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];
}