I am working to add support for wide color photos in iOS 10. When the user takes a photo from the camera, I need to use the new API that supports the new color space to save the photo data - UIGraphicsImageRenderer
's jpegData
instead of UIImageJPEGRepresentation
.
I'm running into some troubles with image orientations. Taking a photo on my iPad in portrait, the image isn't being drawn correctly. See the comments below:
Old API:
let image = info[UIImagePickerControllerOriginalImage] as! UIImage
let imageData = UIImageJPEGRepresentation(image, 1)
New API:
let image = info[UIImagePickerControllerOriginalImage] as! UIImage
let cgImage = image.cgImage!
let ciImage = CIImage(cgImage: cgImage)
let format = UIGraphicsImageRendererFormat()
format.scale = 1
format.prefersExtendedRange = true
let renderer = UIGraphicsImageRenderer(bounds: ciImage.extent, format: format)
let imageData = renderer.jpegData(withCompressionQuality: 1, actions: { context in
context.cgContext.draw(cgImage, in: ciImage.extent) //draws flipped horizontally
//image.draw(at: .zero) //draws rotated 90 degrees leaving black at bottom
//image.draw(in: ciImage.extent) //draws rotated 90 degrees stretching and compressing the image to fill the rect
})
What's the correct way to replace UIImageJPEGRepresentation
with UIGraphicsImageRenderer
's jpegData
?
UIImage
can have different orientation depending on camera rotation.
You can dynamically resolve the transformation needed to be applied to the image depending on that orientation, like this:
let renderer = UIGraphicsImageRenderer(size: image.size, format: format)
let imageData = renderer.jpegData(withCompressionQuality: 1, actions: { context in
var workSize = image.size;
workSize.width = floor(workSize.width / image.scale)
workSize.height = floor(workSize.height / image.scale)
// No-op if the orientation is already correct
// if image.imageOrientation == .up { draw image }
// 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.identity
switch image.imageOrientation
{
case .down, .downMirrored:
transform = transform.translatedBy(x: workSize.width, y: workSize.height)
transform = transform.rotated(by: CGFloat(Double.pi))
break
case .left, .leftMirrored:
transform = transform.translatedBy(x: workSize.width, y: 0.0)
transform = transform.rotated(by: CGFloat(Double.pi / 2.0))
break
case .right, .rightMirrored:
transform = transform.translatedBy(x: 0.0, y: workSize.height)
transform = transform.rotated(by: CGFloat(-Double.pi / 2.0))
break
case .up, .upMirrored:
break
}
switch image.imageOrientation
{
case .upMirrored, .downMirrored:
transform = transform.translatedBy(x: workSize.width, y: 0.0)
transform = transform.scaledBy(x: -1.0, y: 1.0)
break
case .leftMirrored, .rightMirrored:
transform = transform.translatedBy(x: workSize.height, y: 0.0);
transform = transform.scaledBy(x: -1.0, y: 1.0);
break
case .up, .down, .left, .right:
break
}
// Now we draw the underlying CGImage into a new context, applying the transform
// calculated above.
let ctx = context.cgContext
ctx.concatenate(transform)
switch image.imageOrientation {
case .left, .leftMirrored, .right, .rightMirrored:
ctx.draw(image.cgImage!, in: CGRect(x: 0.0, y:0.0, width: workSize.height, height: workSize.width))
break;
default:
ctx.draw(image.cgImage!, in: CGRect(origin: .zero, size: workSize))
break;
}
})
Answer based on UIImage+fixOrientation
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