wallet-core/lib/wallet/chromeBadge.ts

/*
 This file is part of TALER
 (C) 2016 INRIA

 TALER is free software; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 TALER is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

 You should have received a copy of the GNU General Public License along with
 TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */

import {
  Badge
} from "./wallet";


/**
 * Polyfill for requestAnimationFrame, which
 * doesn't work from a background page.
 */
function rAF(cb: (ts: number) => void) {
  window.setTimeout(() => {
    cb(performance.now());
  }, 100);
}


export class ChromeBadge implements Badge {
  canvas: HTMLCanvasElement;
  ctx: CanvasRenderingContext2D;
  talerLogo: HTMLImageElement;
  isBusy: boolean = false;
  rotationAngle: number = 0;
  static rotationAngleMax = 50000;

  constructor() {
    let bg = chrome.extension.getBackgroundPage();
    this.canvas = bg.document.createElement("canvas");
    this.canvas.width = 32;
    this.canvas.height = 32;
    this.ctx = this.canvas.getContext("2d")!;

    this.talerLogo = bg.document.getElementById("taler-logo") as HTMLImageElement;
    if (!(this.talerLogo instanceof HTMLImageElement)) {
      throw Error();
    }

    this.draw();
  }

  /**
   * Draw the badge based on the current state.
   */
  private draw() {
    // Reset to identity
    this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
    this.ctx.setTransform(1, 0, 0, 1, 0, 0);
    this.ctx.translate(this.canvas.width / 2, this.canvas.height / 2);
    this.ctx.rotate(this.rotationAngle / ChromeBadge.rotationAngleMax * Math.PI * 2);
    this.ctx.translate(-this.canvas.width / 2, -this.canvas.height / 2);
    this.ctx.drawImage(this.talerLogo,
                       0,
                       0,
                       this.talerLogo.width,
                       this.talerLogo.height,
                       0, 0, this.canvas.width, this.canvas.height);

    let imageData = this.ctx.getImageData(0,
                                          0,
                                          this.canvas.width,
                                          this.canvas.height);
    chrome.browserAction.setIcon({imageData});
  }

  private animate() {
    let bg: Window = chrome.extension.getBackgroundPage();
    let start: number|undefined = undefined;
    let step = (timestamp: number) => {
      if (!start) {
        start = timestamp;
      }
      let delta = (timestamp - start);
      if (!this.isBusy && this.rotationAngle + delta >= ChromeBadge.rotationAngleMax) {
        // stop if we're close enough to origin
        this.rotationAngle = 0;
      } else {
        this.rotationAngle = (this.rotationAngle + timestamp - start) % ChromeBadge.rotationAngleMax;
      }
      if (this.isBusy || this.rotationAngle != 0) {
        rAF(step);
      }
      this.draw();
    };
    rAF(step);
  }

  setText(s: string) {
    chrome.browserAction.setBadgeText({text: s});
  }

  setColor(c: string) {
    chrome.browserAction.setBadgeBackgroundColor({color: c});
  }

  startBusy() {
    this.isBusy = true;
    this.animate();
  }

  stopBusy() {
    this.isBusy = false;
  }
}