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 184 matching lines @@
     /**
      *  Get the next destination row to decode to
      */
     void* getDstRow() {
         // kDesignateRow_NextMode does not update the fDstRow ptr.  This function is
         // unnecessary in that case since fDstRow will always be equal to the pointer
         // passed to CreateSwizzler().
         SkASSERT(kDesignateRow_NextMode != fNextMode);
         return fDstRow;
     }
+    /**
+     *  set the sample size in the x direction

[scroggo, 2015/07/27 15:09:19]

Must be >= 1

[emmaleer, 2015/07/27 18:31:39]

Acknowledged.

+     */
+    void setSampleX(int sampleX);
 
 private:
 
 #ifdef SK_DEBUG
     /*
      *
      * Keep track of which version of next the caller is using
      *
      */
     enum NextMode {
@@ skipping 15 matching lines @@
      *  @param y Line of source.
      *  @param ctable Colors (used for kIndex source).
      */
     typedef ResultAlpha (*RowProc)(void* SK_RESTRICT dstRow,
                                    const uint8_t* SK_RESTRICT src,
                                    int width, int deltaSrc, int y,
                                    const SkPMColor ctable[]);
 
     const RowProc       fRowProc;
     const SkPMColor*    fColorTable;      // Unowned pointer
     const int           fDeltaSrc;        // if bitsPerPixel % 8 == 0

[scroggo, 2015/07/27 15:09:20]

Maybe there is a better name for this than "fDeltaSrc", which is intended to
mean "delta between source pixels". Now the true delta ends up being fDeltaSrc *
fSampleX. I haven't come up with a better name yet, though.

[emmaleer, 2015/07/27 18:31:38]

Well fDeltaSrc is always the bytes or bits between pixels.
Then, we pass fDeltaSrc * fSampleX to next(), which is the real deltaSrc.
What about calling fDeltaSrc fDeltaPixels, or fPixelDelta?
I think having pixel in the name would make sense, what do you think?

[scroggo, 2015/07/27 19:29:57]

Maybe. I'm fine to leave it as-is for now. It is still the delta not including
sampling.

[emmaleer, 2015/07/28 14:19:16]

Acknowledged.

                                           //     deltaSrc is bytesPerPixel
                                           // else
                                           //     deltaSrc is bitsPerPixel
     const SkImageInfo   fDstInfo;
     void*               fDstRow;
     const size_t        fDstRowBytes;
     int                 fCurrY;
+    int                 fX0;              // first X coord to sample. Is constant

[scroggo, 2015/07/27 15:09:19]

These are actually not const - they are modified inside setSampleX

[emmaleer, 2015/07/27 18:31:38]

Acknowledged.

+    int                 fSampleX;         // step between X samples. Is constant
 
     SkSwizzler(RowProc proc, const SkPMColor* ctable, int deltaSrc,
                const SkImageInfo& info, void* dst, size_t rowBytes);
 
 };
 #endif // SkSwizzler_DEFINED