荼菜的ios笔记–图片裁剪黑魔法。

#import <UIKit/UIKit.h>
#import "UIImageView+WebCache.h"
@interface UIImageView (WebImage)
/**
 *  @author Tucai, 16-02-23 12:02:53
 *
 *  设置能够自动裁剪的网络图，基于SDWebImage实现
 *
 */
// 模糊图渲染
- (void)renderBlurredImageWithUrl:(NSString *)url placeholder:(UIImage *)placeholder completed:(imageDownloadCompletedBlock) completedBlock;
//按比例缩放网络图片
- (void)yg_setTrimImageWithUrl:(NSString *)url placeholderImage:(UIImage *)placeholder;

#import "UIImageView+WebImage.h"
#import "NSString+URLEncoding.h"
@implementation UIImageView (WebImage)
#pragma mark - 模糊图渲染
- (void)renderBlurredImageWithUrl:(NSString *)url placeholder:(UIImage *)placeholder completed:(imageDownloadCompletedBlock) completedBlock
{
    // 这里必须开启内存缓存
    [SDWebImageManager sharedManager].imageCache.shouldCacheImagesInMemory = YES;
    
    // 渲染背景
    __weak typeof(self) ws = self;
    [ws sd_setImageWithURL:[NSURL URLWithString:url] completed:^(UIImage *webImage, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
        // 999 是一个标记
        if (ws.tag != 999) {
            UIVisualEffectView *visualView = [[UIVisualEffectView alloc] initWithFrame:ws.bounds];
            UIBlurEffect *effect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
            visualView.effect = effect;
            NSLog(@"only once");
            [ws addSubview:visualView];
            ws.tag = 999;
        }
        ws.alpha =0.6;
        ws.image = nil;
        ws.image = webImage;
        if (completedBlock) {
            completedBlock(webImage);
        }
    }];
}
#pragma mark - 裁剪图片
- (void)yg_setTrimImageWithUrl:(NSString *)url placeholderImage:(UIImage *)placeholder{
    
    __weak typeof(self) ws = self;
        [SDWebImageManager sharedManager].imageCache.shouldCacheImagesInMemory = NO;
    
    [self sd_setImageWithURL:[NSURL URLWithString:url] placeholderImage:placeholder completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
        if (image) {
            UIImage *img=[self yg_trimImageWithImage:image];
            ws.image=img;
        }else{
            ws.image =[self yg_trimImageWithImage:placeholder];
        }
    }];
}
-(UIImage *)yg_trimImageWithImage:(UIImage *)image{
    
    //imageView的宽高比
    CGFloat imageViewWidthHeightRatio =self.frame.size.width/self.frame.size.height;
    //屏幕分辨率
//    CGFloat imageScale = [[UIScreen mainScreen] scale];
    CGFloat imageScale = 1;
    
    CGFloat imageWith = image.size.width*imageScale;
    
    CGFloat imageHeight =image.size.height*imageScale;
    
    //image的宽高比
    CGFloat imageWidthHeightRatio =imageWith/imageHeight;
    CGImageRef imageRef = nil;
    
    CGRect rect;
    
//    NSLog(@"nimageWith === %fnimageHeight === %fnImageView宽高比 == %fnimageScale == %f",imageWith,imageHeight,imageViewWidthHeightRatio,imageScale);
    
    if (imageWidthHeightRatio>imageViewWidthHeightRatio) {
        
        rect = CGRectMake((imageWith-imageHeight*imageViewWidthHeightRatio)/2, 0, imageHeight*imageViewWidthHeightRatio, imageHeight);
        
    }else if (imageWidthHeightRatio<imageViewWidthHeightRatio) {
        
        rect = CGRectMake(0, (imageHeight-imageWith/imageViewWidthHeightRatio)/2, imageWith, imageWith/imageViewWidthHeightRatio);
        
    }else {
        rect = CGRectMake(0, 0, imageWith, imageHeight);
    }
    
    imageRef = CGImageCreateWithImageInRect([image CGImage], rect);
    UIImage *res = [UIImage imageWithCGImage:imageRef scale:imageScale orientation:UIImageOrientationUp];
    /**
     一定要，千万要release，否则等着内存泄露吧，稍微高清点的图一张图就是几M内存，很快App就挂了
     */
    CGImageRelease(imageRef);
    
    return res;
}
@end