UIImage拉伸、合成、截取、保存到相册、截屏
一.拉伸
- (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0,0, newSize.width, newSize.height)];
UIImage *newImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
二.Combine two UIImages－合成
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;
}
三.Create a UIImage from a part of another UIImage－截取
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;
}
四.Save UIImage to Photo Album－保存到相册
This is just a one-liner:
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];
}
五.截屏
- (UIImage *)screenShotsImage
{
UIGraphicsBeginImageContext(self.view.bounds.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}