我正试图弄清楚是否有办法镜像一张图片。举个例子,拍摄某人的脸部照片并将其剪成两半,显示每一侧反转后的脸部。在CGAffineTransform函数中貌似没有任何可以达成此要求的技巧。请各位图形专家帮忙!!!
我正试图弄清楚是否有办法镜像一张图片。举个例子,拍摄某人的脸部照片并将其剪成两半,显示每一侧反转后的脸部。在CGAffineTransform函数中貌似没有任何可以达成此要求的技巧。请各位图形专家帮忙!!!
这里的基本“技巧”是使用关于X或Y轴的缩放变换,因子为-1。例如,您可以使用此方法创建“水平轴翻转”的变换:
CGAffineTransform transform = CGAffineTransformScale(transform, -1, 1);
你可以在UIImageView
上设置transform
属性来翻转分配的图像,或者将它与另一个变换串联起来以进行更复杂的效果。要获得你描述的确切效果,你可能需要编写一些自定义绘图代码将原始图像绘制到上下文中,然后将翻转的一半覆盖在其上面。在Core Graphics中,这相对简单。
如果您只计划支持4.0版本以上
UIImageOrientation flippedOrientation = UIImageOrientationUpMirrored;
switch (image.imageOrientation) {
case UIImageOrientationUp: break;
case UIImageOrientationDown: flippedOrientation = UIImageOrientationDownMirrored; break;
// ...
}
UIImage * flippedImage = [UIImage imageWithCGImage:image.CGImage scale:image.scale orientation:flippedOrientation];
你可能会想,为什么要费心去处理冗长的switch语句呢?
? UIImage *flip = [UIImage imageWithCGImage:image.CGImage
? scale:image.scale
? orientation:(image.imageOrientation + 4) % 8];
typedef NS_ENUM(NSInteger, UIImageOrientation) {
UIImageOrientationUp, // default orientation
UIImageOrientationDown, // 180 deg rotation
UIImageOrientationLeft, // 90 deg CCW
UIImageOrientationRight, // 90 deg CW
UIImageOrientationUpMirrored, // as above but image mirrored along other axis. horizontal flip
UIImageOrientationDownMirrored, // horizontal flip
UIImageOrientationLeftMirrored, // vertical flip
UIImageOrientationRightMirrored, // vertical flip
};
UIImageOrientation mirroredImageOrientation(UIImageOrientation orientation) {
switch(orientation) {
case UIImageOrientationUp: return UIImageOrientationUpMirrored;
case UIImageOrientationDown: return UIImageOrientationDownMirrored;
case UIImageOrientationLeft: return UIImageOrientationLeftMirrored;
case UIImageOrientationRight: return UIImageOrientationRightMirrored;
case UIImageOrientationUpMirrored: return UIImageOrientationUp;
case UIImageOrientationDownMirrored: return UIImageOrientationDown;
case UIImageOrientationLeftMirrored: return UIImageOrientationLeft;
case UIImageOrientationRightMirrored: return UIImageOrientationRight;
default: return orientation;
}
}
像这样使用函数:
UIImage *flip = [UIImage imageWithCGImage:image.CGImage
scale:image.scale
orientation:mirroredImageOrientation(image.imageOrientation)];
我已经添加了问号来表示可疑的、有异味的代码。类似于编程实践
只需要使用以下方法即可:
UIImage(assetIdentifier: .myIcon)?.withHorizontallyFlippedOrientation()
以上回答均未涉及到问题的一半镜像而非整个图像翻转的部分。混合这些解决方案将导致以下示例函数,您可以将其用作UIImage + Mirroring等类别:
(UIImage *) horizontalMirror {
UIImageOrientation flippedOrientation = UIImageOrientationUpMirrored;
switch (self.imageOrientation) {
case UIImageOrientationUp: break;
case UIImageOrientationDown: flippedOrientation = UIImageOrientationDownMirrored; break;
}
UIImage * flippedImage = [UIImage imageWithCGImage:self.CGImage scale:1.0 orientation:flippedOrientation];
CGImageRef inImage = self.CGImage;
CGContextRef ctx = CGBitmapContextCreate(NULL,
CGImageGetWidth(inImage),
CGImageGetHeight(inImage),
CGImageGetBitsPerComponent(inImage),
CGImageGetBytesPerRow(inImage),
CGImageGetColorSpace(inImage),
CGImageGetBitmapInfo(inImage)
);
CGRect cropRect = CGRectMake(flippedImage.size.width/2, 0, flippedImage.size.width/2, flippedImage.size.height);
CGImageRef TheOtherHalf = CGImageCreateWithImageInRect(flippedImage.CGImage, cropRect);
CGContextDrawImage(ctx, CGRectMake(0, 0, CGImageGetWidth(inImage), CGImageGetHeight(inImage)), inImage);
CGAffineTransform transform = CGAffineTransformMakeTranslation(flippedImage.size.width, 0.0);
transform = CGAffineTransformScale(transform, -1.0, 1.0);
CGContextConcatCTM(ctx, transform);
CGContextDrawImage(ctx, cropRect, TheOtherHalf);
CGImageRef imageRef = CGBitmapContextCreateImage(ctx);
CGContextRelease(ctx);
UIImage *finalImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return finalImage;
}
您可以使用以下代码来适用于Swift 4.0
func didTakePicture(_ real_image: UIImage) {
//suppose real_image = :)
var flipped_image = UIImage(CGImage: real_image.CGImage!, scale: real_image.scale, orientation: .leftMirrored)
// flipped_image is (:
}
myImageView.transform = CGAffineTransformMakeScale(-1, 1);
。 - chris P