Scanline decoding for bmp

src/codec/SkBmpStandardCodec.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 "SkBmpStandardCodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 35 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;
     }
 
-    // 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(dstInfo.alphaType(), inputColorCount)) {
-        SkCodecPrintf("Error: could not create color table.\n");
-        return kInvalidInput;
-    }
-
-    // Copy the color table to the client if necessary
-    copy_color_table(dstInfo, fColorTable, inputColorPtr, inputColorCount);
-
-    // Initialize a swizzler if necessary
-    if (!this->initializeSwizzler(dstInfo, opts)) {
-        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);
 }
 
 /*
  * Process the color table for the bmp input
  */
  bool SkBmpStandardCodec::createColorTable(SkAlphaType alphaType, int* numColors) {
     // Allocate memory for color table
@@ skipping 83 matching lines @@
         }
     }
 
     // Return true on success
     return true;
 }
 
 bool SkBmpStandardCodec::initializeSwizzler(const SkImageInfo& dstInfo,
                                             const Options& opts) {
     // Allocate space for a row buffer
-    const size_t rowBytes = SkAlign4(compute_row_bytes(dstInfo.width(), this->bitsPerPixel()));
+    const size_t rowBytes = SkAlign4(compute_row_bytes(this->getInfo().width(),
+            this->bitsPerPixel()));
     fSrcBuffer.reset(SkNEW_ARRAY(uint8_t, rowBytes));
 
     // Get swizzler configuration
     SkSwizzler::SrcConfig config;
     switch (this->bitsPerPixel()) {
         case 1:
             config = SkSwizzler::kIndex1;
             break;
         case 2:
             config = SkSwizzler::kIndex2;
@@ skipping 60 matching lines @@
             SkASSERT(false);
             return 0;
     }
     return fillColorOrIndex;
 }
 
 /*
  * Performs the bitmap decoding for standard input format
  */
 SkCodec::Result SkBmpStandardCodec::decode(const SkImageInfo& dstInfo,
-                                   void* dst, size_t dstRowBytes,
-                                   const Options& opts) {
+                                           void* dst, size_t dstRowBytes,
+                                           const Options& opts) {
     // Set constant values
-    const int width = dstInfo.width();
+    const int width = this->getInfo().width();
     const int height = dstInfo.height();
     const size_t rowBytes = SkAlign4(compute_row_bytes(width, this->bitsPerPixel()));
 
     // Iterate over rows of the image
     for (int y = 0; y < height; y++) {
         // Read a row of the input
         if (this->stream()->read(fSrcBuffer.get(), rowBytes) != rowBytes) {
             SkCodecPrintf("Warning: incomplete input stream.\n");
             // Fill the destination image on failure
             // Get the fill color/index and check if it is 0
             uint32_t fillColorOrIndex = get_fill_color_or_index(this->bitsPerPixel(),
                     dstInfo.alphaType());
             bool zeroFill = (0 == fillColorOrIndex);
 
             if (kNo_ZeroInitialized == opts.fZeroInitialized || !zeroFill) {
                 // Get a pointer to the color table if it exists
                 const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());
 
                 void* dstStart = this->getDstStartRow(dst, dstRowBytes, y);
                 SkSwizzler::Fill(dstStart, dstInfo, dstRowBytes, dstInfo.height() - y,
                         fillColorOrIndex, colorPtr);
             }
             return kIncompleteInput;
         }
 
         // Decode the row in destination format
-        uint32_t row;
-        if (SkBmpCodec::kTopDown_RowOrder == this->rowOrder()) {
-            row = y;
-        } else {
-            row = height - 1 - y;
-        }
+        uint32_t row = this->getDstRow(y);
 
         void* dstRow = SkTAddOffset<void>(dst, row * dstRowBytes);
         fSwizzler->swizzle(dstRow, fSrcBuffer.get());
     }
 
     // Finally, apply the AND mask for bmp-in-ico images
     if (fInIco) {
         // BMP in ICO have transparency, so this cannot be 565, and this mask
         // prevents us from using kIndex8. The below code depends on the output
         // being an SkPMColor.
         SkASSERT(dstInfo.colorType() == kN32_SkColorType);
 
         // The AND mask is always 1 bit per pixel
         const size_t rowBytes = SkAlign4(compute_row_bytes(width, 1));
 
         SkPMColor* dstPtr = (SkPMColor*) dst;
         for (int y = 0; y < height; y++) {
             // The srcBuffer will at least be large enough
             if (stream()->read(fSrcBuffer.get(), rowBytes) != rowBytes) {
                 SkCodecPrintf("Warning: incomplete AND mask for bmp-in-ico.\n");
                 return kIncompleteInput;
             }
 
-            int row;
-            if (SkBmpCodec::kBottomUp_RowOrder == this->rowOrder()) {
-                row = height - y - 1;
-            } else {
-                row = y;
-            }
+            int row = this->getDstRow(y);
 
             SkPMColor* dstRow =
                     SkTAddOffset<SkPMColor>(dstPtr, row * dstRowBytes);
 
             for (int x = 0; x < width; x++) {
                 int quotient;
                 int modulus;
                 SkTDivMod(x, 8, &quotient, &modulus);
                 uint32_t shift = 7 - modulus;
                 uint32_t alphaBit =
                         (fSrcBuffer.get()[quotient] >> shift) & 0x1;
                 dstRow[x] &= alphaBit - 1;
             }
         }
     }
 
     // Finished decoding the entire image
     return kSuccess;
 }
+
+SkCodec::Result SkBmpStandardCodec::prepareToDecode(const SkImageInfo& dstInfo,
+        const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
+    // 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(dstInfo.alphaType(), 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 swizzler if necessary
+    if (!this->initializeSwizzler(dstInfo, options)) {
+        SkCodecPrintf("Error: cannot initialize swizzler.\n");
+        return SkCodec::kInvalidConversion;
+    }
+    return SkCodec::kSuccess;
+}