Support decoding PNG to 565.

src/codec/SkSwizzler.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
 #include "SkSwizzler.h"
@@ skipping 98 matching lines @@
     for (int x = 0; x < width; x++) {
         SkPMColor c = ctable[src[x]];
         UPDATE_RESULT_ALPHA(c >> SK_A32_SHIFT);
         if (c != 0) {
             dst[x] = c;
         }
     }
     return COMPUTE_RESULT_ALPHA;
 }
 
+static SkSwizzler::ResultAlpha swizzle_index_to_565(
+      void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
+      int bytesPerPixel, const SkPMColor ctable[]) {
+    // FIXME: Support dithering? Requires knowing y, which I think is a bigger
+    // change.
+    uint16_t* SK_RESTRICT dst = (uint16_t*)dstRow;
+    for (int x = 0; x < width; x++) {
+        dst[x] = SkPixel32ToPixel16(ctable[*src]);
+        src += bytesPerPixel;
+    }
+    return SkSwizzler::kOpaque_ResultAlpha;
+}
+
+
 #undef A32_MASK_IN_PLACE
 
 // kGray
 
 static SkSwizzler::ResultAlpha swizzle_gray_to_n32(
         void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
         int bytesPerPixel, const SkPMColor ctable[]) {
 
     SkPMColor* SK_RESTRICT dst = (SkPMColor*)dstRow;
     for (int x = 0; x < width; x++) {
         dst[x] = SkPackARGB32NoCheck(0xFF, src[x], src[x], src[x]);
     }
     return SkSwizzler::kOpaque_ResultAlpha;
 }
 
 static SkSwizzler::ResultAlpha swizzle_gray_to_gray(
         void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
         int bytesPerPixel, const SkPMColor ctable[]) {
     memcpy(dstRow, src, width);
     return SkSwizzler::kOpaque_ResultAlpha;
 }
 
+static SkSwizzler::ResultAlpha swizzle_gray_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++) {
+        dst[x] = SkPack888ToRGB16(src[0], src[0], src[0]);
+        src += bytesPerPixel;
+    }
+    return SkSwizzler::kOpaque_ResultAlpha;
+}
+
 // kBGRX
 
 static SkSwizzler::ResultAlpha swizzle_bgrx_to_n32(
         void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
         int bytesPerPixel, const SkPMColor ctable[]) {
 
     SkPMColor* SK_RESTRICT dst = (SkPMColor*)dstRow;
     for (int x = 0; x < width; x++) {
         dst[x] = SkPackARGB32NoCheck(0xFF, src[2], src[1], src[0]);
         src += bytesPerPixel;
@@ skipping 26 matching lines @@
     INIT_RESULT_ALPHA;
     for (int x = 0; x < width; x++) {
         uint8_t alpha = src[3];
         UPDATE_RESULT_ALPHA(alpha);
         dst[x] = SkPreMultiplyARGB(alpha, src[2], src[1], src[0]);
         src += bytesPerPixel;
     }
     return COMPUTE_RESULT_ALPHA;
 }
 
-// n32
+// kRGBX
 static SkSwizzler::ResultAlpha swizzle_rgbx_to_n32(
         void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
         int bytesPerPixel, const SkPMColor ctable[]) {
 
     SkPMColor* SK_RESTRICT dst = (SkPMColor*)dstRow;
     for (int x = 0; x < width; x++) {
         dst[x] = SkPackARGB32(0xFF, src[0], src[1], src[2]);
         src += bytesPerPixel;
     }
     return SkSwizzler::kOpaque_ResultAlpha;
 }
 
+static SkSwizzler::ResultAlpha swizzle_rgbx_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++) {
+        dst[x] = SkPack888ToRGB16(src[0], src[1], src[2]);
+        src += bytesPerPixel;
+    }
+    return SkSwizzler::kOpaque_ResultAlpha;
+}
+
+
+// kRGBA
 static SkSwizzler::ResultAlpha swizzle_rgba_to_n32_premul(
         void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
         int bytesPerPixel, const SkPMColor ctable[]) {
 
     SkPMColor* SK_RESTRICT dst = (SkPMColor*)dstRow;
     INIT_RESULT_ALPHA;
     for (int x = 0; x < width; x++) {
         unsigned alpha = src[3];
         UPDATE_RESULT_ALPHA(alpha);
         dst[x] = SkPreMultiplyARGB(alpha, src[0], src[1], src[2]);
@@ skipping 93 matching lines @@
                 case kN32_SkColorType:
                     // We assume the color premultiplied ctable (or not) as desired.
                     if (SkCodec::kYes_ZeroInitialized == zeroInit) {
                         proc = &swizzle_index_to_n32_skipZ;
                         break;
                     } else {
                         proc = &swizzle_index_to_n32;
                         break;
                     }
                     break;
+                case kRGB_565_SkColorType:
+                    proc = &swizzle_index_to_565;
+                    break;
                 case kIndex_8_SkColorType:
                     proc = &swizzle_index_to_index;
                     break;
                 default:
                     break;
             }
             break;
         case kGray:
             switch (info.colorType()) {
                 case kN32_SkColorType:
                     proc = &swizzle_gray_to_n32;
                     break;
                 case kGray_8_SkColorType:
                     proc = &swizzle_gray_to_gray;
+                    break;
+                case kRGB_565_SkColorType:
+                    proc = &swizzle_gray_to_565;
+                    break;
                 default:
                     break;
             }
             break;
         case kBGR:
         case kBGRX:
             switch (info.colorType()) {
                 case kN32_SkColorType:
                     proc = &swizzle_bgrx_to_n32;
                     break;
@@ skipping 18 matching lines @@
                 default:
                     break;
             }
             break;
         case kRGBX:
             // TODO: Support other swizzles.
             switch (info.colorType()) {
                 case kN32_SkColorType:
                     proc = &swizzle_rgbx_to_n32;
                     break;
+                case kRGB_565_SkColorType:
+                    proc = &swizzle_rgbx_to_565;
                 default:
                     break;
             }
             break;
         case kRGBA:
             switch (info.colorType()) {
                 case kN32_SkColorType:
                     if (info.alphaType() == kUnpremul_SkAlphaType) {
                         // Respect zeroInit?
                         proc = &swizzle_rgba_to_n32_unpremul;
@@ skipping 103 matching lines @@
             // bits of SK_ColorBLACK are identical to the 565 representation
             // for black.
             memset(dstStartRow, (uint16_t) colorOrIndex, bytesToFill);
             break;
         default:
             SkCodecPrintf("Error: Unsupported dst color type for fill().  Doing nothing.\n");
             SkASSERT(false);
             break;
     }
 }