Question

How can I draw to an image in objective-c? all I need to do is create an image with a size I set, draw few AA lines and save the image to a png file. I tried to find it in apple docs but there are CGImage, NSImage, CIImage and more. which one is easiest for my goal? I only need to support the latest mac os x version so new things are not a problem.

Answer 1

Probably the easiest way is to use an NSImage and draw directly into it after calling lockFocus.

Example:

NSSize imageSize = NSMakeSize(512, 512);
NSImage *image = [[[NSImage alloc] initWithSize:imageSize] autorelease];
[image lockFocus];
//draw a line:
[NSBezierPath strokeLineFromPoint:NSMakePoint(100, 100) toPoint:NSMakePoint(200, 200)];
//...
NSBitmapImageRep *imageRep = [[[NSBitmapImageRep alloc] initWithFocusedViewRect:NSMakeRect(0, 0, imageSize.width, imageSize.height)] autorelease];
NSData *pngData = [imageRep representationUsingType:NSPNGFileType properties:nil];
[image unlockFocus];
[pngData writeToFile:@"/path/to/your/file.png" atomically:YES];