Scanline decoding for bmp

src/codec/SkBmpMaskCodec.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 "SkBmpMaskCodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 28 matching lines @@
     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;
     }
 
-    // Initialize a the mask swizzler
-    if (!this->initializeSwizzler(dstInfo)) {
-        SkCodecPrintf("Error: cannot initialize swizzler.\n");
-        return kInvalidConversion;
+    Result result = this->prepareToDecode(dstInfo, opts, inputColorPtr, inputColorCount);
+    if (kSuccess != result) {
+        return result;
     }
 
     return this->decode(dstInfo, dst, dstRowBytes, opts);
 }
 
 bool SkBmpMaskCodec::initializeSwizzler(const SkImageInfo& dstInfo) {
     // Allocate space for a row buffer
     const size_t rowBytes = SkAlign4(compute_row_bytes(dstInfo.width(), this->bitsPerPixel()));
     fSrcBuffer.reset(SkNEW_ARRAY(uint8_t, rowBytes));
 
@@ skipping 30 matching lines @@
                     SK_ColorBLACK : SK_ColorTRANSPARENT;
             if (kNo_ZeroInitialized == opts.fZeroInitialized || 0 != fillColor) {
                 void* dstStart = this->getDstStartRow(dst, dstRowBytes, y);
                 SkSwizzler::Fill(dstStart, dstInfo, dstRowBytes, dstInfo.height() - y, fillColor,
                         NULL);
             }
             return kIncompleteInput;
         }
 
         // Decode the row in destination format
-        int row = SkBmpCodec::kBottomUp_RowOrder == this->rowOrder() ? height - 1 - y : y;
+        uint32_t row = this->getDstRow(y);
         void* dstRow = SkTAddOffset<void>(dst, row * dstRowBytes);
         fMaskSwizzler->swizzle(dstRow, srcRow);
     }
 
     // Finished decoding the entire image
     return kSuccess;
 }
+
+SkCodec::Result SkBmpMaskCodec::prepareToDecode(const SkImageInfo& dstInfo,
+        const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
+    // Initialize a the mask swizzler
+    if (!this->initializeSwizzler(dstInfo)) {
+        SkCodecPrintf("Error: cannot initialize swizzler.\n");
+        return SkCodec::kInvalidConversion;
+    }
+
+    return SkCodec::kSuccess;
+}