Filx complier issue [-Werror, -Wvla]

src/codec/SkRawCodec.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 387 matching lines @@
     // Because the DNG SDK can not guarantee to render to requested size, we allow a small
     // difference. Only the overlapping region will be converted.
     const float maxDiffRatio = 1.03f;
     const dng_point& imageSize = image->Size();
     if (imageSize.h / width > maxDiffRatio || imageSize.h < width ||
         imageSize.v / height > maxDiffRatio || imageSize.v < height) {
         return SkCodec::kInvalidScale;
     }
 
     void* dstRow = dst;
-    uint8_t srcRow[width * 3];
+
+    static const int kStackBytes = 640 * 1024;  // Ought to be enough for anybody.

[msarett, 2016/01/27 14:51:05]

Any reason to not put this on the heap?

[yujieqin, 2016/01/27 14:53:00]

I do not have preference here. Just follow the code in
https://bugs.chromium.org/p/skia/issues/detail?id=4861#c1. 

Should I do somehow differently?

[mtklein, 2016/01/27 14:53:32]

Sorry, that number was a bit of a joke.  How long is a typical row?  Is it a
reasonable thing to put on the stack?

If not, SkAutoTMalloc<uint8_t> srcRow(width * 3); will put it on the heap
unconditionally as Matt suggests.

[yujieqin, 2016/01/27 14:57:53]

Normally I would think it should be around thousands of pixels. But it is not
possible to limit the width of an image somehow (e.g. panorama image). I think
the condition here could still be good?

[msarett, 2016/01/27 15:02:14]

Let's use this:
SkAutoTMalloc<uint8_t> srcRow(width * 3);

It matches our other codecs, it avoid putting a (potentially very large)
allocation on the stack, and it prevents us from worrying about how large width
can truly be.

[yujieqin, 2016/01/27 15:16:23]

Done.

+    SkAutoSTMalloc<kStackBytes, uint8_t> srcRow(width * 3);
 
     dng_pixel_buffer buffer;
     buffer.fData = &srcRow[0];
     buffer.fPlane = 0;
     buffer.fPlanes = 3;
     buffer.fColStep = buffer.fPlanes;
     buffer.fPlaneStep = 1;
     buffer.fPixelType = ttByte;
     buffer.fPixelSize = sizeof(uint8_t);
     buffer.fRowStep = sizeof(srcRow);
@@ skipping 47 matching lines @@
     SkISize sizeFloor = this->onGetScaledDimensions(1.f / std::floor(fullShortEdge / shortEdge));
     SkISize sizeCeil = this->onGetScaledDimensions(1.f / std::ceil(fullShortEdge / shortEdge));
     return sizeFloor == dim || sizeCeil == dim;
 }
 
 SkRawCodec::~SkRawCodec() {}
 
 SkRawCodec::SkRawCodec(SkDngImage* dngImage)
     : INHERITED(dngImage->getImageInfo(), nullptr)
     , fDngImage(dngImage) {}