Transient quarter display with a HiDPI /4k screen and a 200% scaling

https://bugs.webkit.org/show_bug.cgi?id=219202

Patch by Alexander Mikhaylenko <alexm@gnome.org> on 2021-05-27
Reviewed by Adrian Perez de Castro.

Set the root layer transformation before syncing animations and not after.
This way we avoid having the first frame use the wrong scale on hidpi.

* Shared/CoordinatedGraphics/CoordinatedGraphicsScene.cpp:
(WebKit::CoordinatedGraphicsScene::paintToCurrentGLContext):

Canonical link: https://commits.webkit.org/238200@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@278156 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebKit/ChangeLog

@@ -1,3 +1,16 @@
+2021-05-27  Alexander Mikhaylenko  <alexm@gnome.org>
+
+        Transient quarter display with a HiDPI /4k screen and a 200% scaling
+        https://bugs.webkit.org/show_bug.cgi?id=219202
+
+        Reviewed by Adrian Perez de Castro.
+
+        Set the root layer transformation before syncing animations and not after.
+        This way we avoid having the first frame use the wrong scale on hidpi.
+
+        * Shared/CoordinatedGraphics/CoordinatedGraphicsScene.cpp:
+        (WebKit::CoordinatedGraphicsScene::paintToCurrentGLContext):
+
 2021-05-26  Chris Dumez  <cdumez@apple.com>
 
         Leverage the new Vector(const T*, size_t) constructor

Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.cpp

@@ -68,13 +68,13 @@ void CoordinatedGraphicsScene::paintToCurrentGLContext(const TransformationMatri
     if (!currentRootLayer)
         return;
 
+    if (currentRootLayer->transform() != matrix)
+        currentRootLayer->setTransform(matrix);
+
     bool sceneHasRunningAnimations = currentRootLayer->applyAnimationsRecursively(MonotonicTime::now());
     m_textureMapper->beginPainting(PaintFlags);
     m_textureMapper->beginClip(TransformationMatrix(), FloatRoundedRect(clipRect));
 
-    if (currentRootLayer->transform() != matrix)
-        currentRootLayer->setTransform(matrix);
-
     currentRootLayer->paint(*m_textureMapper);
     m_fpsCounter.updateFPSAndDisplay(*m_textureMapper, clipRect.location(), matrix);
     m_textureMapper->endClip();