Created
May 25, 2018 17:39
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Properly rotate the underlying cgImage of a UIimage given its orientation
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| func fixOrientation(uiImage: UIImage) -> UIImage{ | |
| // No-op if the orientation is already correct | |
| if ( uiImage.imageOrientation == UIImageOrientation.up ) { | |
| return UIImage(cgImage: uiImage.cgImage!, scale: uiImage.scale, orientation: uiImage.imageOrientation) | |
| } | |
| // We need to calculate the proper transformation to make the image upright. | |
| // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored. | |
| var transform: CGAffineTransform = CGAffineTransform.identity | |
| if ( uiImage.imageOrientation == UIImageOrientation.down || uiImage.imageOrientation == UIImageOrientation.downMirrored ) { | |
| transform = transform.translatedBy(x: uiImage.size.width, y: uiImage.size.height) | |
| transform = transform.rotated(by: CGFloat(Double.pi)) | |
| } | |
| if ( uiImage.imageOrientation == UIImageOrientation.left || uiImage.imageOrientation == UIImageOrientation.leftMirrored ) { | |
| transform = transform.translatedBy(x: uiImage.size.width, y: 0) | |
| transform = transform.rotated(by: CGFloat(Double.pi/2)) | |
| } | |
| if ( uiImage.imageOrientation == UIImageOrientation.right || uiImage.imageOrientation == UIImageOrientation.rightMirrored ) { | |
| transform = transform.translatedBy(x: 0, y: uiImage.size.height) | |
| transform = transform.rotated(by: CGFloat(-Double.pi/2)) } | |
| if ( uiImage.imageOrientation == UIImageOrientation.upMirrored || uiImage.imageOrientation == UIImageOrientation.downMirrored ) { | |
| transform = transform.translatedBy(x: uiImage.size.width, y: 0) | |
| transform = transform.scaledBy(x: -1 , y: 1) | |
| } | |
| if ( uiImage.imageOrientation == UIImageOrientation.leftMirrored || uiImage.imageOrientation == UIImageOrientation.rightMirrored ) { | |
| transform = transform.translatedBy(x: uiImage.size.height, y: 0) | |
| transform = transform.scaledBy(x: -1, y: 1) | |
| } | |
| // Now we draw the underlying CGImage into a new context, applying the transform | |
| // calculated above. | |
| let ctx: CGContext = CGContext(data: nil, width: Int(uiImage.size.width), height: Int(uiImage.size.height), | |
| bitsPerComponent: (uiImage.cgImage?.bitsPerComponent)!, bytesPerRow: 0, | |
| space: (uiImage.cgImage!.colorSpace)!, | |
| bitmapInfo: uiImage.cgImage!.bitmapInfo.rawValue)! | |
| ctx.concatenate(transform) | |
| if ( uiImage.imageOrientation == UIImageOrientation.left || | |
| uiImage.imageOrientation == UIImageOrientation.leftMirrored || | |
| uiImage.imageOrientation == UIImageOrientation.right || | |
| uiImage.imageOrientation == UIImageOrientation.rightMirrored ) { | |
| ctx.draw(uiImage.cgImage!, in: CGRect(x: 0,y: 0,width: uiImage.size.height,height: uiImage.size.width)) | |
| } else { | |
| ctx.draw(uiImage.cgImage!, in: CGRect(x: 0,y: 0,width: uiImage.size.width,height: uiImage.size.height)) | |
| } | |
| // And now we just create a new UIImage from the drawing context and return it | |
| return UIImage(cgImage: ctx.makeImage()!) | |
| } |
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