How drawBitmapMesh works in android canvas

Question

I want to draw a bitmap on a rectangle. I use the values below:

    this.meshWidth = 1;
    this.meshHeight = 1;
    this.verts = new float[8];
    this.points[0].x = (float)(this.getWidth()/4);
    this.points[0].y = (float)(this.getHeight()/4);
    this.points[1].x = (float)(this.points[0].x+this.getWidth()/2);
    this.points[1].y = (float)(this.points[0].y);
    this.points[2].x = (float)(this.points[0].x);
    this.points[2].y = (float)(this.points[0].y+this.getHeight()/2);
    this.points[3].x = (float)(this.points[1].x);
    this.points[3].y = (float)(this.points[2].y);

points array is my vertex array.

my onDraw method

public void onDraw(Canvas canvas){
    //canvas.drawBitmap(bitmap, 20,20, null);
    Paint paint = new Paint();
    paint.setColor(Color.BLUE);
    canvas.drawLine(this.points[0].x, this.points[0].y, this.points[1].x, this.points[1].y, paint);
    canvas.drawLine(this.points[1].x, this.points[1].y, this.points[3].x, this.points[3].y, paint);
    canvas.drawLine(this.points[3].x, this.points[3].y, this.points[2].x, this.points[2].y, paint);
    canvas.drawLine(this.points[2].x, this.points[2].y, this.points[0].x, this.points[0].y, paint);
    canvas.drawBitmapMesh(this.bitmap, meshWidth, meshHeight, verts, 0, null, 0, null);
}

The output is this

I want to draw bitmap on rectangle surrounded with blue lines..