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_LoadTIF_RW(SDL_RWops *src)
{
	return LoadImageFromRWops(src, kUTTypeTIFF);
}