Add single frame encoder for type-gif (#899)

* Add single frame encoder for type-gif

* Fix linting errors

* Update packages/type-gif/package.json

Co-authored-by: Andrew Lisowski <lisowski54@gmail.com>

packages/jimp/test/filetypes.test.js

@@ -36,6 +36,13 @@ describe('FileType', () => {
 
     image.getMIME().should.be.equal(clone.getMIME());
   });
+
+  it('clones gif with the correct MIME type', async () => {
+    const image = await Jimp.read(imagesDir + '/flower.gif');
+    const clone = image.clone();
+
+    image.getMIME().should.be.equal(clone.getMIME());
+  });
 });
 
 describe('hasAlpha', () => {

packages/type-gif/package.json

@@ -19,6 +19,7 @@
   "dependencies": {
     "@babel/runtime": "^7.7.2",
     "@jimp/utils": "link:../utils",
+    "gifwrap": "^0.9.2",
     "omggif": "^1.0.9"
   },
   "peerDependencies": {

packages/type-gif/src/index.js

@@ -1,4 +1,5 @@
 import GIF from 'omggif';
+import { GifUtil, GifFrame, BitmapImage, GifCodec } from 'gifwrap';
 
 const MIME_TYPE = 'image/gif';
 
@@ -22,5 +23,17 @@ export default () => ({
         height: gifObj.height
       };
     }
+  },
+
+  encoders: {
+    [MIME_TYPE]: data => {
+      const bitmap = new BitmapImage(data.bitmap);
+      GifUtil.quantizeDekker(bitmap, 256);
+      const newFrame = new GifFrame(bitmap);
+      const gifCodec = new GifCodec();
+      return gifCodec.encodeGif([newFrame], {}).then(newGif => {
+        return newGif.buffer;
+      });
+    }
   }
 });

packages/type-gif/test/gif.test.js

@@ -0,0 +1,29 @@
+import { Jimp, getTestDir } from '@jimp/test-utils';
+import configure from '@jimp/custom';
+
+import gif from '../src';
+
+const jimp = configure({ types: [gif] }, Jimp);
+
+describe('GIF', () => {
+  const imagesDir = getTestDir(__dirname) + '/images';
+
+  it('load GIF', async () => {
+    const image = await jimp.read(imagesDir + '/flower.gif');
+    image.getPixelColor(10, 10).should.be.equal(0xe5e6d9ff);
+  });
+
+  it('load animated GIF', async () => {
+    const image = await jimp.read(imagesDir + '/animated.gif');
+    image.getPixelColor(10, 10).should.be.equal(0xa1d2f1ff);
+  });
+
+  it('export GIF', async () => {
+    const jgd = await jimp.read(imagesDir + '/flower.gif');
+    const buffer = await jgd.getBufferAsync('image/gif');
+    buffer
+      .toString()
+      .startsWith('GIF')
+      .should.be.equal(true);
+  });
+});