Add TXI RGBA4444 encoding support and bump to 1.1.6 (#38)

* Update PixelEncoder with texture format formulas. * Add test image references and update unit tests to include RGBA4444. Signed-off-by: Bogdan Purcareata <[email protected]>
Fitbit · Mar 17, 2022 · 06cb674 · 06cb674
1 parent 3874ea9
commit 06cb674
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Showing 10 changed files with 43 additions and 1 deletion.
diff --git a/README.md b/README.md
@@ -32,6 +32,7 @@ TXI is an image format used on some Fitbit devices. This package is used to conv
 ```
 {
   RGB565 = 'RGB565',
+  RGBA4444 = 'RGBA4444',
   RGBA6666 = 'RGBA6666',
   RGBA8888 = 'RGBA8888',
   A8 = 'A8',

diff --git a/bench.ts b/bench.ts
@@ -26,6 +26,12 @@ suite
       outputFormat: imageCodecTxi.TXIOutputFormat.RGBA8888,
     });
   })
+  .add('RGBA4444', () => {
+    imageCodecTxi.encode(inputImage, {
+      rle: 'auto',
+      outputFormat: imageCodecTxi.TXIOutputFormat.RGBA4444,
+    });
+  })
   .add('RGBA6666', () => {
     imageCodecTxi.encode(inputImage, {
       rle: 'auto',

diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@fitbit/image-codec-txi",
-  "version": "1.1.5",
+  "version": "1.1.6",
   "description": "TXI image format encoder library",
   "files": [
     "lib",

diff --git a/src/__test__/rgb_image.txi.rgba4444 b/src/__test__/rgb_image.txi.rgba4444
diff --git a/src/__test__/rgb_image.txi.rgba4444.rle b/src/__test__/rgb_image.txi.rgba4444.rle
diff --git a/src/__test__/transparency-palette.txi.rgba4444.rle b/src/__test__/transparency-palette.txi.rgba4444.rle
diff --git a/src/__test__/transparency-palette.txi.rgba6666.rle b/src/__test__/transparency-palette.txi.rgba6666.rle
diff --git a/src/encoder.test.ts b/src/encoder.test.ts
@@ -49,6 +49,8 @@ for (const withRLE of [true, false]) {
       checkImage('rgb_image', withRLE));
     it('converts an RGB PNG to RGB565', () =>
       checkImage('rgb_image', withRLE, TXIOutputFormat.RGB565));
+    it('converts an RGB PNG to RGBA4444', () =>
+      checkImage('rgb_image', withRLE, TXIOutputFormat.RGBA4444));
     it('converts an RGB PNG to RGBA6666', () =>
       checkImage('rgb_image', withRLE, TXIOutputFormat.RGBA6666));
     it('converts a paletted PNG', () => checkImage('palette', withRLE));
@@ -101,6 +103,14 @@ describe('readPNG', () => {
         const png = readPNG(loadTestResource('transparency-palette.png'));
         expect(png.data[3]).toBe(0);
       });
+
+      it('goes through the RGBA4444 corner cases', () => {
+        checkImage('transparency-palette', 'auto', TXIOutputFormat.RGBA4444);
+      });
+
+      it('goes through the RGBA6666 corner cases', () => {
+        checkImage('transparency-palette', 'auto', TXIOutputFormat.RGBA6666);
+      });
     });
   });
 

diff --git a/src/encoder.ts b/src/encoder.ts
@@ -6,6 +6,7 @@ enum TextureFormat {
   A8 = 0x00080008,
   BGR565 = 0x01100565,
   BGRA8888 = 0x01208888,
+  ABGR4444 = 0x02104444,
   ABGR6666 = 0x02186666,
   ABGR8888 = 0x02208888,
 }
@@ -30,6 +31,7 @@ const textureBPP: { [format: number]: number } = {
   [TextureFormat.ABGR8888]: 4,
   [TextureFormat.BGR565]: 2,
   [TextureFormat.ABGR6666]: 3,
+  [TextureFormat.ABGR4444]: 2,
 };
 
 type PixelEncoder = (data: Uint8Array, offset: number, output: Pixel) => void;
@@ -58,6 +60,21 @@ const pixelEncoders: { [format: number]: PixelEncoder } = {
     output[0] = 0xff & ((g6 << 5) | b5); // gggbbbbb
     output[1] = 0xff & ((g6 >> 3) | (r5 << 3)); // rrrrrggg
   },
+  [TextureFormat.ABGR4444]: (data, offset, output) => {
+    if (data[offset + 3] === 0) {
+      output[0] = 0;
+      output[1] = 0;
+      return;
+    }
+
+    const r = rescaleColor(data[offset], 15);
+    const g = rescaleColor(data[offset + 1], 15);
+    const b = rescaleColor(data[offset + 2], 15);
+    const a = rescaleColor(data[offset + 3], 15);
+
+    output[0] = 0xff & ((b << 4) | a); // bbbbaaaa
+    output[1] = 0xff & ((r << 4) | g); // rrrrgggg
+  },
   [TextureFormat.ABGR6666]: (data, offset, output) => {
     if (data[offset + 3] === 0) {
       output[0] = 0;
@@ -86,6 +103,8 @@ function findTextureFormat(outputFormat: TXIOutputFormat, rle: boolean) {
       return TextureFormat.A8;
     case TXIOutputFormat.RGB565:
       return TextureFormat.BGR565;
+    case TXIOutputFormat.RGBA4444:
+      return TextureFormat.ABGR4444;
     case TXIOutputFormat.RGBA6666:
       return TextureFormat.ABGR6666;
   }

diff --git a/src/types.ts b/src/types.ts
@@ -8,6 +8,7 @@ export interface ImageData {
 
 export enum TXIOutputFormat {
   RGB565 = 'RGB565',
+  RGBA4444 = 'RGBA4444',
   RGBA6666 = 'RGBA6666',
   RGBA8888 = 'RGBA8888',
   A8 = 'A8',
@@ -17,3 +18,8 @@ export interface TXIEncoderOptions {
   rle?: boolean | 'auto';
   outputFormat?: TXIOutputFormat;
 }
+
+export type RGBAOutputFormat =
+  | TXIOutputFormat.RGBA8888
+  | TXIOutputFormat.RGBA6666
+  | TXIOutputFormat.RGBA4444;