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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 "SkColorPriv.h"
#include "SkStream.h"
#include "SkCodec_wbmp.h"
// 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) {
uint64_t width, height;
uint16_t data;
if (stream->read(&data, 2) != 2 || data != 0) {
return false;
}
if (!read_mbf(stream, &width) || width > 0xFFFF || !width) {
return false;
}
if (!read_mbf(stream, &height) || width > 0xFFFF || !height) {
return false;
}
if (size) {
*size = SkISize::Make(SkToS32(width), SkToS32(height));
}
return true;
}
#define BLACK SkPackARGB32NoCheck(0xFF, 0, 0, 0)
#define WHITE SkPackARGB32NoCheck(0xFF, 0xFF, 0xFF, 0xFF)
#define GRAYSCALE_BLACK 0
#define GRAYSCALE_WHITE 0xFF
#define RGB565_BLACK 0
#define RGB565_WHITE 0xFFFF
static SkPMColor bit_to_pmcolor(U8CPU bit) { return bit ? WHITE : BLACK; }
static uint8_t bit_to_bit(U8CPU bit) { return bit; }
static uint8_t bit_to_grayscale(U8CPU bit) {
return bit ? GRAYSCALE_WHITE : GRAYSCALE_BLACK;
}
static uint16_t bit_to_rgb565(U8CPU bit) {
return bit ? RGB565_WHITE : RGB565_BLACK;
}
typedef void (*ExpandProc)(uint8_t*, const uint8_t*, int);
// TODO(halcanary): Add this functionality (grayscale and indexed output) to
// SkSwizzler and use it here.
template <typename T, T (*TRANSFORM)(U8CPU)>
static void expand_bits_to_T(uint8_t* dstptr, const uint8_t* src, int bits) {
T* dst = reinterpret_cast<T*>(dstptr);
int bytes = bits >> 3;
for (int i = 0; i < bytes; i++) {
U8CPU mask = *src++;
for (int j = 0; j < 8; j++) {
dst[j] = TRANSFORM((mask >> (7 - j)) & 1);
}
dst += 8;
}
bits &= 7;
if (bits > 0) {
U8CPU mask = *src;
do {
*dst++ = TRANSFORM((mask >> 7) & 1);
mask <<= 1;
} while (--bits != 0);
}
}
SkWbmpCodec::SkWbmpCodec(const SkImageInfo& info, SkStream* stream)
: INHERITED(info, stream) {}
SkEncodedFormat SkWbmpCodec::onGetEncodedFormat() const {
return kWBMP_SkEncodedFormat;
}
SkImageGenerator::Result SkWbmpCodec::onGetPixels(const SkImageInfo& info,
void* pixels,
size_t rowBytes,
const Options&,
SkPMColor ctable[],
int* ctableCount) {
SkCodec::RewindState rewindState = this->rewindIfNeeded();
if (rewindState == kCouldNotRewind_RewindState) {
return SkImageGenerator::kCouldNotRewind;
} else if (rewindState == kRewound_RewindState) {
(void)read_header(this->stream(), NULL);
}
if (info.dimensions() != this->getInfo().dimensions()) {
return SkImageGenerator::kInvalidScale;
}
ExpandProc proc = NULL;
switch (info.colorType()) {
case kGray_8_SkColorType:
proc = expand_bits_to_T<uint8_t, bit_to_grayscale>;
break;
case kN32_SkColorType:
proc = expand_bits_to_T<SkPMColor, bit_to_pmcolor>;
break;
case kIndex_8_SkColorType:
ctable[0] = BLACK;
ctable[1] = WHITE;
*ctableCount = 2;
proc = expand_bits_to_T<uint8_t, bit_to_bit>;
break;
case kRGB_565_SkColorType:
proc = expand_bits_to_T<uint16_t, bit_to_rgb565>;
break;
default:
return SkImageGenerator::kInvalidConversion;
}
SkISize size = info.dimensions();
uint8_t* dst = static_cast<uint8_t*>(pixels);
size_t srcRowBytes = SkAlign8(size.width()) >> 3;
SkAutoTMalloc<uint8_t> src(srcRowBytes);
for (int y = 0; y < size.height(); ++y) {
if (this->stream()->read(src.get(), srcRowBytes) != srcRowBytes) {
return SkImageGenerator::kIncompleteInput;
}
proc(dst, src.get(), size.width());
dst += rowBytes;
}
return SkImageGenerator::kSuccess;
}
bool SkWbmpCodec::IsWbmp(SkStream* stream) {
return read_header(stream, NULL);
}
SkCodec* SkWbmpCodec::NewFromStream(SkStream* stream) {
SkAutoTDelete<SkStream> streamDeleter(stream);
SkISize size;
if (!read_header(stream, &size)) {
return NULL;
}
SkImageInfo info =
SkImageInfo::Make(size.width(), size.height(), kGray_8_SkColorType,
kOpaque_SkAlphaType);
return SkNEW_ARGS(SkWbmpCodec, (info, streamDeleter.detach()));
}
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