MVP

test.js

@@ -9,15 +9,19 @@ const writeImage = require("./write-image");
 test("jpg to png", async ({ eq }) => {
   const jpg = findAndRead("flower.jpg");
   const { height, width, pixels } = await readim({ data: jpg });
-  const png = await writeImage({ data: pixels, debug: true, format: "png", height, width });
-  console.log("png:", png);
-  fs.writeFileSync("jpg-to-png.png", png);
+  const result = await writeImage({ data: pixels, debug: false, format: "png", height, width });
+  fs.writeFileSync("jpg-to-png.png", result.data);
+  eq(result.height, height);
+  eq(result.width, width);
+  eq(Buffer.isBuffer(result.data), true);
 });
 
 test("png to jpg", async ({ eq }) => {
   const png = findAndRead("flower.png");
   const { height, width, pixels } = await readim({ data: png });
-  const jpg = await writeImage({ data: pixels, debug: true, format: "jpg", height, width });
-  console.log("jpg:", jpg);
-  fs.writeFileSync("png-to-jpg.jpg", jpg);
+  const result = await writeImage({ data: pixels, debug: false, format: "jpg", height, width });
+  fs.writeFileSync("png-to-jpg.jpg", result.data);
+  eq(result.height, height);
+  eq(result.width, width);
+  eq(Buffer.isBuffer(result.data), true);
 });

write-image.js

@@ -12,14 +12,18 @@ module.exports = async function writeImage({ data, debug = false, format, height
   const imageData = toImageData({ data, height, width });
   if (debug) console.log(`[write-image] image data is`, imageData);
 
+  let result;
   if (format === "PNG") {
     const png = new PNG({ filterType: 4, height, width });
     png.data = imageData.data;
     if (debug) console.log(`[write-image] png is`, png);
     const buffer = PNG.sync.write(png);
-    return { data: buffer, height, width };
+    result = { data: buffer, height, width };
   } else if (format === "JPG") {
-    const { data, height, width } = jpeg.encode(imageData, quality).data;
-    return { data, height, width };
+    const encoded = jpeg.encode(imageData, quality).data;
+    if (debug) console.log("`[write-image] jpeg.encode returned", encoded);
+    result = { data: encoded, height, width };
   }
+  if (debug) console.log(`[write-image] returning`, result);
+  return result;
 };