iphone UIimage 常用 方法

http://iphoneincubator.com/blog/tag/uiimage

Recently there have been some interesting developer news related to working with images on the iPhone.

• First there is Chris Greening’s open source project simple-iphone-image-processing , that provides a set of common image processing tasks .
• Today I listened to the Mobile Orchard’s podcast Interview with Paul Cantrell , and the discussion was about UIKit, views, layers, etc. This was the most enlightening information I’ve come across on this topic ever. Highly recommended.

So, I thought I’d contribute a few UIImage routines that I’ve found useful.

Combine two UIImages

To add two UIImages together you need to make use of Graphics Context.

 - (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2 {
     UIGraphicsBeginImageContext(image1.size);

     // Draw image1
     [image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];

     // Draw image2
     [image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];

     UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();

     UIGraphicsEndImageContext();

     return  resultingImage;
 }

- (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2 {
	UIGraphicsBeginImageContext(image1.size);

	// Draw image1
	[image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];

	// Draw image2
	[image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];

	UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();

	UIGraphicsEndImageContext();

	return resultingImage;
}

Create a UIImage from a part of another UIImage

This requires a round-trip to Core Graphics land:

 - (UIImage *)imageFromImage:(UIImage *)image inRect:(CGRect)rect {
     CGImageRef sourceImageRef = [image CGImage];
     CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, rect);
     UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
     return  newImage;
 }

- (UIImage *)imageFromImage:(UIImage *)image inRect:(CGRect)rect {
	CGImageRef sourceImageRef = [image CGImage];
	CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, rect);
	UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
	return newImage;
}

Save UIImage to Photo Album

This is just a one-liner:

 UIImageWriteToSavedPhotosAlbum(image, self, @selector(imageSavedToPhotosAlbum: didFinishSavingWithError: contextInfo:), context);

UIImageWriteToSavedPhotosAlbum(image, self, @selector(imageSavedToPhotosAlbum: didFinishSavingWithError: contextInfo:), context);

And to know if the save was successful:

 - ( void )imageSavedToPhotosAlbum:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:( void  *)contextInfo {
     NSString *message;
     NSString *title;
     if  (!error) {
         title = NSLocalizedString(@"SaveSuccessTitle" , @ "" );
         message = NSLocalizedString(@"SaveSuccessMessage" , @ "" );
     } else  {
         title = NSLocalizedString(@"SaveFailedTitle" , @ "" );
         message = [error description];
     }
     UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title
                                                     message:message
                                                    delegate:nil
                                           cancelButtonTitle:NSLocalizedString(@"ButtonOK" , @ "" )
                                           otherButtonTitles:nil];
     [alert show];
     [alert release];
 }