Fill incomplete images in SkCodec parent class

src/codec/SkSampler.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 SkSampler_DEFINED
 #define SkSampler_DEFINED
 
 #include "SkTypes.h"
 
 class SkSampler : public SkNoncopyable {
 public:
     /**
      *  Update the sampler to sample every sampleX'th pixel. Returns the
      *  width after sampling.
      */
     int setSampleX(int sampleX) {
         return this->onSetSampleX(sampleX);
     }
 
+    /**
+     * Get the the scaled width of the image.
+     *
+     * SkSampler needs the scaled width to fill uninitialized memory in
+     * incomplete images.
+     */
+    int getScaledWidth() {
+        return this->onGetScaledWidth();
+    }
+
+    /**
+     * Fill the remainder of the destination with a single color
+     *
+     * @param dst
+     * The destination row to fill from.
+     *
+     * @param colorType
+     * The color type of the rows to fill.
+     *
+     * @param width
+     * The width of the destination rows to fill
+     *
+     * @param numRows
+     * The number of rows that we need to fill.
+     *
+     * @param rowBytes
+     * Stride in bytes of the destination.
+     *
+     * @param colorOrIndex
+     * If colorType is kN32, colorOrIndex is treated as a 32-bit color.
+     * If colorType is k565, colorOrIndex is treated as a 16-bit color.
+     * If colorType is kGray, colorOrIndex is treated as an 8-bit color.
+     * If colorType is kIndex, colorOrIndex is treated as an 8-bit index.
+     * Other SkColorTypes are not supported.
+     *
+     * @param zeroInit
+     * Indicates whether memory is already zero initialized.
+     *
+     */
+    static void Fill(void* dst, SkColorType colorType, int width, int numRows, size_t rowBytes,
+            uint32_t colorOrIndex, SkCodec::ZeroInitialized zeroInit);
+
+    /**
+     * Alternate version of fill where the sampler provides the scaled width.
+     */
+    void fill(void* dst, SkColorType colorType, int numRows, size_t rowBytes, uint32_t colorOrIndex,
+            SkCodec::ZeroInitialized zeroInit) {
+        int width = this->onGetScaledWidth();
+        Fill(dst, colorType, width, numRows, rowBytes, colorOrIndex, zeroInit);
+    }
+
     virtual ~SkSampler() {}
 private:
+
+    virtual int onGetScaledWidth() = 0;
+
     virtual int onSetSampleX(int) = 0;
 };
 
 #endif // SkSampler_DEFINED