This question already has answers here:
Swift 3 and CGContextDrawImage
(2 answers)
Closed 6 years ago.
I have an UIImage extension that uses CGContextDrawImage.
It simply rotate a UIImage.
I updated to Xcode8 and Swift3 and cant figure out how to use CGContextDrawImage.
I got error on CGContextDrawImage.
"Cannot convert value of type "CGImage.Type to expected argument type 'CGImage?'"
My code is :
CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)
And whole extension :
extension UIImage {
public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage {
let radiansToDegrees: (CGFloat) -> CGFloat = {
return $0 * (180.0 / CGFloat(M_PI))
}
let degreesToRadians: (CGFloat) -> CGFloat = {
return $0 / 180.0 * CGFloat(M_PI)
}
// calculate the size of the rotated view's containing box for our drawing space
let rectZero = CGPoint(dictionaryRepresentation: CGRect.zero as! CFDictionary)
let rotatedViewBox = UIView(frame: CGRect(origin: rectZero!, size: size))
let t = CGAffineTransform(rotationAngle: degreesToRadians(degrees));
rotatedViewBox.transform = t
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);
// // Rotate the image context
bitmap!.rotate(by: degreesToRadians(degrees));
// 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)
CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
}
In Swift 3, many functions for CGContext are imported as an instance method of CGContext, the property name CGImage has renamed to cgImage. And CGRectMake is removed.
Try this:
bitmap!.draw(cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2, width: size.width, height: size.height))
(Hope ! would be safe for your usage.)
func draw(CGImage, in: CGRect, byTiling: Bool)
Related
I want to rotate UIImage in clockwise direction. But my current code do not perform function accurate some time it rotate and some time its skip rotation. I want my UIImage will continuously rotate clockwise on my action button.
Here is my current code:
imageView.image = imageView.image!.imageRotatedByDegrees(angle, flip: false)
angle = angle + 90
if angle > 360{
angle = 0
}
This works for me:
works Fine :)
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: CGRectMake(0, 0, oldImage.size.width, oldImage.size.height))
let t: CGAffineTransform = CGAffineTransformMakeRotation(degrees * CGFloat(M_PI / 180))
rotatedViewBox.transform = t
let rotatedSize: CGSize = rotatedViewBox.frame.size
//Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize)
let bitmap: CGContextRef = UIGraphicsGetCurrentContext()!
//Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2)
//Rotate the image context
CGContextRotateCTM(bitmap, (degrees * CGFloat(M_PI / 180)))
//Now, draw the rotated/scaled image into the context
CGContextScaleCTM(bitmap, 1.0, -1.0)
CGContextDrawImage(bitmap, CGRectMake(-oldImage.size.width / 2, -oldImage.size.height / 2, oldImage.size.width, oldImage.size.height), oldImage.CGImage)
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}
Swift 3:
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.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.pi / 180))
//Now, draw the rotated/scaled image into the context
bitmap.scaleBy(x: 1.0, y: -1.0)
bitmap.draw(oldImage.cgImage!, in: CGRect(x: -oldImage.size.width / 2, y: -oldImage.size.height / 2, width: oldImage.size.width, height: oldImage.size.height))
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
extension UIImage {
public func imageRotatedByDegrees(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: self.size.width, height: self.size.height))
let t: CGAffineTransform = CGAffineTransform(rotationAngle: degrees * CGFloat.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.pi / 180))
//Now, draw the rotated/scaled image into the context
bitmap.scaleBy(x: 1.0, y: -1.0)
bitmap.draw(self.cgImage!, in: CGRect(x: -self.size.width / 2, y: -self.size.height / 2, width: self.size.width, height: self.size.height))
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
public func fixedOrientation() -> UIImage {
if imageOrientation == UIImageOrientation.up {
return self
}
var transform: CGAffineTransform = CGAffineTransform.identity
switch imageOrientation {
case UIImageOrientation.down, UIImageOrientation.downMirrored:
transform = transform.translatedBy(x: size.width, y: size.height)
transform = transform.rotated(by: CGFloat.pi)
break
case UIImageOrientation.left, UIImageOrientation.leftMirrored:
transform = transform.translatedBy(x: size.width, y: 0)
transform = transform.rotated(by: CGFloat.pi/2)
break
case UIImageOrientation.right, UIImageOrientation.rightMirrored:
transform = transform.translatedBy(x: 0, y: size.height)
transform = transform.rotated(by: -CGFloat.pi/2)
break
case UIImageOrientation.up, UIImageOrientation.upMirrored:
break
}
switch imageOrientation {
case UIImageOrientation.upMirrored, UIImageOrientation.downMirrored:
transform.translatedBy(x: size.width, y: 0)
transform.scaledBy(x: -1, y: 1)
break
case UIImageOrientation.leftMirrored, UIImageOrientation.rightMirrored:
transform.translatedBy(x: size.height, y: 0)
transform.scaledBy(x: -1, y: 1)
case UIImageOrientation.up, UIImageOrientation.down, UIImageOrientation.left, UIImageOrientation.right:
break
}
let ctx: CGContext = CGContext(data: nil,
width: Int(size.width),
height: Int(size.height),
bitsPerComponent: self.cgImage!.bitsPerComponent,
bytesPerRow: 0,
space: self.cgImage!.colorSpace!,
bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)!
ctx.concatenate(transform)
switch imageOrientation {
case UIImageOrientation.left, UIImageOrientation.leftMirrored, UIImageOrientation.right, UIImageOrientation.rightMirrored:
ctx.draw(self.cgImage!, in: CGRect(x: 0, y: 0, width: size.height, height: size.width))
default:
ctx.draw(self.cgImage!, in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
break
}
let cgImage: CGImage = ctx.makeImage()!
return UIImage(cgImage: cgImage)
}
}
#Jason, You should fix orientation of image before rotation.
let image = oldimage.fixedOrientation().imageRotatedByDegrees(90.0)
#Jason Chitla, I cant comment yet, so Im posting it as a new answer. The above solution from #Albert works, but only for square images. The problem is, that
bitmap.draw(oldImage.cgImage!, in: CGRect(x: -oldImage.size.width / 2, y: -oldImage.size.height / 2, width: oldImage.size.width, height: oldImage.size.height))
is still using the original size, so if you rotate it 90 degrees, aspect is wrong.
What works for me is to use the new rotatedSize, like this:
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(self.cgImage!, in: CGRect(x: -rotatedSize.width / 2, y: -rotatedSize.height / 2, width: rotatedSize.width, height: rotatedSize.height))
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
You can create a function like this to make your image rotate in clockwise forever:
override func viewDidLoad() {
super.viewDidLoad()
let kRotationAnimationKey = "com.myapplication.rotationanimationkey"
func rotateView(view: UIView, duration: Double = 1) {
if view.layer.animationForKey(kRotationAnimationKey) == nil {
let rotationAnimation = CABasicAnimation(keyPath: "transform.rotation")
rotationAnimation.fromValue = 0.0
rotationAnimation.toValue = Float(M_PI * 2.0)
rotationAnimation.duration = duration
rotationAnimation.repeatCount = Float.infinity
view.layer.addAnimation(rotationAnimation, forKey: kRotationAnimationKey)
}
}
rotateView(self.imageView)
}
Result is:
For those who need the code from #Mughees in Swift 3:
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.cgImage!, in: CGRect(x: -oldImage.size.width / 2, y: -oldImage.size.height / 2, width: oldImage.size.width, height: oldImage.size.height))
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
I fixed first function of #gleb's answer little bit. Size calculation is not necessary there. We simply should do it with reverse.
Because if you do it size of 1149 x 356 with #gleb's function then you will get image sized 357 x 1149.
extension UIImage {
public func imageRotatedByDegrees(degrees: CGFloat) -> UIImage {
let rotatedSize: CGSize = CGRect(x: 0, y: 0, width: self.size.height, height: self.size.width).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.pi / 180))
//Now, draw the rotated/scaled image into the context
bitmap.scaleBy(x: 1.0, y: -1.0)
bitmap.draw(self.cgImage!, in: CGRect(x: -self.size.width / 2, y: -self.size.height / 2, width: self.size.width, height: self.size.height))
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
}
This s probably easier and it is Swift 5 syntax:
// MARK: Rotate
extension UIImage {
func rotate(radians: Float) -> UIImage? {
var newSize = CGRect(origin: CGPoint.zero, size: self.size).applying(CGAffineTransform(rotationAngle: CGFloat(radians))).size
// Trim off the extremely small float value to prevent core graphics from rounding it up
newSize.width = floor(newSize.width)
newSize.height = floor(newSize.height)
UIGraphicsBeginImageContextWithOptions(newSize, false, self.scale)
let context = UIGraphicsGetCurrentContext()!
// Move origin to middle
context.translateBy(x: newSize.width/2, y: newSize.height/2)
// Rotate around middle
context.rotate(by: CGFloat(radians))
// Draw the image at its center
self.draw(in: CGRect(x: -self.size.width/2, y: -self.size.height/2, width: self.size.width, height: self.size.height))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}
}
I believe it's worth to post solution using CoreImage. It's just couple of lines and it works great for me.
Please note: when getting final UIImage, it's necessary to convert to CGImage first to respect extent of CIImage
extension UIImage {
func imageRotated(by degrees: CGFloat) -> UIImage {
let orientation = CGImagePropertyOrientation(imageOrientation)
// Create CIImage respecting image's orientation
guard let inputImage = CIImage(image: self)?.oriented(orientation)
else { return self }
// Rotate the image itself
let rotation = CGAffineTransform(rotationAngle: (degrees * CGFloat.pi / 180))
let outputImage = inputImage.transformed(by: rotation)
// Create CGImage first
guard let cgImage = CIContext().createCGImage(outputImage, from: outputImage.extent)
else { return self }
// Create output UIImage from CGImage
return UIImage(cgImage: cgImage)
}
}
I have a problem with swift, I have an app that, when a button is pressed, must rotate an image of 90°, for doing this I use this code
extension UIImage {
public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage {
let radiansToDegrees: (CGFloat) -> CGFloat = {
return $0 * (180.0 / CGFloat(M_PI))
}
let degreesToRadians: (CGFloat) -> CGFloat = {
return $0 / 180.0 * CGFloat(M_PI)
}
// calculate the size of the rotated view's containing box for our drawing space
let rotatedViewBox = UIView(frame: CGRect(origin: CGPointZero, size: size))
let t = CGAffineTransformMakeRotation(degreesToRadians(degrees));
rotatedViewBox.transform = t
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.
CGContextTranslateCTM(bitmap, 0.5 * rotatedSize.width, 0.5 * rotatedSize.height);
// // Rotate the image context
CGContextRotateCTM(bitmap, degreesToRadians(degrees));
// Now, draw the rotated/scaled image into the context
var yFlip: CGFloat
if(flip){
yFlip = CGFloat(-1.0)
} else {
yFlip = CGFloat(1.0)
}
CGContextScaleCTM(bitmap, yFlip, -1.0)
CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}}
with pictures in landscape i haven't any problem but when I try to rotate an image in portrait, on the first press of the button the image is scaled adapting its width to the width of the ImageView, losing his proportions, and without rotate, it is rotated, always with new proportions, only with the second pressure... can anyone help me?
here a screenshot of the starting situation
after first press
after second press
how could i transform image to look like one from the image ?
just want to reach how that transformation works
for rotating im using an extention of UIImage, but thats all a got for now, just new in swift
public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage {
let radiansToDegrees: (CGFloat) -> CGFloat = {
return $0 * (180.0 / CGFloat(M_PI))
}
let degreesToRadians: (CGFloat) -> CGFloat = {
return $0 / 180.0 * CGFloat(M_PI)
}
// calculate the size of the rotated view's containing box for our drawing space
let rotatedViewBox = UIView(frame: CGRect(origin: CGPointZero, size: size))
let t = CGAffineTransformMakeRotation(degreesToRadians(degrees));
rotatedViewBox.transform = t
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.
CGContextTranslateCTM(bitmap, rotatedSize.width / 2.0, rotatedSize.height / 2.0);
// // Rotate the image context
CGContextRotateCTM(bitmap, degreesToRadians(degrees));
// Now, draw the rotated/scaled image into the context
var yFlip: CGFloat
if(flip){
yFlip = CGFloat(-1.0)
} else {
yFlip = CGFloat(1.0)
}
CGContextScaleCTM(bitmap, yFlip, -1.0)
CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}
You would need to use Core Animation with CATransform3D, and tweak the transform to give an impression of depth. What you do is to apply a small negative value (-1/200 is a good starting point) to the M34 component of the transformation matrix. You could ether do that to the layer of each of your views, or use a CATransformLayer on a super layer and then add the other images as sublayers of the transform layer.
This is tricky, fussy stuff. I haven't messed with it in a while so I don't remember the fine details any more, but that should be enough to get you started. I suggest searching on "iOS perspective", "M34" and "CATransformLayer" to find out more.
Lets say we have an image of 600X400 pixel and we want to end up with an new image of 1000x1000 pixel which contains the initial image in the centre and transparent space around it. How can I achieve that in code?
In Swift you can write an extension to UIImage that draws image with insets around it.
Swift 3:
import UIKit
extension UIImage {
func imageWithInsets(insets: UIEdgeInsets) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(
CGSize(width: self.size.width + insets.left + insets.right,
height: self.size.height + insets.top + insets.bottom), false, self.scale)
let _ = UIGraphicsGetCurrentContext()
let origin = CGPoint(x: insets.left, y: insets.top)
self.draw(at: origin)
let imageWithInsets = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return imageWithInsets
}
}
OLD ANSWER:
import UIKit
extension UIImage {
func imageWithInsets(insets: UIEdgeInsets) -> UIImage {
UIGraphicsBeginImageContextWithOptions(
CGSizeMake(self.size.width + insets.left + insets.right,
self.size.height + insets.top + insets.bottom), false, self.scale)
let context = UIGraphicsGetCurrentContext()
let origin = CGPoint(x: insets.left, y: insets.top)
self.drawAtPoint(origin)
let imageWithInsets = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return imageWithInsets
}
}
This is the solution in Swift 4 inspired by DrummerB answer:
import UIKit
extension UIImage {
func addImagePadding(x: CGFloat, y: CGFloat) -> UIImage? {
let width: CGFloat = size.width + x
let height: CGFloat = size.height + y
UIGraphicsBeginImageContextWithOptions(CGSize(width: width, height: height), false, 0)
let origin: CGPoint = CGPoint(x: (width - size.width) / 2, y: (height - size.height) / 2)
draw(at: origin)
let imageWithPadding = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return imageWithPadding
}
}
How to apply:
let image = UIImage(named: "your-image")!
let imageView = UIImageView(image: image.addImagePadding(x: 50, y: 50))
imageView.backgroundColor = UIColor.gray
view.addSubview(imageView)
Features:
Simply pass padding values via parameters
Colored padding (by setting the UIGraphicsBeginImageContextWithOptions opaque parameter to false)
You create a new image context that is 1000x1000, draw your old image in the middle, then get the new UIImage from the context.
// Setup a new context with the correct size
CGFloat width = 1000;
CGFloat height = 1000;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(width, height), NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
UIGraphicsPushContext(context);
// Now we can draw anything we want into this new context.
CGPoint origin = CGPointMake((width - oldImage.size.width) / 2.0f,
(height - oldImage.size.height) / 2.0f);
[oldImage drawAtPoint:origin];
// Clean up and get the new image.
UIGraphicsPopContext();
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
A fix for appsunited's answer with better naming convension. To not confuse it the function is mutating or not:
extension UIImage {
func withPadding(_ padding: CGFloat) -> UIImage? {
return withPadding(x: padding, y: padding)
}
func withPadding(x: CGFloat, y: CGFloat) -> UIImage? {
let newWidth = size.width + 2 * x
let newHeight = size.height + 2 * y
let newSize = CGSize(width: newWidth, height: newHeight)
UIGraphicsBeginImageContextWithOptions(newSize, false, 0)
let origin = CGPoint(x: (newWidth - size.width) / 2, y: (newHeight - size.height) / 2)
draw(at: origin)
let imageWithPadding = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return imageWithPadding
}
}
Make a category on UIImage and try this:
+ (UIImage *)imageWithInsets:(CGRect)insetRect image:(UIImage *)image {
CGRect newRect = CGRectMake(0.0, 0.0, insetRect.origin.x+insetRect.size.width+image.size.width, insetRect.origin.y+insetRect.size.height+image.size.height);
// Setup a new context with the correct size
UIGraphicsBeginImageContextWithOptions(newRect.size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
UIGraphicsPushContext(context);
// Now we can draw anything we want into this new context.
CGPoint origin = CGPointMake(insetRect.origin.x, insetRect.origin.y);
[image drawAtPoint:origin];
// Clean up and get the new image.
UIGraphicsPopContext();
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
I have a UIImageView that contains an image. At the minute the user can click to save the image within the UIImageView to disk.
I would like to make it so that the the user can click to rotate the UIImageView and also rotate the UImage within the view so that when the image is saved it keeps the new rotation.
At the minute I have
- (IBAction)rotateImage:(id)sender {
float degrees = 90; //the value in degrees
self.imagePreview.transform = CGAffineTransformMakeRotation(degrees * M_PI/180);
}
Can someone point me in the right direction regarding keeping the current rotation.
Thanks
I have such code in my old app. But this code can be simplified because you have no need to rotate it on non-90 degrees angle.
Objective-C
#implementation UIImage (Rotation)
- (UIImage *)imageRotatedOnDegrees:(CGFloat)degrees
{
// Follow ing code can only rotate images on 90, 180, 270.. degrees.
CGFloat roundedDegrees = (CGFloat)(round(degrees / 90.0) * 90.0);
BOOL sameOrientationType = ((NSInteger)roundedDegrees) % 180 == 0;
CGFloat radians = M_PI * roundedDegrees / 180.0;
CGSize newSize = sameOrientationType ? self.size : CGSizeMake(self.size.height, self.size.width);
UIGraphicsBeginImageContext(newSize);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGImageRef cgImage = self.CGImage;
if (ctx == NULL || cgImage == NULL) {
UIGraphicsEndImageContext();
return self;
}
CGContextTranslateCTM(ctx, newSize.width / 2.0, newSize.height / 2.0);
CGContextRotateCTM(ctx, radians);
CGContextScaleCTM(ctx, 1, -1);
CGPoint origin = CGPointMake(-(self.size.width / 2.0), -(self.size.height / 2.0));
CGRect rect = CGRectZero;
rect.origin = origin;
rect.size = self.size;
CGContextDrawImage(ctx, rect, cgImage);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image ?: self;
}
#end
Swift
extension UIImage {
func imageRotated(on degrees: CGFloat) -> UIImage {
// Following code can only rotate images on 90, 180, 270.. degrees.
let degrees = round(degrees / 90) * 90
let sameOrientationType = Int(degrees) % 180 == 0
let radians = CGFloat.pi * degrees / CGFloat(180)
let newSize = sameOrientationType ? size : CGSize(width: size.height, height: size.width)
UIGraphicsBeginImageContext(newSize)
defer {
UIGraphicsEndImageContext()
}
guard let ctx = UIGraphicsGetCurrentContext(), let cgImage = cgImage else {
return self
}
ctx.translateBy(x: newSize.width / 2, y: newSize.height / 2)
ctx.rotate(by: radians)
ctx.scaleBy(x: 1, y: -1)
let origin = CGPoint(x: -(size.width / 2), y: -(size.height / 2))
let rect = CGRect(origin: origin, size: size)
ctx.draw(cgImage, in: rect)
let image = UIGraphicsGetImageFromCurrentImageContext()
return image ?? self
}
}
This will rotate an image by any given radians.
Note this works 2x and 3x retina as well
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees {
CGFloat radians = DegreesToRadians(degrees);
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0, self.size.width, self.size.height)];
CGAffineTransform t = CGAffineTransformMakeRotation(radians);
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
UIGraphicsBeginImageContextWithOptions(rotatedSize, NO, [[UIScreen mainScreen] scale]);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2);
CGContextRotateCTM(bitmap, radians);
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2 , self.size.width, self.size.height), self.CGImage );
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
In Swift 4
imageView.transform = CGAffineTransform(rotationAngle: CGFloat(Double.pi/2))
The highlighted state of a UIButton did not take the correct orientation of the normal inserted turned image. So I had to redraw the image like #RyanG showed. Here is the Swift 2.2 code for that:
extension UIImage
{
/// Rotate an image by any given radians.
/// Works for 2x and 3x retina as well.
func imageRotatedByDegrees(degrees: Double) -> UIImage
{
let radians = CGFloat(degrees * (M_PI / 180.0))
let rotatedViewBox = UIView(frame: CGRect(origin: CGPointZero, size: self.size))
let t: CGAffineTransform = CGAffineTransformMakeRotation(radians)
rotatedViewBox.transform = t
let rotatedSize = rotatedViewBox.frame.size
UIGraphicsBeginImageContextWithOptions(rotatedSize, false, self.scale)
let bitmap = UIGraphicsGetCurrentContext()
CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2)
CGContextRotateCTM(bitmap, radians)
CGContextScaleCTM(bitmap, 1.0, -1.0)
CGContextDrawImage(bitmap, CGRect(origin: CGPoint(x: -self.size.width / 2, y: -self.size.height / 2), size: self.size), self.CGImage)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}
}
Swift version made from answer of #RyanG with some fixes:
func rotated(by degrees: CGFloat) -> UIImage {
let radians : CGFloat = degrees * CGFloat(.pi / 180.0)
let rotatedViewBox = UIView(frame: CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height))
let t = CGAffineTransform(rotationAngle: radians)
rotatedViewBox.transform = t
let rotatedSize = rotatedViewBox.frame.size
UIGraphicsBeginImageContextWithOptions(rotatedSize, false, self.scale)
defer { UIGraphicsEndImageContext() }
guard let bitmap = UIGraphicsGetCurrentContext(), let cgImage = self.cgImage else {
return self
}
bitmap.translateBy(x: rotatedSize.width / 2, y: rotatedSize.height / 2)
bitmap.rotate(by: radians)
bitmap.scaleBy(x: 1.0, y: -1.0)
bitmap.draw(cgImage, in: CGRect(x: -self.size.width / 2, y: -self.size.height / 2, width: self.size.width, height: self.size.height))
guard let newImage = UIGraphicsGetImageFromCurrentImageContext() else {
return self
}
return newImage
}
self.imageview.transform = CGAffineTransformMakeRotation(M_PI/2);