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/*
* 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.h"
#include "SkCodecPriv.h"
#include "SkColorPriv.h"
#include "SkColorTable.h"
#include "SkData.h"
#include "SkStream.h"
#include "SkWbmpCodec.h"
// Each bit represents a pixel, so width is actually a number of bits.
// A row will always be stored in bytes, so we round width up to the
// nearest multiple of 8 to get the number of bits actually in the row.
// We then divide by 8 to convert to bytes.
static inline size_t get_src_row_bytes(int width) {
return SkAlign8(width) >> 3;
}
static inline void setup_color_table(SkColorType colorType,
SkPMColor* colorPtr, int* colorCount) {
if (kIndex_8_SkColorType == colorType) {
colorPtr[0] = SK_ColorBLACK;
colorPtr[1] = SK_ColorWHITE;
*colorCount = 2;
}
}
static inline bool valid_color_type(SkColorType colorType, SkAlphaType alphaType) {
switch (colorType) {
case kN32_SkColorType:
case kIndex_8_SkColorType:
return true;
case kGray_8_SkColorType:
case kRGB_565_SkColorType:
return kOpaque_SkAlphaType == alphaType;
default:
return false;
}
}
static bool read_byte(SkStream* stream, uint8_t* data)
{
return stream->read(data, 1) == 1;
}
// http://en.wikipedia.org/wiki/Variable-length_quantity
static bool read_mbf(SkStream* stream, uint64_t* value) {
uint64_t n = 0;
uint8_t data;
const uint64_t kLimit = 0xFE00000000000000;
SkASSERT(kLimit == ~((~static_cast<uint64_t>(0)) >> 7));
do {
if (n & kLimit) { // Will overflow on shift by 7.
return false;
}
if (stream->read(&data, 1) != 1) {
return false;
}
n = (n << 7) | (data & 0x7F);
} while (data & 0x80);
*value = n;
return true;
}
static bool read_header(SkStream* stream, SkISize* size) {
{
uint8_t data;
if (!read_byte(stream, &data) || data != 0) { // unknown type
return false;
}
if (!read_byte(stream, &data) || (data & 0x9F)) { // skip fixed header
return false;
}
}
uint64_t width, height;
if (!read_mbf(stream, &width) || width > 0xFFFF || !width) {
return false;
}
if (!read_mbf(stream, &height) || height > 0xFFFF || !height) {
return false;
}
if (size) {
*size = SkISize::Make(SkToS32(width), SkToS32(height));
}
return true;
}
bool SkWbmpCodec::onRewind() {
return read_header(this->stream(), nullptr);
}
SkSwizzler* SkWbmpCodec::initializeSwizzler(const SkImageInfo& info, const SkPMColor* ctable,
const Options& opts) {
return SkSwizzler::CreateSwizzler(SkSwizzler::kBit, ctable, info, opts);
}
bool SkWbmpCodec::readRow(uint8_t* row) {
return this->stream()->read(row, fSrcRowBytes) == fSrcRowBytes;
}
SkWbmpCodec::SkWbmpCodec(const SkImageInfo& info, SkStream* stream)
: INHERITED(info, stream)
, fSrcRowBytes(get_src_row_bytes(this->getInfo().width()))
, fSwizzler(nullptr)
, fColorTable(nullptr)
{}
SkEncodedFormat SkWbmpCodec::onGetEncodedFormat() const {
return kWBMP_SkEncodedFormat;
}
SkCodec::Result SkWbmpCodec::onGetPixels(const SkImageInfo& info,
void* dst,
size_t rowBytes,
const Options& options,
SkPMColor ctable[],
int* ctableCount,
int* rowsDecoded) {
if (options.fSubset) {
// Subsets are not supported.
return kUnimplemented;
}
if (!valid_color_type(info.colorType(), info.alphaType()) ||
!valid_alpha(info.alphaType(), this->getInfo().alphaType())) {
return kInvalidConversion;
}
// Prepare a color table if necessary
setup_color_table(info.colorType(), ctable, ctableCount);
// Initialize the swizzler
SkAutoTDelete<SkSwizzler> swizzler(this->initializeSwizzler(info, ctable, options));
SkASSERT(swizzler);
// Perform the decode
SkISize size = info.dimensions();
SkAutoTMalloc<uint8_t> src(fSrcRowBytes);
void* dstRow = dst;
for (int y = 0; y < size.height(); ++y) {
if (!this->readRow(src.get())) {
*rowsDecoded = y;
return kIncompleteInput;
}
swizzler->swizzle(dstRow, src.get());
dstRow = SkTAddOffset<void>(dstRow, rowBytes);
}
return kSuccess;
}
bool SkWbmpCodec::IsWbmp(const void* buffer, size_t bytesRead) {
SkAutoTUnref<SkData> data(SkData::NewWithoutCopy(buffer, bytesRead));
SkMemoryStream stream(data);
return read_header(&stream, nullptr);
}
SkCodec* SkWbmpCodec::NewFromStream(SkStream* stream) {
SkAutoTDelete<SkStream> streamDeleter(stream);
SkISize size;
if (!read_header(stream, &size)) {
return nullptr;
}
SkImageInfo info = SkImageInfo::Make(size.width(), size.height(),
kGray_8_SkColorType, kOpaque_SkAlphaType);
return new SkWbmpCodec(info, streamDeleter.detach());
}
int SkWbmpCodec::onGetScanlines(void* dst, int count, size_t dstRowBytes) {
void* dstRow = dst;
for (int y = 0; y < count; ++y) {
if (!this->readRow(fSrcBuffer.get())) {
return y;
}
fSwizzler->swizzle(dstRow, fSrcBuffer.get());
dstRow = SkTAddOffset<void>(dstRow, dstRowBytes);
}
return count;
}
bool SkWbmpCodec::onSkipScanlines(int count) {
const size_t bytesToSkip = count * fSrcRowBytes;
return this->stream()->skip(bytesToSkip) == bytesToSkip;
}
SkCodec::Result SkWbmpCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
const Options& options, SkPMColor inputColorTable[], int* inputColorCount) {
if (options.fSubset) {
// Subsets are not supported.
return kUnimplemented;
}
if (!valid_color_type(dstInfo.colorType(), dstInfo.alphaType()) ||
!valid_alpha(dstInfo.alphaType(), this->getInfo().alphaType())) {
return kInvalidConversion;
}
// Fill in the color table
setup_color_table(dstInfo.colorType(), inputColorTable, inputColorCount);
// Copy the color table to a pointer that can be owned by the scanline decoder
if (kIndex_8_SkColorType == dstInfo.colorType()) {
fColorTable.reset(new SkColorTable(inputColorTable, 2));
}
// Initialize the swizzler
fSwizzler.reset(this->initializeSwizzler(dstInfo, get_color_ptr(fColorTable.get()), options));
SkASSERT(fSwizzler);
fSrcBuffer.reset(fSrcRowBytes);
return kSuccess;
}
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