cameracanvas.java

J2ME MIDP_Example_Applications

// Copyright 2002 Nokia Corporation. 
// 
// THIS SOURCE CODE IS PROVIDED 'AS IS', WITH NO WARRANTIES WHATSOEVER, 
// EXPRESS OR IMPLIED, INCLUDING ANY WARRANTY OF MERCHANTABILITY, FITNESS 
// FOR ANY PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE 
// OR TRADE PRACTICE, RELATING TO THE SOURCE CODE OR ANY WARRANTY OTHERWISE 
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// RIGHTS GRANTED HEREUNDER DOES NOT INFRINGE OR MAY NOT CAUSE INFRINGEMENT 
// OF ANY PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OWNED OR CONTROLLED 
// BY THIRD PARTIES 
// 
// Furthermore, information provided in this source code is preliminary, 
// and may be changed substantially prior to final release. Nokia Corporation 
// retains the right to make changes to this source code at 
// any time, without notice. This source code is provided for informational 
// purposes only. 
// 
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// Corporation.
// Java and all Java-based marks are trademarks or registered trademarks of
// Sun Microsystems, Inc.
// Other product and company names mentioned herein may be trademarks or
// trade names of their respective owners.
// 
// A non-exclusive, non-transferable, worldwide, limited license is hereby 
// granted to the Licensee to download, print, reproduce and modify the 
// source code. The licensee has the right to market, sell, distribute and 
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// unnamed package

import javax.microedition.lcdui.*;
import javax.microedition.media.*;
import javax.microedition.media.control.*;
import java.io.IOException;


class CameraCanvas
    extends Canvas
    implements CommandListener
{
    private final CameraMIDlet midlet;
    private final Command exitCommand;
    private Command captureCommand = null;
    private Player player = null;
    private VideoControl videoControl = null;

    private boolean active = false;

    // Two strings for displaying error messages
    private String message1 = null;
    private String message2 = null;


    CameraCanvas(CameraMIDlet midlet)
    {
        this.midlet = midlet;

        exitCommand = new Command("Exit", Command.EXIT, 1);
        addCommand(exitCommand);
        setCommandListener(this);

        try
        {
            player = Manager.createPlayer("capture://video");
            player.realize();
        
            // Grab the video control and set it to the current display.
            videoControl = (VideoControl)(player.getControl("VideoControl"));
            if (videoControl == null)
            {
                discardPlayer();
                message1 = "Unsupported:";
                message2 = "Can't get video control";
            }
            else
            {
                videoControl.initDisplayMode(VideoControl.USE_DIRECT_VIDEO,
                                             this);
                // centre video, letting it be clipped if it's too big
                int canvasWidth = getWidth();
                int canvasHeight = getHeight();
                int displayWidth = videoControl.getDisplayWidth();
                int displayHeight = videoControl.getDisplayHeight();
                int x = (canvasWidth - displayWidth) / 2;
                int y = (canvasHeight - displayHeight) / 2;
                videoControl.setDisplayLocation(x, y);
                
                captureCommand = new Command("Capture", Command.SCREEN, 1);
                addCommand(captureCommand);
            }
        }
        catch (IOException ioe)
        {
            discardPlayer();
            message1 = "IOException:";
            message2 = ioe.getMessage();
        }
        catch (MediaException me)
        {
            discardPlayer();
            message1 = "MediaException:";
            message2 = me.getMessage();
        }
        catch (SecurityException se)
        {
            discardPlayer();
            message1 = "SecurityException";
            message2 = se.getMessage();
        }
    }


    // Called in case of exception to make sure invalid players are closed
    private void discardPlayer()
    {
        if (player != null)
        {
            player.close();
            player = null;
        }
        videoControl = null;
    }
    

    public void paint(Graphics g)
    {
        g.setColor(0x00FFFF00);   // yellow
        g.fillRect(0, 0, getWidth(), getHeight());

        if (message1 != null)
        {
            g.setColor(0x00000000);   // black
            g.drawString(message1, 1, 1, Graphics.TOP | Graphics.LEFT);
            g.drawString(message2, 1, 1 + g.getFont().getHeight(),
                                         Graphics.TOP | Graphics.LEFT);
        }
    }


    synchronized void start()
    {
        if ((player != null) && !active)
        {
            try
            {
                player.start();
                videoControl.setVisible(true);
            }
            catch (MediaException me)
            {
                message1 = "Media exception:";
                message2 = me.getMessage();
            }
            catch (SecurityException se)
            {
                message1 = "SecurityException";
                message2 = se.getMessage();
            }
            active = true;
        }
    }


    synchronized void stop()
    {
        if ((player != null) && active)
        {
            try
            {
                videoControl.setVisible(false);
                player.stop();
            }
            catch (MediaException me)
            {
                message1 = "MediaException:";
                message2 = me.getMessage();
            }
            active = false;
        }
    }


    public void commandAction(Command c, Displayable d)
    {
        if (c == exitCommand)
        {
            midlet.cameraCanvasExit();
        }
        else if (c == captureCommand)
        {
            takeSnapshot();
        }
    }


    public void keyPressed(int keyCode)
    {
        if (getGameAction(keyCode) == FIRE)
        {
            takeSnapshot();
        }
    }


    private void takeSnapshot()
    {
        if (player != null)
        {
            try
            {
                byte[] pngImage = videoControl.getSnapshot(null);
                midlet.cameraCanvasCaptured(pngImage);
            }
            catch (MediaException me)
            {
                message1 = "MediaException:";
                message2 = me.getMessage();
            }
        }
    }
}