A more easy way to do that is get your points and extend the ImageView that will display your image to draw the points, than you just need to pass the points that you want to draw .
In my project I did this:
public class ImageDraw extends ImageView{
private Paint mPaint = new Paint();
List<Point> pts = new ArrayList<Point>() ;
public ImageDraw(Context context) {
super(context);
}
//used to send the location of the points to draw on the screen
//must be called before every redraw to update the points on the screen
public void SetPointsToDraw(List<Point> pts)
{
this.pts = pts;
}
public ImageDraw(Context context, AttributeSet attrs)
{
super(context,attrs);
}
public ImageDraw(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
}
@Override
public void onDraw(Canvas canvas)
{
super.onDraw(canvas);
Paint paintColor = mPaint;
paintColor.setColor(Color.YELLOW);
paintColor.setStrokeWidth(3);
if(pts.size() > 0)
{
canvas.drawCircle(pts.get(0).x, pts.get(0).y, 7, paintColor);
}
if (pts.size() > 1)
{
for (int i = 1 ; i < pts.size(); i++) {
paintColor.setColor(Color.YELLOW);
canvas.drawCircle(pts.get(i).x, pts.get(i).y, 7, paintColor);
paintColor.setColor(Color.RED);
canvas.drawLine(pts.get(i-1).x, pts.get(i-1).y, pts.get(i).x, pts.get(i).y, paintColor);
}
}
}
}
When you extends the Imageview and create the layout with xml don`t forget to put the entire package of you new widget like:
com.Myapp.MyImageView