legacy/src/images/SkImageDecoder_libico.cpp - platform/external/skia - Git at Google


 /*
  * 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);

	/*
	* 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 + ((lineWidthhbitCount) >> 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);