IMG_UIImage.m

/*
 *  IMG_ImageIO.c
 *  SDL_image
 *
 *  Created by Eric Wing on 1/2/09.
 *  Copyright 2009 __MyCompanyName__. All rights reserved.
 *
 */
#include "SDL_image.h"
#import <UIKit/UIKit.h>
#import <MobileCoreServices/MobileCoreServices.h> // for UTCoreTypes.h

// Once we have our image, we need to get it into an SDL_Surface
// (Copied straight from the ImageIO backend.)
static SDL_Surface* Create_SDL_Surface_From_CGImage(CGImageRef image_ref)
{
    /* This code is adapted from Apple's Documentation found here:
     * http://developer.apple.com/documentation/GraphicsImaging/Conceptual/OpenGL-MacProgGuide/index.html
     * Listing 9-4††Using a Quartz image as a texture source.
     * Unfortunately, this guide doesn't show what to do about
     * non-RGBA image formats so I'm making the rest up.
     * All this code should be scrutinized.
     */

    size_t w = CGImageGetWidth(image_ref);
    size_t h = CGImageGetHeight(image_ref);
    CGRect rect = {{0, 0}, {w, h}};

    CGImageAlphaInfo alpha = CGImageGetAlphaInfo(image_ref);
    //size_t bits_per_pixel = CGImageGetBitsPerPixel(image_ref);
    size_t bits_per_component = 8;

    SDL_Surface* surface;
    Uint32 Amask;
    Uint32 Rmask;
    Uint32 Gmask;
    Uint32 Bmask;

    CGContextRef bitmap_context;
    CGBitmapInfo bitmap_info;
    CGColorSpaceRef color_space = CGColorSpaceCreateDeviceRGB();

    if (alpha == kCGImageAlphaNone ||
        alpha == kCGImageAlphaNoneSkipFirst ||
        alpha == kCGImageAlphaNoneSkipLast) {
        bitmap_info = kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Host; /* XRGB */
        Amask = 0x00000000;
    } else {
        /* kCGImageAlphaFirst isn't supported */
        //bitmap_info = kCGImageAlphaFirst | kCGBitmapByteOrder32Host; /* ARGB */
        bitmap_info = kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host; /* ARGB */
        Amask = 0xFF000000;
    }

    Rmask = 0x00FF0000;
    Gmask = 0x0000FF00;
    Bmask = 0x000000FF;

    surface = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, 32, Rmask, Gmask, Bmask, Amask);
    if (surface)
    {
        // Sets up a context to be drawn to with surface->pixels as the area to be drawn to
        bitmap_context = CGBitmapContextCreate(
                                                            surface->pixels,
                                                            surface->w,
                                                            surface->h,
                                                            bits_per_component,
                                                            surface->pitch,
                                                            color_space,
                                                            bitmap_info
                                                            );

        // Draws the image into the context's image_data
        CGContextDrawImage(bitmap_context, rect, image_ref);

        CGContextRelease(bitmap_context);

        // FIXME: Reverse the premultiplied alpha
        if ((bitmap_info & kCGBitmapAlphaInfoMask) == kCGImageAlphaPremultipliedFirst) {
            int i, j;
            Uint8 *p = (Uint8 *)surface->pixels;
            for (i = surface->h * surface->pitch/4; i--; ) {
#if __LITTLE_ENDIAN__
                Uint8 A = p[3];
                if (A) {
                    for (j = 0; j < 3; ++j) {
                        p[j] = (p[j] * 255) / A;
                    }
                }
#else
                Uint8 A = p[0];
                if (A) {
                    for (j = 1; j < 4; ++j) {
                        p[j] = (p[j] * 255) / A;
                    }
                }
#endif /* ENDIAN */
                p += 4;
            }
        }
    }

    if (color_space)
    {
        CGColorSpaceRelease(color_space);
    }

    return surface;
}

static SDL_Surface* LoadImageFromRWops(SDL_RWops* rw_ops, CFStringRef uti_string_hint)
{
    NSAutoreleasePool* autorelease_pool = [[NSAutoreleasePool alloc] init];
    SDL_Surface* sdl_surface;
    UIImage* ui_image;

    int bytes_read = 0;
    // I don't know what a good size is.
    // Max recommended texture size is 1024x1024 on iPhone so maybe base it on that?
    const int block_size = 1024*4;
    char temp_buffer[block_size];

    NSMutableData* ns_data = [[NSMutableData alloc] initWithCapacity:1024*1024*4];


    do
    {
        bytes_read = SDL_RWread(rw_ops, temp_buffer, 1, block_size);
        [ns_data appendBytes:temp_buffer length:bytes_read];
    } while(bytes_read > 0);

    ui_image = [[UIImage alloc] initWithData:ns_data];

    sdl_surface = Create_SDL_Surface_From_CGImage([ui_image CGImage]);

    [ui_image release];
    [ns_data release];

    [autorelease_pool drain];

    return sdl_surface;
}

static SDL_Surface* LoadImageFromFile(const char *file)
{
    NSAutoreleasePool* autorelease_pool = [[NSAutoreleasePool alloc] init];
    SDL_Surface* sdl_surface = NULL;
    UIImage* ui_image;
    NSString* ns_string;

    ns_string = [[NSString alloc] initWithUTF8String:file];
    ui_image = [[UIImage alloc] initWithContentsOfFile:ns_string];
    if(ui_image != NULL)
    {
        sdl_surface = Create_SDL_Surface_From_CGImage([ui_image CGImage]);
    }

    [ui_image release];
    [ns_string release];

    [autorelease_pool drain];

    return sdl_surface;
}


/* Since UIImage doesn't really support streams well, we should optimize for the file case. */
SDL_Surface *IMG_Load(const char *file)
{
    SDL_Surface* sdl_surface = NULL;

    sdl_surface = LoadImageFromFile(file);
    if(NULL == sdl_surface)
    {
        // Either the file doesn't exist or ImageIO doesn't understand the format.
        // For the latter case, fallback to the native SDL_image handlers.

        SDL_RWops *src = SDL_RWFromFile(file, "rb");
        char *ext = strrchr(file, '.');
        if(ext) {
            ext++;
        }
        if(!src) {
            /* The error message has been set in SDL_RWFromFile */
            return NULL;
        }
        sdl_surface = IMG_LoadTyped_RW(src, 1, ext);
    }
    return sdl_surface;
}


int IMG_InitJPG()
{
    return 0;
}

void IMG_QuitJPG()
{
}

int IMG_InitPNG()
{
    return 0;
}

void IMG_QuitPNG()
{
}

int IMG_InitTIF()
{
    return 0;
}

void IMG_QuitTIF()
{
}

/* Copied straight from other files so I don't have to alter them. */
static int IMG_isICOCUR(SDL_RWops *src, int type)
{
    int start;
    int is_ICOCUR;

    /* The Win32 ICO file header (14 bytes) */
    Uint16 bfReserved;
    Uint16 bfType;
    Uint16 bfCount;

    if ( !src )
        return 0;
    start = SDL_RWtell(src);
    is_ICOCUR = 0;
    bfReserved = SDL_ReadLE16(src);
    bfType = SDL_ReadLE16(src);
    bfCount = SDL_ReadLE16(src);
    if ((bfReserved == 0) && (bfType == type) && (bfCount != 0))
        is_ICOCUR = 1;
    SDL_RWseek(src, start, SEEK_SET);

    return (is_ICOCUR);
}

int IMG_isICO(SDL_RWops *src)
{
    return IMG_isICOCUR(src, 1);
}

int IMG_isCUR(SDL_RWops *src)
{
    return IMG_isICOCUR(src, 2);
}

int IMG_isBMP(SDL_RWops *src)
{
    int start;
    int is_BMP;
    char magic[2];

    if ( !src )
        return 0;
    start = SDL_RWtell(src);
    is_BMP = 0;
    if ( SDL_RWread(src, magic, sizeof(magic), 1) ) {
        if ( strncmp(magic, "BM", 2) == 0 ) {
            is_BMP = 1;
        }
    }
    SDL_RWseek(src, start, SEEK_SET);
    return(is_BMP);
}

int IMG_isGIF(SDL_RWops *src)
{
    int start;
    int is_GIF;
    char magic[6];

    if ( !src )
        return 0;
    start = SDL_RWtell(src);
    is_GIF = 0;
    if ( SDL_RWread(src, magic, sizeof(magic), 1) ) {
        if ( (strncmp(magic, "GIF", 3) == 0) &&
            ((memcmp(magic + 3, "87a", 3) == 0) ||
             (memcmp(magic + 3, "89a", 3) == 0)) ) {
            is_GIF = 1;
        }
    }
    SDL_RWseek(src, start, SEEK_SET);
    return(is_GIF);
}

int IMG_isJPG(SDL_RWops *src)
{
    int start;
    int is_JPG;
    int in_scan;
    Uint8 magic[4];

    /* This detection code is by Steaphan Greene <stea@cs.binghamton.edu> */
    /* Blame me, not Sam, if this doesn't work right. */
    /* And don't forget to report the problem to the the sdl list too! */

    if ( !src )
        return 0;
    start = SDL_RWtell(src);
    is_JPG = 0;
    in_scan = 0;
    if ( SDL_RWread(src, magic, 2, 1) ) {
        if ( (magic[0] == 0xFF) && (magic[1] == 0xD8) ) {
            is_JPG = 1;
            while (is_JPG == 1) {
                if(SDL_RWread(src, magic, 1, 2) != 2) {
                    is_JPG = 0;
                } else if( (magic[0] != 0xFF) && (in_scan == 0) ) {
                    is_JPG = 0;
                } else if( (magic[0] != 0xFF) || (magic[1] == 0xFF) ) {
                    /* Extra padding in JPEG (legal) */
                    /* or this is data and we are scanning */
                    SDL_RWseek(src, -1, SEEK_CUR);
                } else if(magic[1] == 0xD9) {
                    /* Got to end of good JPEG */
                    break;
                } else if( (in_scan == 1) && (magic[1] == 0x00) ) {
                    /* This is an encoded 0xFF within the data */
                } else if( (magic[1] >= 0xD0) && (magic[1] < 0xD9) ) {
                    /* These have nothing else */
                } else if(SDL_RWread(src, magic+2, 1, 2) != 2) {
                    is_JPG = 0;
                } else {
                    /* Yes, it's big-endian */
                    Uint32 start;
                    Uint32 size;
                    Uint32 end;
                    start = SDL_RWtell(src);
                    size = (magic[2] << 8) + magic[3];
                    end = SDL_RWseek(src, size-2, SEEK_CUR);
                    if ( end != start + size - 2 ) is_JPG = 0;
                    if ( magic[1] == 0xDA ) {
                        /* Now comes the actual JPEG meat */
#ifdef  FAST_IS_JPEG
                        /* Ok, I'm convinced.  It is a JPEG. */
                        break;
#else
                        /* I'm not convinced.  Prove it! */
                        in_scan = 1;
#endif
                    }
                }
            }
        }
    }
    SDL_RWseek(src, start, SEEK_SET);
    return(is_JPG);
}

int IMG_isPNG(SDL_RWops *src)
{
    int start;
    int is_PNG;
    Uint8 magic[4];

    if ( !src )
        return 0;
    start = SDL_RWtell(src);
    is_PNG = 0;
    if ( SDL_RWread(src, magic, 1, sizeof(magic)) == sizeof(magic) ) {
        if ( magic[0] == 0x89 &&
            magic[1] == 'P' &&
            magic[2] == 'N' &&
            magic[3] == 'G' ) {
            is_PNG = 1;
        }
    }
    SDL_RWseek(src, start, SEEK_SET);
    return(is_PNG);
}

int IMG_isTIF(SDL_RWops* src)
{
    int start;
    int is_TIF;
    Uint8 magic[4];

    if ( !src )
        return 0;
    start = SDL_RWtell(src);
    is_TIF = 0;
    if ( SDL_RWread(src, magic, 1, sizeof(magic)) == sizeof(magic) ) {
        if ( (magic[0] == 'I' &&
              magic[1] == 'I' &&
              magic[2] == 0x2a &&
              magic[3] == 0x00) ||
            (magic[0] == 'M' &&
             magic[1] == 'M' &&
             magic[2] == 0x00 &&
             magic[3] == 0x2a) ) {
            is_TIF = 1;
        }
    }
    SDL_RWseek(src, start, SEEK_SET);
    return(is_TIF);
}

SDL_Surface* IMG_LoadCUR_RW(SDL_RWops *src)
{
    /* FIXME: Is this a supported type? */
    return LoadImageFromRWops(src, CFSTR("com.microsoft.cur"));
}
SDL_Surface* IMG_LoadICO_RW(SDL_RWops *src)
{
    return LoadImageFromRWops(src, kUTTypeICO);
}
SDL_Surface* IMG_LoadBMP_RW(SDL_RWops *src)
{
    return LoadImageFromRWops(src, kUTTypeBMP);
}
SDL_Surface* IMG_LoadGIF_RW(SDL_RWops *src)
{
    return LoadImageFromRWops(src, kUTTypeGIF);
}
SDL_Surface* IMG_LoadJPG_RW(SDL_RWops *src)
{
    return LoadImageFromRWops(src, kUTTypeJPEG);
}
SDL_Surface* IMG_LoadPNG_RW(SDL_RWops *src)
{
    return LoadImageFromRWops(src, kUTTypePNG);
}
SDL_Surface* IMG_LoadTGA_RW(SDL_RWops *src)
{
    return LoadImageFromRWops(src, CFSTR("com.truevision.tga-image"));
}
SDL_Surface* IMG_LoadTIF_RW(SDL_RWops *src)
{
    return LoadImageFromRWops(src, kUTTypeTIFF);
}