Move all knowledge of X sampling into SkScaledCodec

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 25 matching lines @@
  */
 SkCodec::Result SkBmpRLECodec::onGetPixels(const SkImageInfo& dstInfo,
                                            void* dst, size_t dstRowBytes,
                                            const Options& opts,
                                            SkPMColor* inputColorPtr,
                                            int* inputColorCount) {
     if (opts.fSubset) {
         // Subsets are not supported.
         return kUnimplemented;
     }
-    if (dstInfo.dimensions() != this->getInfo().dimensions()) {
-        SkCodecPrintf("Error: scaling not supported.\n");
-        return kInvalidScale;
-    }
     if (!conversion_possible(dstInfo, this->getInfo())) {
         SkCodecPrintf("Error: cannot convert input type to output type.\n");
         return kInvalidConversion;
     }
 
     Result result = this->prepareToDecode(dstInfo, opts, inputColorPtr, inputColorCount);
     if (kSuccess != result) {
         return result;
     }
 
@@ skipping 186 matching lines @@
                 // This case should not be reached.  We should catch an invalid
                 // color type when we check that the conversion is possible.
                 SkASSERT(false);
                 break;
         }
     }
 }
 
 SkCodec::Result SkBmpRLECodec::prepareToDecode(const SkImageInfo& dstInfo,
         const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
+    // Reset fSampleX. If it needs to be a value other than 1, it will get modified by
+    // the sampler.
+    fSampleX = 1;
     // Create the color table if necessary and prepare the stream for decode
     // Note that if it is non-NULL, inputColorCount will be modified
     if (!this->createColorTable(inputColorCount)) {
         SkCodecPrintf("Error: could not create color table.\n");
         return SkCodec::kInvalidInput;
     }
 
     // Copy the color table to the client if necessary
     copy_color_table(dstInfo, this->fColorTable, inputColorPtr, inputColorCount);
 
     // Initialize a buffer for encoded RLE data
     if (!this->initializeStreamBuffer()) {
         SkCodecPrintf("Error: cannot initialize stream buffer.\n");
         return SkCodec::kInvalidConversion;
     }
 
-    SkScaledCodec::ComputeSampleSize(dstInfo, this->getInfo(), &fSampleX, NULL);
-
     return SkCodec::kSuccess;
 }
 
 /*
  * Performs the bitmap decoding for RLE input format
  * RLE decoding is performed all at once, rather than a one row at a time
  */
-SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& dstInfo,
+SkCodec::Result SkBmpRLECodec::decodeRows(const SkImageInfo& info,
                                           void* dst, size_t dstRowBytes,
                                           const Options& opts) {
     // Set RLE flags
     static const uint8_t RLE_ESCAPE = 0;
     static const uint8_t RLE_EOL = 0;
     static const uint8_t RLE_EOF = 1;
     static const uint8_t RLE_DELTA = 2;
 
     // Set constant values
     const int width = this->getInfo().width();
-    const int height = dstInfo.height();
+    const int height = info.height();
+
+    // Account for sampling.
+    SkImageInfo dstInfo = info.makeWH(get_scaled_dimension(width, fSampleX), height);
 
     // Destination parameters
     int x = 0;
     int y = 0;
 
     // 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());
@@ skipping 156 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;
                 }
             }
         }
     }
 }
+
+class SkBmpRLESampler : public SkSampler {
+public:
+    SkBmpRLESampler(SkBmpRLECodec* codec)
+        : fCodec(codec)
+    {
+        SkASSERT(fCodec);
+    }
+
+private:
+    int onSetSampleX(int sampleX) {
+        return fCodec->setSampleX(sampleX);
+    }
+
+    // Unowned pointer. fCodec will delete this class in its destructor.
+    SkBmpRLECodec* fCodec;
+};
+
+SkSampler* SkBmpRLECodec::getSampler() {
+    if (!fSampler) {
+        fSampler.reset(new SkBmpRLESampler(this));
+    }
+
+    return fSampler;
+}
+
+int SkBmpRLECodec::setSampleX(int sampleX) {
+    fSampleX = sampleX;
+    return get_scaled_dimension(this->getInfo().width(), sampleX);
+}