[GPU Process] [iOS] REGRESSION(r293570): Snapshot rendering is not sc…

…aled with the device scale factor

https://bugs.webkit.org/show_bug.cgi?id=240100
rdar://92635752

Reviewed by Simon Fraser.

The scaling factor is not set in the GraphicsContext of the
ImageBufferShareableBitmapBackend.

To fix this bug is to make snapshotFrameRectWithClip() handle the scaling
outside the ImageBuffer creation. This is similar to what we do in
GraphicsContext::createAlignedImageBuffer() where we scale the size and
create the ImageBuffer with scaleFactor = 1.

* page/FrameSnapshotting.cpp:
(WebCore::snapshotFrameRectWithClip):

Canonical link: https://commits.webkit.org/250298@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@293825 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/ChangeLog

@@ -1,3 +1,22 @@
+2022-05-05  Said Abou-Hallawa  <said@apple.com>
+
+        [GPU Process] [iOS] REGRESSION(r293570): Snapshot rendering is not scaled with the device scale factor
+        https://bugs.webkit.org/show_bug.cgi?id=240100
+        rdar://92635752
+
+        Reviewed by Simon Fraser.
+
+        The scaling factor is not set in the GraphicsContext of the
+        ImageBufferShareableBitmapBackend.
+
+        To fix this bug is to make snapshotFrameRectWithClip() handle the scaling
+        outside the ImageBuffer creation. This is similar to what we do in
+        GraphicsContext::createAlignedImageBuffer() where we scale the size and
+        create the ImageBuffer with scaleFactor = 1.
+
+        * page/FrameSnapshotting.cpp:
+        (WebCore::snapshotFrameRectWithClip):
+
 2022-05-05  Youenn Fablet  <youenn@apple.com>
 
         SWOriginStore is no longer needed

Source/WebCore/page/FrameSnapshotting.cpp

@@ -115,19 +115,23 @@ RefPtr<ImageBuffer> snapshotFrameRectWithClip(Frame& frame, const IntRect& image
     if (options.flags.contains(SnapshotFlags::PaintWithIntegralScaleFactor))
         scaleFactor = ceilf(scaleFactor);
 
+    auto scaledImageRect = imageRect;
+    scaledImageRect.scale(scaleFactor);
+
     auto purpose = options.flags.contains(SnapshotFlags::Shareable) ? RenderingPurpose::ShareableSnapshot : RenderingPurpose::Snapshot;
     auto hostWindow = (document->view() && document->view()->root()) ? document->view()->root()->hostWindow() : nullptr;
 
-    auto buffer = ImageBuffer::create(imageRect.size(), purpose, scaleFactor, options.colorSpace, options.pixelFormat, { }, { hostWindow });
+    auto buffer = ImageBuffer::create(scaledImageRect.size(), purpose, 1, options.colorSpace, options.pixelFormat, { }, { hostWindow });
     if (!buffer)
         return nullptr;
 
-    buffer->context().translate(-imageRect.x(), -imageRect.y());
+    buffer->context().translate(-scaledImageRect.location());
+    buffer->context().scale(scaleFactor);
 
     if (!clipRects.isEmpty()) {
         Path clipPath;
         for (auto& rect : clipRects)
-            clipPath.addRect(encloseRectToDevicePixels(rect, scaleFactor));
+            clipPath.addRect(rect);
         buffer->context().clipPath(clipPath);
     }