SurfaceView with drawing thread

suggest change

This example describes how to create a SurfaceView with a dedicated drawing thread. This implementation also handles edge cases such as manufacture specific issues as well as starting/stopping the thread to save cpu time.

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
/**
* Defines a custom SurfaceView class which handles the drawing thread
**/
public class BaseSurface extends SurfaceView implements SurfaceHolder.Callback, View.OnTouchListener, Runnable
{

    /**
     * Holds the surface frame
     */
    private SurfaceHolder holder;

    /**
     * Draw thread
     */
    private Thread drawThread;

    /**
     * True when the surface is ready to draw
     */
    private boolean surfaceReady = false;

    /**
     * Drawing thread flag
     */

    private boolean drawingActive = false;

    /**
     * Paint for drawing the sample rectangle
     */
    private Paint samplePaint = new Paint();

    /**
     * Time per frame for 60 FPS
     */
    private static final int MAX_FRAME_TIME = (int) (1000.0 / 60.0);

    private static final String LOGTAG = "surface";    

    public BaseSurface(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        SurfaceHolder holder = getHolder();
        holder.addCallback(this);
        setOnTouchListener(this);

        // red
        samplePaint.setColor(0xffff0000);
        // smooth edges
        samplePaint.setAntiAlias(true);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
    {
        if (width == 0 || height == 0)
        {
            return;
        }

        // resize your UI
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder)
    {
        this.holder = holder;

        if (drawThread != null)
        {
            Log.d(LOGTAG, "draw thread still active..");
            drawingActive = false;
            try
            {
                drawThread.join();
            } catch (InterruptedException e)
            { // do nothing
            }
        }

        surfaceReady = true;
        startDrawThread();
        Log.d(LOGTAG, "Created");
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder)
    {
        // Surface is not used anymore - stop the drawing thread
        stopDrawThread();
        // and release the surface
        holder.getSurface().release();

        this.holder = null;
        surfaceReady = false;
        Log.d(LOGTAG, "Destroyed");
    }

    @Override
    public boolean onTouch(View v, MotionEvent event)
    {
        // Handle touch events
        return true;
    }

    /**
     * Stops the drawing thread
     */
    public void stopDrawThread()
    {
        if (drawThread == null)
        {
            Log.d(LOGTAG, "DrawThread is null");
            return;
        }
        drawingActive = false;
        while (true)
        {
            try
            {
                Log.d(LOGTAG, "Request last frame");
                drawThread.join(5000);
                break;
            } catch (Exception e)
            {
                Log.e(LOGTAG, "Could not join with draw thread");
            }
        }
        drawThread = null;
    }

    /**
     * Creates a new draw thread and starts it.
     */
    public void startDrawThread()
    {
        if (surfaceReady && drawThread == null)
        {
            drawThread = new Thread(this, "Draw thread");
            drawingActive = true;
            drawThread.start();
        }
    }

    @Override
    public void run()
    {
        Log.d(LOGTAG, "Draw thread started");
        long frameStartTime;
        long frameTime;

        /*
         * In order to work reliable on Nexus 7, we place ~500ms delay at the start of drawing thread
         * (AOSP - Issue 58385)
         */
        if (android.os.Build.BRAND.equalsIgnoreCase("google") && android.os.Build.MANUFACTURER.equalsIgnoreCase("asus") && android.os.Build.MODEL.equalsIgnoreCase("Nexus 7"))
        {
            Log.w(LOGTAG, "Sleep 500ms (Device: Asus Nexus 7)");
            try
            {
                Thread.sleep(500);
            } catch (InterruptedException ignored)
            {
            }
        }
        try
        {
            while (drawingActive)
            {
                if (holder == null)
                {
                    return;
                }

                frameStartTime = System.nanoTime();
                Canvas canvas = holder.lockCanvas();
                if (canvas != null)
                {
                    // clear the screen using black
                    canvas.drawARGB(255, 0, 0, 0);

                    try
                    {
                        // Your drawing here
                        canvas.drawRect(0, 0, getWidth() / 2, getHeight() / 2, samplePaint);
                    } finally
                    {

                        holder.unlockCanvasAndPost(canvas);
                    }
                }

                // calculate the time required to draw the frame in ms
                frameTime = (System.nanoTime() - frameStartTime) / 1000000;

                if (frameTime < MAX_FRAME_TIME) // faster than the max fps - limit the FPS
                {
                    try
                    {
                        Thread.sleep(MAX_FRAME_TIME - frameTime);
                    } catch (InterruptedException e)
                    {
                        // ignore
                    }
                }
            }
        } catch (Exception e)
        {
            Log.w(LOGTAG, "Exception while locking/unlocking");
        }
        Log.d(LOGTAG, "Draw thread finished");
    }
}

This layout only contains the custom SurfaceView and maximizes it to the screen size.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="sample.devcore.org.surfaceviewsample.MainActivity">

    <sample.devcore.org.surfaceviewsample.BaseSurface
        android:id="@+id/baseSurface"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

The activity which uses the SurfaceView is responsible for starting and stopping the drawing thread. This approach saves battery as the drawing is stopped as soon as the activity gets in the background.

import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity
{

    /**
     * Surface object
     */
    private BaseSurface surface;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        surface = (BaseSurface) findViewById(R.id.baseSurface);
    }

    @Override
    protected void onResume()
    {
        super.onResume();
        // start the drawing
        surface.startDrawThread();
    }

    @Override
    protected void onPause()
    {
        // stop the drawing to save cpu time
        surface.stopDrawThread();
        super.onPause();
    }
}

Feedback about page:

Feedback:
Optional: your email if you want me to get back to you:


Canvas drawing using SurfaceView:
* SurfaceView with drawing thread

Table Of Contents
2 Gradle
5 Intent
17 Service
19 WebView
31 SQLite
35 Glide
37 Dialog
38 ACRA
44 Handler
53 Toast
63 Menu
65 Picasso
70 Volley
71 Widgets
78 Realm
90 Spinner
95 OkHttp
98 Canvas drawing using SurfaceView
108 TextView
109 ListView
111 Loader
118 Xposed
119 Security
121 ImageView
123 Doze Mode
130 Drawables
131 Colors
134 Fresco
139 AdMob
145 Keyboard
146 Button
150 EditText
155 Vk SDK
163 ExoPlayer
169 XMPP
175 OpenCV
177 Threads
184 ORMLite
186 TabLayout
190 LruCache
192 Zip files
194 Fastlane
199 FileIO
202 Moshi
210 VideoView
216 Paint
218 ProGuard
226 CleverTap
228 ADB shell
229 Ping ICMP
230 AIDL
234 Context
240 JCodec
242 Okio
249 FuseView
254 Looper
261 Fastjson
263 Jackson
267 Smartcard