Changeset 65020 in webkit

Timestamp:

Aug 9, 2010 5:25:18 PM (14 years ago)

Author:

eric@webkit.org

Message:

2010-08-09 Nat Duca <​nduca@chromium.org>

Reviewed by Dimitri Glazkov.

[chromium] Blue line visible at the right hand side of the window with accelerated compositor
​https://bugs.webkit.org/show_bug.cgi?id=43748

Correct the ortho projection matrix for the root layer, which was
too large by 0.5px in both width and height. For even view sizes,
this would cause the viewport to appear 1 pixel too small.

Fixing this requires removal of several 0.5 correction factors
that were previously added to compensate for the too-large viewport.

Finally, compute the translation for the root layer quad using
floating point rather than integer arithmetic. This avoids us losing
a key half-pixel of translation when the width of the window is odd.

To test, size window to even/odd dimensions. No blue line should be visible.

• platform/graphics/chromium/LayerRendererChromium.cpp: (WebCore::LayerRendererChromium::drawLayers):

Location:

trunk/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/chromium/LayerRendererChromium.cpp (modified) (3 diffs)

trunk/WebCore/ChangeLog

@@ +1 @@
+2010-08-09  Nat Duca  <nduca@chromium.org>
+
+        Reviewed by Dimitri Glazkov.
+
+        [chromium] Blue line visible at the right hand side of the window with accelerated compositor
+        https://bugs.webkit.org/show_bug.cgi?id=43748
+
+        Correct the ortho projection matrix for the root layer, which was
+        too large by 0.5px in both width and height. For even view sizes,
+        this would cause the viewport to appear 1 pixel too small.
+
+        Fixing this requires removal of several 0.5 correction factors
+        that were previously added to compensate for the too-large viewport.
+
+        Finally, compute the translation for the root layer quad using
+        floating point rather than integer arithmetic. This avoids us losing
+        a key half-pixel of translation when the width of the window is odd.
+
+        To test, size window to even/odd dimensions. No blue line should be visible.
+
+        * platform/graphics/chromium/LayerRendererChromium.cpp:
+        (WebCore::LayerRendererChromium::drawLayers):
+
 2010-08-09  Ryosuke Niwa  <rniwa@webkit.org>
 

trunk/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp

@@ -334 +334 @@
         m_rootLayerTextureHeight = visibleRect.height();
 
-        m_projectionMatrix = orthoMatrix(0, visibleRectWidth + 0.5, visibleRectHeight + 0.5, 0, -1000, 1000);
+        m_projectionMatrix = orthoMatrix(0, visibleRectWidth, visibleRectHeight, 0, -1000, 1000);
         glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_rootLayerTextureWidth, m_rootLayerTextureHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
 
@@ -392 +392 @@
 #endif
 
-        scrolledLayerMatrix.translate3d((int)floorf(0.5 * visibleRect.width() + 0.5) - scrollDelta.x(),
-            (int)floorf(0.5 * visibleRect.height() + 0.5) + scaleFactor * scrollDelta.y(), 0);
+        scrolledLayerMatrix.translate3d((int)floorf(0.5 * visibleRect.width()) - scrollDelta.x(),
+            (int)floorf(0.5 * visibleRect.height()) + scaleFactor * scrollDelta.y(), 0);
         scrolledLayerMatrix.scale3d(1, -1, 1);
 
@@ -458 +458 @@
     checkGLError();
     TransformationMatrix layerMatrix;
-    layerMatrix.translate3d(visibleRect.width() / 2, visibleRect.height() / 2, 0);
+    layerMatrix.translate3d(visibleRect.width() * 0.5f, visibleRect.height() * 0.5f, 0);
     drawTexturedQuad(layerMatrix, visibleRect.width(), visibleRect.height(), 1);
     checkGLError();