Changeset 73890 in webkit

Timestamp:

Dec 13, 2010 1:11:59 AM (13 years ago)

Author:

commit-queue@webkit.org

Message:

2010-12-13 Noel Gordon <​noel.gordon@gmail.com>

Reviewed by Eric Seidel.

[chromium] Reduce canvas.toDataURL("image/jpeg") run-time cost by 10%
​https://bugs.webkit.org/show_bug.cgi?id=50804

Follow on from r73173, unroll the SkUnPreMultiply::PMColorToColor() call
viz., compute the unpremultiplatcion in-place. This reduces the run-time
cost of jpeg encoding by 10-15% for my image test set.

No new tests: canvas.toDataURL() is covered by existing tests.

• platform/image-encoders/skia/JPEGImageEncoder.cpp: (WebCore::preMultipliedBGRAtoRGB):

Location:

trunk/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/image-encoders/skia/JPEGImageEncoder.cpp (modified) (2 diffs)

trunk/WebCore/ChangeLog

@@ +1 @@
+2010-12-13  Noel Gordon  <noel.gordon@gmail.com>
+
+        Reviewed by Eric Seidel.
+
+        [chromium] Reduce canvas.toDataURL("image/jpeg") run-time cost by 10%
+        https://bugs.webkit.org/show_bug.cgi?id=50804
+
+        Follow on from r73173, unroll the SkUnPreMultiply::PMColorToColor() call
+        viz., compute the unpremultiplatcion in-place. This reduces the run-time
+        cost of jpeg encoding by 10-15% for my image test set.
+
+        No new tests: canvas.toDataURL() is covered by existing tests.
+
+        * platform/image-encoders/skia/JPEGImageEncoder.cpp:
+        (WebCore::preMultipliedBGRAtoRGB):
+
 2010-12-13  Helder Correia  <helder@sencha.com>
 

trunk/WebCore/platform/image-encoders/skia/JPEGImageEncoder.cpp

@@ -35 +35 @@
 #include "SkBitmap.h"
 #include "SkUnPreMultiply.h"
+#include "SkColorPriv.h"
 extern "C" {
 #include <stdio.h> // jpeglib.h needs stdio.h FILE
@@ -83 +84 @@
 void preMultipliedBGRAtoRGB(const SkPMColor* input, unsigned int pixels, unsigned char* output)
 {
-    while (pixels-- > 0) {
-        SkColor unmultiplied = SkUnPreMultiply::PMColorToColor(*input++);
-        *output++ = SkColorGetR(unmultiplied);
-        *output++ = SkColorGetG(unmultiplied);
-        *output++ = SkColorGetB(unmultiplied);
+    static const SkUnPreMultiply::Scale* scale = SkUnPreMultiply::GetScaleTable();
+
+    for (; pixels-- > 0; ++input) {
+        const unsigned alpha = SkGetPackedA32(*input);
+        if ((alpha != 0) && (alpha != 255)) {
+            *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedR32(*input));
+            *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedG32(*input));
+            *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedB32(*input));
+        } else {
+            *output++ = SkGetPackedR32(*input);
+            *output++ = SkGetPackedG32(*input);
+            *output++ = SkGetPackedB32(*input);
+        }
     }
 }