Dusk texture creator

tools/editor/common/png.js

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+"use strict";
+
+// DuskPNG – PNG export using pngjs (window.PNG)
+// Falls back to canvas.toBlob if pngjs is unavailable.
+
+const DuskPNG = (() => {
+  function _pngAvailable() {
+    return typeof PNG !== "undefined" && PNG.sync && typeof PNG.sync.write === "function";
+  }
+
+  // Encode RGBA pixel data into a PNG Buffer via pngjs.
+  // Returns a Uint8Array (Buffer) if pngjs is available, otherwise null.
+  function encode(width, height, rgbaData) {
+    if (!_pngAvailable()) return null;
+
+    const png = new PNG({ width, height });
+    const src = rgbaData instanceof Uint8ClampedArray
+      ? rgbaData
+      : new Uint8ClampedArray(rgbaData);
+
+    for (let i = 0; i < src.length; i++) {
+      png.data[i] = src[i];
+    }
+
+    return PNG.sync.write(png); // returns a Buffer (Uint8Array subclass)
+  }
+
+  // Trigger a browser download of the RGBA data as a PNG file.
+  function download(filename, width, height, rgbaData) {
+    const buf = encode(width, height, rgbaData);
+
+    if (buf) {
+      // pngjs path
+      const blob = new Blob([buf], { type: "image/png" });
+      _triggerDownload(URL.createObjectURL(blob), filename);
+    } else {
+      // Canvas fallback
+      const canvas = Object.assign(document.createElement("canvas"), { width, height });
+      const ctx    = canvas.getContext("2d");
+      const src    = rgbaData instanceof Uint8ClampedArray
+        ? rgbaData
+        : new Uint8ClampedArray(rgbaData);
+      ctx.putImageData(new ImageData(src, width, height), 0, 0);
+      canvas.toBlob(blob => _triggerDownload(URL.createObjectURL(blob), filename), "image/png");
+    }
+  }
+
+  function _triggerDownload(url, filename) {
+    const a = Object.assign(document.createElement("a"), { href: url, download: filename });
+    a.click();
+    URL.revokeObjectURL(url);
+  }
+
+  return Object.freeze({ encode, download });
+})();