darling-cocotron/Onyx2D/O2ImageSource_GIF.m

/* Copyright (c) 2009 Christopher J. W. Lloyd

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */

#import <Onyx2D/O2ColorSpace.h>
#import <Onyx2D/O2DataProvider.h>
#import <Onyx2D/O2Image.h>
#import <Onyx2D/O2ImageSource_GIF.h>

static int readCallback(GifFileType *ft, GifByteType *buf, int count) {
    NSInputStream *stream = (NSInputStream *) ft->UserData;
    return [stream read: buf maxLength: count];
}

@implementation O2ImageSource_GIF

+ (BOOL) isPresentInDataProvider: (O2DataProvider *) provider {
    enum { signatureLength = 4 };
    unsigned char signature[signatureLength] = {'G', 'I', 'F', '8'};
    unsigned char check[signatureLength];
    NSInteger i, size = [provider getBytes: check
                                     range: NSMakeRange(0, signatureLength)];

    if (size != signatureLength)
        return NO;

    for (i = 0; i < signatureLength; i++)
        if (signature[i] != check[i])
            return NO;

    return YES;
}

- initWithDataProvider: (O2DataProvider *) provider
               options: (NSDictionary *) options
{
    [super initWithDataProvider: provider options: options];

    NSInputStream *stream = [_provider inputStream];
    if ((_gif = DGifOpen(stream, readCallback, NULL)) == NULL) {
        [self dealloc];
        return nil;
    }

    DGifSlurp(_gif);
    return self;
}

- (void) dealloc {
    if (_gif != NULL)
        DGifCloseFile(_gif, NULL);

    [super dealloc];
}

- (CFStringRef) type {
    return (CFStringRef) @"com.compuserve.gif";
}

- (NSUInteger) count {
    return _gif->ImageCount;
}

- (CFDictionaryRef) copyPropertiesAtIndex: (NSUInteger) index
                                  options: (CFDictionaryRef) options
{
    return (CFDictionaryRef)[@{
        kO2ImagePropertyDPIHeight : @(72),
        kO2ImagePropertyDPIHeight : @(72)
    } retain];
}

- (O2Image *) createImageAtIndex: (NSUInteger) index
                         options: (NSDictionary *) options
{

    if (index >= _gif->ImageCount)
        return nil;

    SavedImage *gifImage = _gif->SavedImages + index;
    ColorMapObject *colorMap = _gif->SColorMap;
    if (colorMap == NULL)
        colorMap = gifImage->ImageDesc.ColorMap;
    int bgColorIndex = (_gif->SColorMap == NULL) ? -1 : _gif->SBackGroundColor;
    int colorCount = colorMap->ColorCount;
    GifColorType *colorLUT = colorMap->Colors;
    unsigned char *gifRaster = gifImage->RasterBits;
    O2ColorSpaceRef colorSpace = O2ColorSpaceCreateDeviceRGB();
    size_t width = gifImage->ImageDesc.Width;
    size_t height = gifImage->ImageDesc.Height;
    size_t bytesPerRow = width * sizeof(O2rgba8u_BE);
    size_t bitsPerComponent = 8;
    size_t bitsPerPixel = 32;
    O2rgba8u_BE *pixels = NSZoneMalloc(NULL, bytesPerRow * height);
    O2rgba8u_BE *scanline = pixels;
    BOOL interlace = gifImage->ImageDesc.Interlace;
    int interlacePass = 1;
    int interlaceDelta = 8;
    NSData *bitmap = [[NSData alloc] initWithBytesNoCopy: pixels
                                                  length: bytesPerRow * height];

    GraphicsControlBlock gcb;
    gcb.TransparentColor = NO_TRANSPARENT_COLOR;
    DGifSavedExtensionToGCB(_gif, index, &gcb);

    size_t r, c;

    for (r = 0; r < height; r++) {

        for (c = 0; c < width; c++) {
            unsigned char colorIndex = *gifRaster;

            if (colorIndex == bgColorIndex) {
                scanline->a = 0;
                scanline->r = 0;
                scanline->g = 0;
                scanline->b = 0;
            } else if (colorIndex < colorCount) {
                GifColorType *gifColor = colorLUT + colorIndex;

                scanline->a = 255;
                if (gcb.TransparentColor != NO_TRANSPARENT_COLOR &&
                    gcb.TransparentColor == colorIndex)
                    scanline->a = 0;

                scanline->r = gifColor->Red;
                scanline->g = gifColor->Green;
                scanline->b = gifColor->Blue;
            } else {
                scanline->a = 0;
                scanline->r = 0;
                scanline->g = 0;
                scanline->b = 0;
            }
            scanline++;
            gifRaster++;
        }

        if (interlace) {
            scanline += (interlaceDelta - 1) * width;
            if (scanline >= pixels + width * height) {
                interlacePass++;

                switch (interlacePass) {
                case 2:
                    scanline = pixels + width * 4;
                    interlaceDelta = 8;
                    break;
                case 3:
                    scanline = pixels + width * 2;
                    interlaceDelta = 4;
                    break;
                case 4:
                    scanline = pixels + width * 1;
                    interlaceDelta = 2;
                    break;
                }
            }
        }
    }

    O2DataProvider *provider =
            O2DataProviderCreateWithCFData((CFDataRef) bitmap);
    O2BitmapInfo info =
            kO2BitmapByteOrder32Big | kO2ImageAlphaPremultipliedLast;

    O2Image *result =
            [[O2Image alloc] initWithWidth: width
                                    height: height
                          bitsPerComponent: bitsPerComponent
                              bitsPerPixel: bitsPerPixel
                               bytesPerRow: bytesPerRow
                                colorSpace: colorSpace
                                bitmapInfo: info
                                   decoder: NULL
                                  provider: provider
                                    decode: NULL
                               interpolate: NO
                           renderingIntent: kO2RenderingIntentDefault];

    [colorSpace release];
    [provider release];
    [bitmap release];

    return result;
}

@end