Android: 非UI Thread更動 UI

當Threrad在同個Activity時，蠻方便的作法:

runOnUiThread(new Runnable() {
    @Override
    public void run() {
       // 更新UI.....
    }
  }
);
 

Android: 轉換 Immutable Bitmap into Mutable

BitmapFactory.Options options = new BitmapFactory.Options();
options.inMutable = true;  //加上這個選項!!!! (API level 11以上)

Bitmap bm = BitmapFactory.decodeByteArray(data, 0, data.length, options);
Canvas canvas = new Canvas(bm);  // 不然會有錯誤產生！
.......