/*
* Copyright 2006 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkImageDecoder.h"
#include "SkStream.h"
#include "SkColorPriv.h"
#include "SkTypes.h"
class SkICOImageDecoder : public SkImageDecoder {
public:
SkICOImageDecoder();
virtual Format getFormat() const {
return kICO_Format;
}
protected:
virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode);
};
SkImageDecoder* SkCreateICOImageDecoder();
SkImageDecoder* SkCreateICOImageDecoder() {
return new SkICOImageDecoder;
}
/////////////////////////////////////////////////////////////////////////////////////////
//read bytes starting from the begin-th index in the buffer
//read in Intel order, and return an integer
#define readByte(buffer,begin) buffer[begin]
#define read2Bytes(buffer,begin) buffer[begin]+(buffer[begin+1]<<8)
#define read4Bytes(buffer,begin) buffer[begin]+(buffer[begin+1]<<8)+(buffer[begin+2]<<16)+(buffer[begin+3]<<24)
/////////////////////////////////////////////////////////////////////////////////////////
SkICOImageDecoder::SkICOImageDecoder()
{
}
//helpers - my function pointer will call one of these, depending on the bitCount, each time through the inner loop
static void editPixelBit1(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors);
static void editPixelBit4(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors);
static void editPixelBit8(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors);
static void editPixelBit24(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors);
static void editPixelBit32(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors);
static int calculateRowBytesFor8888(int w, int bitCount)
{
// Default rowBytes is w << 2 for kARGB_8888
// In the case of a 4 bit image with an odd width, we need to add some
// so we can go off the end of the drawn bitmap.
// Add 4 to ensure that it is still a multiple of 4.
if (4 == bitCount && (w & 0x1)) {
return (w + 1) << 2;
}
// Otherwise return 0, which will allow it to be calculated automatically.
return 0;
}
bool SkICOImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode)
{
size_t length = stream->read(NULL, 0);
SkAutoMalloc autoMal(length);
unsigned char* buf = (unsigned char*)autoMal.get();
if (stream->read((void*)buf, length) != length) {
return false;
}
//these should always be the same - should i use for error checking? - what about files that have some
//incorrect values, but still decode properly?
int reserved = read2Bytes(buf, 0); // 0
int type = read2Bytes(buf, 2); // 1
if (reserved != 0 || type != 1)
return false;
int count = read2Bytes(buf, 4);
//need to at least have enough space to hold the initial table of info
if (length < (size_t)(6 + count*16))
return false;
int choice;
Chooser* chooser = this->getChooser();
//FIXME:if no chooser, consider providing the largest color image
//what are the odds that the largest image would be monochrome?
if (NULL == chooser) {
choice = 0;
} else {
chooser->begin(count);
for (int i = 0; i < count; i++)
{
//need to find out the config, width, and height from the stream
int width = readByte(buf, 6 + i*16);
int height = readByte(buf, 7 + i*16);
int offset = read4Bytes(buf, 18 + i*16);
int bitCount = read2Bytes(buf, offset+14);
SkBitmap::Config c;
//currently only provide ARGB_8888_, but maybe we want kIndex8_Config for 1 and 4, and possibly 8?
//or maybe we'll determine this based on the provided config
switch (bitCount)
{
case 1:
case 4:
// In reality, at least for the moment, these will be decoded into kARGB_8888 bitmaps.
// However, this will be used to distinguish between the lower quality 1bpp and 4 bpp
// images and the higher quality images.
c = SkBitmap::kIndex8_Config;
break;
case 8:
case 24:
case 32:
c = SkBitmap::kARGB_8888_Config;
break;
default:
SkDEBUGF(("Image with %ibpp not supported\n", bitCount));
continue;
}
chooser->inspect(i, c, width, height);
}
choice = chooser->choose();
}
//you never know what the chooser is going to supply
if (choice >= count || choice < 0)
return false;
//skip ahead to the correct header
//commented out lines are not used, but if i switch to other read method, need to know how many to skip
//otherwise, they could be used for error checking
int w = readByte(buf, 6 + choice*16);
int h = readByte(buf, 7 + choice*16);
int colorCount = readByte(buf, 8 + choice*16);
//int reservedToo = readByte(buf, 9 + choice*16); //0
//int planes = read2Bytes(buf, 10 + choice*16); //1 - but often 0
//int fakeBitCount = read2Bytes(buf, 12 + choice*16); //should be real - usually 0
int size = read4Bytes(buf, 14 + choice*16); //matters?
int offset = read4Bytes(buf, 18 + choice*16);
if ((size_t)(offset + size) > length)
return false;
//int infoSize = read4Bytes(buf, offset); //40
//int width = read4Bytes(buf, offset+4); //should == w
//int height = read4Bytes(buf, offset+8); //should == 2*h
//int planesToo = read2Bytes(buf, offset+12); //should == 1 (does it?)
int bitCount = read2Bytes(buf, offset+14);
void (*placePixel)(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors) = NULL;
switch (bitCount)
{
case 1:
placePixel = &editPixelBit1;
colorCount = 2;
break;
case 4:
placePixel = &editPixelBit4;
colorCount = 16;
break;
case 8:
placePixel = &editPixelBit8;
colorCount = 256;
break;
case 24:
placePixel = &editPixelBit24;
colorCount = 0;
break;
case 32:
placePixel = &editPixelBit32;
colorCount = 0;
break;
default:
SkDEBUGF(("Decoding %ibpp is unimplemented\n", bitCount));
return false;
}
//these should all be zero, but perhaps are not - need to check
//int compression = read4Bytes(buf, offset+16); //0
//int imageSize = read4Bytes(buf, offset+20); //0 - sometimes has a value
//int xPixels = read4Bytes(buf, offset+24); //0
//int yPixels = read4Bytes(buf, offset+28); //0
//int colorsUsed = read4Bytes(buf, offset+32) //0 - might have an actual value though
//int colorsImportant = read4Bytes(buf, offset+36); //0
int begin = offset + 40;
//this array represents the colortable
//if i allow other types of bitmaps, it may actually be used as a part of the bitmap
SkPMColor* colors = NULL;
int blue, green, red;
if (colorCount)
{
colors = new SkPMColor[colorCount];
for (int j = 0; j < colorCount; j++)
{
//should this be a function - maybe a #define?
blue = readByte(buf, begin + 4*j);
green = readByte(buf, begin + 4*j + 1);
red = readByte(buf, begin + 4*j + 2);
colors[j] = SkPackARGB32(0xFF, red & 0xFF, green & 0xFF, blue & 0xFF);
}
}
int bitWidth = w*bitCount;
int test = bitWidth & 0x1F;
int mask = -(((test >> 4) | (test >> 3) | (test >> 2) | (test >> 1) | test) & 0x1); //either 0xFFFFFFFF or 0
int lineBitWidth = (bitWidth & 0xFFFFFFE0) + (0x20 & mask);
int lineWidth = lineBitWidth/bitCount;
int xorOffset = begin + colorCount*4; //beginning of the color bitmap
//other read method means we will just be here already
int andOffset = xorOffset + ((lineWidth*h*bitCount) >> 3);
/*int */test = w & 0x1F; //the low 5 bits - we are rounding up to the next 32 (2^5)
/*int */mask = -(((test >> 4) | (test >> 3) | (test >> 2) | (test >> 1) | test) & 0x1); //either 0xFFFFFFFF or 0
int andLineWidth = (w & 0xFFFFFFE0) + (0x20 & mask);
//if we allow different Configs, everything is the same til here
//change the config, and use different address getter, and place index vs color, and add the color table
//FIXME: what is the tradeoff in size?
//if the andbitmap (mask) is all zeroes, then we can easily do an index bitmap
//however, with small images with large colortables, maybe it's better to still do argb_8888
if (SkImageDecoder::kDecodeBounds_Mode == mode) {
bm->setConfig(SkBitmap::kARGB_8888_Config, w, h, calculateRowBytesFor8888(w, bitCount));
delete[] colors;
return true;
}
#ifdef SK_BUILD_FOR_ANDROID
// No Bitmap reuse supported for this format
if (!bm->isNull()) {
return false;
}
#endif
bm->setConfig(SkBitmap::kARGB_8888_Config, w, h, calculateRowBytesFor8888(w, bitCount));
if (!this->allocPixelRef(bm, NULL))
{
delete[] colors;
return false;
}
SkAutoLockPixels alp(*bm);
for (int y = 0; y < h; y++)
{
for (int x = 0; x < w; x++)
{
//U32* address = bm->getAddr32(x, y);
//check the alpha bit first, but pass it along to the function to figure out how to deal with it
int andPixelNo = andLineWidth*(h-y-1)+x;
//only need to get a new alphaByte when x %8 == 0
//but that introduces an if and a mod - probably much slower
//that's ok, it's just a read of an array, not a stream
int alphaByte = readByte(buf, andOffset + (andPixelNo >> 3));
int shift = 7 - (andPixelNo & 0x7);
int m = 1 << shift;
int pixelNo = lineWidth*(h-y-1)+x;
placePixel(pixelNo, buf, xorOffset, x, y, w, bm, alphaByte, m, shift, colors);
}
}
delete [] colors;
//ensure we haven't read off the end?
//of course this doesn't help us if the andOffset was a lie...
//return andOffset + (andLineWidth >> 3) <= length;
return true;
} //onDecode
//function to place the pixel, determined by the bitCount
static void editPixelBit1(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors)
{
// note that this should be the same as/similar to the AND bitmap
SkPMColor* address = bm->getAddr32(x,y);
int byte = readByte(buf, xorOffset + (pixelNo >> 3));
int colorBit;
int alphaBit;
// Read all of the bits in this byte.
int i = x + 8;
// Pin to the width so we do not write outside the bounds of
// our color table.
i = i > w ? w : i;
// While loop to check all 8 bits individually.
while (x < i)
{
colorBit = (byte & m) >> shift;
alphaBit = (alphaByte & m) >> shift;
*address = (alphaBit-1)&(colors[colorBit]);
x++;
// setup for the next pixel
address = address + 1;
m = m >> 1;
shift -= 1;
}
x--;
}
static void editPixelBit4(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors)
{
SkPMColor* address = bm->getAddr32(x, y);
int byte = readByte(buf, xorOffset + (pixelNo >> 1));
int pixel = (byte >> 4) & 0xF;
int alphaBit = (alphaByte & m) >> shift;
*address = (alphaBit-1)&(colors[pixel]);
x++;
//if w is odd, x may be the same as w, which means we are writing to an unused portion of the bitmap
//but that's okay, since i've added an extra rowByte for just this purpose
address = address + 1;
pixel = byte & 0xF;
m = m >> 1;
alphaBit = (alphaByte & m) >> (shift-1);
//speed up trick here
*address = (alphaBit-1)&(colors[pixel]);
}
static void editPixelBit8(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors)
{
SkPMColor* address = bm->getAddr32(x, y);
int pixel = readByte(buf, xorOffset + pixelNo);
int alphaBit = (alphaByte & m) >> shift;
*address = (alphaBit-1)&(colors[pixel]);
}
static void editPixelBit24(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors)
{
SkPMColor* address = bm->getAddr32(x, y);
int blue = readByte(buf, xorOffset + 3*pixelNo);
int green = readByte(buf, xorOffset + 3*pixelNo + 1);
int red = readByte(buf, xorOffset + 3*pixelNo + 2);
int alphaBit = (alphaByte & m) >> shift;
//alphaBit == 1 => alpha = 0
int alpha = (alphaBit-1) & 0xFF;
*address = SkPreMultiplyARGB(alpha, red, green, blue);
}
static void editPixelBit32(const int pixelNo, const unsigned char* buf,
const int xorOffset, int& x, int y, const int w,
SkBitmap* bm, int alphaByte, int m, int shift, SkPMColor* colors)
{
SkPMColor* address = bm->getAddr32(x, y);
int blue = readByte(buf, xorOffset + 4*pixelNo);
int green = readByte(buf, xorOffset + 4*pixelNo + 1);
int red = readByte(buf, xorOffset + 4*pixelNo + 2);
int alphaBit = (alphaByte & m) >> shift;
#if 1 // don't trust the alphaBit for 32bit images <mrr>
alphaBit = 0;
#endif
int alpha = readByte(buf, xorOffset + 4*pixelNo + 3) & ((alphaBit-1)&0xFF);
*address = SkPreMultiplyARGB(alpha, red, green, blue);
}
/////////////////////////////////////////////////////////////////////////////////////////
#include "SkTRegistry.h"
static SkImageDecoder* Factory(SkStream* stream) {
// Check to see if the first four bytes are 0,0,1,0
// FIXME: Is that required and sufficient?
SkAutoMalloc autoMal(4);
unsigned char* buf = (unsigned char*)autoMal.get();
stream->read((void*)buf, 4);
int reserved = read2Bytes(buf, 0);
int type = read2Bytes(buf, 2);
if (reserved != 0 || type != 1) {
// This stream does not represent an ICO image.
return NULL;
}
return SkNEW(SkICOImageDecoder);
}
static SkTRegistry<SkImageDecoder*, SkStream*> gReg(Factory);