Support alpha in QQuickWindow::grabWindow().

Change-Id: I2dd69745427d8f5e882303d2a4de3935ddca02e9
Task-number: QTBUG-48787
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

4 files changed, 8 insertions, 4 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index c8256ed62a..6542bde4f1 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -3306,7 +3306,8 @@ QImage QQuickWindow::grabWindow()
         d->syncSceneGraph();
         d->renderSceneGraph(size());
 
-        QImage image = qt_gl_read_framebuffer(size() * effectiveDevicePixelRatio(), false, false);
+        bool alpha = format().alphaBufferSize() > 0 && color().alpha() < 255;
+        QImage image = qt_gl_read_framebuffer(size() * effectiveDevicePixelRatio(), alpha, alpha);
         d->cleanupNodesOnShutdown();
         d->context->invalidate();
         context.doneCurrent();
diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index 3059b750f2..87dd521807 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -398,7 +398,8 @@ void QSGGuiThreadRenderLoop::renderWindow(QQuickWindow *window)
     Q_QUICK_SG_PROFILE_RECORD(QQuickProfiler::SceneGraphRenderLoopFrame);
 
     if (data.grabOnly) {
-        grabContent = qt_gl_read_framebuffer(window->size() * window->effectiveDevicePixelRatio(), false, false);
+        bool alpha = window->format().alphaBufferSize() > 0 && window->color().alpha() != 255;
+        grabContent = qt_gl_read_framebuffer(window->size() * window->effectiveDevicePixelRatio(), alpha, alpha);
         data.grabOnly = false;
     }
 
diff --git a/src/quick/scenegraph/qsgthreadedrenderloop.cpp b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
index 4b78fefa99..8d6bea9e67 100644
--- a/src/quick/scenegraph/qsgthreadedrenderloop.cpp
+++ b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
@@ -421,7 +421,8 @@ bool QSGRenderThread::event(QEvent *e)
             QQuickWindowPrivate::get(ce->window)->renderSceneGraph(ce->window->size());
 
             qCDebug(QSG_LOG_RENDERLOOP) << QSG_RT_PAD << "- grabbing result";
-            *ce->image = qt_gl_read_framebuffer(windowSize * ce->window->effectiveDevicePixelRatio(), false, false);
+            bool alpha = ce->window->format().alphaBufferSize() > 0 && ce->window->color().alpha() != 255;
+            *ce->image = qt_gl_read_framebuffer(windowSize * ce->window->effectiveDevicePixelRatio(), alpha, alpha);
         }
         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 7fd9651618..04a46bf929 100644
--- a/src/quick/scenegraph/qsgwindowsrenderloop.cpp
+++ b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
@@ -312,7 +312,8 @@ QImage QSGWindowsRenderLoop::grab(QQuickWindow *window)
     d->syncSceneGraph();
     d->renderSceneGraph(window->size());
 
-    QImage image = qt_gl_read_framebuffer(window->size() * window->effectiveDevicePixelRatio(), false, false);
+    bool alpha = window->format().alphaBufferSize() > 0 && window->color().alpha() != 255;
+    QImage image = qt_gl_read_framebuffer(window->size() * window->effectiveDevicePixelRatio(), alpha, alpha);
     return image;
 }