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旋转我正在尝试将我的图像旋转 90 度。它在没有旋转的情况下工作，但是当我旋转和平移时它不显示。我究竟做错了什么？

            NSString *filePath = [[NSBundle mainBundle] pathForResource:@"check" ofType:@"jpg"];
UIImage *newImage = [[UIImage alloc] initWithContentsOfFile:filePath];

UIGraphicsBeginImageContext(newImage.size);
//CGContextRef c = UIGraphicsGetCurrentContext();

CGContextTranslateCTM(UIGraphicsGetCurrentContext(), newImage.size.width, 0);
//CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0, newImage.size.width);
//CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0);
CGContextRotateCTM(UIGraphicsGetCurrentContext(), 90);
CGRect imageRect = CGRectMake(0, 0, newImage.size.height, newImage.size.width);   
CGContextDrawImage(UIGraphicsGetCurrentContext(), imageRect, newImage.CGImage);
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();

ImageView.image = viewImage;
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3 回答 3

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我建议使用图像视图并像这样使用它的变换：

UIImage *newImage = [[UIImage alloc] initWithContentsOfFile:filePath];
UIImageView *newImageView = [[UIImageView alloc] initWithImage:newImage]; 
newImageView.transform = CGAffineTransformMakeRotation(M_PI_2);
于 2012-11-13T14:24:58.137 回答
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你应该做：

UIGraphicsBeginImageContext(newImage.size);

CGContextRef context = UIGraphicsGetCurrentContext();
CGContextRotateCTM (context, 90* M_PI/180); //Degrees should be in radians.

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

UIImage *viewImage =  UIGraphicsGetImageFromCurrentImageContext();

祝你好运。

更新：

实际上，这是如何将 UIImage 旋转 90 度的副本？

于 2012-11-13T14:34:11.587 回答
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问题是我的定义声明，我需要翻转图像。这是完整的代码：（图像必须是完美的，因为 OCR 会处理图像，即使有一点偏差，也会被拒绝。

    CGContextRef c = UIGraphicsGetCurrentContext();
CGContextSaveGState(c);

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"check" ofType:@"jpg"];
UIImage *newImage = [[UIImage alloc] initWithContentsOfFile:filePath];

NSLog(@"Rect width: %@", NSStringFromCGSize(newImage.size) );
UIGraphicsBeginImageContext(newImage.size);
CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0, newImage.size.width);
CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0);

CGContextTranslateCTM( UIGraphicsGetCurrentContext(), 0.5f * newImage.size.width, 0.5f * newImage.size.height ) ;
CGContextRotateCTM( UIGraphicsGetCurrentContext(), radians( -90 ) ) ;
    CGRect imageRect = CGRectMake(-(newImage.size.height* 0.5f) + 200,  -(0.5f * newImage.size.width) + 200 , newImage.size.height - 200, newImage.size.width - 200);
CGContextDrawImage(UIGraphicsGetCurrentContext(), imageRect, newImage.CGImage);

UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
ImageView.image = viewImage;

CGContextRestoreGState(c);
于 2012-11-13T15:20:28.183 回答