使用 clipToMask 时图像旋转 90 度答案

【问题标题】：Image is rotated 90 degrees when using clipToMask使用 clipToMask 时图像旋转 90 度
【发布时间】：2012-06-18 21:35:47
【问题描述】：

我正在尝试剪辑我用相机拍摄的图像的一部分。这是我的剪辑代码：

- (UIImage*) maskImage:(UIImage *)image {

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

UIImage *maskImage = [UIImage imageNamed:@"mask3.png"];
CGImageRef maskImageRef = [maskImage CGImage];

// create a bitmap graphics context the size of the image
CGContextRef mainViewContentContext = CGBitmapContextCreate (NULL, maskImage.size.width, maskImage.size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);


if (mainViewContentContext==NULL)
    return NULL;

CGFloat ratio = 0;

ratio = maskImage.size.width/ image.size.width;

if(ratio * image.size.height < maskImage.size.height) {
    ratio = maskImage.size.height/ image.size.height;
} 

CGRect rect1  = {{0, 0}, {maskImage.size.width, maskImage.size.height}};
CGRect rect2  = {{-((image.size.width*ratio)-maskImage.size.width)/2 , -((image.size.height*ratio)-maskImage.size.height)/2}, {image.size.width*ratio, image.size.height*ratio}};


CGContextClipToMask(mainViewContentContext, rect1, maskImageRef);
CGContextDrawImage(mainViewContentContext, rect2, image.CGImage);


// Create CGImageRef of the main view bitmap content, and then
// release that bitmap context
CGImageRef newImage = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);

UIImage *theImage = [UIImage imageWithCGImage:newImage];

CGImageRelease(newImage);

// return the image
return theImage;

}

我在 viewcontroller 的 captureNow 方法中调用上述方法。我正在使用 AVFoundation 来捕获静止图像：

-(void) captureNow
{

AVCaptureConnection *videoConnection = nil;
for (AVCaptureConnection *connection in stillImageOutput.connections)
{
    for (AVCaptureInputPort *port in [connection inputPorts])
    {
        if ([[port mediaType] isEqual:AVMediaTypeVideo] )
        {
            videoConnection = connection;
            break;
        }
    }
    if (videoConnection) { break; }
}

NSLog(@"about to request a capture from: %@", stillImageOutput);



[stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
 {


     NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
     UIImage *image = [[UIImage alloc] initWithData:imageData];



     [testImageView setImage:[self maskImage:image]];


     self.firstPieceView.frame = CGRectMake(0, 0, 320, 480);

     self.firstPieceView.contentMode = UIViewContentModeScaleAspectFill;
   //  self.firstPieceView.image = image;

   //  [firstPieceView setNeedsDisplay];

     NSLog(@"self.firstPiece.frame is %@", NSStringFromCGRect(self.firstPieceView.frame));
    // [myView becomeFirstResponder];

     }];

self.previewParentView.hidden = YES;
self.photoBtn.hidden=YES;
self.imageMask.hidden = NO;

//add the gesture after taking the first image.
[myView addGestureRecognizersToPiece:self.myView];

}

由于某种原因，我的图像在剪辑时总是旋转 90 度。有谁知道为什么以及如何解决这个问题？提前致谢。

【问题讨论】：

我有一个非常相似的问题，似乎无法挽救我的生命。这是我问的问题：stackoverflow.com/questions/10307521/…你最终弄清楚了吗？

标签： iphone ios quartz-2d cgimage

【解决方案1】：

这里将图像旋转到 90 度的替代解决方案，其代码如下...

yourImageView.transform = CGAffineTransformMakeRotation(3.14159265/2);

当您当时想要分享或保存图片时，只需将图像旋转 90 度，如果需要，则旋转 180 度....

如果我有任何其他想法，这是替代解决方案，那么我将再次发布... 希望对你有帮助...

【讨论】：