When importing BGRA or RGBA data for encoding, provide variants of

the WEBPImportPicture API for RGBX and BRGX data meaning the alpha
channel should be ignored.

Note: the existing WEBPImportPictureRGBA|BGRA routines also ignore
the alpha channel, but won't in a future version of libwebp. Thus,
if WebKit continues using the existing routines, the alpha channel
will be imported and encoded in libwebp.next, and hence will break
canvas.toDataURL("image/webp") and its layout tests.

BUG=130144
TEST=Webkit test pass when using the new functions.


Review URL: https://chromiumcodereview.appspot.com/10496016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@140264 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 25 insertions, 2 deletions

diff --git a/third_party/libwebp/README.chromium b/third_party/libwebp/README.chromium
index 758051a..525267b 100644
--- a/third_party/libwebp/README.chromium
+++ b/third_party/libwebp/README.chromium
@@ -21,6 +21,8 @@ Local changes:
  * Removed examples/, documentation and build related files, keeping only
    the contents of src/.
  * Merged COPYING/PATENTS to LICENSE
+ * Add BGRX and RGBX variants to the WEBPImportPicture API (needs to be
+   upstreamed to libwebp master).
 Upstream cherry-picks:
 7bb6a9c idec: fix internal state corruption
 89cd1bb idec: fix WebPIUpdate failure
diff --git a/third_party/libwebp/enc/picture.c b/third_party/libwebp/enc/picture.c
index 2f3c96e..56ff85f3 100644
--- a/third_party/libwebp/enc/picture.c
+++ b/third_party/libwebp/enc/picture.c
@@ -593,6 +593,20 @@ int WebPPictureImportBGRA(WebPPicture* const picture,
   return Import(picture, rgba, rgba_stride, 4, 1, 1);
 }
 
+int WebPPictureImportRGBX(WebPPicture* const picture,
+                          const uint8_t* const rgba, int rgba_stride) {
+  picture->colorspace &= ~WEBP_CSP_ALPHA_BIT;
+  if (!WebPPictureAlloc(picture)) return 0;
+  return Import(picture, rgba, rgba_stride, 4, 0, 0);
+}
+
+int WebPPictureImportBGRX(WebPPicture* const picture,
+                          const uint8_t* const rgba, int rgba_stride) {
+  picture->colorspace &= ~WEBP_CSP_ALPHA_BIT;
+  if (!WebPPictureAlloc(picture)) return 0;
+  return Import(picture, rgba, rgba_stride, 4, 1, 0);
+}
+
 //------------------------------------------------------------------------------
 // Simplest call:
 
diff --git a/third_party/libwebp/webp/encode.h b/third_party/libwebp/webp/encode.h
index 31f0539..ae98419 100644
--- a/third_party/libwebp/webp/encode.h
+++ b/third_party/libwebp/webp/encode.h
@@ -249,15 +249,22 @@ WEBP_EXTERN(int) WebPPictureRescale(WebPPicture* const pic,
 // Returns 0 in case of memory error.
 WEBP_EXTERN(int) WebPPictureImportRGB(
     WebPPicture* const picture, const uint8_t* const rgb, int rgb_stride);
-// Same, but for RGBA buffer
+// Same, but for RGBA buffer.
 WEBP_EXTERN(int) WebPPictureImportRGBA(
     WebPPicture* const picture, const uint8_t* const rgba, int rgba_stride);
+// Same, but for RGBA buffer. Imports the RGB direct from the 32-bit format
+// input buffer ignoring the alpha channel. Avoids needing to copy the data
+// to a temporary 24-bit RGB buffer to import the RGB only.
+WEBP_EXTERN(int) WebPPictureImportRGBX(
+    WebPPicture* const picture, const uint8_t* const rgbx, int rgbx_stride);
 
-// Variant of the above, but taking BGR(A) input:
+// Variants of the above, but taking BGR(A|X) input.
 WEBP_EXTERN(int) WebPPictureImportBGR(
     WebPPicture* const picture, const uint8_t* const bgr, int bgr_stride);
 WEBP_EXTERN(int) WebPPictureImportBGRA(
     WebPPicture* const picture, const uint8_t* const bgra, int bgra_stride);
+WEBP_EXTERN(int) WebPPictureImportBGRX(
+    WebPPicture* const picture, const uint8_t* const bgrx, int bgrx_stride);
 
 //------------------------------------------------------------------------------
 // Main call