macos: colorized Ghostty icon begins!

macos/Sources/Helpers/NSImage+Extension.swift

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+import Cocoa
+
+extension NSImage {
+    /// Combine multiple images with the given blend modes. This is useful given a set
+    /// of layers to create a final rasterized image.
+    static func combine(images: [NSImage], blendingModes: [CGBlendMode]) -> NSImage? {
+        guard images.count == blendingModes.count else { return nil }
+        guard images.count > 0 else { return nil }
+
+        // The final size will be the same size as our first image.
+        let size = images.first!.size
+
+        // Create a bitmap context manually
+        guard let bitmapContext = CGContext(
+            data: nil,
+            width: Int(size.width),
+            height: Int(size.height),
+            bitsPerComponent: 8,
+            bytesPerRow: 0,
+            space: CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        ) else { return nil }
+
+        // Clear the context
+        bitmapContext.setFillColor(.clear)
+        bitmapContext.fill(.init(origin: .zero, size: size))
+
+        // Draw each image with its corresponding blend mode
+        for (index, image) in images.enumerated() {
+            guard let cgImage = image.cgImage(
+                forProposedRect: nil,
+                context: nil,
+                hints: nil
+            ) else { return nil }
+
+            let blendMode = blendingModes[index]
+            bitmapContext.setBlendMode(blendMode)
+            bitmapContext.draw(cgImage, in: CGRect(origin: .zero, size: size))
+        }
+
+        // Create a CGImage from the context
+        guard let combinedCGImage = bitmapContext.makeImage() else { return nil }
+
+        // Wrap the CGImage in an NSImage
+        return NSImage(cgImage: combinedCGImage, size: size)
+    }
+
+    /// Apply a gradient onto this image, using this image as a mask.
+    func gradient(colors: [NSColor]) -> NSImage? {
+        let resultImage = NSImage(size: size)
+        resultImage.lockFocus()
+        defer { resultImage.unlockFocus() }
+
+        // Draw the gradient
+        guard let gradient = NSGradient(colors: colors) else { return nil }
+        gradient.draw(in: .init(origin: .zero, size: size), angle: 90)
+
+        // Apply the mask
+        draw(at: .zero, from: .zero, operation: .destinationIn, fraction: 1.0)
+
+        return resultImage
+    }
+
+    // Tint an NSImage with the given color by applying a basic fill on top of it.
+    func tint(color: NSColor) -> NSImage? {
+        // Create a new image with the same size as the base image
+        let newImage = NSImage(size: size)
+
+        // Draw into the new image
+        newImage.lockFocus()
+        defer { newImage.unlockFocus() }
+
+        // Set up the drawing context
+        guard let context = NSGraphicsContext.current?.cgContext else { return nil }
+        defer { context.restoreGState() }
+
+        // Draw the base image
+        guard let cgImage = cgImage(forProposedRect: nil, context: nil, hints: nil) else { return nil }
+        context.draw(cgImage, in: .init(origin: .zero, size: size))
+
+        // Set the tint color and blend mode
+        context.setFillColor(color.cgColor)
+        context.setBlendMode(.sourceAtop)
+
+        // Apply the tint color over the entire image
+        context.fill(.init(origin: .zero, size: size))
+
+        return newImage
+    }
+}