Add transparent padding around NSImage - swift

Question

I need to add some transparent padding around an NSImage.I referred this SO post Placing an NSImage on a transparent canvas in Swift
It was pointing to the the Github code https://gist.github.com/MaciejGad/11d8469b218817290ee77012edb46608 where it mentions of tweaking the resizeWhileMaintainingAspectRatioToSize method. I tried what the post has suggested but swift seems to miss the NSImage.copy method with the NSrect as parameter.So wrote the below extension method with my limited knowledge
func addPadding() -> NSImage? {
let newSize: NSSize
let widthRatio = size.width / self.size.width
let heightRatio = size.height / self.size.height
if widthRatio > heightRatio {
newSize = NSSize(width: floor(self.size.width * widthRatio), height: floor(self.size.height * widthRatio))
} else {
newSize = NSSize(width: floor(self.size.width * heightRatio), height: floor(self.size.height * heightRatio))
}
let img = NSImage(size: newSize)
let frame = NSRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
// Set the drawing context and make sure to remove the focus before returning.
img.lockFocus()
defer { img.unlockFocus() }
let representation = self.bestRepresentation(for: frame, context: nil, hints: nil)
// Draw the new image
if representation!.draw(in: frame) {
return img
}
// Return nil in case something went wrong.
return nil
}
But this does nothing to add padding to the image.

Answer 1

You can do it with this code:
extension NSImage {
var pixelSize: NSSize {
if let rep = self.representations.first {
let size = NSSize(
width: rep.pixelsWide,
height: rep.pixelsHigh
)
return size
}
return NSSize(width: 0, height: 0)
}
func withPadding(percent: Int) -> NSImage {
let originalSize = self.pixelSize
let newHeight = originalSize.height - originalSize.height * CGFloat(percent) / 100
let newWidth = originalSize.width - originalSize.width * CGFloat(percent) / 100
let sizeWithPadding = NSSize(
width: newWidth,
height: newHeight
)
guard let representation = NSBitmapImageRep(
bitmapDataPlanes: nil,
pixelsWide: Int(originalSize.width),
pixelsHigh: Int(originalSize.height),
bitsPerSample: 8,
samplesPerPixel: 4,
hasAlpha: true,
isPlanar: false,
colorSpaceName: .calibratedRGB,
bytesPerRow: 0,
bitsPerPixel: 0
)
else {
return self
}
representation.size = originalSize
NSGraphicsContext.saveGraphicsState()
NSGraphicsContext.current = NSGraphicsContext.init(bitmapImageRep: representation)
let xPoint = (originalSize.width - newWidth) / 2
let yPoint = (originalSize.height - newHeight) / 2
self.draw(
in: NSRect(
x: xPoint,
y: yPoint,
width: sizeWithPadding.width,
height: sizeWithPadding.height
),
from: .zero,
operation: .copy,
fraction: 1.0
)
NSGraphicsContext.restoreGraphicsState()
let newImage = NSImage(size: originalSize)
newImage.addRepresentation(representation)
return newImage
}
}