Changeset 50408 in webkit

Timestamp:

Nov 2, 2009 7:27:16 AM (14 years ago)

Author:

senorblanco@chromium.org

Message:

This is the WebKit-side change needed to fix canvas.getImageData() for
Chromium. The unpremultiply code in Skia assumes that unpremultiplied
values should be rounded, while CG does not. In addition, the fixed
point inversion used by Skia introduces slight inaccuracies that make
us fail this test. This change brings Chromium in line with
the CG path.
​https://bugs.webkit.org/show_bug.cgi?id=30825

Reviewed by Dmitry Titov.

Covered by LayoutTests/fast/canvas/canvas-getImageData.html

• platform/graphics/skia/ImageBufferSkia.cpp:

(WebCore::getImageData):

Location:

trunk/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/skia/ImageBufferSkia.cpp (modified) (1 diff)

trunk/WebCore/ChangeLog

@@ +1 @@
+2009-10-27  Stephen White  <senorblanco@chromium.org>
+
+        Reviewed by Dmitry Titov.
+
+        This is the WebKit-side change needed to fix canvas.getImageData() for
+        Chromium.  The unpremultiply code in Skia assumes that unpremultiplied
+        values should be rounded, while CG does not.  In addition, the fixed
+        point inversion used by Skia introduces slight inaccuracies that make
+        us fail this test.  This change brings Chromium in line with
+        the CG path.
+        https://bugs.webkit.org/show_bug.cgi?id=30825
+
+        Covered by LayoutTests/fast/canvas/canvas-getImageData.html
+
+        * platform/graphics/skia/ImageBufferSkia.cpp:
+        (WebCore::getImageData):
+
 2009-11-01  Kelly Norton  <knorton@google.com>
 

trunk/WebCore/platform/graphics/skia/ImageBufferSkia.cpp

@@ -165 +165 @@
             unsigned char* destPixel = &destRow[x * 4];
             if (multiplied == Unmultiplied) {
-                SkColor color = SkPMColorToColor(srcRow[x]);
-                destPixel[0] = SkColorGetR(color);
-                destPixel[1] = SkColorGetG(color);
-                destPixel[2] = SkColorGetB(color);
-                destPixel[3] = SkColorGetA(color);
+                SkColor color = srcRow[x];
+                unsigned a = SkColorGetA(color);
+                destPixel[0] = a ? SkColorGetR(color) * 255 / a : 0;
+                destPixel[1] = a ? SkColorGetG(color) * 255 / a : 0;
+                destPixel[2] = a ? SkColorGetB(color) * 255 / a : 0;
+                destPixel[3] = a;
             } else {
                 // Input and output are both pre-multiplied, we just need to re-arrange the