package app.test;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
class Dot extends View {
private static final float RADIUS = 20;
private float x = 30;
private float y = 30;
private float initialX;
private float initialY;
private float offsetX;
private float offsetY;
private Paint myPaint;
private Paint backgroundPaint;
public Dot(Context context, AttributeSet attrs) {
super(context, attrs);
backgroundPaint = new Paint();
backgroundPaint.setColor(Color.BLUE);
myPaint = new Paint();
myPaint.setColor(Color.WHITE);
myPaint.setAntiAlias(true);
}
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
initialX = x;
initialY = y;
offsetX = event.getX();
offsetY = event.getY();
break;
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
x = initialX + event.getX() - offsetX;
y = initialY + event.getY() - offsetY;
break;
}
return (true);
}
public void draw(Canvas canvas) {
int width = canvas.getWidth();
int height = canvas.getHeight();
canvas.drawRect(0, 0, width, height, backgroundPaint);
canvas.drawCircle(x, y, RADIUS, myPaint);
invalidate();
}
}
public class Test extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
//main.xml
android:layout_width="fill_parent" android:layout_height="fill_parent" >
android:layout_width="wrap_content" android:layout_height="wrap_content" />