CGRect 图像大小调整

Question

我正在使用 CGRect 来显示图像。我希望 CGRect 使用图像的宽度和高度，而无需我指定它。

可以这样：

CGRectMake(0.0f, 40.0f, 480.0f, 280.0f);

变成这样：

CGRectMake(0.0f, 40.0f, myImage.width, myImage.height);

当我指定参数时，某些图像会变形。

这是代码：

CGRect myImageRect = CGRectMake(0.0f, 40.0f, 480.0f, 280.0f);
UIImageView *myImage = [[UIImageView alloc] initWithFrame:myImageRect];
[myImage setImage:[UIImage imageNamed:recipe.img]];

感谢您的帮助。

Answer 1

获得 UIImage 后，您可以通过查看 大小 属性：

UIImage * image = [UIImage imageNamed:recipe.img];
CGRect rect = CGRectMake(0.0f, 40.0f, image.size.width, image.size.height);

UIImageView * imageView = [[UIImageView alloc] initWithFrame:rect];
[imageView setImage:image];

Answer 2

UIImage 上的这个类别可能会有所帮助。

像这样使用它：aImage =[aImage imageByScalingProportionallyToSize: myImageRect]

@implementation UIImage (Extras)

- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize {

    UIImage *sourceImage = self;
    UIImage *newImage = nil;

    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;

    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;

    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;

    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {

        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor < heightFactor) 
            scaleFactor = widthFactor;
        else
            scaleFactor = heightFactor;

        scaledWidth  = width * scaleFactor;
        scaledHeight = height * scaleFactor;

        // center the image

//        if (widthFactor < heightFactor) {
//          thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; 
//        } else if (widthFactor > heightFactor) {
//          thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
//        }

        //thumbnailPoint.x
    }


    // this is actually the interesting part:

    UIGraphicsBeginImageContext(targetSize);

    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width  = scaledWidth;
    thumbnailRect.size.height = scaledHeight;

    [sourceImage drawInRect:thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    if(newImage == nil) NSLog(@"could not scale image");


    return newImage ;
}

@end;