Add mirroring to graphics module

[unitythemaker]

For some reason, I need to revert the image that'll be displaying to the oled. But not like rotating/flipping image more like mirroring. It'd awesome if it's added. Currently, I'm physically adding a mirror to make what I want and I'm trying to shrink it's size but I don't know C lang. Right now, I'm trying to add that functionality using JS with existing API features for graphics module.

Normal

Rotated/Flipped

Mirrored

https://note.nkmk.me/en/python-pillow-flip-mirror/

[niklauslee]

I think writing an image manipulation library is more appropriate than adding to the builtin graphics API.

[unitythemaker]

I did what I wanted by editing SSD1306-i2c module's code and I'm sharing for the future comers.

https://kaluma.io/@niklauslee/ssd1306-i2c/code/index.js (LN 79-107)

/**
   * Return a graphic context
   * @return {GraphicContext}
   */
  getContext() {
    if (!this.context) {
      this.context = new BufferedGraphicsContext(this.width, this.height, {
        rotation: this.rotation,
        bpp: 1,
        display: (buffer) => {
          var cmds = new Uint8Array([
            0x22, // pages
            0, (this.height >> 3) - 1,
            0x21, // columns
            0, this.width - 1
          ]);
          this.sendCommands(cmds);
          var WIRE_MAX = 128;
          var chunk = new Uint8Array(WIRE_MAX + 1);
          chunk[0] = 0x40;
+         var mirrored = new Uint8Array(buffer.byteLength);
          for (var i = 0; i < mirrored.byteLength; i += WIRE_MAX) {
+           mirrored.set(buffer.subarray(i, i + this.width).reverse(), i, this.width);
            chunk.set(new Uint8Array(mirrored.buffer, i, WIRE_MAX), 1);
            this.i2c.write(chunk, this.address);
          }
        }
      });
    }
    return this.context;
  }