图片简单处理(尺寸变换)

图片拉伸和尺寸变换

• 图片拉伸

- (UIImage *)stretchableImageWithLeftCapWidth:(NSInteger)leftCapWidth topCapHeight:(NSInteger)topCapHeight;

一般leftCapWidth = imageWidth *.5f, topCapHeight = imageWidth * .5f;
//尺寸变换：
//resize图片
- (UIImage *)reSizeImage:(UIImage *)image toSize:(CGSize)reSize{
    UIGraphicsBeginImageContext(CGSizeMake(reSize.width, reSize.height));
    [image drawInRect:CGRectMake(0, 0, reSize.width, reSize.height)];
    UIImage *reSizeImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return reSizeImage;
}

图片的处理大概分 截图(capture), 缩放(scale), 设定大小(resize), 存储(save)

1.等比率缩放：

- (UIImage *)scaleImage:(UIImage *)image toScale:(float)scaleSize{
    UIGraphicsBeginImageContext(CGSizeMake(image.size.width * scaleSize, image.size.height * scaleSize);
    [image drawInRect:CGRectMake(0, 0, image.size.width * scaleSize, image.size.height * scaleSize)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return scaledImage;
}

2.自定长宽:

- (UIImage *)reSizeImage:(UIImage *)image toSize:(CGSize)reSize{
    UIGraphicsBeginImageContext(CGSizeMake(reSize.width, reSize.height));
    [image drawInRect:CGRectMake(0, 0, reSize.width, reSize.height)];
    UIImage *reSizeImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return reSizeImage;
}

3.处理某个特定View只要是继承UIView的object 都可以处理必须先import QuzrtzCore.framework:

-(UIImage*)captureView:(UIView *)theView
{
    CGRect rect = theView.frame;UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    [theView.layer renderInContext:context];
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return img;
}

4.储存图片储存图片这里分成储存到app的文件里和储存到手机的图片库里:

//1) 储存到app的文件里
    NSString *path = [[NSHomeDirectory()stringByAppendingPathComponent:@"Documents"]stringByAppendingPathComponent:@"image.png"];
    [UIImagePNGRepresentation(image) writeToFile:pathatomically:YES];
//把要处理的图片, 以image.png名称存到app home下的Documents目录里
//2)储存到手机的图片库里(必须在真机使用，模拟器无法使用)
    CGImageRef screen = UIGetScreenImage();UIImage* image = [UIImage imageWithCGImage:screen];
    CGImageRelease(screen);
    UIImageWriteToSavedPhotosAlbum(image, self, nil, nil);
    UIGetScreenImage(); // 原来是private(私有)api, 用来截取整个画面,不过SDK 4.0后apple就开放了