Support more swizzles to 565 in SkCodec

src/codec/SkMaskSwizzler.cpp

Index: src/codec/SkMaskSwizzler.cpp
diff --git a/src/codec/SkMaskSwizzler.cpp b/src/codec/SkMaskSwizzler.cpp
index d0bb646740a10a2a484a324524a85f2e1d9daee9..fca1530fa7ae1b3374e4e56cec3e03bb7dedb599 100644
--- a/src/codec/SkMaskSwizzler.cpp
+++ b/src/codec/SkMaskSwizzler.cpp
@@ -63,6 +63,22 @@ static SkSwizzler::ResultAlpha swizzle_mask16_to_n32_premul(
     return COMPUTE_RESULT_ALPHA;
 }
 
+static SkSwizzler::ResultAlpha swizzle_mask16_to_565(

[msarett, 2015/08/10 17:44:24]

Would you mind adding a TODO (msarett) here to improve this routine?  IMO, one
of the few reasonable uses of bmp mask mode is to an encode an image as 565.  I
think we ought to be able to recognize that the image is encoded as 565 and
swizzle directly to 565 rather than promote to 888 and then move back down to
565.

This is something that I neglected in the past that I think should be done.

[scroggo, 2015/08/10 17:50:45]

Done.

+        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {
+
+    // Use the masks to decode to the destination
+    uint16_t* srcPtr = (uint16_t*) srcRow;
+    uint16_t* dstPtr = (uint16_t*) dstRow;
+    for (int i = 0; i < width; i++) {
+        uint16_t p = srcPtr[i];
+        uint8_t red = masks->getRed(p);
+        uint8_t green = masks->getGreen(p);
+        uint8_t blue = masks->getBlue(p);
+        dstPtr[i] = SkPack888ToRGB16(red, green, blue);
+    }
+    return SkSwizzler::kOpaque_ResultAlpha;
+}
+
 static SkSwizzler::ResultAlpha swizzle_mask24_to_n32_opaque(
         void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {
 
@@ -114,6 +130,21 @@ static SkSwizzler::ResultAlpha swizzle_mask24_to_n32_premul(
     return COMPUTE_RESULT_ALPHA;
 }
 
+static SkSwizzler::ResultAlpha swizzle_mask24_to_565(
+        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {
+
+    // Use the masks to decode to the destination
+    uint16_t* dstPtr = (uint16_t*) dstRow;
+    for (int i = 0; i < 3*width; i += 3) {
+        uint32_t p = srcRow[i] | (srcRow[i + 1] << 8) | srcRow[i + 2] << 16;
+        uint8_t red = masks->getRed(p);
+        uint8_t green = masks->getGreen(p);
+        uint8_t blue = masks->getBlue(p);
+        dstPtr[i/3] = SkPack888ToRGB16(red, green, blue);
+    }
+    return SkSwizzler::kOpaque_ResultAlpha;
+}
+
 static SkSwizzler::ResultAlpha swizzle_mask32_to_n32_opaque(
         void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {
 
@@ -168,6 +199,21 @@ static SkSwizzler::ResultAlpha swizzle_mask32_to_n32_premul(
     return COMPUTE_RESULT_ALPHA;
 }
 
+static SkSwizzler::ResultAlpha swizzle_mask32_to_565(
+        void* dstRow, const uint8_t* srcRow, int width, SkMasks* masks) {
+    // Use the masks to decode to the destination
+    uint32_t* srcPtr = (uint32_t*) srcRow;
+    uint16_t* dstPtr = (uint16_t*) dstRow;
+    for (int i = 0; i < width; i++) {
+        uint32_t p = srcPtr[i];
+        uint8_t red = masks->getRed(p);
+        uint8_t green = masks->getGreen(p);
+        uint8_t blue = masks->getBlue(p);
+        dstPtr[i] = SkPack888ToRGB16(red, green, blue);
+    }
+    return SkSwizzler::kOpaque_ResultAlpha;
+}
+
 /*
  *
  * Create a new mask swizzler
@@ -196,6 +242,15 @@ SkMaskSwizzler* SkMaskSwizzler::CreateMaskSwizzler(
                             break;
                     }
                     break;
+                case kRGB_565_SkColorType:
+                    switch (info.alphaType()) {
+                        case kOpaque_SkAlphaType:
+                            proc = &swizzle_mask16_to_565;
+                            break;
+                        default:
+                            break;
+                    }
+                    break;
                 default:
                     break;
             }
@@ -217,6 +272,15 @@ SkMaskSwizzler* SkMaskSwizzler::CreateMaskSwizzler(
                             break;
                     }
                     break;
+                case kRGB_565_SkColorType:
+                    switch (info.alphaType()) {
+                        case kOpaque_SkAlphaType:
+                            proc = &swizzle_mask24_to_565;
+                            break;
+                        default:
+                            break;
+                    }
+                    break;
                 default:
                     break;
             }
@@ -238,6 +302,15 @@ SkMaskSwizzler* SkMaskSwizzler::CreateMaskSwizzler(
                             break;
                     }
                     break;
+                case kRGB_565_SkColorType:
+                    switch (info.alphaType()) {
+                        case kOpaque_SkAlphaType:
+                            proc = &swizzle_mask32_to_565;
+                            break;
+                        default:
+                            break;
+                    }
+                    break;
                 default:
                     break;
             }