/*
* 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 "SkColorPriv.h"
#include "SkImageDecoder.h"
#include "SkStream.h"
#include "SkStreamPriv.h"
#include "SkTypes.h"
class SkICOImageDecoder : public SkImageDecoder {
public:
SkICOImageDecoder();
Format getFormat() const override {
return kICO_Format;
}
protected:
Result onDecode(SkStream* stream, SkBitmap* bm, Mode) override;
private:
typedef SkImageDecoder INHERITED;
};
/////////////////////////////////////////////////////////////////////////////////////////
//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;
}
SkImageDecoder::Result SkICOImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode)
{
SkAutoMalloc autoMal;
const size_t length = SkCopyStreamToStorage(&autoMal, stream);
// Check that the buffer is large enough to read the directory header
if (length < 6) {
return kFailure;
}
unsigned char* buf = (unsigned char*)autoMal.get();
//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 kFailure;
}
int count = read2Bytes(buf, 4);
// Check that there are directory entries
if (count < 1) {
return kFailure;
}
// Check that buffer is large enough to read directory entries.
// We are guaranteed that count is at least 1. We might as well assume
// count is 1 because this deprecated decoder only looks at the first
// directory entry.
if (length < (size_t)(6 + count*16)) {
return kFailure;
}
//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);
int h = readByte(buf, 7);
SkASSERT(w >= 0 && h >= 0);
int colorCount = readByte(buf, 8);
//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
const size_t size = read4Bytes(buf, 14); //matters?
const size_t offset = read4Bytes(buf, 18);
// promote the sum to 64-bits to avoid overflow
// Check that buffer is large enough to read image data
if (offset > length || size > length || ((uint64_t)offset + size) > length) {
return kFailure;
}
// Check to see if this is a PNG image inside the ICO
{
SkMemoryStream subStream(buf + offset, size, false);
SkAutoTDelete<SkImageDecoder> otherDecoder(SkImageDecoder::Factory(&subStream));
if (otherDecoder.get() != NULL) {
// Disallow nesting ICO files within one another
// FIXME: Can ICO files contain other formats besides PNG?
if (otherDecoder->getFormat() == SkImageDecoder::kICO_Format) {
return kFailure;
}
// Set fields on the other decoder to be the same as this one.
this->copyFieldsToOther(otherDecoder.get());
const Result result = otherDecoder->decode(&subStream, bm, this->getDefaultPref(),
mode);
// FIXME: Should we just return result here? Is it possible that data that looked like
// a subimage was not, but was actually a valid ICO?
if (result != kFailure) {
return result;
}
}
}
//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?)
// For ico images, only a byte is used to store each dimension
// 0 is used to represent 256
if (w == 0) {
w = 256;
}
if (h == 0) {
h = 256;
}
// Check that buffer is large enough to read the bit depth
if (length < offset + 16) {
return kFailure;
}
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 kFailure;
}
//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 = SkToInt(offset + 40);
// Check that the buffer is large enough to read the color table
// For bmp-in-icos, there should be 4 bytes per color
if (length < (size_t) (begin + 4*colorCount)) {
return kFailure;
}
//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
bm->setInfo(SkImageInfo::MakeN32Premul(w, h), calculateRowBytesFor8888(w, bitCount));
if (SkImageDecoder::kDecodeBounds_Mode == mode) {
delete[] colors;
return kSuccess;
}
if (!this->allocPixelRef(bm, NULL))
{
delete[] colors;
return kFailure;
}
// The AND mask is a 1-bit alpha mask for each pixel that comes after the
// XOR mask in the bmp. If we check that the largest AND offset is safe,
// it should mean all other buffer accesses will be at smaller indices and
// will therefore be safe.
size_t maxAndOffset = andOffset + ((andLineWidth*(h-1)+(w-1)) >> 3);
if (length <= maxAndOffset) {
return kFailure;
}
// Here we assert that all reads from the buffer using the XOR offset are
// less than the AND offset. This should be guaranteed based on the above
// calculations.
#ifdef SK_DEBUG
int maxPixelNum = lineWidth*(h-1)+w-1;
int maxByte;
switch (bitCount) {
case 1:
maxByte = maxPixelNum >> 3;
break;
case 4:
maxByte = maxPixelNum >> 1;
break;
case 8:
maxByte = maxPixelNum;
break;
case 24:
maxByte = maxPixelNum * 3 + 2;
break;
case 32:
maxByte = maxPixelNum * 4 + 3;
break;
default:
SkASSERT(false);
return kFailure;
}
int maxXOROffset = xorOffset + maxByte;
SkASSERT(maxXOROffset < andOffset);
#endif
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 kSuccess;
} //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);
}
///////////////////////////////////////////////////////////////////////////////
DEFINE_DECODER_CREATOR(ICOImageDecoder);
/////////////////////////////////////////////////////////////////////////////////////////
static bool is_ico(SkStreamRewindable* stream) {
// Check to see if the first four bytes are 0,0,1,0
// FIXME: Is that required and sufficient?
char buf[4];
if (stream->read((void*)buf, 4) != 4) {
return false;
}
int reserved = read2Bytes(buf, 0);
int type = read2Bytes(buf, 2);
return 0 == reserved && 1 == type;
}
static SkImageDecoder* sk_libico_dfactory(SkStreamRewindable* stream) {
if (is_ico(stream)) {
return SkNEW(SkICOImageDecoder);
}
return NULL;
}
static SkImageDecoder_DecodeReg gReg(sk_libico_dfactory);
static SkImageDecoder::Format get_format_ico(SkStreamRewindable* stream) {
if (is_ico(stream)) {
return SkImageDecoder::kICO_Format;
}
return SkImageDecoder::kUnknown_Format;
}
static SkImageDecoder_FormatReg gFormatReg(get_format_ico);