Question

我正在开发一个应用程序，它必须将从摄像头拍摄的图像（通常大约5-6MB）加载到tableview中。我正在异步加载图像并缓存它但我想知道有什么方法可以通过它将这个大尺寸图像更改为更小的尺寸？

Answer 1

尝试这种简单的方法......我在这篇文章What's the easiest way to resize/optimize an image size with the iPhone SDK?

中找到了

+ (UIImage*)imageWithImage:(UIImage*)image 
           scaledToSize:(CGSize)newSize;
{
   UIGraphicsBeginImageContext( newSize );
   [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
   UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   return newImage;
}

Answer 2

这里我将裁剪和调整大小图像的逻辑，根据您的要求使用它。

获取裁剪图片：

UIImage *croppedImg = nil;
CGRect cropRect = CGRectMake(AS YOu Need); // set frame as you need
croppedImg = [self croppIngimageByImageName:self.imageView.image toRect:cropRect];

以下方法返回UIImage（，如您所希望的图像大小）

- (UIImage *)croppIngimageByImageName:(UIImage *)imageToCrop toRect:(CGRect)rect
    {
        //CGRect CropRect = CGRectMake(rect.origin.x, rect.origin.y, rect.size.width, rect.size.height+15);

        CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect);
        UIImage *cropped = [UIImage imageWithCGImage:imageRef];
        CGImageRelease(imageRef);

        return cropped;
    }

在这里你得到通过上述方法返回的Croped Image;

或重新调整

并且还使用以下方法将图像的特定高和宽度用于调整大小：

+ (UIImage*)resizeImage:(UIImage*)image withWidth:(CGFloat)width withHeight:(CGFloat)height
{
    CGSize newSize = CGSizeMake(width, height);
    CGFloat widthRatio = newSize.width/image.size.width;
    CGFloat heightRatio = newSize.height/image.size.height;

    if(widthRatio > heightRatio)
    {
        newSize=CGSizeMake(image.size.width*heightRatio,image.size.height*heightRatio);
    }
    else
    {
        newSize=CGSizeMake(image.size.width*widthRatio,image.size.height*widthRatio);
    }


    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

此方法返回 NewImage ，具有您想要的特定大小。

在IOS中将大图像转换为低尺寸

2 个答案: