IOS UIImage的图像上下颠倒(IOS UIImage Image upside down)

如果我画我的形象我固定的问题使用CGAffintrasform

CGAffineTransform myTr = CGAffineTransformMake(1, 0, 0, -1, 0, backImage.size.height);
CGContextConcatCTM(context, myTr);
[backImage drawInRect:CGRectMake(cbx, -cby, backImage.size.width, backImage.size.height)];
myTr = CGAffineTransformMake(1, 0, 0, -1, 0, backImage.size.height);
CGContextConcatCTM(context, myTr);

当我想写入文件我用这个

 NSData *imageData = UIImageJPEGRepresentation(backImage, 0);  

然后图像上下颠倒怎么样？

Answer 1:

如果你想获得一个UIImage保存，使用方法：

UIGraphicsBeginImageContextWithOptions(size, isOpaque, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextDrawImage(context, (CGRect){ {0,0}, origSize }, [origImage CGImage]);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;

然后做：

 NSData *imageData = UIImageJPEGRepresentation(backImage, 0);

Answer 2:

首先要识别矩阵。

1, 0, 0
0, 1, 0
0, 0, 1

CGAffineTransform matrix = CGAffineTransformMake(1, 0, 0, 1, 0, 0);

移动位置绘制...

matrix = CGAffineTransformTranslate(matrix, x, y);

翻转矩阵水平。

matrix = CGAffineTransformScale(matrix, -1, 1);

翻转矩阵垂直。

matrix = CGAffineTransformScale(matrix, 1, -1);

旋转矩阵

matrix = CGAffineTransformRotate(matrix, angle);

适合大规模的UIImage到UIView的。

matrix = CGAffineTransformScale(matrix, imageWidth/viewWidth, imageheight/viewHeight);

启动基质进入环境。

CGContextConcatCTM(context, matrix);

绘制图像。

[backImage drawAtPoint:CGPointMake(0, 0)];

:)

文章来源: IOS UIImage Image upside down