Android : How to implement drag and zoom for text on canvas in android

Added some text to canvas as follows ,how to implement drag functionality and zoom functionality for text on canvas.Here is my code to add some text on canvas

public class Test extends Activity {
  ImageView drawingImageView;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    drawingImageView = (ImageView) this.findViewById(R.id.DrawingImageView);
    Bitmap bitmap = Bitmap.createBitmap((int) getWindowManager()
        .getDefaultDisplay().getWidth(), (int) getWindowManager()
        .getDefaultDisplay().getHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    drawingImageView.setImageBitmap(bitmap);

    // Custom Font Text

    Paint paint = new Paint();
    paint.setColor(Color.GREEN);
    paint.setTextSize(40);
    Typeface chops = Typeface.createFromAsset(this.getAssets(),
        "WC_Speed_Bold_Bta.ttf");
    paint.setTypeface(chops);
    float text_x = 120;
    float text_y = 120;
    canvas.drawText("Hello", text_x, text_y, paint);

  }
}