YUV software decode path stride fixes.

cc/texture_uploader.cc

Index: cc/texture_uploader.cc
diff --git a/cc/texture_uploader.cc b/cc/texture_uploader.cc
index a1c812a855a9e0a1482f4728bb28a51973ca439a..50d77cf598b8d839d93dbab0b01997f315230b31 100644
--- a/cc/texture_uploader.cc
+++ b/cc/texture_uploader.cc
@@ -229,11 +229,15 @@ void TextureUploader::uploadWithTexSubImage(const uint8* image,
 
     const uint8* pixel_source;
     unsigned int bytes_per_pixel = Resource::bytesPerPixel(format);
+    // Use 4-byte row alignment (OpenGL default) for upload performance.
+    unsigned int upload_image_stride =
+        (bytes_per_pixel * source_rect.width() + 3) & ~0x3;

[danakj, 2012/11/19 22:57:00]

Oh, I see. This is ((image_stride + 3) / 4) * 4. Can you just write it like
that?

[danakj, 2012/11/19 22:58:11]

Or, make a nice descriptively named static function to do this. That'd be quite
nice.

+    m_context->pixelStorei(GL_UNPACK_ALIGNMENT, 4);
 
-    if (image_rect.width() == source_rect.width() && !offset.x()) {
-        pixel_source = &image[bytes_per_pixel * offset.y() * image_rect.width()];
+    if (upload_image_stride == image_rect.width() * bytes_per_pixel && !offset.x()) {
+        pixel_source = &image[image_rect.width() * bytes_per_pixel * offset.y()];
     } else {
-        size_t needed_size = source_rect.width() * source_rect.height() * bytes_per_pixel;
+        size_t needed_size = upload_image_stride * source_rect.height();
         if (m_subImageSize < needed_size) {
             m_subImage.reset(new uint8[needed_size]);
             m_subImageSize = needed_size;
@@ -241,7 +245,7 @@ void TextureUploader::uploadWithTexSubImage(const uint8* image,
         // Strides not equal, so do a row-by-row memcpy from the
         // paint results into a temp buffer for uploading.
         for (int row = 0; row < source_rect.height(); ++row)
-            memcpy(&m_subImage[source_rect.width() * bytes_per_pixel * row],
+            memcpy(&m_subImage[upload_image_stride * row],
                    &image[bytes_per_pixel * (offset.x() +
                           (offset.y() + row) * image_rect.width())],
                    source_rect.width() * bytes_per_pixel);
@@ -294,6 +298,12 @@ void TextureUploader::uploadWithMapTexSubImage(const uint8* image,
     // Offset from image-rect to source-rect.
     gfx::Vector2d offset(source_rect.origin() - image_rect.origin());
 
+    unsigned int bytes_per_pixel = Resource::bytesPerPixel(format);
+    // Use 4-byte row alignment (OpenGL default) for upload performance.
+    unsigned int upload_image_stride =
+        (bytes_per_pixel * source_rect.width() + 3) & ~0x3;
+    m_context->pixelStorei(GL_UNPACK_ALIGNMENT, 4);
+
     // Upload tile data via a mapped transfer buffer
     uint8* pixel_dest = static_cast<uint8*>(
         m_context->mapTexSubImage2DCHROMIUM(GL_TEXTURE_2D,
@@ -312,17 +322,15 @@ void TextureUploader::uploadWithMapTexSubImage(const uint8* image,
         return;
     }
 
-    unsigned int bytes_per_pixel = Resource::bytesPerPixel(format);
-
-    if (image_rect.width() == source_rect.width() && !offset.x()) {
+    if (upload_image_stride == image_rect.width() * bytes_per_pixel && !offset.x()) {
         memcpy(pixel_dest,
-               &image[offset.y() * image_rect.width() * bytes_per_pixel],
-               image_rect.width() * source_rect.height() * bytes_per_pixel);
+               &image[image_rect.width() * bytes_per_pixel * offset.y()],
+               source_rect.height() * image_rect.width() * bytes_per_pixel);
     } else {
         // Strides not equal, so do a row-by-row memcpy from the
         // paint results into the pixelDest
         for (int row = 0; row < source_rect.height(); ++row)
-            memcpy(&pixel_dest[source_rect.width() * row * bytes_per_pixel],
+            memcpy(&pixel_dest[upload_image_stride * row],
                    &image[bytes_per_pixel * (offset.x() +
                           (offset.y() + row) * image_rect.width())],
                    source_rect.width() * bytes_per_pixel);