rearrange some sources

Sources/Voxelotl/Resource/NSImageLoader.swift

@@ -0,0 +1,104 @@
+import AppKit
+
+struct NSImageLoader {
+  private static let flipVertically = true
+
+  static func open(url: URL) throws -> Image2D {
+    try autoreleasepool {
+      // Open as a CoreGraphics image
+      guard let nsImage = NSImage(contentsOf: url),
+        let cgImage = nsImage.cgImage(forProposedRect: nil, context: nil, hints: nil)
+      else {
+        throw ImageLoaderError.openFailed("Failed to open image \"\(url.absoluteString)\"")
+      }
+
+      // Convert 8-bit ARGB (sRGB) w/ pre-multiplied alpha
+      let alphaInfo = cgImage.alphaInfo == .none
+        ? CGImageAlphaInfo.noneSkipLast
+        : CGImageAlphaInfo.premultipliedLast
+      guard let colorSpace = CGColorSpace(name: CGColorSpace.sRGB),
+        let context = CGContext(
+          data: nil,
+          width: cgImage.width,
+          height: cgImage.height,
+          bitsPerComponent: 8,
+          bytesPerRow: cgImage.width * 4,
+          space: colorSpace,
+          bitmapInfo: alphaInfo.rawValue | CGBitmapInfo.byteOrder32Big.rawValue)
+      else {
+        throw ImageLoaderError.openFailed("Couldn't create graphics context")
+      }
+
+      let dstRect = CGRect(x: 0, y: 0, width: cgImage.width, height: cgImage.height)
+      if flipVertically {
+        // Flip the image vertically
+        let flipVertical = CGAffineTransform(a: 1, b: 0, c: 0, d: -1, tx: 0, ty: CGFloat(cgImage.height))
+        context.concatenate(flipVertical)
+        context.draw(cgImage, in: dstRect)
+      } else {
+        context.draw(cgImage, in: dstRect)
+      }
+
+      // Convert the context to a raw Data block and return as an Image2D
+      guard let data = context.data else {
+        throw ImageLoaderError.openFailed("Context data is null")
+      }
+      return Image2D(
+        Data(bytes: data, count: context.bytesPerRow * context.height),
+        format: .argb8888,
+        width: context.width,
+        height: context.height,
+        stride: context.bytesPerRow)
+    }
+  }
+}
+
+struct Image2D {
+  let data: Data
+  let format: Format
+  let width: Int, height: Int, stride: Int
+
+  public enum Format {
+    case argb8888, abgr8888
+    case rgb888, bgr888
+    //case l8, l16, a8, al88
+    case s3tc_bc1, s3tc_bc2_premul
+    case s3tc_bc2, s3tc_bc3_premul
+    case s3tc_bc3, rgtc_bc4, rgtc_bc5_3dc
+  }
+}
+
+extension Image2D {
+  init(_ data: Data, format: Format, width: Int, height: Int, stride: Int) {
+    self.data = data
+    self.format = format
+    self.width = width
+    self.height = height
+    self.stride = stride
+  }
+}
+
+enum ImageLoaderError: Error {
+  case openFailed(_ message: String)
+}
+
+
+extension Bundle {
+  func getResource(_ path: String) throws -> URL {
+    guard let extIndex = path.lastIndex(of: ".") else {
+      throw ContentError.resourceNotFound("Malformed resource path \"\(path)\"")
+    }
+    let name = String(path[..<extIndex]), ext = String(path[extIndex...])
+    guard let resourceUrl: URL = Bundle.main.url(
+      forResource: name,
+      withExtension: ext)
+    else {
+      throw ContentError.resourceNotFound("Resource \"\(path)\" doesn't exist")
+    }
+    return resourceUrl
+  }
+}
+
+public enum ContentError: Error {
+  case resourceNotFound(_ message: String)
+}