Support more swizzles to 565 in SkCodec

src/codec/SkSwizzler.cpp

Index: src/codec/SkSwizzler.cpp
diff --git a/src/codec/SkSwizzler.cpp b/src/codec/SkSwizzler.cpp
index b2b7f927ac262913d86fcfd6c89af7cf430723cb..ed36d469f53126922a1e32440f675886cc8bbe6e 100644
--- a/src/codec/SkSwizzler.cpp
+++ b/src/codec/SkSwizzler.cpp
@@ -137,6 +137,28 @@ static SkSwizzler::ResultAlpha swizzle_small_index_to_index(
     return COMPUTE_RESULT_ALPHA;
 }
 
+static SkSwizzler::ResultAlpha swizzle_small_index_to_565(
+        void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
+        int bitsPerPixel, const SkPMColor ctable[]) {
+
+    uint16_t* SK_RESTRICT dst = (uint16_t*) dstRow;
+    const uint32_t pixelsPerByte = 8 / bitsPerPixel;
+    const size_t rowBytes = compute_row_bytes_ppb(width, pixelsPerByte);
+    const uint8_t mask = (1 << bitsPerPixel) - 1;
+    int x = 0;
+    for (uint32_t byte = 0; byte < rowBytes; byte++) {
+        uint8_t pixelData = src[byte];
+        for (uint32_t p = 0; p < pixelsPerByte && x < width; p++) {
+            uint8_t index = (pixelData >> (8 - bitsPerPixel)) & mask;
+            uint16_t c = SkPixel32ToPixel16(ctable[index]);
+            dst[x] = c;
+            pixelData <<= bitsPerPixel;
+            x++;
+        }
+    }
+    return SkSwizzler::kOpaque_ResultAlpha;
+}
+
 static SkSwizzler::ResultAlpha swizzle_small_index_to_n32(
         void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
         int bitsPerPixel, const SkPMColor ctable[]) {
@@ -271,6 +293,19 @@ static SkSwizzler::ResultAlpha swizzle_bgrx_to_n32(
     return SkSwizzler::kOpaque_ResultAlpha;
 }
 
+static SkSwizzler::ResultAlpha swizzle_bgrx_to_565(
+       void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
+       int bytesPerPixel, const SkPMColor ctable[]) {
+    // FIXME: Support dithering?
+    uint16_t* SK_RESTRICT dst = (uint16_t*)dstRow;
+    for (int x = 0; x < width; x++) {
+        // FIXME: I believe this is correct - still need to test.

[scroggo_chromium, 2015/08/10 17:26:16]

Oops. Will remove this in a followup

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

Acknowledged.

+        dst[x] = SkPack888ToRGB16(src[2], src[1], src[0]);
+        src += bytesPerPixel;
+    }
+    return SkSwizzler::kOpaque_ResultAlpha;
+}
+
 // kBGRA
 
 static SkSwizzler::ResultAlpha swizzle_bgra_to_n32_unpremul(
@@ -489,6 +524,9 @@ SkSwizzler* SkSwizzler::CreateSwizzler(SkSwizzler::SrcConfig sc,
                 case kN32_SkColorType:
                     proc = &swizzle_bgrx_to_n32;
                     break;
+                case kRGB_565_SkColorType:
+                    proc = &swizzle_bgrx_to_565;
+                    break;
                 default:
                     break;
             }