SkScaledCodec class

src/codec/SkSwizzler.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkSwizzler_DEFINED
 #define SkSwizzler_DEFINED
 
@@ skipping 97 matching lines @@
      *
      */
     static int BytesPerPixel(SrcConfig sc) {
         SkASSERT(SkIsAlign8(BitsPerPixel(sc)));
         return BitsPerPixel(sc) >> 3;
     }
 
     /**
      *  Create a new SkSwizzler.
      *  @param SrcConfig Description of the format of the source.
-     *  @param SkImageInfo dimensions() describe both the src and the dst.
-     *              Other fields describe the dst.
+     *  @param dstInfo dimensions() describe destination.

[scroggo, 2015/07/31 13:35:33]

The comment used to distinguish between the dimensions, which applied to both
source and width, and the other fields, which only applied to the dst. Now the
whole struct describes the dst (not just the dimensions).

[emmaleer, 2015/07/31 18:41:56]

Acknowledged.

      *  @param dst Destination to write pixels. Must match info and dstRowBytes
      *  @param dstRowBytes rowBytes for dst.
      *  @param ZeroInitialized Whether dst is zero-initialized. The
                                implementation may choose to skip writing zeroes
      *                         if set to kYes_ZeroInitialized.
+     *  @param srcWidth is the width of the source. Used to calculate the width samplesize. 

[scroggo, 2015/07/31 13:35:33]

I think this could use a little bit more explanation. I think it's correct that
we support a width sample size but not a height, but it's not necessarily
intuitive. It would be good to explain the use here.

[emmaleer, 2015/07/31 18:41:56]

Acknowledged.

      *  @return A new SkSwizzler or NULL on failure.
      */
     static SkSwizzler* CreateSwizzler(SrcConfig, const SkPMColor* ctable,
-                                      const SkImageInfo&, void* dst,
+                                      const SkImageInfo& dstInfo, void* dst,
                                       size_t dstRowBytes,
-                                      SkCodec::ZeroInitialized);
+                                      SkCodec::ZeroInitialized, int srcWidth);
 
     /**
      * Fill the remainder of the destination with a single color
      *
      * @param dstStartRow
      * The destination row to fill from.
      *
      * @param numRows
      * The number of rows to fill.
      *
@@ skipping 97 matching lines @@
     const RowProc       fRowProc;
     const SkPMColor*    fColorTable;      // Unowned pointer
     const int           fDeltaSrc;        // if bitsPerPixel % 8 == 0
                                           //     deltaSrc is bytesPerPixel
                                           // else
                                           //     deltaSrc is bitsPerPixel
     const SkImageInfo   fDstInfo;
     void*               fDstRow;
     const size_t        fDstRowBytes;
     int                 fCurrY;
+    const int           fX0;              // first X coord to sample
+    const int           fSampleX;         // step between X samples
 
     SkSwizzler(RowProc proc, const SkPMColor* ctable, int deltaSrc,
-               const SkImageInfo& info, void* dst, size_t rowBytes);
+               const SkImageInfo& info, void* dst, size_t rowBytes, int sampleX);
 
 };
 #endif // SkSwizzler_DEFINED