UIImage 图片处理

1.等比率缩放

//等比率缩放
- (UIImage *)scaleImage:(UIImage *)image toScale:(float)scaleSize {
    //设置图片的上下文
    UIGraphicsBeginImageContext(CGSizeMake(image.size.width*scaleSize, image.size.height*scaleSize));
    //绘制图片的大小
    [image drawInRect:CGRectMake(0, 0, image.size.width*scaleSize, image.size.height*scaleSize)];
    //生成新的图片
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    //结束上下文的编辑
    UIGraphicsEndImageContext();
    //返回图片
    return scaledImage;
}

2.自定义宽高

//自定长宽
- (UIImage *)reSizeImage:(UIImage *)image toSize:(CGSize)reSize {
    //设置上下文
    UIGraphicsBeginImageContext(CGSizeMake(reSize.width, reSize.height));
    //重定义大小
    [image drawInRect:CGRectMake(0, 0, reSize.width, reSize.height)];
    //生成新图片
    UIImage *reSizeImage = UIGraphicsGetImageFromCurrentImageContext();
    //结束上下文
    UIGraphicsEndImageContext();
    //返回图片
    return reSizeImage;
}

3.处理某个特定的view

//处理某个特定的view
- (UIImage *)captureView:(UIView *)theView {
    //取得当前view的frame
    CGRect rect = theView.frame;
    //开始上下文
    UIGraphicsBeginImageContext(rect.size);
    //
    CGContextRef context = UIGraphicsGetCurrentContext();
    //
    [theView.layer renderInContext:context];
    //将view转换为图片
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    //结束上下文
    UIGraphicsEndImageContext();
    //返回图片
    return img;
}

其中，在view里面实现

UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
        imageView.image = [UIImage imageNamed:@"1.jpg"];
        [self addSubview:imageView];

4.存储图片,存到app的文件里

- (void)saveImage:(UIImage *)image image:(int)location{
    if (location == 1) {
        //存储路径，以及存储的文件名字
        NSString *path = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"xiaoye.png"];
        //将图片写入文件
        [UIImagePNGRepresentation(image) writeToFile:path atomically:YES];
        //找到Documents文件目录
        NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
        //输出Documents目录下得文件名字
        NSLog(@"存储到docments目录下的文件有:%@",[[NSFileManager defaultManager] subpathsAtPath:docPath]);
    }
}

5.在viewdidload里测试

 UIImage *image = [UIImage imageNamed:@"1.jpg"];
    
    //等比率的缩放
    UIImage *scaledImage = [self scaleImage:image toScale:0.5f];
    NSLog(@"%@",scaledImage);
    
    //自定长宽
    UIImage *reSizeImage = [self reSizeImage:image toSize:CGSizeMake(100.0f, 50.0f)];
    NSLog(@"%@",reSizeImage);
    
    //处理特定的view，继承自uiview，需要导入QuzrtzCore.framework
    MyView *view = [[MyView alloc] initWithFrame:CGRectMake(0, 0, 160, 240)];
    UIImage *img = [self captureView:view];
    NSLog(@"%@",img);
    
    //存储图片到Documents目录下
    [self saveImage:image image:1];
    
    //测试图片，scaledImage，reSizeImage，img
    self.view.backgroundColor = [UIColor colorWithPatternImage:img];