SimpleDrawingView.java

package com.codepath.example.customviewdemo.views;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

/*
 * Simple drawing with paths
 */
public class SimpleDrawingView extends View {
	// setup initial color
	private final int paintColor = Color.BLACK;
	// defines paint and canvas
	private Paint drawPaint;
	// stores next circle
	private Path path = new Path();

	public SimpleDrawingView(Context context, AttributeSet attrs) {
		super(context, attrs);
		setFocusable(true);
		setFocusableInTouchMode(true);
		setupPaint();
	}

	private void setupPaint() {
		// Setup paint with color and stroke styles
		drawPaint = new Paint();
		drawPaint.setColor(paintColor);
		drawPaint.setAntiAlias(true);
		drawPaint.setStrokeWidth(5);
		drawPaint.setStyle(Paint.Style.STROKE);
		drawPaint.setStrokeJoin(Paint.Join.ROUND);
		drawPaint.setStrokeCap(Paint.Cap.ROUND);
	}

	@Override
	protected void onDraw(Canvas canvas) {
		canvas.drawPath(path, drawPaint);
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		float pointX = event.getX();
		float pointY = event.getY();
		// Checks for the event that occurs
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:  
			path.moveTo(pointX, pointY);
			return true;
		case MotionEvent.ACTION_MOVE:
			path.lineTo(pointX, pointY);
			break;
		default:
			return false;
		}
		// Force a view to draw again
		postInvalidate();
		return true;
	}
}