Changeset 101286 in webkit

Timestamp:

Nov 28, 2011 2:55:32 PM (12 years ago)

Author:

noel.gordon@gmail.com

Message:

[chromium] Use data decoding swizzle for turbo JPEG image decoding.
​https://bugs.webkit.org/show_bug.cgi?id=59670

Reviewed by Kenneth Russell.

Add a BGRX row decode data swizzle for the little-endian ports that use libjpeg-turbo
(Chromium win/linux/mac) to reduce JPEG image decoding time by ~2x.

JPEG images of type JSC_GRAYSCALE are excluded since layout regressions were observed
for grayscale images produced by older tools (XV 3.10a 12/19/94). libjpeg decodes the
images without error; libjpeg-turbo caused visible artifacts (see bug for examples).

This patch is based on the work of Hironori Bono. He provided the original patch, and
the quantitative results confirming the significant performance improvement.

No new tests. Covered by many existing tests.

• platform/image-decoders/jpeg/JPEGImageDecoder.cpp:

(rgbOutputColorSpace): If JCS_EXTENSIONS is defined (libjpeg-turbo), and the port is
little-endian, define a BGRX data swizzle for use when decoding pixel rows.
(turboSwizzled):
(WebCore::JPEGImageReader::decode): Select a possibly swizzled rgbOutputColorSpace()
for JSC_RGB and JCS_YCbCr input color space images. Exclude JSC_GRAYSCALE images.
(WebCore::JPEGImageDecoder::outputScanlines): Swizzle decode, if applicable.

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/image-decoders/jpeg/JPEGImageDecoder.cpp (modified) (3 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2011-11-28  Noel Gordon  <noel.gordon@gmail.com>
+
+        [chromium] Use data decoding swizzle for turbo JPEG image decoding.
+        https://bugs.webkit.org/show_bug.cgi?id=59670
+
+        Reviewed by Kenneth Russell.
+
+        Add a BGRX row decode data swizzle for the little-endian ports that use libjpeg-turbo
+        (Chromium win/linux/mac) to reduce JPEG image decoding time by ~2x.
+
+        JPEG images of type JSC_GRAYSCALE are excluded since layout regressions were observed
+        for grayscale images produced by older tools (XV 3.10a 12/19/94). libjpeg decodes the
+        images without error; libjpeg-turbo caused visible artifacts (see bug for examples).
+
+        This patch is based on the work of Hironori Bono. He provided the original patch, and
+        the quantitative results confirming the significant performance improvement.
+
+        No new tests. Covered by many existing tests.
+
+        * platform/image-decoders/jpeg/JPEGImageDecoder.cpp:
+        (rgbOutputColorSpace):  If JCS_EXTENSIONS is defined (libjpeg-turbo), and the port is
+        little-endian, define a BGRX data swizzle for use when decoding pixel rows.
+        (turboSwizzled):
+        (WebCore::JPEGImageReader::decode):  Select a possibly swizzled rgbOutputColorSpace()
+        for JSC_RGB and JCS_YCbCr input color space images.  Exclude JSC_GRAYSCALE images.
+        (WebCore::JPEGImageDecoder::outputScanlines):  Swizzle decode, if applicable.
+
 2011-11-28  Fady Samuel  <fsamuel@chromium.org>
 

trunk/Source/WebCore/platform/image-decoders/jpeg/JPEGImageDecoder.cpp

@@ -64 +64 @@
 #include <setjmp.h>
 
+#if CPU(BIG_ENDIAN) || CPU(MIDDLE_ENDIAN)
+#define ASSUME_LITTLE_ENDIAN 0
+#else
+#define ASSUME_LITTLE_ENDIAN 1
+#endif
+
+#if defined(JCS_EXTENSIONS) && ASSUME_LITTLE_ENDIAN
+#define TURBO_JPEG_RGB_SWIZZLE
+inline J_COLOR_SPACE rgbOutputColorSpace() { return JCS_EXT_BGRX; }
+inline bool turboSwizzled(J_COLOR_SPACE colorSpace) { return colorSpace == rgbOutputColorSpace(); }
+#else
+inline J_COLOR_SPACE rgbOutputColorSpace() { return JCS_RGB; }
+#endif
+
 namespace WebCore {
 
@@ -222 +236 @@
                 // again, resulting in horizontal distortions.
                 m_decoder->setIgnoreGammaAndColorProfile(true);
-                // Note fall-through!
+                m_info.out_color_space = JCS_RGB;
+                break;
             case JCS_YCbCr:
             case JCS_RGB:
-                m_info.out_color_space = JCS_RGB;
+                m_info.out_color_space = rgbOutputColorSpace();
                 break;
             case JCS_CMYK:
@@ -482 +497 @@
 
     jpeg_decompress_struct* info = m_reader->info();
+
+#if !ENABLE(IMAGE_DECODER_DOWN_SAMPLING) && defined(TURBO_JPEG_RGB_SWIZZLE)
+    if (turboSwizzled(info->out_color_space)) {
+         ASSERT(!m_scaled);
+         while (info->output_scanline < info->output_height) {
+             unsigned char* row = reinterpret_cast<unsigned char*>(buffer.getAddr(0, info->output_scanline));
+             if (jpeg_read_scanlines(info, &row, 1) != 1)
+                  return false;
+         }
+         return true;
+     }
+#endif
+
     JSAMPARRAY samples = m_reader->samples();