Using libjpeg from Objective C in XCode - objective-c

Question

Basically I am doing a screen capture app with optimum image size.
I am trying to capture my Mac screen and save it as JPEG file.
I wanted to capture the screen using Cocoa API [CGWindowListCreateImage] and save the file as JPEG using libjpeg9. I included the static library [libjpeg.a] and the header files[jpeglib.h, jconfig.h, jerror.h and jmorecfg.h] using the "Add Files to Project_Name" option in XCode.
The code I used to save as JPEG file is
int write_jpeg_file( char *filename )
{
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
/* this is a pointer to one row of image data */
JSAMPROW row_pointer[1];
FILE *outfile = fopen( filename, "wb" );
if ( !outfile )
{
printf("Error opening output jpeg file %s\n!", filename );
return -1;
}
cinfo.err = jpeg_std_error( &jerr );
jpeg_create_compress(&cinfo);
jpeg_stdio_dest(&cinfo, outfile);
/* Setting the parameters of the output file here */
cinfo.image_width = width;
cinfo.image_height = height;
cinfo.input_components = bytes_per_pixel;
cinfo.in_color_space = color_space;
/* default compression parameters, we shouldn't be worried about these */
jpeg_set_defaults( &cinfo );
/* Now do the compression .. */
jpeg_start_compress( &cinfo, TRUE );
/* like reading a file, this time write one row at a time */
while( cinfo.next_scanline < cinfo.image_height )
{
row_pointer[0] = &raw_image[ cinfo.next_scanline * cinfo.image_width * cinfo.input_components];
jpeg_write_scanlines( &cinfo, row_pointer, 1 );
}
/* similar to read file, clean up after we're done compressing */
jpeg_finish_compress( &cinfo );
jpeg_destroy_compress( &cinfo );
fclose( outfile );
/* success code is 1! */
return 1;
}
When I Build and Run the project I am getting following error
Parse Issue
Expected }
in the line
typedef enum { FALSE = 0, TRUE = 1 } boolean;
in jmorecfg.h which is libjpeg header file. I am not sure why I am getting this error. Please help me.
I know there is a way to save the file using Cocoa API instead of using libjpeg.
I first tried in XCode using Cocoa. I am able to get the JPEG file. The file size is relatively bigger(~200KB). When I create the image in C using libjpeg the file size is ~100KB.
The code I used:
CGFloat imageCompression = 0.6;
- (NSImage *)captureImageForRect:(NSRect)rect {
CGImageRef screenShot = CGWindowListCreateImage(CGRectInfinite, kCGWindowListOptionOnScreenOnly, kCGNullWindowID, kCGWindowImageDefault);
NSBitmapImageRep *imageRep = [[NSBitmapImageRep alloc] initWithCGImage:screenShot];
NSLog(#"Bits per pixel : %ld", [imageRep bitsPerPixel]);
NSImage *result = [[NSImage alloc] init];
[result addRepresentation:imageRep];
screenShot=nil;
imageRep=nil;
return result;
}
-(NSData *)jpegReresentationOfImage:(NSImage *) image {
NSBitmapImageRep* myBitmapImageRep=nil;
NSSize imageSize = [image size];
[image lockFocus];
NSRect imageRect = NSMakeRect(0, 0, imageSize.width, imageSize.height);
myBitmapImageRep = [[NSBitmapImageRep alloc] initWithFocusedViewRect:imageRect];
[image unlockFocus];
// set up the options for creating a JPEG
NSDictionary* options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithDouble:imageCompression], NSImageCompressionFactor,
[NSNumber numberWithBool:NO], NSImageProgressive,
nil];
NSData* imageData = [myBitmapImageRep representationUsingType:NSJPEGFileType properties:options];
myBitmapImageRep=nil;
return ( imageData);
}
-(void)captureAndSave {
NSString *fileName = #"/Volumes/Official/images/output/Mac_Window_1.jpg";
NSImage *screenshot = [self captureImageForRect:[[NSScreen mainScreen] frame]];
NSData *jpgRep = [self jpegReresentationOfImage:screenshot];
[jpgRep writeToFile:[fileName stringByExpandingTildeInPath] atomically:NO];
[NSApp terminate:self];
}

Answer 1

Adding the following line to jconfig.h solved the problem. After adding this, I am not getting compile error and I am able to use libjpeg inside my Objetive-C program.
#define USE_MAC_MEMMGR
In jmemmac.c, I found the following code which helped me to fix it. Just adding the above line worked!
#ifndef USE_MAC_MEMMGR /* make sure user got configuration right */
You forgot to define USE_MAC_MEMMGR in jconfig.h. /* deliberate syntax error */
#endif