Implement onSkipScanlines() for bmp and wbmp

src/codec/SkBmpRLECodec.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 "SkBmpRLECodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 183 matching lines @@
     fRLEBytes = remainingBytes + additionalBytes;
     return fRLEBytes;
 }
 
 /*
  * Set an RLE pixel using the color table
  */
 void SkBmpRLECodec::setPixel(void* dst, size_t dstRowBytes,
                              const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
                              uint8_t index) {
-    if (is_coord_necessary(x, fSampleX, dstInfo.width())) {
+    if (dst && is_coord_necessary(x, fSampleX, dstInfo.width())) {
         // Set the row
         uint32_t row = this->getDstRow(y, dstInfo.height());
 
         // Set the pixel based on destination color type
         const int dstX = get_dst_coord(x, fSampleX);
         switch (dstInfo.colorType()) {
             case kN32_SkColorType: {
                 SkPMColor* dstRow = SkTAddOffset<SkPMColor>(dst, row * (int) dstRowBytes);
                 dstRow[dstX] = fColorTable->operator[](index);
                 break;
@@ skipping 12 matching lines @@
     }
 }
 
 /*
  * Set an RLE pixel from R, G, B values
  */
 void SkBmpRLECodec::setRGBPixel(void* dst, size_t dstRowBytes,
                                 const SkImageInfo& dstInfo, uint32_t x,
                                 uint32_t y, uint8_t red, uint8_t green,
                                 uint8_t blue) {
-    if (is_coord_necessary(x, fSampleX, dstInfo.width())) {
+    if (dst && is_coord_necessary(x, fSampleX, dstInfo.width())) {
         // Set the row
         uint32_t row = this->getDstRow(y, dstInfo.height());
 
         // Set the pixel based on destination color type
         const int dstX = get_dst_coord(x, fSampleX);
         switch (dstInfo.colorType()) {
             case kN32_SkColorType: {
                 SkPMColor* dstRow = SkTAddOffset<SkPMColor>(dst, row * (int) dstRowBytes);
                 dstRow[dstX] = SkPackARGB32NoCheck(0xFF, red, green, blue);
                 break;
@@ skipping 61 matching lines @@
     int height = info.height();
 
     // Account for sampling.
     SkImageInfo dstInfo = info.makeWH(get_scaled_dimension(width, fSampleX), height);
 
     // Set the background as transparent.  Then, if the RLE code skips pixels,
     // the skipped pixels will be transparent.
     // Because of the need for transparent pixels, kN32 is the only color
     // type that makes sense for the destination format.
     SkASSERT(kN32_SkColorType == dstInfo.colorType());
-    SkSampler::Fill(dstInfo, dst, dstRowBytes, SK_ColorTRANSPARENT, opts.fZeroInitialized);
+    if (dst) {
+        SkSampler::Fill(dstInfo, dst, dstRowBytes, SK_ColorTRANSPARENT, opts.fZeroInitialized);
+    }
 
     // Adjust the height and the dst if the previous call to decodeRows() left us
     // with lines that need to be skipped.
     if (height > fLinesToSkip) {
         height -= fLinesToSkip;
         dst = SkTAddOffset<void>(dst, fLinesToSkip * dstRowBytes);
         fLinesToSkip = 0;
     } else {
         fLinesToSkip -= height;
         return height;
@@ skipping 163 matching lines @@
                 // Set the indicated number of pixels
                 for (int which = 0; x < endX; x++) {
                     setPixel(dst, dstRowBytes, dstInfo, x, y, indices[which]);
                     which = !which;
                 }
             }
         }
     }
 }
 
+bool SkBmpRLECodec::skipRows(int count) {
+    const SkImageInfo rowInfo = SkImageInfo::Make(this->getInfo().width(), count, kN32_SkColorType,
+            kUnpremul_SkAlphaType);
+
+    return count == this->decodeRows(rowInfo, nullptr, 0, this->options());
+}
+
 // FIXME: Make SkBmpRLECodec have no knowledge of sampling.
 //        Or it should do all sampling natively.
 //        It currently is a hybrid that needs to know what SkScaledCodec is doing.
 class SkBmpRLESampler : public SkSampler {
 public:
     SkBmpRLESampler(SkBmpRLECodec* codec)
         : fCodec(codec)
     {
         SkASSERT(fCodec);
     }
@@ skipping 17 matching lines @@
         fSampler.reset(new SkBmpRLESampler(this));
     }
 
     return fSampler;
 }
 
 int SkBmpRLECodec::setSampleX(int sampleX){
     fSampleX = sampleX;
     return get_scaled_dimension(this->getInfo().width(), sampleX);
 }