裁剪后的图像在iPhone中被放大了

Question

我有一个应用程序，我缩放我的图像(360,480)到(320,480)，然后裁剪图像。它工作得很好。但当我们得到图像时它会得到一个缩放类型的图像。投影到前面。我是这样做的。

[self imageWithImage:(UIImage *)image scaledToSize:CGSizeMake(160.0f,240.0f)];

，我的定义是-

-(UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
    //UIGraphicsBeginImageContext(newSize);
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    [self cropimage:newImage];
    return newImage;
}

在cropimage中我这样做-

-(void)cropimage:(UIImage *)image
{
   CGRect cropRect = CGRectMake(20,100,280,200);
     CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], cropRect);
    UIImage* croppedImage = [UIImage imageWithCGImage:imageRef];
         CGImageRelease(imageRef);
    NSData *pictureData = [NSData dataWithData:UIImagePNGRepresentation(croppedImage)];
}

有人能找出我的方法有什么问题吗?

Answer 1

尝试传递图像。缩放比例而不是0.0，以强制它使用传入的图像比例。

-(UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
    //UIGraphicsBeginImageContext(newSize);
    UIGraphicsBeginImageContextWithOptions(newSize, NO, image.scale);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    [self cropimage:newImage];
    return newImage;
}