePixelRatio(window->effectiveDevicePixelRatio());
     return image;
 }