IMG_ImageIO.m
author Sam Lantinga <slouken@libsdl.org>
Tue, 01 Jan 2013 11:40:47 -0800
changeset 340 3999783ed889
parent 332 5a8a45cd54c9
child 368 8a61842d00ce
permissions -rw-r--r--
Fixed bug 1413 - Cannot load images with ImageIO enabled on Mac OS X

The attached diff fixes the library so ImageIO can be used and images are
displayed again without corruption and black screens.

(Based on http://pastebin.com/T3s15UXF and
http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html)

I suspect the matrix passed to CGColorSpaceCreateCalibratedRGB() as implemented
in r292 is invalid and the CoreGraphics framework on 10.5 doesn't reject it,
but later ones do. Unfortunately all the documentation I can find doesn't
actually specify what the valid range of values of the arguments is.
     1 /*
     2  *  IMG_ImageIO.c
     3  *  SDL_image
     4  *
     5  *  Created by Eric Wing on 1/1/09.
     6  *  Copyright 2009 __MyCompanyName__. All rights reserved.
     7  *
     8  */
     9 
    10 #if defined(__APPLE__) && !defined(SDL_IMAGE_USE_COMMON_BACKEND)
    11 
    12 #include "SDL_image.h"
    13 
    14 // Used because CGDataProviderCreate became deprecated in 10.5
    15 #include <AvailabilityMacros.h>
    16 #include <TargetConditionals.h>
    17 #include <Foundation/Foundation.h>
    18 
    19 #if (TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1)
    20 #ifdef ALLOW_UIIMAGE_FALLBACK
    21 #define USE_UIIMAGE_BACKEND() ([UIImage instancesRespondToSelector:@selector(initWithCGImage:scale:orientation:)] == NO)
    22 #else
    23 #define USE_UIIMAGE_BACKEND() (Internal_checkImageIOisAvailable())
    24 #endif
    25 #import <MobileCoreServices/MobileCoreServices.h> // for UTCoreTypes.h
    26 #import <ImageIO/ImageIO.h>
    27 #import <UIKit/UIImage.h>
    28 #else
    29 // For ImageIO framework and also LaunchServices framework (for UTIs)
    30 #include <ApplicationServices/ApplicationServices.h>
    31 #endif
    32 
    33 /**************************************************************
    34  ***** Begin Callback functions for block reading *************
    35  **************************************************************/
    36 
    37 // This callback reads some bytes from an SDL_rwops and copies it
    38 // to a Quartz buffer (supplied by Apple framework).
    39 static size_t MyProviderGetBytesCallback(void* rwops_userdata, void* quartz_buffer, size_t the_count)
    40 {
    41     return (size_t)SDL_RWread((struct SDL_RWops *)rwops_userdata, quartz_buffer, 1, the_count);
    42 }
    43 
    44 // This callback is triggered when the data provider is released
    45 // so you can clean up any resources.
    46 static void MyProviderReleaseInfoCallback(void* rwops_userdata)
    47 {
    48     // What should I put here? 
    49     // I think the user and SDL_RWops controls closing, so I don't do anything.
    50 }
    51 
    52 static void MyProviderRewindCallback(void* rwops_userdata)
    53 {
    54     SDL_RWseek((struct SDL_RWops *)rwops_userdata, 0, RW_SEEK_SET);
    55 }
    56 
    57 #if MAC_OS_X_VERSION_MAX_ALLOWED >= 1050 // CGDataProviderCreateSequential was introduced in 10.5; CGDataProviderCreate is deprecated
    58 off_t MyProviderSkipForwardBytesCallback(void* rwops_userdata, off_t the_count)
    59 {
    60     off_t start_position = SDL_RWtell((struct SDL_RWops *)rwops_userdata);
    61     SDL_RWseek((struct SDL_RWops *)rwops_userdata, the_count, RW_SEEK_CUR);
    62     off_t end_position = SDL_RWtell((struct SDL_RWops *)rwops_userdata);
    63     return (end_position - start_position);	
    64 }
    65 #else // CGDataProviderCreate was deprecated in 10.5
    66 static void MyProviderSkipBytesCallback(void* rwops_userdata, size_t the_count)
    67 {
    68     SDL_RWseek((struct SDL_RWops *)rwops_userdata, the_count, RW_SEEK_CUR);
    69 }
    70 #endif
    71 
    72 /**************************************************************
    73  ***** End Callback functions for block reading ***************
    74  **************************************************************/
    75 
    76 // This creates a CGImageSourceRef which is a handle to an image that can be used to examine information
    77 // about the image or load the actual image data.
    78 static CGImageSourceRef CreateCGImageSourceFromRWops(SDL_RWops* rw_ops, CFDictionaryRef hints_and_options)
    79 {
    80     CGImageSourceRef source_ref;
    81     
    82     // Similar to SDL_RWops, Apple has their own callbacks for dealing with data streams.
    83     
    84 #if MAC_OS_X_VERSION_MAX_ALLOWED >= 1050 // CGDataProviderCreateSequential was introduced in 10.5; CGDataProviderCreate is deprecated
    85     CGDataProviderSequentialCallbacks provider_callbacks =
    86     {
    87         0,
    88         MyProviderGetBytesCallback,
    89         MyProviderSkipForwardBytesCallback,
    90         MyProviderRewindCallback,
    91         MyProviderReleaseInfoCallback
    92     };
    93     
    94     CGDataProviderRef data_provider = CGDataProviderCreateSequential(rw_ops, &provider_callbacks);
    95     
    96     
    97 #else // CGDataProviderCreate was deprecated in 10.5
    98     
    99     CGDataProviderCallbacks provider_callbacks =
   100     {
   101         MyProviderGetBytesCallback,
   102         MyProviderSkipBytesCallback,
   103         MyProviderRewindCallback,
   104         MyProviderReleaseInfoCallback
   105     };
   106     
   107     CGDataProviderRef data_provider = CGDataProviderCreate(rw_ops, &provider_callbacks);
   108 #endif
   109     // Get the CGImageSourceRef.
   110     // The dictionary can be NULL or contain hints to help ImageIO figure out the image type.
   111     source_ref = CGImageSourceCreateWithDataProvider(data_provider, hints_and_options);
   112     CGDataProviderRelease(data_provider);
   113     return source_ref;
   114 }
   115 
   116 /* Create a CGImageSourceRef from a file. */
   117 /* Remember to CFRelease the created source when done. */
   118 static CGImageSourceRef CreateCGImageSourceFromFile(const char* the_path)
   119 {
   120     CFURLRef the_url = NULL;
   121     CGImageSourceRef source_ref = NULL;
   122     CFStringRef cf_string = NULL;
   123     
   124     /* Create a CFString from a C string */
   125     cf_string = CFStringCreateWithCString(NULL, the_path, kCFStringEncodingUTF8);
   126     if (!cf_string) {
   127         return NULL;
   128     }
   129     
   130     /* Create a CFURL from a CFString */
   131     the_url = CFURLCreateWithFileSystemPath(NULL, cf_string, kCFURLPOSIXPathStyle, false);
   132     
   133     /* Don't need the CFString any more (error or not) */
   134     CFRelease(cf_string);
   135     
   136     if(!the_url)
   137     {
   138         return NULL;
   139     }
   140     
   141     
   142     source_ref = CGImageSourceCreateWithURL(the_url, NULL);
   143     /* Don't need the URL any more (error or not) */
   144     CFRelease(the_url);
   145     
   146     return source_ref;
   147 }
   148 
   149 static CGImageRef CreateCGImageFromCGImageSource(CGImageSourceRef image_source)
   150 {
   151     CGImageRef image_ref = NULL;
   152     
   153     if(NULL == image_source)
   154     {
   155         return NULL;
   156     }
   157     
   158     // Get the first item in the image source (some image formats may
   159     // contain multiple items).
   160     image_ref = CGImageSourceCreateImageAtIndex(image_source, 0, NULL);
   161     if(NULL == image_ref)
   162     {
   163         IMG_SetError("CGImageSourceCreateImageAtIndex() failed");
   164     }
   165     return image_ref;
   166 }
   167 
   168 static CFDictionaryRef CreateHintDictionary(CFStringRef uti_string_hint)
   169 {
   170     CFDictionaryRef hint_dictionary = NULL;
   171     
   172     if(uti_string_hint != NULL)
   173     {
   174         // Do a bunch of work to setup a CFDictionary containing the jpeg compression properties.
   175         CFStringRef the_keys[1];
   176         CFStringRef the_values[1];
   177         
   178         the_keys[0] = kCGImageSourceTypeIdentifierHint;
   179         the_values[0] = uti_string_hint;
   180         
   181         // kCFTypeDictionaryKeyCallBacks or kCFCopyStringDictionaryKeyCallBacks?
   182         hint_dictionary = CFDictionaryCreate(NULL, (const void**)&the_keys, (const void**)&the_values, 1, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
   183     }
   184     return hint_dictionary;
   185 }
   186 
   187 // Once we have our image, we need to get it into an SDL_Surface
   188 static SDL_Surface* Create_SDL_Surface_From_CGImage_RGB(CGImageRef image_ref)
   189 {
   190     /* This code is adapted from Apple's Documentation found here:
   191      * http://developer.apple.com/documentation/GraphicsImaging/Conceptual/OpenGL-MacProgGuide/index.html
   192      * Listing 9-4††Using a Quartz image as a texture source.
   193      * Unfortunately, this guide doesn't show what to do about
   194      * non-RGBA image formats so I'm making the rest up.
   195      * All this code should be scrutinized.
   196      */
   197     
   198     size_t w = CGImageGetWidth(image_ref);
   199     size_t h = CGImageGetHeight(image_ref);
   200     CGRect rect = {{0, 0}, {w, h}};
   201     
   202     CGImageAlphaInfo alpha = CGImageGetAlphaInfo(image_ref);
   203     //size_t bits_per_pixel = CGImageGetBitsPerPixel(image_ref);
   204     size_t bits_per_component = 8;
   205     
   206     SDL_Surface* surface;
   207     Uint32 Amask;
   208     Uint32 Rmask;
   209     Uint32 Gmask;
   210     Uint32 Bmask;
   211     
   212     CGContextRef bitmap_context;
   213     CGBitmapInfo bitmap_info;
   214 
   215 	/* This sets up a color space that results in identical values
   216 	 * as the image data itself, which is the same as the standalone
   217 	 * libpng loader.
   218 	 * Thanks to Allegro. :)
   219 	 */
   220 	CGFloat whitePoint[3] = { 0.950, 1.000, 1.089 };
   221 	CGFloat blackPoint[3] = { 0.000, 0.000, 0.000 };
   222 	CGFloat gamma[3] = { 2.2, 2.2, 2.2 };
   223 	CGFloat matrix[9] = {
   224 		0.412, 0.213, 0.019,
   225 		0.358, 0.715, 0.119,
   226 		0.180, 0.072, 0.950
   227 	};
   228 	CGColorSpaceRef color_space =
   229 		CGColorSpaceCreateCalibratedRGB(
   230 									whitePoint, blackPoint, gamma, matrix
   231 									);   
   232 	
   233     if (alpha == kCGImageAlphaNone ||
   234         alpha == kCGImageAlphaNoneSkipFirst ||
   235         alpha == kCGImageAlphaNoneSkipLast) {
   236         bitmap_info = kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Host; /* XRGB */
   237         Amask = 0x00000000;
   238     } else {
   239         /* kCGImageAlphaFirst isn't supported */
   240         //bitmap_info = kCGImageAlphaFirst | kCGBitmapByteOrder32Host; /* ARGB */
   241         bitmap_info = kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host; /* ARGB */
   242         Amask = 0xFF000000;
   243     }
   244     
   245     Rmask = 0x00FF0000;
   246     Gmask = 0x0000FF00;
   247     Bmask = 0x000000FF;
   248     
   249     surface = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, 32, Rmask, Gmask, Bmask, Amask);
   250     if (surface)
   251     {
   252         // Sets up a context to be drawn to with surface->pixels as the area to be drawn to
   253         bitmap_context = CGBitmapContextCreate(
   254                                                surface->pixels,
   255                                                surface->w,
   256                                                surface->h,
   257                                                bits_per_component,
   258                                                surface->pitch,
   259                                                color_space,
   260                                                bitmap_info
   261                                                );
   262         
   263         // Draws the image into the context's image_data
   264         CGContextDrawImage(bitmap_context, rect, image_ref);
   265         
   266         CGContextRelease(bitmap_context);
   267         
   268         // FIXME: Reverse the premultiplied alpha
   269         if ((bitmap_info & kCGBitmapAlphaInfoMask) == kCGImageAlphaPremultipliedFirst) {
   270             int i, j;
   271             Uint8 *p = (Uint8 *)surface->pixels;
   272             for (i = surface->h * surface->pitch/4; i--; ) {
   273 #if __LITTLE_ENDIAN__
   274                 Uint8 A = p[3];
   275                 if (A) {
   276                     for (j = 0; j < 3; ++j) {
   277                         p[j] = (p[j] * 255) / A;
   278                     }
   279                 }
   280 #else
   281                 Uint8 A = p[0];
   282                 if (A) {
   283                     for (j = 1; j < 4; ++j) {
   284                         p[j] = (p[j] * 255) / A;
   285                     }
   286                 }
   287 #endif /* ENDIAN */
   288                 p += 4;
   289             }
   290         }
   291     }
   292     
   293     if (color_space)
   294     {
   295         CGColorSpaceRelease(color_space);			
   296     }
   297     
   298     return surface;
   299 }
   300 static SDL_Surface* Create_SDL_Surface_From_CGImage_Index(CGImageRef image_ref)
   301 {
   302     size_t w = CGImageGetWidth(image_ref);
   303     size_t h = CGImageGetHeight(image_ref);
   304     size_t bits_per_pixel = CGImageGetBitsPerPixel(image_ref);
   305     size_t bytes_per_row = CGImageGetBytesPerRow(image_ref);
   306 
   307     SDL_Surface* surface;
   308     SDL_Palette* palette;
   309 	CGColorSpaceRef color_space = CGImageGetColorSpace(image_ref);
   310     CGColorSpaceRef base_color_space = CGColorSpaceGetBaseColorSpace(color_space);
   311     size_t num_components = CGColorSpaceGetNumberOfComponents(base_color_space);
   312     size_t num_entries = CGColorSpaceGetColorTableCount(color_space);
   313     uint8_t *entry, entries[num_components * num_entries];
   314 
   315     /* What do we do if it's not RGB? */
   316     if (num_components != 3) {
   317         SDL_SetError("Unknown colorspace components %lu", num_components);
   318         return NULL;
   319     }
   320     if (bits_per_pixel != 8) {
   321         SDL_SetError("Unknown bits_per_pixel %lu", bits_per_pixel);
   322         return NULL;
   323     }
   324 
   325     CGColorSpaceGetColorTable(color_space, entries);
   326     surface = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, bits_per_pixel, 0, 0, 0, 0);
   327     if (surface) {
   328         uint8_t* pixels = (uint8_t*)surface->pixels;
   329         CGDataProviderRef provider = CGImageGetDataProvider(image_ref);
   330         NSData* data = (id)CGDataProviderCopyData(provider);
   331         [data autorelease];
   332         const uint8_t* bytes = [data bytes];
   333         size_t i;
   334 
   335         palette = surface->format->palette;
   336         for (i = 0, entry = entries; i < num_entries; ++i) {
   337             palette->colors[i].r = entry[0];
   338             palette->colors[i].g = entry[1];
   339             palette->colors[i].b = entry[2];
   340             entry += num_components;
   341         }
   342 
   343         for (i = 0; i < h; ++i) {
   344             SDL_memcpy(pixels, bytes, w);
   345             pixels += surface->pitch;
   346             bytes += bytes_per_row;
   347         }
   348     }
   349     return surface;
   350 }
   351 static SDL_Surface* Create_SDL_Surface_From_CGImage(CGImageRef image_ref)
   352 {
   353 	CGColorSpaceRef color_space = CGImageGetColorSpace(image_ref);
   354     if (CGColorSpaceGetModel(color_space) == kCGColorSpaceModelIndexed) {
   355         return Create_SDL_Surface_From_CGImage_Index(image_ref);
   356     } else {
   357         return Create_SDL_Surface_From_CGImage_RGB(image_ref);
   358     }
   359 }
   360 
   361 
   362 #pragma mark -
   363 #pragma mark IMG_Init stubs
   364 #if !defined(ALLOW_UIIMAGE_FALLBACK) && ((TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1))
   365 static int Internal_checkImageIOisAvailable() {
   366     // just check if we are running on ios 4 or more, else throw exception
   367     if ([UIImage instancesRespondToSelector:@selector(initWithCGImage:scale:orientation:)])
   368         return 0;
   369     [NSException raise:@"UIImage fallback not enabled at compile time"
   370                 format:@"ImageIO is not available on your platform, please recompile SDL_Image with ALLOW_UIIMAGE_FALLBACK."];
   371     return -1;
   372 }
   373 #endif
   374 
   375 int IMG_InitJPG()
   376 {
   377     return 0;
   378 }
   379 
   380 void IMG_QuitJPG()
   381 {
   382 }
   383 
   384 int IMG_InitPNG()
   385 {
   386     return 0;
   387 }
   388 
   389 void IMG_QuitPNG()
   390 {
   391 }
   392 
   393 int IMG_InitTIF()
   394 {
   395     return 0;
   396 }
   397 
   398 void IMG_QuitTIF()
   399 {
   400 }
   401 
   402 #pragma mark -
   403 #pragma mark Get type of image
   404 static int Internal_isType_UIImage (SDL_RWops *rw_ops, CFStringRef uti_string_to_test)
   405 {
   406     int is_type = 0;
   407     
   408 #if defined(ALLOW_UIIMAGE_FALLBACK) && ((TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1))
   409     int start = SDL_RWtell(rw_ops);
   410     if ((0 == CFStringCompare(uti_string_to_test, kUTTypeICO, 0)) ||
   411         (0 == CFStringCompare(uti_string_to_test, CFSTR("com.microsoft.cur"), 0))) {
   412         
   413         // The Win32 ICO file header (14 bytes)
   414         Uint16 bfReserved;
   415         Uint16 bfType;
   416         Uint16 bfCount;
   417         int type = (0 == CFStringCompare(uti_string_to_test, kUTTypeICO, 0)) ? 1 : 2;
   418         
   419         bfReserved = SDL_ReadLE16(rw_ops);
   420         bfType = SDL_ReadLE16(rw_ops);
   421         bfCount = SDL_ReadLE16(rw_ops);
   422         if ((bfReserved == 0) && (bfType == type) && (bfCount != 0)) 
   423             is_type = 1;
   424     } else if (0 == CFStringCompare(uti_string_to_test, kUTTypeBMP, 0)) {
   425         char magic[2];
   426         
   427         if ( SDL_RWread(rw_ops, magic, sizeof(magic), 1) ) {
   428             if ( strncmp(magic, "BM", 2) == 0 ) {
   429                 is_type = 1;
   430             }
   431         }
   432     } else if (0 == CFStringCompare(uti_string_to_test, kUTTypeGIF, 0)) {
   433         char magic[6];
   434         
   435         if ( SDL_RWread(rw_ops, magic, sizeof(magic), 1) ) {
   436             if ( (strncmp(magic, "GIF", 3) == 0) &&
   437                 ((memcmp(magic + 3, "87a", 3) == 0) ||
   438                  (memcmp(magic + 3, "89a", 3) == 0)) ) {
   439                     is_type = 1;
   440                 }
   441         }
   442     } else if (0 == CFStringCompare(uti_string_to_test, kUTTypeJPEG, 0)) {
   443         int in_scan = 0;
   444         Uint8 magic[4];
   445         
   446         // This detection code is by Steaphan Greene <stea@cs.binghamton.edu>
   447         // Blame me, not Sam, if this doesn't work right. */
   448         // And don't forget to report the problem to the the sdl list too! */
   449         
   450         if ( SDL_RWread(rw_ops, magic, 2, 1) ) {
   451             if ( (magic[0] == 0xFF) && (magic[1] == 0xD8) ) {
   452                 is_type = 1;
   453                 while (is_type == 1) {
   454                     if(SDL_RWread(rw_ops, magic, 1, 2) != 2) {
   455                         is_type = 0;
   456                     } else if( (magic[0] != 0xFF) && (in_scan == 0) ) {
   457                         is_type = 0;
   458                     } else if( (magic[0] != 0xFF) || (magic[1] == 0xFF) ) {
   459                         /* Extra padding in JPEG (legal) */
   460                         /* or this is data and we are scanning */
   461                         SDL_RWseek(rw_ops, -1, SEEK_CUR);
   462                     } else if(magic[1] == 0xD9) {
   463                         /* Got to end of good JPEG */
   464                         break;
   465                     } else if( (in_scan == 1) && (magic[1] == 0x00) ) {
   466                         /* This is an encoded 0xFF within the data */
   467                     } else if( (magic[1] >= 0xD0) && (magic[1] < 0xD9) ) {
   468                         /* These have nothing else */
   469                     } else if(SDL_RWread(rw_ops, magic+2, 1, 2) != 2) {
   470                         is_type = 0;
   471                     } else {
   472                         /* Yes, it's big-endian */
   473                         Uint32 start;
   474                         Uint32 size;
   475                         Uint32 end;
   476                         start = SDL_RWtell(rw_ops);
   477                         size = (magic[2] << 8) + magic[3];
   478                         end = SDL_RWseek(rw_ops, size-2, SEEK_CUR);
   479                         if ( end != start + size - 2 ) is_type = 0;
   480                         if ( magic[1] == 0xDA ) {
   481                             /* Now comes the actual JPEG meat */
   482 #ifdef	FAST_IS_JPEG
   483                             /* Ok, I'm convinced.  It is a JPEG. */
   484                             break;
   485 #else
   486                             /* I'm not convinced.  Prove it! */
   487                             in_scan = 1;
   488 #endif
   489                         }
   490                     }
   491                 }
   492             }
   493         }
   494     } else if (0 == CFStringCompare(uti_string_to_test, kUTTypePNG, 0)) {
   495         Uint8 magic[4];
   496         
   497         if ( SDL_RWread(rw_ops, magic, 1, sizeof(magic)) == sizeof(magic) ) {
   498             if ( magic[0] == 0x89 &&
   499                 magic[1] == 'P' &&
   500                 magic[2] == 'N' &&
   501                 magic[3] == 'G' ) {
   502                 is_type = 1;
   503             }
   504         }
   505     } else if (0 == CFStringCompare(uti_string_to_test, CFSTR("com.truevision.tga-image"), 0)) {
   506         //TODO: fill me!
   507     } else if (0 == CFStringCompare(uti_string_to_test, kUTTypeTIFF, 0)) {
   508         Uint8 magic[4];
   509         
   510         if ( SDL_RWread(rw_ops, magic, 1, sizeof(magic)) == sizeof(magic) ) {
   511             if ( (magic[0] == 'I' &&
   512                   magic[1] == 'I' &&
   513                   magic[2] == 0x2a &&
   514                   magic[3] == 0x00) ||
   515                 (magic[0] == 'M' &&
   516                  magic[1] == 'M' &&
   517                  magic[2] == 0x00 &&
   518                  magic[3] == 0x2a) ) {
   519                     is_type = 1;
   520                 }
   521         }
   522     }
   523     
   524     // reset the file descption pointer
   525     SDL_RWseek(rw_ops, start, SEEK_SET);
   526 
   527 #endif  /* #if defined(ALLOW_UIIMAGE_FALLBACK) && ((TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1)) */
   528     return is_type;
   529 }
   530 
   531 static int Internal_isType_ImageIO (SDL_RWops *rw_ops, CFStringRef uti_string_to_test)
   532 {
   533     int is_type = 0;
   534     
   535     CFDictionaryRef hint_dictionary = CreateHintDictionary(uti_string_to_test);	
   536     CGImageSourceRef image_source = CreateCGImageSourceFromRWops(rw_ops, hint_dictionary);
   537     
   538     if (hint_dictionary != NULL) {
   539         CFRelease(hint_dictionary);		
   540     }
   541     
   542     if (NULL == image_source) {
   543         return 0;
   544     }
   545     
   546     // This will get the UTI of the container, not the image itself.
   547     // Under most cases, this won't be a problem.
   548     // But if a person passes an icon file which contains a bmp,
   549     // the format will be of the icon file.
   550     // But I think the main SDL_image codebase has this same problem so I'm not going to worry about it.	
   551     CFStringRef uti_type = CGImageSourceGetType(image_source);
   552     //	CFShow(uti_type);
   553     
   554     // Unsure if we really want conformance or equality
   555     is_type = (int)UTTypeConformsTo(uti_string_to_test, uti_type);
   556     
   557     CFRelease(image_source);
   558     return is_type;
   559 }
   560 
   561 static int Internal_isType (SDL_RWops *rw_ops, CFStringRef uti_string_to_test)
   562 {
   563     if (rw_ops == NULL)
   564         return 0;
   565     
   566 #if (TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1)
   567     if (USE_UIIMAGE_BACKEND())
   568         return Internal_isType_UIImage(rw_ops, uti_string_to_test);
   569     else
   570 #endif
   571         return Internal_isType_ImageIO(rw_ops, uti_string_to_test);
   572 }
   573 
   574 #ifdef BMP_USES_IMAGEIO
   575 
   576 int IMG_isCUR(SDL_RWops *src)
   577 {
   578     /* FIXME: Is this a supported type? */
   579     return Internal_isType(src, CFSTR("com.microsoft.cur"));
   580 }
   581 
   582 int IMG_isICO(SDL_RWops *src)
   583 {
   584     return Internal_isType(src, kUTTypeICO);
   585 }
   586 
   587 int IMG_isBMP(SDL_RWops *src)
   588 {
   589     return Internal_isType(src, kUTTypeBMP);
   590 }
   591 
   592 #endif /* BMP_USES_IMAGEIO */
   593 
   594 int IMG_isGIF(SDL_RWops *src)
   595 {
   596     return Internal_isType(src, kUTTypeGIF);
   597 }
   598 
   599 // Note: JPEG 2000 is kUTTypeJPEG2000
   600 int IMG_isJPG(SDL_RWops *src)
   601 {
   602     return Internal_isType(src, kUTTypeJPEG);
   603 }
   604 
   605 int IMG_isPNG(SDL_RWops *src)
   606 {
   607     return Internal_isType(src, kUTTypePNG);
   608 }
   609 
   610 // This isn't a public API function. Apple seems to be able to identify tga's.
   611 int IMG_isTGA(SDL_RWops *src)
   612 {
   613     return Internal_isType(src, CFSTR("com.truevision.tga-image"));
   614 }
   615 
   616 int IMG_isTIF(SDL_RWops *src)
   617 {
   618     return Internal_isType(src, kUTTypeTIFF);
   619 }
   620 
   621 #pragma mark -
   622 #pragma mark Load image engine
   623 static SDL_Surface *LoadImageFromRWops_UIImage (SDL_RWops* rw_ops, CFStringRef uti_string_hint)
   624 {
   625     SDL_Surface *sdl_surface = NULL;
   626 
   627 #if defined(ALLOW_UIIMAGE_FALLBACK) && ((TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1))
   628     NSAutoreleasePool* autorelease_pool = [[NSAutoreleasePool alloc] init];
   629     UIImage *ui_image;
   630     int bytes_read = 0;
   631     // I don't know what a good size is. 
   632     // Max recommended texture size is 1024x1024 on iPhone so maybe base it on that?
   633     const int block_size = 1024*4;
   634     char temp_buffer[block_size];
   635     
   636     NSMutableData* ns_data = [[NSMutableData alloc] initWithCapacity:1024*1024*4];
   637     do {
   638         bytes_read = SDL_RWread(rw_ops, temp_buffer, 1, block_size);
   639         [ns_data appendBytes:temp_buffer length:bytes_read];
   640     } while (bytes_read > 0);
   641     
   642     ui_image = [[UIImage alloc] initWithData:ns_data];
   643     if (ui_image != nil)
   644         sdl_surface = Create_SDL_Surface_From_CGImage([ui_image CGImage]);
   645     [ui_image release];
   646     [ns_data release];          
   647     [autorelease_pool drain];
   648 
   649 #endif  /* #if defined(ALLOW_UIIMAGE_FALLBACK) && ((TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1)) */
   650     return sdl_surface;
   651 }
   652 
   653 static SDL_Surface *LoadImageFromRWops_ImageIO (SDL_RWops *rw_ops, CFStringRef uti_string_hint)
   654 {
   655     CFDictionaryRef hint_dictionary = CreateHintDictionary(uti_string_hint);
   656     CGImageSourceRef image_source = CreateCGImageSourceFromRWops(rw_ops, hint_dictionary);
   657 
   658     if (hint_dictionary != NULL)
   659         CFRelease(hint_dictionary);		
   660 
   661     if (NULL == image_source)
   662         return NULL;
   663     
   664     CGImageRef image_ref = CreateCGImageFromCGImageSource(image_source);
   665     CFRelease(image_source);
   666 
   667     if (NULL == image_ref)
   668         return NULL;
   669     SDL_Surface *sdl_surface = Create_SDL_Surface_From_CGImage(image_ref);
   670     CFRelease(image_ref);
   671 
   672     return sdl_surface;
   673 }
   674 
   675 static SDL_Surface *LoadImageFromRWops (SDL_RWops *rw_ops, CFStringRef uti_string_hint)
   676 {
   677 #if (TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1)
   678     if (USE_UIIMAGE_BACKEND()) 
   679         return LoadImageFromRWops_UIImage(rw_ops, uti_string_hint);
   680     else
   681 #endif
   682         return LoadImageFromRWops_ImageIO(rw_ops, uti_string_hint);
   683 }
   684 
   685 static SDL_Surface* LoadImageFromFile_UIImage (const char *file)
   686 {
   687     SDL_Surface *sdl_surface = NULL;
   688 
   689 #if defined(ALLOW_UIIMAGE_FALLBACK) && ((TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1))
   690     NSAutoreleasePool* autorelease_pool = [[NSAutoreleasePool alloc] init];
   691     NSString *ns_string = [[NSString alloc] initWithUTF8String:file];
   692     UIImage *ui_image = [[UIImage alloc] initWithContentsOfFile:ns_string];
   693     if (ui_image != nil)
   694         sdl_surface = Create_SDL_Surface_From_CGImage([ui_image CGImage]);
   695     [ui_image release];
   696     [ns_string release];
   697     [autorelease_pool drain];
   698 
   699 #endif  /* #if defined(ALLOW_UIIMAGE_FALLBACK) && ((TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1)) */
   700     return sdl_surface;	
   701 }
   702 
   703 static SDL_Surface* LoadImageFromFile_ImageIO (const char *file)
   704 {
   705     CGImageSourceRef image_source = NULL;
   706 
   707     image_source = CreateCGImageSourceFromFile(file);
   708 
   709     if(NULL == image_source)
   710         return NULL;
   711     
   712     CGImageRef image_ref = CreateCGImageFromCGImageSource(image_source);
   713     CFRelease(image_source);
   714 
   715     if (NULL == image_ref)
   716         return NULL;
   717     SDL_Surface *sdl_surface = Create_SDL_Surface_From_CGImage(image_ref);
   718     CFRelease(image_ref);
   719     return sdl_surface;	
   720 }
   721 
   722 static SDL_Surface* LoadImageFromFile (const char *file)
   723 {
   724 #if (TARGET_OS_IPHONE == 1) || (TARGET_IPHONE_SIMULATOR == 1)
   725     if (USE_UIIMAGE_BACKEND())
   726         return LoadImageFromFile_UIImage(file);
   727     else
   728 #endif
   729         return LoadImageFromFile_ImageIO(file);
   730 }
   731 
   732 #ifdef BMP_USES_IMAGEIO
   733 
   734 SDL_Surface* IMG_LoadCUR_RW (SDL_RWops *src)
   735 {
   736     /* FIXME: Is this a supported type? */
   737     return LoadImageFromRWops(src, CFSTR("com.microsoft.cur"));
   738 }
   739 
   740 SDL_Surface* IMG_LoadICO_RW (SDL_RWops *src)
   741 {
   742     return LoadImageFromRWops(src, kUTTypeICO);
   743 }
   744 
   745 SDL_Surface* IMG_LoadBMP_RW (SDL_RWops *src)
   746 {
   747     return LoadImageFromRWops(src, kUTTypeBMP);
   748 }
   749 
   750 #endif /* BMP_USES_IMAGEIO */
   751 
   752 SDL_Surface* IMG_LoadGIF_RW (SDL_RWops *src)
   753 {
   754     return LoadImageFromRWops (src, kUTTypeGIF);
   755 }
   756 
   757 SDL_Surface* IMG_LoadJPG_RW (SDL_RWops *src)
   758 {
   759     return LoadImageFromRWops (src, kUTTypeJPEG);
   760 }
   761 
   762 SDL_Surface* IMG_LoadPNG_RW (SDL_RWops *src)
   763 {
   764     return LoadImageFromRWops (src, kUTTypePNG);
   765 }
   766 
   767 SDL_Surface* IMG_LoadTGA_RW (SDL_RWops *src)
   768 {
   769     return LoadImageFromRWops(src, CFSTR("com.truevision.tga-image"));
   770 }
   771 
   772 SDL_Surface* IMG_LoadTIF_RW (SDL_RWops *src)
   773 {
   774     return LoadImageFromRWops(src, kUTTypeTIFF);
   775 }
   776 
   777 // Since UIImage doesn't really support streams well, we should optimize for the file case.
   778 // Apple provides both stream and file loading functions in ImageIO.
   779 // Potentially, Apple can optimize for either case.
   780 SDL_Surface* IMG_Load (const char *file)
   781 {
   782     SDL_Surface* sdl_surface = NULL;
   783     
   784     sdl_surface = LoadImageFromFile(file);
   785     if(NULL == sdl_surface)
   786     {
   787         // Either the file doesn't exist or ImageIO doesn't understand the format.
   788         // For the latter case, fallback to the native SDL_image handlers.
   789         SDL_RWops *src = SDL_RWFromFile(file, "rb");
   790         char *ext = strrchr(file, '.');
   791         if (ext) {
   792             ext++;
   793         }
   794         if (!src) {
   795             /* The error message has been set in SDL_RWFromFile */
   796             return NULL;
   797         }
   798         sdl_surface = IMG_LoadTyped_RW(src, 1, ext);
   799     }
   800     return sdl_surface;
   801 }
   802 
   803 #endif /* defined(__APPLE__) && !defined(SDL_IMAGE_USE_COMMON_BACKEND) */