Rotate NSImage in Swift, Cocoa, Mac OSX

Question

Is there an easy way to rotate a NSImage in a Mac OSX app? Or just set the orientation from portrait to landscape using Swift?

I am playing around with CATransform3DMakeAffineTransform but I can't get it to work.

CATransform3DMakeAffineTransform(CGAffineTransformMakeRotation(CGFloat(M_PI) * 90/180))

It's the first time for me to work with transformations. So please be patient with me :) Maybe I'm working on a wrong approach...

Can anybody help me please?

Thanks!

Answer 1

public extension NSImage {
public func imageRotatedByDegreess(degrees:CGFloat) -> NSImage {

    var imageBounds = NSZeroRect ; imageBounds.size = self.size
    let pathBounds = NSBezierPath(rect: imageBounds)
    var transform = NSAffineTransform()
    transform.rotateByDegrees(degrees)
    pathBounds.transformUsingAffineTransform(transform)
    let rotatedBounds:NSRect = NSMakeRect(NSZeroPoint.x, NSZeroPoint.y, pathBounds.bounds.size.width, pathBounds.bounds.size.height )
    let rotatedImage = NSImage(size: rotatedBounds.size)

    //Center the image within the rotated bounds
    imageBounds.origin.x = NSMidX(rotatedBounds) - (NSWidth(imageBounds) / 2)
    imageBounds.origin.y  = NSMidY(rotatedBounds) - (NSHeight(imageBounds) / 2)

    // Start a new transform
    transform = NSAffineTransform()
    // Move coordinate system to the center (since we want to rotate around the center)
    transform.translateXBy(+(NSWidth(rotatedBounds) / 2 ), yBy: +(NSHeight(rotatedBounds) / 2))
    transform.rotateByDegrees(degrees)
    // Move the coordinate system bak to normal 
    transform.translateXBy(-(NSWidth(rotatedBounds) / 2 ), yBy: -(NSHeight(rotatedBounds) / 2))
    // Draw the original image, rotated, into the new image
    rotatedImage.lockFocus()
    transform.concat()
    self.drawInRect(imageBounds, fromRect: NSZeroRect, operation: NSCompositingOperation.CompositeCopy, fraction: 1.0)
    rotatedImage.unlockFocus()

    return rotatedImage
}


var image = NSImage(named:"test.png")!.imageRotatedByDegreess(CGFloat(90))  //use only this values 90, 180, or 270
}

Updated for Swift 3:

public extension NSImage {
public func imageRotatedByDegreess(degrees:CGFloat) -> NSImage {

    var imageBounds = NSZeroRect ; imageBounds.size = self.size
    let pathBounds = NSBezierPath(rect: imageBounds)
    var transform = NSAffineTransform()
    transform.rotate(byDegrees: degrees)
    pathBounds.transform(using: transform as AffineTransform)
    let rotatedBounds:NSRect = NSMakeRect(NSZeroPoint.x, NSZeroPoint.y, pathBounds.bounds.size.width, pathBounds.bounds.size.height )
    let rotatedImage = NSImage(size: rotatedBounds.size)

    //Center the image within the rotated bounds
    imageBounds.origin.x = NSMidX(rotatedBounds) - (NSWidth(imageBounds) / 2)
    imageBounds.origin.y  = NSMidY(rotatedBounds) - (NSHeight(imageBounds) / 2)

    // Start a new transform
    transform = NSAffineTransform()
    // Move coordinate system to the center (since we want to rotate around the center)
    transform.translateX(by: +(NSWidth(rotatedBounds) / 2 ), yBy: +(NSHeight(rotatedBounds) / 2))
    transform.rotate(byDegrees: degrees)
    // Move the coordinate system bak to normal
    transform.translateX(by: -(NSWidth(rotatedBounds) / 2 ), yBy: -(NSHeight(rotatedBounds) / 2))
    // Draw the original image, rotated, into the new image
    rotatedImage.lockFocus()
    transform.concat()
    self.draw(in: imageBounds, from: NSZeroRect, operation: NSCompositingOperation.copy, fraction: 1.0)
    rotatedImage.unlockFocus()

    return rotatedImage
    }
}

class SomeClass: NSViewController {
       var image = NSImage(named:"test.png")!.imageRotatedByDegreess(degrees: CGFloat(90))  //use only this values 90, 180, or 270
}