iOS UIImage扩展方法(category):放大、旋转、合并UIImage、增加渐变层、添加阴影、调节透明度、保存到相册

来源：互联网发布：java aop自定义编辑：程序博客网时间：2024/05/16 05:40

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;

- (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;
- (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

- (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();
    return resultingImage;}

- (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;