Revert of Delete SkImageDecoder

src/images/SkImageDecoder_libico.cpp

Index: src/images/SkImageDecoder_libico.cpp
diff --git a/src/images/SkImageDecoder_libico.cpp b/src/images/SkImageDecoder_libico.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..ff04d74d066f936b941602f9cd5b34972a29e528
--- /dev/null
+++ b/src/images/SkImageDecoder_libico.cpp
@@ -0,0 +1,456 @@
+/*
+ * 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 "SkData.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]+SkLeftShift(buffer[begin+1],8)
+#define read4Bytes(buffer,begin) buffer[begin]+SkLeftShift(buffer[begin+1],8)+SkLeftShift(buffer[begin+2],16)+SkLeftShift(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) {
+    auto data = SkCopyStreamToData(stream);
+    if (!data) {
+        return kFailure;
+    }
+
+    const size_t length = data->size();
+    // Check that the buffer is large enough to read the directory header
+    if (length < 6) {
+        return kFailure;
+    }
+
+    unsigned char* buf = (unsigned char*) data->data();
+
+    //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() != nullptr) {
+            // 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) = nullptr;
+    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 = nullptr;
+    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, nullptr))
+    {
+        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 new SkICOImageDecoder;
+    }
+    return nullptr;
+}
+
+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);