CODEWITHSUNDEEP
swiftmacostransparencyalphansimage
code
code

Reputation: 23

I want to set the transparency of NSImage again

Change the value of NSSlider and repeat setting the opacity of NSImage using the

public extension NSImage {

    func withAlpha(_ alpha: CGFloat) -> NSImage {
        guard alpha >= 0.0 && alpha <= 1.0 else { return self }
        let newImage = NSImage(size: size)
        newImage.lockFocus()
        let rect = NSRect(origin: .zero, size: size)
        draw(in: rect, from: rect, operation: .sourceOver, fraction: alpha)
        newImage.unlockFocus()
        return newImage
    }

    func averageAlpha(sampleRate: Int = 10) -> CGFloat? {
        guard sampleRate > 0 else { return nil }
        guard let tiffData = self.tiffRepresentation,
              let bitmapImageRep = NSBitmapImageRep(data: tiffData)
        else { return nil }
        let width = bitmapImageRep.pixelsWide
        let height = bitmapImageRep.pixelsHigh
        var totalAlpha: CGFloat = 0.0
        var pixelCount: Int = 0
        for x in stride(from: 0, to: width, by: sampleRate) {
            for y in stride(from: 0, to: height, by: sampleRate) {
                if let color = bitmapImageRep.colorAt(x: x, y: y) {
                    totalAlpha += color.alphaComponent
                    pixelCount += 1
                }
            }
        }
        return pixelCount > 0 ? totalAlpha / CGFloat(pixelCount) : nil
    }

}
let originalImage = imageView.image
let oneImage = originalImage.withAlpha(0.3)
let twoImage = originalImage.withAlpha(0.8)
let value = twoImage.averageAlpha()

What should I do in the withAlpha(_ :) method so that the value is 0.8

Upvotes: 0

Views: 21

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