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/**
** Copyright 2006, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
#include "SkImageDecoder.h"
#include "SkColor.h"
#include "SkColorPriv.h"
#include "SkMath.h"
#include "SkStream.h"
#include "SkTemplates.h"
#include "SkUtils.h"
class SkWBMPImageDecoder : public SkImageDecoder {
public:
virtual Format getFormat() const {
return kWBMP_Format;
}
protected:
virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode);
};
static bool read_byte(SkStream* stream, uint8_t* data)
{
return stream->read(data, 1) == 1;
}
static bool read_mbf(SkStream* stream, int* value)
{
int n = 0;
uint8_t data;
do {
if (!read_byte(stream, &data)) {
return false;
}
n = (n << 7) | (data & 0x7F);
} while (data & 0x80);
*value = n;
return true;
}
struct wbmp_head {
int fWidth;
int fHeight;
bool init(SkStream* stream)
{
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;
}
if (!read_mbf(stream, &fWidth) || (unsigned)fWidth > 0xFFFF) {
return false;
}
if (!read_mbf(stream, &fHeight) || (unsigned)fHeight > 0xFFFF) {
return false;
}
return fWidth != 0 && fHeight != 0;
}
};
static void expand_bits_to_bytes(uint8_t dst[], const uint8_t src[], int bits)
{
int bytes = bits >> 3;
for (int i = 0; i < bytes; i++) {
unsigned mask = *src++;
dst[0] = (mask >> 7) & 1;
dst[1] = (mask >> 6) & 1;
dst[2] = (mask >> 5) & 1;
dst[3] = (mask >> 4) & 1;
dst[4] = (mask >> 3) & 1;
dst[5] = (mask >> 2) & 1;
dst[6] = (mask >> 1) & 1;
dst[7] = (mask >> 0) & 1;
dst += 8;
}
bits &= 7;
if (bits > 0) {
unsigned mask = *src;
do {
*dst++ = (mask >> 7) & 1;;
mask <<= 1;
} while (--bits != 0);
}
}
#define SkAlign8(x) (((x) + 7) & ~7)
bool SkWBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap,
Mode mode)
{
wbmp_head head;
if (!head.init(stream)) {
return false;
}
int width = head.fWidth;
int height = head.fHeight;
// assign these directly, in case we return kDimensions_Result
decodedBitmap->setConfig(SkBitmap::kIndex8_Config, width, height);
decodedBitmap->setIsOpaque(true);
if (SkImageDecoder::kDecodeBounds_Mode == mode)
return true;
const SkPMColor colors[] = { SK_ColorBLACK, SK_ColorWHITE };
SkColorTable* ct = SkNEW_ARGS(SkColorTable, (colors, 2));
SkAutoUnref aur(ct);
if (!this->allocPixelRef(decodedBitmap, ct)) {
return false;
}
SkAutoLockPixels alp(*decodedBitmap);
uint8_t* dst = decodedBitmap->getAddr8(0, 0);
// store the 1-bit valuess at the end of our pixels, so we won't stomp
// on them before we're read them. Just trying to avoid a temp allocation
size_t srcRB = SkAlign8(width) >> 3;
size_t srcSize = height * srcRB;
uint8_t* src = dst + decodedBitmap->getSize() - srcSize;
if (stream->read(src, srcSize) != srcSize) {
return false;
}
for (int y = 0; y < height; y++)
{
expand_bits_to_bytes(dst, src, width);
dst += decodedBitmap->rowBytes();
src += srcRB;
}
return true;
}
///////////////////////////////////////////////////////////////////////////////
#include "SkTRegistry.h"
static SkImageDecoder* Factory(SkStream* stream) {
wbmp_head head;
if (head.init(stream)) {
return SkNEW(SkWBMPImageDecoder);
}
return NULL;
}
static SkTRegistry<SkImageDecoder*, SkStream*> gReg(Factory);
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