I am unable to rotate the image by 90 degrees in swift. I have written below code but there is an error and doesn't compile
func imageRotatedByDegrees(oldImage: UIImage, deg degrees: CGFloat) -> UIImage {
//Calculate the size of the rotated view's containing box for our drawing space
let rotatedViewBox: UIView = UIView(frame: CGRect(x: 0, y: 0, width: oldImage.size.width, height: oldImage.size.height))
let t: CGAffineTransform = CGAffineTransform(rotationAngle: degrees * CGFloat(M_PI / 180))
rotatedViewBox.transform = t
let rotatedSize: CGSize = rotatedViewBox.frame.size
//Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize)
let bitmap: CGContext = UIGraphicsGetCurrentContext()!
//Move the origin to the middle of the image so we will rotate and scale around the center.
bitmap.translateBy(x: rotatedSize.width / 2, y: rotatedSize.height / 2)
//Rotate the image context
bitmap.rotate(by: (degrees * CGFloat(M_PI / 180)))
//Now, draw the rotated/scaled image into the context
bitmap.scaleBy(x: 1.0, y: -1.0)
bitmap.draw(oldImage, in: CGRect(origin: (x: -oldImage.size.width / 2, y: -oldImage.size.height / 2, width: oldImage.size.width, height: oldImage.size.height), size: oldImage.cgImage))
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
below is the code i am not sure about
bitmap.draw(oldImage, in: CGRect(origin: (x: -oldImage.size.width / 2, y: -oldImage.size.height / 2, width: oldImage.size.width, height: oldImage.size.height), size: oldImage.cgImage))
This is an extension of UIImage that targets Swift 4.0 and can rotate just the image without the need for a UIImageView. Tested successfully that the image was rotated, and not just had its exif data changed.
import UIKit
extension UIImage {
func rotate(radians: CGFloat) -> UIImage {
let rotatedSize = CGRect(origin: .zero, size: size)
.applying(CGAffineTransform(rotationAngle: CGFloat(radians)))
.integral.size
UIGraphicsBeginImageContext(rotatedSize)
if let context = UIGraphicsGetCurrentContext() {
let origin = CGPoint(x: rotatedSize.width / 2.0,
y: rotatedSize.height / 2.0)
context.translateBy(x: origin.x, y: origin.y)
context.rotate(by: radians)
draw(in: CGRect(x: -origin.y, y: -origin.x,
width: size.width, height: size.height))
let rotatedImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return rotatedImage ?? self
}
return self
}
}
To perform a 180 degree rotation, you can call it like this:
let rotatedImage = image.rotate(radians: .pi)
If for whatever reason it fails to rotate, the original image will then be returned.
set ImageView image
ImageView.transform = ImageView.transform.rotated(by: CGFloat(M_PI_2))
let angle = CGFloat(M_PI_2)
let tr = CGAffineTransform.identity.rotated(by: angle)
ImageView.transform = tr
In one line:
rotatedViewBox.transform = CGAffineTransform(rotationAngle: CGFloat.pi/2)
In Swift 4.2 and Xcode 10.0
dropDownImageView.transform = dropDownImageView.transform.rotated(by: CGFloat(Double.pi / 2))
If you want to add animation...
UIView.animate(withDuration: 2.0, animations: {
self.dropDownImageView.transform = self.dropDownImageView.transform.rotated(by: CGFloat(Double.pi / 2))
})
You can use the code below for Swift 3:
extension UIImage {
func fixImageOrientation() -> UIImage? {
var flip:Bool = false //used to see if the image is mirrored
var isRotatedBy90:Bool = false // used to check whether aspect ratio is to be changed or not
var transform = CGAffineTransform.identity
//check current orientation of original image
switch self.imageOrientation {
case .down, .downMirrored:
transform = transform.rotated(by: CGFloat(M_PI));
case .left, .leftMirrored:
transform = transform.rotated(by: CGFloat(M_PI_2));
isRotatedBy90 = true
case .right, .rightMirrored:
transform = transform.rotated(by: CGFloat(-M_PI_2));
isRotatedBy90 = true
case .up, .upMirrored:
break
}
switch self.imageOrientation {
case .upMirrored, .downMirrored:
transform = transform.translatedBy(x: self.size.width, y: 0)
flip = true
case .leftMirrored, .rightMirrored:
transform = transform.translatedBy(x: self.size.height, y: 0)
flip = true
default:
break;
}
// calculate the size of the rotated view's containing box for our drawing space
let rotatedViewBox = UIView(frame: CGRect(origin: CGPoint(x:0, y:0), size: size))
rotatedViewBox.transform = transform
let rotatedSize = rotatedViewBox.frame.size
// Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize)
let bitmap = UIGraphicsGetCurrentContext()
// Move the origin to the middle of the image so we will rotate and scale around the center.
bitmap!.translateBy(x: rotatedSize.width / 2.0, y: rotatedSize.height / 2.0);
// Now, draw the rotated/scaled image into the context
var yFlip: CGFloat
if(flip){
yFlip = CGFloat(-1.0)
} else {
yFlip = CGFloat(1.0)
}
bitmap!.scaleBy(x: yFlip, y: -1.0)
//check if we have to fix the aspect ratio
if isRotatedBy90 {
bitmap?.draw(self.cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2, width: size.height,height: size.width))
} else {
bitmap?.draw(self.cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2, width: size.width,height: size.height))
}
let fixedImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return fixedImage
}
You can first set your image in imageView and rotate get your image in imageView
Here:
let customImageView = UIImageView()
customImageView.frame = CGRect.init(x: 0, y: 0, w: 250, h: 250)
customImageView.image = UIImage(named: "yourImage")
customImageView .transform = customImageView .transform.rotated(by: CGFloat.init(M_PI_2))
var rotatedImage = UIImage()
rotatedImage = customImageView.image!
Your code is not that far off from functional. You can apply the transform as you are doing directly to the bitmap, you don't need an intermediate view:
func imageRotatedByDegrees(oldImage: UIImage, deg degrees: CGFloat) -> UIImage {
let size = oldImage.size
UIGraphicsBeginImageContext(size)
let bitmap: CGContext = UIGraphicsGetCurrentContext()!
//Move the origin to the middle of the image so we will rotate and scale around the center.
bitmap.translateBy(x: size.width / 2, y: size.height / 2)
//Rotate the image context
bitmap.rotate(by: (degrees * CGFloat(M_PI / 180)))
//Now, draw the rotated/scaled image into the context
bitmap.scaleBy(x: 1.0, y: -1.0)
let origin = CGPoint(x: -size.width / 2, y: -size.width / 2)
bitmap.draw(oldImage.cgImage!, in: CGRect(origin: origin, size: size))
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
Also, if you're going to create a function that rotates an image, it is typically good form to include a clockwise: Bool parameter that will interpret the degrees argument as rotating clockwise or not. The implementation and appropriate conversion to radians I leave to you.
Also note that it's a bit hand-wavy on my part to assume that oldImage.size is non-zero. If it is, force-unwrapping UIGraphicsGetCurrentContext()! will probably crash. You should validate the oldImage's size and if it's invalid just return oldImage.
Your problem is that you use non-existing initializer for CGRect. If you want to use CGRect(origin:size:), then create origin properly, without width and height parameters. Or remove size parameter and use CGRect(x:y:width:height:).
Just replace this line
bitmap.draw(oldImage, in: CGRect(origin: (x: -oldImage.size.width / 2, y: -oldImage.size.height / 2, width: oldImage.size.width, height: oldImage.size.height), size: oldImage.cgImage))
with this one:
let rect = CGRect(origin: CGPoint(x: -oldImage.size.width / 2, y: -oldImage.size.height / 2), size: oldImage.size)
bitmap.draw(oldImage.cgImage!, in: rect)
来源：https://stackoverflow.com/questions/40882487/how-to-rotate-image-in-swift