Creating a square thumbnail using Objective-C and Quartz

Here are some code to create a square thumbnail in Quartz and Objective-C

#include <CoreServices/CoreServices.h>
#include <Quartz/Quartz.h>

int main (int argc, const char * argv[]) {
	
	NSAutoreleasePool *pool =  [[NSAutoreleasePool alloc] init];
	NSString * sourcePath = [NSString stringWithCString:argv[1] encoding:NSUTF8StringEncoding]; 
	NSString * destPath = [NSString stringWithCString:argv[2] encoding:NSUTF8StringEncoding]; 
	int desiredWidth = 128;
	int desiredHeight = 128;
	
	// determined the size of image to scale
	NSImage * image = [[NSImage alloc] initWithContentsOfFile:sourcePath];
	NSSize targetSize = NSMakeSize(desiredWidth, desiredHeight);
	NSSize originalSize = [image size];
	float originalWidth = originalSize.width;
	float originalHeight = originalSize.height;
	float targetWidth = targetSize.width;
	float targetHeight = targetSize.height;
	float scaleFactor = 1.0;
	if(originalWidth > originalHeight)
	{
		scaleFactor = targetHeight / originalHeight;			
	}
	else
	{
		scaleFactor = targetWidth / originalWidth;
	}	
	float scaledWidth = originalWidth * scaleFactor;
	float scaledHeight = originalHeight * scaleFactor;	
	targetSize = NSMakeSize(scaledWidth, scaledHeight);
	
	// resize image
	NSPoint thumbnailPoint = NSZeroPoint;
	NSImage* newImage = [[NSImage alloc] initWithSize:targetSize];
	[newImage lockFocus];
	NSRect thumbnailRect;
	thumbnailRect.origin = thumbnailPoint;
	thumbnailRect.size.width = targetSize.width;
	thumbnailRect.size.height = targetSize.height;
	[image drawInRect: thumbnailRect
			 fromRect: NSZeroRect
			operation: NSCompositeSourceOver
			 fraction: 1.0];
	[newImage unlockFocus];	
	
	NSSize sx = NSMakeSize(desiredWidth, desiredHeight);
	float width = 0;
	if(targetSize.width > targetSize.height)
	{
		thumbnailPoint.x = (targetSize.width - targetSize.height) / 2; 
		width = targetSize.height;
	}
	else
	{
		thumbnailPoint.y = (targetSize.height - targetSize.width) / 2;
		width = targetSize.width;
	}	
	
	// create square thumbnail
	NSImage *newImage2 = [[NSImage alloc] initWithSize:sx];
	[newImage2 lockFocus];
	
	NSRect drawInRect;
	drawInRect.origin = NSZeroPoint;
	drawInRect.size.width = width;
	drawInRect.size.height = width;
	
	NSRect fromRect;
	fromRect.origin = thumbnailPoint;
	fromRect.size.width = width;
	fromRect.size.height = width;
	[newImage drawInRect: drawInRect
	     	    fromRect: fromRect
		       operation: NSCompositeSourceOver
				fraction: 1.0];
	[newImage2 unlockFocus];	
	
	// Save the image
	NSData *imageData = [newImage2 TIFFRepresentation];
	NSBitmapImageRep *imageRep = [NSBitmapImageRep imageRepWithData: imageData];
	NSDictionary *imageProps = [NSDictionary dictionaryWithObject:[NSNumber numberWithFloat:1.0] forKey:NSImageCompressionFactor];
	NSData *data = [imageRep representationUsingType:NSJPEGFileType properties:imageProps];
	[data writeToFile: destPath atomically:YES];
	
	[pool release];
	
	NSLog(@"Done");

	return 0;
}