SkJpegCodec

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 50 matching lines @@
             SkPMColor c = ctable[index];
             UPDATE_RESULT_ALPHA(c >> SK_A32_SHIFT);
             dst[x] = c;
             pixelData <<= bitsPerPixel;
             x++;
         }
     }
     return COMPUTE_RESULT_ALPHA;
 }
 
+// kIndex
+
 static SkSwizzler::ResultAlpha swizzle_index_to_index(
         void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
         int bytesPerPixel, int y, const SkPMColor ctable[]) {
 
     uint8_t* SK_RESTRICT dst = (uint8_t*) dstRow;
     memcpy(dst, src, width);
     // TODO (msarett): Should we skip the loop here and guess that the row is opaque/not opaque?
     //                 SkScaledBitmap sampler just guesses that it is opaque.  This is dangerous
     //                 and probably wrong since gif and bmp (rarely) may have alpha.
     INIT_RESULT_ALPHA;
     for (int x = 0; x < width; x++) {
         UPDATE_RESULT_ALPHA(ctable[src[x]] >> SK_A32_SHIFT);
     }
     return COMPUTE_RESULT_ALPHA;
 }
 
-// kIndex
-
 static SkSwizzler::ResultAlpha swizzle_index_to_n32(
         void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int width,
         int bytesPerPixel, int y, const SkPMColor ctable[]) {
 
     SkPMColor* SK_RESTRICT dst = (SkPMColor*)dstRow;
     INIT_RESULT_ALPHA;
     for (int x = 0; x < width; x++) {
         SkPMColor c = ctable[src[x]];
         UPDATE_RESULT_ALPHA(c >> SK_A32_SHIFT);
         dst[x] = c;
@@ skipping 12 matching lines @@
         UPDATE_RESULT_ALPHA(c >> SK_A32_SHIFT);
         if (c != 0) {
             dst[x] = c;
         }
     }
     return COMPUTE_RESULT_ALPHA;
 }
 
 #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, int y, 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, int y, const SkPMColor ctable[]) {
+    memcpy(dstRow, src, width);
+    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, int y, 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;
     }
     return SkSwizzler::kOpaque_ResultAlpha;
@@ skipping 161 matching lines @@
                         break;
                     }
                     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;
+                default:
+                    break;
+            }
+            break;
         case kBGR:
         case kBGRX:
             switch (info.colorType()) {
                 case kN32_SkColorType:
                     proc = &swizzle_bgrx_to_n32;
                     break;
                 default:
                     break;
             }
             break;
@@ skipping 145 matching lines @@
                     }
                     dstRow = SkTAddOffset<uint32_t>(dstRow, dstRowBytes);
                 }
             }
             break;
         // On an index destination color type, always assume the input is an index
         case kIndex_8_SkColorType:
             SkASSERT(colorOrIndex == (uint8_t) colorOrIndex);
             memset(dstStartRow, colorOrIndex, bytesToFill);
             break;
+        case kGray_8_SkColorType:
+            // Always fill kGray with black
+            memset(dstStartRow, 0xFF, bytesToFill);

[msarett, 2015/04/13 20:54:06]

I'm not exactly sure what the best decision is here.  I chose to always fill
with black for kGray images.

Another possible choice would be to take the low 8 bits of colorOrIndex and fill
with that.  It would be a little more confusing but also more flexible.  It
works equally well for jpeg where we want to fill with black and will pass in
SK_ColorBLACK as the colorOrIndex parameter.

[scroggo, 2015/04/14 13:10:33]

I am not familiar with kGray, but is 0xFF black? I would guess that is white?

[msarett, 2015/04/14 19:30:36]

Wow yes you are right.  This is a nice reminder to create an incomplete gray
image to test on.

+            break;
         default:
             SkCodecPrintf("Error: Unsupported dst color type for fill().  Doing nothing.\n");
             SkASSERT(false);
             break;
     }
 }