Merge "Use alpha channel instead of red in drawCachedGlyphBitmap"

2 files changed, 21 insertions, 1 deletions

diff --git a/libs/hwui/PixelBuffer.h b/libs/hwui/PixelBuffer.h
index 9725a6162a2c..04225a20cfc2 100644
--- a/libs/hwui/PixelBuffer.h
+++ b/libs/hwui/PixelBuffer.h
@@ -175,6 +175,25 @@ public:
         return 0;
     }
 
+    /**
+     * Returns the alpha channel offset in the specified format.
+     *
+     * Supported formats:
+     *      GL_ALPHA
+     *      GL_RGBA
+     */
+    static uint32_t formatAlphaOffset(GLenum format) {
+        switch (format) {
+            case GL_ALPHA:
+                return 0;
+            case GL_RGBA:
+                return 3;
+        }
+
+        ALOGE("unsupported format: %d",format);
+        return 0;
+    }
+
 protected:
     /**
      * Creates a new render buffer in the specified format and dimensions.
diff --git a/libs/hwui/font/Font.cpp b/libs/hwui/font/Font.cpp
index b49329834760..eb33cf1f3fdc 100644
--- a/libs/hwui/font/Font.cpp
+++ b/libs/hwui/font/Font.cpp
@@ -215,6 +215,7 @@ void Font::drawCachedGlyphBitmap(CachedGlyphInfo* glyph, int x, int y, uint8_t*
     PixelBuffer* pixelBuffer = cacheTexture->getPixelBuffer();
 
     uint32_t formatSize = PixelBuffer::formatSize(pixelBuffer->getFormat());
+    uint32_t alpha_channel_offset = PixelBuffer::formatAlphaOffset(pixelBuffer->getFormat());
     uint32_t cacheWidth = cacheTexture->getWidth();
     uint32_t srcStride = formatSize * cacheWidth;
     uint32_t startY = glyph->mStartY * srcStride;
@@ -229,7 +230,7 @@ void Font::drawCachedGlyphBitmap(CachedGlyphInfo* glyph, int x, int y, uint8_t*
             memcpy(&bitmap[bitmapY + dstX], &cacheBuffer[cacheY + glyph->mStartX], glyph->mBitmapWidth);
         } else {
             for (uint32_t i = 0; i < glyph->mBitmapWidth; ++i) {
-                bitmap[bitmapY + dstX + i] = cacheBuffer[cacheY + (glyph->mStartX + i)*formatSize];
+                bitmap[bitmapY + dstX + i] = cacheBuffer[cacheY + (glyph->mStartX + i)*formatSize + alpha_channel_offset];
             }
         }
     }