正确裁剪和缩放UIImage

Question

我正在尝试将图像裁剪成方形,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,或者比它应该更宽.

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();

如何才能达到正确的结果？

Answer 1

我建议你在github上发布用于UIImage的这个类别.它们也是非常简单的类,您也可以使用它们来学习内幕.