Question

I’m quite new to android, but basically I want to set up a program so that when the user clicks on an imageview, a dot is drawn where they click. I have tried many times but just don’t seem to be able to get it to work, and help would be much appreciated.So far I have

package com.smallbore.smallbore;

import android.app.Activity;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.OvalShape;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;

public class targetenter extends Activity {
     /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.targetenter);
        ImageView v = (ImageView) findViewById(R.id.imageView1);
        v.setOnTouchListener(new View.OnTouchListener() {

            @Override
            public boolean onTouch(View arg0, MotionEvent arg1) {
                TextView t1 = (TextView) findViewById(R.id.textView2);
                TextView t2 = (TextView) findViewById(R.id.textView3);
                t1.setText("X: "+arg1.getX());
                t2.setText("Y: "+arg1.getY());
                 int x = (int)arg1.getX();
                    int y = (int)arg1.getY();
                    int width = 50;
                    int height = 50;

                    ShapeDrawable mDrawable = new ShapeDrawable(new OvalShape());
                    mDrawable.getPaint().setColor(0xff74AC23);
                    mDrawable.setBounds(x, y, x + width, y + height);
                    ImageView v = (ImageView) findViewById(R.id.imageView1)
                    v.setImageDrawable(mDrawable);
                    return false;       
    }
            });
        };
    }

Answer 1

To draw the dots, you’ll probably have to use a custom View and override onTouchEvent and onDraw. onTouchEvent will give you the x,y coordinates of the touch event and in onDraw you can draw a circle at this point to the canvas that the framework provides to this method. If you want to clear previous dots, you only need to keep track of the last x,y coordinates. Otherwise, you’ll need to keep a running list (ArrayList or something like that).

In your shoes, I’d probably subclass ImageView so that I get the image drawing stuff for free. Call super.onDraw(canvas) inside the overridden onDraw method, and then draw your dots (canvas.drawCircle).