Merge branch 'feature/white_to_transparent'

Sources/AppetizerCL/main.swift

@@ -24,6 +24,7 @@ func main() {
     let androidIconPathArgument = parser.add(option: "--androidIcon", shortName: "-a", kind: PathArgument.self, usage: "The path to a directory where to generate the Android icon with different sizes.")
     let androidFolderPrefixArgument = parser.add(option: "--androidFolderPrefix", shortName: "-afp", kind: String.self, usage: "The folder prefix for the Android images. Example: 'mipmap' will generate folders like 'mipmap-mdpi' and 'mipmap-xhdpi'. Default is 'drawable'.")
     let singleIconPathArgument = parser.add(option: "--singleIcon", shortName: "-si", kind: PathArgument.self, usage: "The path to a directory where to generate a single icon with the specified size.")
+    let clearWhiteArgument = parser.add(option: "--clearWhite", shortName: "-cw", kind: Bool.self, usage: "Make white color areas transparent. Useful to remove white background.")
 
     do {
         let parsedArguments = try parser.parse(Array(ProcessInfo.processInfo.arguments.dropFirst()))
@@ -39,10 +40,15 @@ func main() {
         let androidIconPath = parsedArguments.get(androidIconPathArgument)
         let androidFolderPrefix = parsedArguments.get(androidFolderPrefixArgument) ?? "drawable"
         let singleIconPath = parsedArguments.get(singleIconPathArgument)
+        let clearWhite = parsedArguments.get(clearWhiteArgument) ?? false
 
         let inputFilePathString = inputFilePath.path.pathString
 
-        let bigImage = try NSImage.from(filePath: inputFilePathString, sizeX: sizeX, sizeY: sizeY)
+        var bigImage = try NSImage.from(filePath: inputFilePathString, sizeX: sizeX, sizeY: sizeY)
+
+        if clearWhite {
+            bigImage = bigImage.clearedWhite()
+        }
 
         let tintedImage = bigImage.tinted(withColor: tintColor)
 

Sources/AppetizerCore/NSImageExtension.swift

@@ -51,6 +51,28 @@ public extension NSImage {
         return copy
     }
 
+    private func cgImageFromCiImage(_ inputImage: CIImage, rect: CGRect) -> CGImage {
+        let context = CIContext(options: nil)
+        if let cgImage = context.createCGImage(inputImage, from: rect) {
+            return cgImage
+        }
+        fatalError("could not convert CIImage to CGImage")
+    }
+
+    func clearedWhite() -> NSImage {
+        let sourceNsImage = self
+        let cgImage = sourceNsImage.cgImage(forProposedRect: nil, context: nil, hints: [:])!
+        let ciImage = CIImage(cgImage: cgImage)
+        let filter = ClearWhiteFilter()
+        filter.assignInputImage(ciImage)
+        let outputImage = filter.outputImage!
+
+        let imageSize = CGSize(width: cgImage.width, height: cgImage.height)
+        let outputCgImage = cgImageFromCiImage(outputImage, rect: .init(origin: .zero, size: imageSize))
+
+        return NSImage(cgImage: outputCgImage, size: sourceNsImage.size)
+    }
+
     func saveAsPng(fileUrl url: URL) throws {
         guard let imageData = self.tiffRepresentation else {
             throw ImageFileWriteError.dataRepresentationError
@@ -64,3 +86,29 @@ public extension NSImage {
         try pngImage.write(to: url)
     }
 }
+
+@objcMembers fileprivate class ClearWhiteFilter : CIFilter {
+    var inputImage: CIImage?
+
+    private static let kernels = CIKernel.makeKernels(source:
+        """
+        kernel vec4 clearWhite(sampler image) {
+            vec4 t = sample(image, samplerCoord(image));
+            float brightness = (t.r + t.g + t.b) / 3.0;
+            float i = 1.0 - brightness;
+            t.a = min(i, t.a);
+            return t;
+        }
+        """
+    )!
+
+    override public var outputImage: CIImage? {
+        let src = CISampler(image: self.inputImage!)
+        let kernel = ClearWhiteFilter.kernels[0]
+        return self.apply(kernel, arguments: [src], options: nil)
+    }
+
+    func assignInputImage(_ image: CIImage) {
+        self.setValue(image, forKey: kCIInputImageKey)
+    }
+}