一有用的 UIImage 扩展，支持（等比例）放大和旋转可在许多 App 中使用。
UIImage-Extensions.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
CGFloat DegreesToRadians(CGFloat degrees);
CGFloat RadiansToDegrees(CGFloat radians);
@interface UIImage (JQ_Extensions)
- (UIImage *)imageAtRect:(CGRect)rect;- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize;
- (UIImage *)imageByScalingToSize:(CGSize)targetSize;
- (UIImage *)imageRotatedByRadians:(CGFloat)radians;
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees;
- (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2;
[objc] view plaincopyprint?
- (UIImage *) imageWithBackgroundColor:(UIColor *)bgColor
shadeAlpha1:(CGFloat)alpha1
shadeAlpha2:(CGFloat)alpha2
shadeAlpha3:(CGFloat)alpha3
shadowColor:(UIColor *)shadowColor
shadowOffset:(CGSize)shadowOffset
shadowBlur:(CGFloat)shadowBlur;
- (UIImage *)imageWithShadowColor:(UIColor *)shadowColor
shadowOffset:(CGSize)shadowOffset
shadowBlur:(CGFloat)shadowBlur;<br>
- (UIImage *)imageByApplyingAlpha:(CGFloat)alpha;
- ( void ) saveToAlbumWithMetadata: ( NSDictionary * ) metadata
customAlbumName: ( NSString * ) customAlbumName
completionBlock: ( void ( ^ )( void )) completionBlock
failureBlock: ( void ( ^ )( NSError * error )) failureBlock
@end;
UIImage-Extensions.m
#import "UIImage-Extensions.h"
CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};
CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;};
@implementation UIImage (JQ_Extensions)
-(UIImage *)imageAtRect:(CGRect)rect
{
CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], rect);
UIImage* subImage = [UIImage imageWithCGImage: imageRef];
CGImageRelease(imageRef);
return subImage;
}
- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize {
UIImage *sourceImage = self;
UIImage *newImage = nil;
CGSize imageSize = sourceImage.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
if (CGSizeEqualToSize(imageSize, targetSize) == NO) {
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if (widthFactor < heightFactor)
scaleFactor = widthFactor;
else
scaleFactor = heightFactor;
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
// center the image
if (widthFactor < heightFactor) {
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
} else if (widthFactor > heightFactor) {
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
// this is actually the interesting part:
UIGraphicsBeginImageContext(targetSize);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
if(newImage == nil) NSLog(@"could not scale image");
return newImage ;
}
- (UIImage *)imageByScalingToSize:(CGSize)targetSize {
UIImage *sourceImage = self;
UIImage *newImage = nil;
// CGSize imageSize = sourceImage.size;
// CGFloat width = imageSize.width;
// CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
// CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
// this is actually the interesting part:
UIGraphicsBeginImageContext(targetSize);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
if(newImage == nil) NSLog(@"could not scale image");
return newImage ;
}
- (UIImage *)imageRotatedByRadians:(CGFloat)radians
{
return [self imageRotatedByDegrees:RadiansToDegrees(radians)];
}
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees
{
// calculate the size of the rotated view's containing box for our drawing space
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)];
CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
[rotatedViewBox release];
// Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
// Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);
// // Rotate the image context
CGContextRotateCTM(bitmap, DegreesToRadians(degrees));
// Now, draw the rotated/scaled image into the context
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
// Combine two UIImages
[objc] view plaincopyprint?
- (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2 {
UIGraphicsBeginImageContext(image2.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();<br>
return resultingImage;
}
[objc] view plaincopyprint?
- (UIImage *) imageWithBackgroundColor:(UIColor *)bgColor
shadeAlpha1:(CGFloat)alpha1
shadeAlpha2:(CGFloat)alpha2
shadeAlpha3:(CGFloat)alpha3
shadowColor:(UIColor *)shadowColor
shadowOffset:(CGSize)shadowOffset
shadowBlur:(CGFloat)shadowBlur {
UIImage *image = self;
CGColorRef cgColor = [bgColor CGColor];
CGColorRef cgShadowColor = [shadowColor CGColor];
CGFloat components[16] = {1,1,1,alpha1,1,1,1,alpha1,1,1,1,alpha2,1,1,1,alpha3};
CGFloat locations[4] = {0,0.5,0.6,1};
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGGradientRef colorGradient = CGGradientCreateWithColorComponents(colorSpace, components, locations, (size_t)4);
CGRect contextRect;
contextRect.origin.x = 0.0f;
contextRect.origin.y = 0.0f;
contextRect.size = [image size];
//contextRect.size = CGSizeMake([image size].width+5,[image size].height+5);
// Retrieve source image and begin image context
UIImage *itemImage = image;
CGSize itemImageSize = [itemImage size];
CGPoint itemImagePosition;
itemImagePosition.x = ceilf((contextRect.size.width - itemImageSize.width) / 2);
itemImagePosition.y = ceilf((contextRect.size.height - itemImageSize.height) / 2);
UIGraphicsBeginImageContext(contextRect.size);
CGContextRef c = UIGraphicsGetCurrentContext();
// Setup shadow
CGContextSetShadowWithColor(c, shadowOffset, shadowBlur, cgShadowColor);
// Setup transparency layer and clip to mask
CGContextBeginTransparencyLayer(c, NULL);
CGContextScaleCTM(c, 1.0, -1.0);
CGContextClipToMask(c, CGRectMake(itemImagePosition.x, -itemImagePosition.y, itemImageSize.width, -itemImageSize.height), [itemImage CGImage]);
// Fill and end the transparency layer
CGContextSetFillColorWithColor(c, cgColor);
contextRect.size.height = -contextRect.size.height;
CGContextFillRect(c, contextRect);
CGContextDrawLinearGradient(c, colorGradient,CGPointZero,CGPointMake(contextRect.size.width*1.0/4.0,contextRect.size.height),0);
CGContextEndTransparencyLayer(c);
//CGPointMake(contextRect.size.width*3.0/4.0, 0)
// Set selected image and end context
UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGColorSpaceRelease(colorSpace);
CGGradientRelease(colorGradient);
return resultImage;
}
- (UIImage *)imageWithShadowColor:(UIColor *)shadowColor
shadowOffset:(CGSize)shadowOffset
shadowBlur:(CGFloat)shadowBlur
{
CGColorRef cgShadowColor = [shadowColor CGColor];
CGColorSpaceRef colourSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef shadowContext = CGBitmapContextCreate(NULL, self.size.width, self.size.height,
CGImageGetBitsPerComponent(self.CGImage), 0,
colourSpace, kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(colourSpace);
// Setup shadow
CGContextSetShadowWithColor(shadowContext, shadowOffset, shadowBlur, cgShadowColor);
CGRect drawRect = CGRectMake(-shadowBlur, -shadowBlur, self.size.width + shadowBlur, self.size.height + shadowBlur);
CGContextDrawImage(shadowContext, drawRect, self.CGImage);
CGImageRef shadowedCGImage = CGBitmapContextCreateImage(shadowContext);
CGContextRelease(shadowContext);
UIImage * shadowedImage = [UIImage imageWithCGImage:shadowedCGImage];
CGImageRelease(shadowedCGImage);
return shadowedImage;
}
- (UIImage *)imageByApplyingAlpha:(CGFloat)alpha {
UIGraphicsBeginImageContextWithOptions(self.size, NO, 0.0f);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGRect area = CGRectMake(0, 0, self.size.width, self.size.height);
CGContextScaleCTM(ctx, 1, -1);
CGContextTranslateCTM(ctx, 0, -area.size.height);
CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
CGContextSetAlpha(ctx, alpha);
CGContextDrawImage(ctx, area, self.CGImage);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
- ( void ) saveToAlbumWithMetadata: ( NSDictionary * ) metadata
customAlbumName: ( NSString * ) customAlbumName
completionBlock: ( void ( ^ )( void )) completionBlock
failureBlock: ( void ( ^ )( NSError * error )) failureBlock
{
NSData * imageData = UIImagePNGRepresentation ( self );
ALAssetsLibrary * assetsLibrary = [[ ALAssetsLibrary alloc ] init ];
void ( ^ AddAsset )( ALAssetsLibrary * , NSURL * ) = ^ ( ALAssetsLibrary * assetsLibrary , NSURL * assetURL ) {
[ assetsLibrary assetForURL : assetURL resultBlock :^ ( ALAsset * asset ) {
[ assetsLibrary enumerateGroupsWithTypes : ALAssetsGroupAll usingBlock :^ ( ALAssetsGroup * group , BOOL * stop ) {
if ([[ group valueForProperty : ALAssetsGroupPropertyName ] isEqualToString : customAlbumName ]) {
[ group addAsset : asset ];
if ( completionBlock ) {
completionBlock ();
}
}
} failureBlock :^ ( NSError * error ) {
if ( failureBlock ) {
failureBlock ( error );
}
}];
} failureBlock :^ ( NSError * error ) {
if ( failureBlock ) {
failureBlock ( error );
}
}];
};
[ assetsLibrary writeImageDataToSavedPhotosAlbum : imageData metadata : metadata completionBlock :^ ( NSURL * assetURL , NSError * error ) {
if ( customAlbumName ) {
[ assetsLibrary addAssetsGroupAlbumWithName : customAlbumName resultBlock :^ ( ALAssetsGroup * group ) {
if ( group ) {
[ assetsLibrary assetForURL : assetURL resultBlock :^ ( ALAsset * asset ) {
[ group addAsset : asset ];
if ( completionBlock ) {
completionBlock ();
}
} failureBlock :^ ( NSError * error ) {
if ( failureBlock ) {
failureBlock ( error );
}
}];
} else {
AddAsset ( assetsLibrary , assetURL );
}
} failureBlock :^ ( NSError * error ) {
AddAsset ( assetsLibrary , assetURL );
}];
} else {
if ( completionBlock ) {
completionBlock ();
}
}
}];
}
@end;