2

我正在尝试将图像裁剪成正方形，然后将其缩放到 200x200 的大小。这是我使用的代码，但它并不适合我。我得到的图像有时处于不同的方向，或者没有从中心裁剪，或者比应有的更宽。

float scale = _avatar.image.scale;
UIImageOrientation orientation = _avatar.image.imageOrientation;

if(_avatar.image.size.width < _avatar.image.size.height){ // avatar is a UIImageView
    float startingY = (_avatar.image.size.height-_avatar.image.size.width)/2; // image is taller, determine the origin of the width-sized square, which will be the new image
    CGImageRef imageRef = CGImageCreateWithImageInRect([_avatar.image CGImage], CGRectMake(0, startingY, _avatar.image.size.width, _avatar.image.size.width));
    _avatar.image = [UIImage imageWithCGImage:imageRef scale:scale orientation:orientation];
    CGImageRelease(imageRef);
} else {
    float startingX = (_avatar.image.size.width-_avatar.image.size.height)/2; // image is wider, determine the origin of the height-sized square, which will be the new image
    CGImageRef imageRef = CGImageCreateWithImageInRect([_avatar.image CGImage], CGRectMake(startingX, 0, _avatar.image.size.height, _avatar.image.size.height));
    _avatar.image = [UIImage imageWithCGImage:imageRef scale:scale orientation:orientation];
    CGImageRelease(imageRef);
}

UIGraphicsBeginImageContextWithOptions(CGSizeMake(200, 200), YES, 0.0);
[_avatar.image drawInRect:CGRectMake(0, 0, 200, 200)];
UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

必须如何做才能达到正确的结果？

4

2 回答 2

5

我建议您将这个类别用于发布在github上的 UIImage 。它们也是非常简单的类，您还可以使用它们来了解引擎盖下的内容。

于 2013-08-01T13:17:55.823 回答
3

UIImage 已经为您完成了所有的坐标和方向技巧。所以你不应该使用 UIImage 对象的宽度和高度来计算正方形的坐标。您可以利用 UIKit 来裁剪图像。 

CGFloat startingX = 0;
CGFloat startingY = 0;
CGFloat squareWidth;
if(_avatar.image.size.width < _avatar.image.size.height){ // avatar is a UIImageView  
    startingY = (_avatar.image.size.height-_avatar.image.size.width)/2; // image is taller, determine the origin of the width-sized square, which will be the new image  
    squareWidth = _avatar.image.size.width;
} else {
    startingX = (_avatar.image.size.width-_avatar.image.size.height)/2; // image is wider, determine the origin of the height-sized square, which will be the new image
    squareWidth = _avatar.image.size.height;
}  

UIGraphicsBeginImageContextWithOptions(CGSizeMake(squareWidth, squareWidth), YES, 0.0);
[_avatar.image drawAtPoint:CGPointMake(-startingX, -startingY)]; // Make an offset to draw part of the image
UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext();  
UIGraphicsEndImageContext();

UIGraphicsBeginImageContextWithOptions(CGSizeMake(200, 200), YES, 0.0);
[croppedImage  drawInRect:CGRectMake(0, 0, 200, 200)];
UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
于 2013-08-01T14:02:59.323 回答