MVP

README.md

@@ -1,2 +1,53 @@
 # write-image
 Write an Image
+
+# install
+```bash
+npm install write-image
+```
+
+# usage
+```js
+import writeImage from 'write-image';
+
+const result = writeImage({
+  // data can be structured in 1, 2 or 3 dimensional arrays
+  data: [
+    [123, 41, ...], // red band
+    [36, 32, ...], // green band
+    [46, 83, ...] // blue band
+  ],
+
+  debug: false, // default false, set to true for increased logging
+
+  // format of the ouput
+  // "JPG" or "PNG"
+  format: "JPG", 
+
+  // height of the input if you know it
+  // we'll try to figure it out if not
+  height: 768, 
+
+  // width of the input if you know it
+  // we'll try to figure it out if not
+  width: 1024, 
+
+  // quality of the output
+  // from 0 to 100
+  // only used for JPG
+  // default is 85
+  quality: 85
+});
+```
+result is an object
+```js
+{
+  // height of the image
+  height: 768,
+
+  // width of the image
+  width: 1024,
+
+  data: <Buffer ff d8 ff e0 00 10 4a 46 49 46 00 01 01 00 00 01 00 01 00 00 ff db 00 84 00 05 03 04 04 04 03 05 04 04 04 05 05 05 06 07 0c 08 07 07 07 07 0f 0b 0b 09 ... 697 more bytes>,
+}
+```

package.json

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+{
+  "name": "write-image",
+  "version": "0.0.0",
+  "description": "Write an Image",
+  "main": "write-image.js",
+  "files": [
+    "write-image.js"
+  ],
+  "scripts": {
+    "format": "npx prettier --arrow-parens=avoid --print-width=120 --trailing-comma=none --write *.js",
+    "test": "node test.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/DanielJDufour/write-image.git"
+  },
+  "keywords": [
+    "image",
+    "jpg",
+    "png"
+  ],
+  "author": "Daniel J. Dufour",
+  "license": "CC0-1.0",
+  "bugs": {
+    "url": "https://github.com/DanielJDufour/write-image/issues"
+  },
+  "homepage": "https://github.com/DanielJDufour/write-image#readme",
+  "dependencies": {
+    "jpeg-js": "^0.4.3",
+    "pngjs": "^6.0.0",
+    "to-image-data": "^0.0.1"
+  },
+  "devDependencies": {
+    "find-and-read": "^1.0.0",
+    "flug": "^2.1.0",
+    "readim": "^0.0.2",
+    "xdim": "^1.2.1"
+  }
+}

test.js

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+const fs = require("fs");
+const test = require("flug");
+const findAndRead = require("find-and-read");
+const toImageData = require("to-image-data");
+const xdim = require("xdim");
+const readim = require("readim");
+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);
+});
+
+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);
+});

write-image.js

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+const jpeg = require("jpeg-js");
+const { PNG } = require("pngjs");
+const toImageData = require("to-image-data");
+
+module.exports = async function writeImage({ data, debug = false, format, height, width, quality = 85 }) {
+  if (!format) throw new Error(`[write-image] please specify a format, "JPG", or "PNG`);
+
+  // normalize format
+  format = format.replace(/^\./, "").toUpperCase();
+  if (debug) console.log(`[write-image] format is "${format}"`);
+
+  const imageData = toImageData({ data, height, width });
+  if (debug) console.log(`[write-image] image data is`, imageData);
+
+  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 };
+  } else if (format === "JPG") {
+    const { data, height, width } = jpeg.encode(imageData, quality).data;
+    return { data, height, width };
+  }
+};