Split SkBmpCodec into three separate classes
Will regress behavior on gold on test32bfv4.bmp, where we
will no longer fix transparent decodes.
TODO: Start fixing transparent decodes again, or decide
that we don't want to fix them and remove isTransparent
from SkSwizzler. I think this may become more clear when I
start implementing the scanline decoder.
BUG=skia:
Review URL: https://codereview.chromium.org/1258863008
diff --git a/src/codec/SkBmpMaskCodec.cpp b/src/codec/SkBmpMaskCodec.cpp
new file mode 100644
index 0000000..f30266b
--- /dev/null
+++ b/src/codec/SkBmpMaskCodec.cpp
@@ -0,0 +1,137 @@
+/*
+ * 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"
+
+/*
+ * Checks if the conversion between the input image and the requested output
+ * image has been implemented
+ */
+static bool conversion_possible(const SkImageInfo& dst,
+ const SkImageInfo& src) {
+ // Ensure that the profile type is unchanged
+ if (dst.profileType() != src.profileType()) {
+ return false;
+ }
+
+ // Ensure the alpha type is valid
+ if (!valid_alpha(dst.alphaType(), src.alphaType())) {
+ return false;
+ }
+
+ // Check for supported color types
+ switch (dst.colorType()) {
+ // Allow output to kN32
+ case kN32_SkColorType:
+ return true;
+ default:
+ return false;
+ }
+}
+
+
+/*
+ * Creates an instance of the decoder
+ */
+SkBmpMaskCodec::SkBmpMaskCodec(const SkImageInfo& info, SkStream* stream,
+ uint16_t bitsPerPixel, SkMasks* masks,
+ SkBmpCodec::RowOrder rowOrder)
+ : INHERITED(info, stream, bitsPerPixel, rowOrder)
+ , fMasks(masks)
+ , fMaskSwizzler(NULL)
+ , fSrcBuffer(NULL)
+{}
+
+/*
+ * Initiates the bitmap decode
+ */
+SkCodec::Result SkBmpMaskCodec::onGetPixels(const SkImageInfo& dstInfo,
+ void* dst, size_t dstRowBytes,
+ const Options& opts,
+ SkPMColor* inputColorPtr,
+ int* inputColorCount) {
+ if (!this->handleRewind(false)) {
+ return kCouldNotRewind;
+ }
+ 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;
+ }
+
+ // Initialize a the mask swizzler
+ if (!this->initializeSwizzler(dstInfo)) {
+ SkCodecPrintf("Error: cannot initialize swizzler.\n");
+ return kInvalidConversion;
+ }
+
+ 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));
+
+ // Create the swizzler
+ fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(
+ dstInfo, fMasks, this->bitsPerPixel()));
+
+ if (NULL == fMaskSwizzler.get()) {
+ return false;
+ }
+
+ return true;
+}
+
+/*
+ * Performs the decoding
+ */
+SkCodec::Result SkBmpMaskCodec::decode(const SkImageInfo& dstInfo,
+ void* dst, size_t dstRowBytes,
+ const Options& opts) {
+ // Set constant values
+ const int width = dstInfo.width();
+ const int height = dstInfo.height();
+ const size_t rowBytes = SkAlign4(compute_row_bytes(width, this->bitsPerPixel()));
+
+ // Iterate over rows of the image
+ uint8_t* srcRow = fSrcBuffer.get();
+ for (int y = 0; y < height; y++) {
+ // Read a row of the input
+ if (this->stream()->read(srcRow, rowBytes) != rowBytes) {
+ SkCodecPrintf("Warning: incomplete input stream.\n");
+ // Fill the destination image on failure
+ SkPMColor fillColor = dstInfo.alphaType() == kOpaque_SkAlphaType ?
+ 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;
+ void* dstRow = SkTAddOffset<void>(dst, row * dstRowBytes);
+ fMaskSwizzler->swizzle(dstRow, srcRow);
+ }
+
+ // Finished decoding the entire image
+ return kSuccess;
+}