wehub-resource-sync
129 lines
4.0 KiB
Swift
129 lines
4.0 KiB
Swift
import AppKit
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import CoreGraphics
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import Foundation
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import simd
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enum MenuBarIconBackgroundRemover {
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static func removingBackground(
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from image: NSImage
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) -> NSImage? {
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guard
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let source = cgImage(from: image),
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let context = bitmapContext(width: source.width, height: source.height)
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else {
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return nil
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}
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let rect = CGRect(x: 0, y: 0, width: source.width, height: source.height)
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context.draw(source, in: rect)
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guard let data = context.data else {
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return nil
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}
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let pointer = data.bindMemory(to: UInt8.self, capacity: source.width * source.height * 4)
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let backgroundColor = averageCornerColor(pointer: pointer, width: source.width, height: source.height)
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applyAlphaMask(
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pointer: pointer,
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width: source.width,
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height: source.height,
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backgroundColor: backgroundColor,
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tolerance: 0.16
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)
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guard let output = context.makeImage() else {
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return nil
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}
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return NSImage(cgImage: output, size: image.size)
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}
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private static func cgImage(from image: NSImage) -> CGImage? {
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var proposedRect = NSRect(origin: .zero, size: image.size)
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return image.cgImage(forProposedRect: &proposedRect, context: nil, hints: nil)
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}
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private static func bitmapContext(width: Int, height: Int) -> CGContext? {
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CGContext(
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data: nil,
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width: width,
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height: height,
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bitsPerComponent: 8,
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bytesPerRow: width * 4,
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space: CGColorSpaceCreateDeviceRGB(),
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bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
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)
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}
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private static func averageCornerColor(
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pointer: UnsafeMutablePointer<UInt8>,
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width: Int,
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height: Int
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) -> SIMD3<Double> {
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let sampleSize = max(1, min(width, height, 8))
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let origins = [
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(x: 0, y: 0),
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(x: max(width - sampleSize, 0), y: 0),
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(x: 0, y: max(height - sampleSize, 0)),
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(x: max(width - sampleSize, 0), y: max(height - sampleSize, 0))
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]
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var total = SIMD3<Double>(repeating: 0)
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var weight = 0.0
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for origin in origins {
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for y in origin.y..<(origin.y + sampleSize) {
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for x in origin.x..<(origin.x + sampleSize) {
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let offset = ((y * width) + x) * 4
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let alpha = Double(pointer[offset + 3]) / 255
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guard alpha > 0 else {
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continue
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}
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total += SIMD3<Double>(
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Double(pointer[offset]) / 255,
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Double(pointer[offset + 1]) / 255,
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Double(pointer[offset + 2]) / 255
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) * alpha
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weight += alpha
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}
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}
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}
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guard weight > 0 else {
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return SIMD3<Double>(repeating: 1)
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}
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return total / weight
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}
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private static func applyAlphaMask(
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pointer: UnsafeMutablePointer<UInt8>,
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width: Int,
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height: Int,
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backgroundColor: SIMD3<Double>,
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tolerance: Double
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) {
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let softEdge = max(tolerance * 0.8, 0.02)
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let count = width * height
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for pixelIndex in 0..<count {
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let offset = pixelIndex * 4
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let color = SIMD3<Double>(
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Double(pointer[offset]) / 255,
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Double(pointer[offset + 1]) / 255,
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Double(pointer[offset + 2]) / 255
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)
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let distance = simd_distance(color, backgroundColor)
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guard distance < tolerance + softEdge else {
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continue
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}
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let alphaFactor = min(max((distance - tolerance) / softEdge, 0), 1)
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let originalAlpha = Double(pointer[offset + 3])
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pointer[offset + 3] = UInt8((originalAlpha * alphaFactor).rounded())
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}
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}
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}
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