ohmm
Class ImageServer

java.lang.Object
  ohmm.ImageServer

public class ImageServer
extends java.lang.Object

HTTP multipart/x-mixed-replace image server.

The source frames are provided via the hook updateImage(java.awt.image.BufferedImage), which also sets the width and height. The compression type, compression quality (if appliccable), and maximum served frames per second are controlled by URL query parameters "fmt" (string, e.g. "jpeg" or "png"), "fps" (float), and "qual" (int, 0=min, 100=max), respectively. They default to defFmt, defFPS, and defQual if the query params are not given.

Key and mouse events are collected from the client and made available in image coordinates via the hooks handleKey(char) and handleMouse(int, int, int, int).

Tested with Chrome and Safari. Firefox might or might not work (Mozilla bug 625012). On any browser, non-alphanumeric keycodes may differ from Java std.

The server knows about the following request paths:

• /server.html (also / and /index.html) - the server page including the image and javascript to send keyboard and mouse events back (accepts the optional "fmt", "fps", and "qual" query params)
• /image - the live image (also accepts the optional "fmt", "fps", and "qual" query params)
• /key - special path to recieve HTML GET requests encoding key events on the client
• /mouse - special path to recieve HTML GET requests encoding mouse events on the client
• /echo - echo the client request for debugging

Once the server is running, you can connect to it from a remote host by bringing up e.g. Google Chrome and browsing to the url

 http://ADDR:PORT/server.html

 

where ADDR is the IP address and PORT the listening port of the server. You can further control the image format, framerate, and quality like this:

 http://ADDR:PORT/server.html?fmt=jpg&fps=10&qual=95

 

Author:

Marsette Vona

Nested Class Summary

protected class

ImageServer.ExchangeState Wraps an HttpExchange with some derived values.

Field Summary

boolean	dbg Debug next server frame.
static java.lang.String	DEF_FMT Default defFmt.
static float	DEF_FPS Default defFPS.
static int	DEF_PORT Default TCP listen port.
static int	DEF_QUAL Default defQual.
static int	DEF_STOP_SEC Default stop(int) delay seconds.
java.lang.String	defFmt Default ImageIO format name.
float	defFPS Default max framerate.
int	defQual Default image quality in the range 0 (min) to 100 (max).
static int	EVENT_FLAG_ALTKEY Event flags for handleMouse(int, int, int, int).
static int	EVENT_FLAG_CTRLKEY Event flags for handleMouse(int, int, int, int).
static int	EVENT_FLAG_LBUTTON Event flags for handleMouse(int, int, int, int).
static int	EVENT_FLAG_MBUTTON Event flags for handleMouse(int, int, int, int).
static int	EVENT_FLAG_RBUTTON Event flags for handleMouse(int, int, int, int).
static int	EVENT_FLAG_SHIFTKEY Event flags for handleMouse(int, int, int, int).
static int	EVENT_LBUTTONDBLCLK Event types for handleMouse(int, int, int, int).
static int	EVENT_LBUTTONDOWN Event types for handleMouse(int, int, int, int).
static int	EVENT_LBUTTONUP Event types for handleMouse(int, int, int, int).
static int	EVENT_MBUTTONDBLCLK Event types for handleMouse(int, int, int, int).
static int	EVENT_MBUTTONDOWN Event types for handleMouse(int, int, int, int).
static int	EVENT_MBUTTONUP Event types for handleMouse(int, int, int, int).
static int	EVENT_MOUSEMOVE Event types for handleMouse(int, int, int, int).
static int	EVENT_RBUTTONDBLCLK Event types for handleMouse(int, int, int, int).
static int	EVENT_RBUTTONDOWN Event types for handleMouse(int, int, int, int).
static int	EVENT_RBUTTONUP Event types for handleMouse(int, int, int, int).
protected java.util.concurrent.ExecutorService	executor The internal transaction executor.
static int	HTTP_FORBIDDEN HTTP response codes
static int	HTTP_NOT_FOUND HTTP response codes
static int	HTTP_OK HTTP response codes
protected int	imageClients Number of clients to which we're currently serving images.
static java.lang.String	MIME_BOUNDARY MIME multipart boundary
java.io.PrintStream	msgStream Strems for messages and warnings, or null to disable.
static java.text.DecimalFormat	NF Number format for printouts.
protected boolean	oneClient Whether to limit serving images to one client.
int	port Server TCP listen port.
protected com.sun.net.httpserver.HttpServer	server The internal server object.
static java.lang.String	SERVER_HTML Server html file.
boolean	spewMouseMoves Whether to output lots of debug messages for mousemove events.
boolean	spewStackTraces Whether to dump stack traces on server errors.
java.io.PrintStream	warnStream Strems for messages and warnings, or null to disable.

Constructor Summary

ImageServer()
Creates server using DEF_PORT.

ImageServer(int port)
Creates server.

Method Summary

protected java.io.InputStream	getServerHTML() Hook to get the html the server sends to the client.
static java.net.InetAddress[]	getServerIPs() Get the server's non-local IP address(es).
protected void	handleEcho(ImageServer.ExchangeState xs) Serves debug echo info.
protected void	handleExchange(com.sun.net.httpserver.HttpExchange xch) Dispatches HTTP exchange to one of the handle*(ExchangeState) methods.
protected void	handleImage(ImageServer.ExchangeState xs) Serves images.
protected void	handleKey(char c) Hook to handle key events.
protected void	handleKey(ImageServer.ExchangeState xs) Handles key event requests.
protected void	handleMouse(ImageServer.ExchangeState xs) Handles mouse event requests.
protected void	handleMouse(int t, int x, int y, int m) Hook to handle mouse events.
protected void	handleServer(ImageServer.ExchangeState xs) Serves SERVER_HTML using getServerHTML().
protected void	handleUnknown(ImageServer.ExchangeState xs) Handles unknown request paths.
static void	main(java.lang.String[] argv) Starts a test server.
protected void	msg(java.lang.String m) Display a message to msgStream, if any.
protected static long	nowMS() Returns current time in milliseconds.
void	start() Starts server.
void	stop() stop(int) delaying DEF_STOP_SEC.
void	stop(int delay) Stops server and executor.
protected java.awt.image.BufferedImage	updateImage(java.awt.image.BufferedImage bi) Hook called to update the server image.
protected void	warn(java.lang.String m) Display a warning to warnStream, if any.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEF_PORT

public static final int DEF_PORT

Default TCP listen port.

See Also:

Constant Field Values

DEF_FMT

public static final java.lang.String DEF_FMT

Default defFmt.

See Also:

Constant Field Values

DEF_FPS

public static final float DEF_FPS

Default defFPS.

See Also:

Constant Field Values

DEF_QUAL

public static final int DEF_QUAL

Default defQual.

See Also:

Constant Field Values

DEF_STOP_SEC

public static final int DEF_STOP_SEC

Default stop(int) delay seconds.

See Also:

Constant Field Values

SERVER_HTML

public static final java.lang.String SERVER_HTML

Server html file.

See Also:

Constant Field Values

HTTP_OK

public static final int HTTP_OK

HTTP response codes

See Also:

Constant Field Values

HTTP_NOT_FOUND

public static final int HTTP_NOT_FOUND

HTTP response codes

See Also:

Constant Field Values

HTTP_FORBIDDEN

public static final int HTTP_FORBIDDEN

HTTP response codes

See Also:

Constant Field Values

MIME_BOUNDARY

public static final java.lang.String MIME_BOUNDARY

MIME multipart boundary

See Also:

Constant Field Values

EVENT_MOUSEMOVE

public static final int EVENT_MOUSEMOVE

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_LBUTTONDOWN

public static final int EVENT_LBUTTONDOWN

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_RBUTTONDOWN

public static final int EVENT_RBUTTONDOWN

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_MBUTTONDOWN

public static final int EVENT_MBUTTONDOWN

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_LBUTTONUP

public static final int EVENT_LBUTTONUP

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_RBUTTONUP

public static final int EVENT_RBUTTONUP

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_MBUTTONUP

public static final int EVENT_MBUTTONUP

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_LBUTTONDBLCLK

public static final int EVENT_LBUTTONDBLCLK

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_RBUTTONDBLCLK

public static final int EVENT_RBUTTONDBLCLK

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_MBUTTONDBLCLK

public static final int EVENT_MBUTTONDBLCLK

Event types for handleMouse(int, int, int, int).

Compatible with OpenCV event types.

See Also:

Constant Field Values

EVENT_FLAG_LBUTTON

public static final int EVENT_FLAG_LBUTTON

Event flags for handleMouse(int, int, int, int).

Compatible with OpenCV event flags.

See Also:

Constant Field Values

EVENT_FLAG_RBUTTON

public static final int EVENT_FLAG_RBUTTON

Event flags for handleMouse(int, int, int, int).

Compatible with OpenCV event flags.

See Also:

Constant Field Values

EVENT_FLAG_MBUTTON

public static final int EVENT_FLAG_MBUTTON

Event flags for handleMouse(int, int, int, int).

Compatible with OpenCV event flags.

See Also:

Constant Field Values

EVENT_FLAG_CTRLKEY

public static final int EVENT_FLAG_CTRLKEY

Event flags for handleMouse(int, int, int, int).

Compatible with OpenCV event flags.

See Also:

Constant Field Values

EVENT_FLAG_SHIFTKEY

public static final int EVENT_FLAG_SHIFTKEY

Event flags for handleMouse(int, int, int, int).

Compatible with OpenCV event flags.

See Also:

Constant Field Values

EVENT_FLAG_ALTKEY

public static final int EVENT_FLAG_ALTKEY

Event flags for handleMouse(int, int, int, int).

Compatible with OpenCV event flags.

See Also:

Constant Field Values

NF

public static final java.text.DecimalFormat NF

Number format for printouts.

port

public final int port

Server TCP listen port.

defFmt

public volatile java.lang.String defFmt

Default ImageIO format name.

defFPS

public volatile float defFPS

Default max framerate.

defQual

public volatile int defQual

Default image quality in the range 0 (min) to 100 (max).

dbg

public volatile boolean dbg

Debug next server frame.

msgStream

public volatile java.io.PrintStream msgStream

Strems for messages and warnings, or null to disable.

warnStream

public volatile java.io.PrintStream warnStream

Strems for messages and warnings, or null to disable.

spewMouseMoves

public volatile boolean spewMouseMoves

Whether to output lots of debug messages for mousemove events.

spewStackTraces

public volatile boolean spewStackTraces

Whether to dump stack traces on server errors.

imageClients

protected volatile int imageClients

Number of clients to which we're currently serving images.

oneClient

protected volatile boolean oneClient

Whether to limit serving images to one client.

server

protected final com.sun.net.httpserver.HttpServer server

The internal server object.

executor

protected final java.util.concurrent.ExecutorService executor

The internal transaction executor.

Constructor Detail

ImageServer

public ImageServer(int port)
            throws java.io.IOException

Creates server.

You may configure public fields before calling start().

Parameters:

port - the TCP listen port

Throws:

java.io.IOException

ImageServer

public ImageServer()
            throws java.io.IOException

Creates server using DEF_PORT.

Throws:

java.io.IOException

Method Detail

handleExchange

protected void handleExchange(com.sun.net.httpserver.HttpExchange xch)
                       throws java.io.IOException

Dispatches HTTP exchange to one of the handle*(ExchangeState) methods.

Throws:

java.io.IOException

handleEcho

protected void handleEcho(ImageServer.ExchangeState xs)
                   throws java.io.IOException

Serves debug echo info.

Throws:

java.io.IOException

handleServer

protected void handleServer(ImageServer.ExchangeState xs)
                     throws java.io.IOException

Serves SERVER_HTML using getServerHTML().

Throws:

java.io.IOException

getServerHTML

protected java.io.InputStream getServerHTML()
                                     throws java.io.IOException

Hook to get the html the server sends to the client.

Default impl uses getResourceAsStream() to open and return SERVER_HTML.

Throws:

java.io.IOException

handleImage

protected void handleImage(ImageServer.ExchangeState xs)
                    throws java.lang.Exception

Serves images.

Throws:

java.lang.Exception

updateImage

protected java.awt.image.BufferedImage updateImage(java.awt.image.BufferedImage bi)

Hook called to update the server image.

Parameters:

bi - the prior image, if any, else null

Returns:

the new image, if any, else null

Will be called by a server exchange handling thread while synchronized on this ImageServer instance.

Default impl does nothing. Subclasses can override this to provide images. To avoid creating a lot of memory garbage it is recommended to create the image once and then to update it in place on subsequent frames.

handleMouse

protected void handleMouse(ImageServer.ExchangeState xs)

Handles mouse event requests.

Parses the event parameters and then calls handleMouse(int, int, int, int) which can be overridden as desired.

handleMouse

protected void handleMouse(int t,
                           int x,
                           int y,
                           int m)

Hook to handle mouse events.

Parameters:

t - one of the EVENT_* constants

x - the x pixel coordinate of the mouse event

y - the y pixel coordinate of the mouse event

m - bitmask of the EVENT_FLAG_* constants

This is called when the client notifies the server that a mouse event has occured over the image.

Default impl does nothing. Subclasses can override this to take action on mouse events over the client image.

handleKey

protected void handleKey(ImageServer.ExchangeState xs)

Handles key event requests.

Parses the event parameters and then calls handleKey(char) which can be overridden as desired.

handleKey

protected void handleKey(char c)

Hook to handle key events.

Parameters:

c - the key character

This is called when the client notifies the server that a key event has occured over the image.

Default impl does nothing. Subclasses can override this to take action on key events over the client image.

handleUnknown

protected void handleUnknown(ImageServer.ExchangeState xs)
                      throws java.io.IOException

Handles unknown request paths.

Throws:

java.io.IOException

nowMS

protected static long nowMS()

Returns current time in milliseconds.

msg

protected void msg(java.lang.String m)

Display a message to msgStream, if any.

warn

protected void warn(java.lang.String m)

Display a warning to warnStream, if any.

start

public void start()
           throws java.io.IOException

Starts server.

Throws:

java.io.IOException

stop

public void stop(int delay)

Stops server and executor.

Parameters:

delay - seconds to wait for any ongoing exchanges to finish

Call this to bring the server down.

stop

public void stop()

stop(int) delaying DEF_STOP_SEC.

getServerIPs

public static java.net.InetAddress[] getServerIPs()
                                           throws java.io.IOException

Get the server's non-local IP address(es).

Throws:

java.io.IOException

main

public static void main(java.lang.String[] argv)
                 throws java.io.IOException

Starts a test server.

Parameters:

argv - up to one arg is accepted giving the TCP listen port

Serves synthetic images marked with their frame number.

Throws:

java.io.IOException