Correct viewport for GL drawing when webview is on FBO

bug:6283539

Change-Id: I0d5fb92a9ad7e8b6781900bbc08e5afd48c53614

1 files changed, 8 insertions, 4 deletions

diff --git a/Source/WebKit/android/nav/WebView.cpp b/Source/WebKit/android/nav/WebView.cpp
index a4381e6..0cf0079 100644
--- a/Source/WebKit/android/nav/WebView.cpp
+++ b/Source/WebKit/android/nav/WebView.cpp
@@ -709,13 +709,17 @@ class GLDrawFunctor : Functor {
         int titlebarHeight = webViewRect.height() - viewRect.height();
 
         uirenderer::DrawGlInfo* info = reinterpret_cast<uirenderer::DrawGlInfo*>(data);
-        WebCore::IntRect localViewRect = viewRect;
-        if (info->isLayer)
-            localViewRect.move(-1 * localViewRect.x(), -1 * localViewRect.y());
-
         WebCore::IntRect clip(info->clipLeft, info->clipTop,
                               info->clipRight - info->clipLeft,
                               info->clipBottom - info->clipTop);
+
+        WebCore::IntRect localViewRect = viewRect;
+        if (info->isLayer) {
+            // When webview is on a layer, we need to use the viewport relative
+            // to the FBO, rather than the screen(which will use viewRect).
+            localViewRect.setX(clip.x());
+            localViewRect.setY(info->height - clip.y() - clip.height());
+        }
         bool shouldDraw = (messageId == uirenderer::DrawGlInfo::kModeDraw);
         TilesManager::instance()->shader()->setWebViewMatrix(info->transform, info->isLayer);
         int returnFlags = (*wvInstance.*funcPtr)(localViewRect, &inval, webViewRect,