[webkit-changes] [109173] trunk/Source/WebCore

Tue, 28 Feb 2012 17:17:37 -0800

Title: [109173] trunk/Source/WebCore
Revision
109173
Author
[email protected]
Date
2012-02-28 17:17:27 -0800 (Tue, 28 Feb 2012)

Log Message

[chromium] Work around IOSurface-related corruption during readback
https://bugs.webkit.org/show_bug.cgi?id=79735

Reviewed by James Robinson.

Copy the compositor's IOSurface-backed output into a temporary
texture and perform the ReadPixels operation against that texture.

It is infeasible to write an automated test for this issue.
Tested manually by performing print preview multiple times against
pages containing WebGL content on 10.7 and observing that the
corruption in the output is no longer present.

* platform/graphics/chromium/LayerRendererChromium.cpp:
(WebCore::LayerRendererChromium::getFramebufferPixels):

Modified Paths

Diff

Modified: trunk/Source/WebCore/ChangeLog (109172 => 109173)


--- trunk/Source/WebCore/ChangeLog	2012-02-29 01:13:08 UTC (rev 109172)
+++ trunk/Source/WebCore/ChangeLog	2012-02-29 01:17:27 UTC (rev 109173)
@@ -1,3 +1,21 @@
+2012-02-28  Kenneth Russell  <[email protected]>
+
+        [chromium] Work around IOSurface-related corruption during readback
+        https://bugs.webkit.org/show_bug.cgi?id=79735
+
+        Reviewed by James Robinson.
+
+        Copy the compositor's IOSurface-backed output into a temporary
+        texture and perform the ReadPixels operation against that texture.
+
+        It is infeasible to write an automated test for this issue.
+        Tested manually by performing print preview multiple times against
+        pages containing WebGL content on 10.7 and observing that the
+        corruption in the output is no longer present.
+
+        * platform/graphics/chromium/LayerRendererChromium.cpp:
+        (WebCore::LayerRendererChromium::getFramebufferPixels):
+
 2012-02-28  Adrienne Walker  <[email protected]>
 
         [chromium] Inform v8 about extra memory used for PatternSkia clamp mode

Modified: trunk/Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp (109172 => 109173)


--- trunk/Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp	2012-02-29 01:13:08 UTC (rev 109172)
+++ trunk/Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp	2012-02-29 01:17:27 UTC (rev 109173)
@@ -135,6 +135,21 @@
 }
 #endif
 
+bool needsLionIOSurfaceReadbackWorkaround()
+{
+#if OS(DARWIN)
+    static SInt32 systemVersion = 0;
+    if (!systemVersion) {
+        if (Gestalt(gestaltSystemVersion, &systemVersion) != noErr)
+            return false;
+    }
+
+    return systemVersion >= 0x1070;
+#else
+    return false;
+#endif
+}
+
 } // anonymous namespace
 
 class LayerRendererSwapBuffersCompleteCallbackAdapter : public Extensions3DChromium::SwapBuffersCompleteCallbackCHROMIUM {
@@ -1059,8 +1074,44 @@
 
     makeContextCurrent();
 
-    GLC(m_context.get(), m_context->readPixels(rect.x(), rect.y(), rect.width(), rect.height(),
-                                         GraphicsContext3D::RGBA, GraphicsContext3D::UNSIGNED_BYTE, pixels));
+    bool doWorkaround = needsLionIOSurfaceReadbackWorkaround();
+
+    Platform3DObject temporaryTexture = NullPlatform3DObject;
+    Platform3DObject temporaryFBO = NullPlatform3DObject;
+    GraphicsContext3D* context = m_context.get();
+
+    if (doWorkaround) {
+        // On Mac OS X 10.7, calling glReadPixels against an FBO whose color attachment is an
+        // IOSurface-backed texture causes corruption of future glReadPixels calls, even those on
+        // different OpenGL contexts. It is believed that this is the root cause of top crasher
+        // http://crbug.com/99393. <rdar://problem/10949687>
+
+        temporaryTexture = context->createTexture();
+        GLC(context, context->bindTexture(GraphicsContext3D::TEXTURE_2D, temporaryTexture));
+        GLC(context, context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_MIN_FILTER, GraphicsContext3D::LINEAR));
+        GLC(context, context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_MAG_FILTER, GraphicsContext3D::LINEAR));
+        GLC(context, context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_WRAP_S, GraphicsContext3D::CLAMP_TO_EDGE));
+        GLC(context, context->texParameteri(GraphicsContext3D::TEXTURE_2D, GraphicsContext3D::TEXTURE_WRAP_T, GraphicsContext3D::CLAMP_TO_EDGE));
+        // Copy the contents of the current (IOSurface-backed) framebuffer into a temporary texture.
+        GLC(context, context->copyTexImage2D(GraphicsContext3D::TEXTURE_2D, 0, GraphicsContext3D::RGBA, 0, 0, rect.maxX(), rect.maxY(), 0));
+        temporaryFBO = context->createFramebuffer();
+        // Attach this texture to an FBO, and perform the readback from that FBO.
+        GLC(context, context->bindFramebuffer(GraphicsContext3D::FRAMEBUFFER, temporaryFBO));
+        GLC(context, context->framebufferTexture2D(GraphicsContext3D::FRAMEBUFFER, GraphicsContext3D::COLOR_ATTACHMENT0, GraphicsContext3D::TEXTURE_2D, temporaryTexture, 0));
+
+        ASSERT(context->checkFramebufferStatus(GraphicsContext3D::FRAMEBUFFER) == GraphicsContext3D::FRAMEBUFFER_COMPLETE);
+    }
+
+    GLC(context, context->readPixels(rect.x(), rect.y(), rect.width(), rect.height(),
+                                     GraphicsContext3D::RGBA, GraphicsContext3D::UNSIGNED_BYTE, pixels));
+
+    if (doWorkaround) {
+        // Clean up.
+        GLC(context, context->bindFramebuffer(GraphicsContext3D::FRAMEBUFFER, 0));
+        GLC(context, context->bindTexture(GraphicsContext3D::TEXTURE_2D, 0));
+        GLC(context, context->deleteFramebuffer(temporaryFBO));
+        GLC(context, context->deleteTexture(temporaryTexture));
+    }
 }
 
 ManagedTexture* LayerRendererChromium::getOffscreenLayerTexture()

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