Flickering and other problems in android custom view for paint app.

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Java

Mobile

Android

Canvas

In my paint app I am hoping that when I drag my finger across the screen a line will appear following my fingers trail. While, my app achieves some of that the screen of my avd flickers and instead of one continuous line it is a lot of smaller lines making a broken larger one.

Here is my code for the custom view:

package com.android.paint;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.view.MotionEvent;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class Panel extends SurfaceView {
	private List<point> points = new ArrayList<point>();
	private Point point = new Point();
	private int strokeColor = Color.RED;
	private DrawingThread thread;
	private Callback callback = new Callback() {
		@Override
		public void surfaceDestroyed(SurfaceHolder holder) {
			boolean retry = true;
			while(retry) {
				try {
					thread.join();
					retry = false;
				} catch(InterruptedException ex) { }
			}
		}
		
		@Override
		public void surfaceCreated(SurfaceHolder holder) {
			thread.setRunning(true);
			thread.start();
		}
		
		@Override
		public void surfaceChanged(SurfaceHolder holder, int format, int width,
				int height) {
			
		}
	};
	
	public Panel(Context context) {
		super(context);
		getHolder().addCallback(callback);
		thread = new DrawingThread(getHolder(), this);
		setFocusable(true);
	}
	
	@Override
	public void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		Paint paint = new Paint();
		paint.setColor(strokeColor);

		try {
			Point previousPoint = points.get(points.size() - 2);
			Point currentPoint = points.get(points.size() - 1);
			canvas.drawLine(previousPoint.x, previousPoint.y, currentPoint.x, currentPoint.y, paint);
		} catch(IndexOutOfBoundsException ex) { }
	}
	
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		super.onTouchEvent(event);
                if(event.getAction() == MotionEvent.ACTION_MOVE) {
		    point = new Point((int) event.getX(), (int) event.getY());
		    points.add(point);
                }
		return true;
	}
}</point></point>

DrawingThread is a simple thread that calls onDraw.
If necessary here is the code:

package com.android.paint;

import android.graphics.Canvas;
import android.view.SurfaceHolder;

public class DrawingThread extends Thread {
	private SurfaceHolder surfaceHolder;
	private Panel panel;
	private boolean running = false;
	
	public DrawingThread(SurfaceHolder surfaceHolder, Panel panel) {
		this.surfaceHolder = surfaceHolder;
		this.panel = panel;
	}
	
	public void setRunning(boolean running) {
		this.running = running;
	}
	
	@Override
	public void run() {
		Canvas c;
		while(running) {
			c = null;
			try {
				c = surfaceHolder.lockCanvas(null);
				synchronized (surfaceHolder) {
					panel.onDraw(c);
				}
			} finally {
				if(c != null)
					surfaceHolder.unlockCanvasAndPost(c);
			}
		}
	}
}

Edit: Code update.