Question

I’m confused if this is even the right way to do. Please correct me. So basically i have a text drawn in my custom view with canvas.drawText method. The text is a number (amount). I’m trying to make the text animate to another number (example: 100 => 800) when an event occurs.

I’m aware that this can be done with a for loop counter in onDraw method and calling canvas.drawText and invalidate() until it reaches the final number. But my app is stuck.

UPDATED code:

I have updated the code. Now the app doesn’t get stuck (as per Simon’s advice). But now it just draws all the numbers at one go (1-99). I dont know how to slow down the loop.

public class CustomView extends View implements OnTouchListener{

   private Canvas main_canvas;

   //...Other codes like, initialization, paint etc!...//

   @Override
   protected void onDraw(Canvas canvas) {
      main_canvas = canvas;
   }

   public boolean onTouch(View v, MotionEvent event) {
      switch(event.getAction()){
      case MotionEvent.ACTION_DOWN:
      //...Some action...//
      case MotionEvent.ACTION_MOVE:
      //...Some action...//
      case MotionEvent.ACTION_UP:
      runTextAnimation();
      }
   }

   private void runTextAnimation() {

        for(int i=1; i < 100; i++){
            main_canvas.drawText(String.valueOf(i), getMeasuredWidth()/2, 100, amountPaint);
            invalidate();
        }
   }

}

Answer 1

I solved this by using a Runnable and using postDelayed for queueing the message for some milliseconds. Though I have to thank Simon for narrowing my search and thoughts. Below is the snippet. Hope this could help someone. Cheers.

    private Handler mHandler;
    private int i;

    mHandler.post(mUpdate); //call this to run

    private Runnable mUpdate = new Runnable() {
               public void run() {

                main_canvas.drawText("Secret Text"+i, getMeasuredWidth()/2, 50, textPaint);

                i++; // incrementing the value

                mHandler.postDelayed(this, 60);
                invalidate();
                }
        };

BTW the snippet above is an infinity counter, watchout to stop it at sometime.