Implementing filling for SkBmpCodec

src/codec/SkCodec_libbmp.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 "SkCodec_libbmp.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 683 matching lines @@
             }
             colorTable[i] = packARGB(alpha, red, green, blue);
         }
 
         // To avoid segmentation faults on bad pixel data, fill the end of the
         // color table with black.  This is the same the behavior as the
         // chromium decoder.
         for (; i < maxColors; i++) {
             colorTable[i] = SkPackARGB32NoCheck(0xFF, 0, 0, 0);
         }
+
+        // Set the color table
+        fColorTable.reset(SkNEW_ARGS(SkColorTable, (colorTable, maxColors)));
     }
 
     // Bmp-in-Ico files do not use an offset to indicate where the pixel data
     // begins.  Pixel data always begins immediately after the color table.
     if (!fIsIco) {
         // Check that we have not read past the pixel array offset
         if(fOffset < colorBytes) {
             // This may occur on OS 2.1 and other old versions where the color
             // table defaults to max size, and the bmp tries to use a smaller
             // color table.  This is invalid, and our decision is to indicate
             // an error, rather than try to guess the intended size of the
             // color table.
             SkCodecPrintf("Error: pixel data offset less than color table size.\n");
             return false;
         }
 
         // After reading the color table, skip to the start of the pixel array
         if (stream()->skip(fOffset - colorBytes) != fOffset - colorBytes) {
             SkCodecPrintf("Error: unable to skip to image data.\n");
             return false;
         }
     }
 
-    // Set the color table and return true on success
-    fColorTable.reset(SkNEW_ARGS(SkColorTable, (colorTable, maxColors)));
+    // Return true on success
     return true;
 }
 
 /*
  *
  * Performs the bitmap decoding for bit masks input format
  *
  */
 SkCodec::Result SkBmpCodec::decodeMask(const SkImageInfo& dstInfo,
                                        void* dst, size_t dstRowBytes) {
@@ skipping 11 matching lines @@
     SkAutoTDelete<SkMaskSwizzler> maskSwizzler(
             SkMaskSwizzler::CreateMaskSwizzler(dstInfo, dst, dstRowBytes,
             fMasks, fBitsPerPixel));
 
     // Iterate over rows of the image
     bool transparent = true;
     for (int y = 0; y < height; y++) {
         // Read a row of the input
         if (stream()->read(srcRow, rowBytes) != rowBytes) {
             SkCodecPrintf("Warning: incomplete input stream.\n");
+            // Fill the destination image on failure
+            // By using zero as the fill value, we will fill with transparent
+            // pixels for non-opaque images and white for opaque images.
+            // These are arbitrary choices but allow for consistent behavior.
+            SkSwizzler::Fill(dst, dstInfo, dstRowBytes, y, 0, NULL,
+                    fRowOrder == kBottomUp_RowOrder);
             return kIncompleteInput;
         }
 
         // Decode the row in destination format
         int row = kBottomUp_RowOrder == fRowOrder ? height - 1 - y : y;
         SkSwizzler::ResultAlpha r = maskSwizzler->next(srcRow, row);
         transparent &= SkSwizzler::IsTransparent(r);
 
         // Move to the next row
         srcRow = SkTAddOffset<uint8_t>(srcRow, rowBytes);
@@ skipping 319 matching lines @@
                 config = SkSwizzler::kBGRX;
             } else {
                 config = SkSwizzler::kBGRA;
             }
             break;
         default:
             SkASSERT(false);
             return kInvalidInput;
     }
 
+    // Get a pointer to the color table if it exists
+    const SkPMColor* colorPtr = NULL != fColorTable.get() ? fColorTable->readColors() : NULL;
+
     // Create swizzler
     SkAutoTDelete<SkSwizzler> swizzler(SkSwizzler::CreateSwizzler(config,
-            fColorTable->readColors(), dstInfo, dst, dstRowBytes,
+            colorPtr, dstInfo, dst, dstRowBytes,
             SkImageGenerator::kNo_ZeroInitialized));
 
     // Allocate space for a row buffer and a source for the swizzler
     SkAutoTDeleteArray<uint8_t> srcBuffer(SkNEW_ARRAY(uint8_t, rowBytes));
 
     // Iterate over rows of the image
     // FIXME: bool transparent = true;
     for (int y = 0; y < height; y++) {
         // Read a row of the input
         if (stream()->read(srcBuffer.get(), rowBytes) != rowBytes) {
             SkCodecPrintf("Warning: incomplete input stream.\n");
+            // Fill the destination image on failure
+            // By using zero as the fill value, we will fill with the first
+            // color in the color table for palette images, transparent
+            // pixels for non-opaque images, and white for opaque images.
+            // These are arbitrary choices but allow for consistent behavior.
+            SkSwizzler::Fill(dst, dstInfo, dstRowBytes, y, 0, colorPtr,
+                    fRowOrder == kBottomUp_RowOrder);
             return kIncompleteInput;
         }
 
         // Decode the row in destination format
         uint32_t row;
         if (kTopDown_RowOrder == fRowOrder) {
             row = y;
         } else {
             row = height - 1 - y;
         }
@@ skipping 61 matching lines @@
                 uint32_t alphaBit =
                         (srcBuffer.get()[quotient] >> shift) & 0x1;
                 dstRow[x] &= alphaBit - 1;
             }
         }
     }
 
     // Finished decoding the entire image
     return kSuccess;
 }