X11TerminalStream

X11TerminalStream Class

X11TerminalStream objects and methods handle input events from X Window System displays. Ctalk’s X11 support focuses on the windows themselves, so this class should almost always be used with a X11Pane object. See X11Pane.

Here is an example program that uses InputEvent objects created by the window’s input stream, xPane, to configure the dimensions of the pane’s window. The X11TerminalStream object is contained in the X11Pane’s inputStream instance variable.

int main () {

  X11Pane new xPane;
  InputEvent new e;

  xPane initialize 25, 30, 100, 100;
  xPane map;
  xPane raiseWindow;
  xPane openEventStream;

  WriteFileStream classInit;

  while (TRUE) {
    xPane inputStream queueInput;
    if (xPane inputStream eventPending) {
      e become xPane inputStream inputQueue unshift;
      switch (e eventClass value) 
	{
	case CONFIGURENOTIFY:
	  stdoutStream printOn "ConfigureNotify\t%d\t%d\t%d\t%d\n",
	    e xEventData1, 
	    e xEventData2, 
	    e xEventData3, 
	    e xEventData4;
	  stdoutStream printOn "Window\t\t%d\t%d\t%d\t%d\n",
	    xPane origin x, 
	    xPane origin y, 
	    xPane size x,
	    xPane size y;
	  break;
	case WINDELETE:
	  xPane deleteAndClose;
	  exit (0);
	  break;
	default:
	  break;
	}
    }
  }
}

When compiling this program, you might also need to add the directory that contains the X include files to the include search path. For example:

$ ctcc -I /usr/include/X11 windemo.c -o windemo       # Recent Linux

Ctalk’s libraries are linked with the system’s X libraries during installation if they are present, but applications may also need to link with X libraries directly in some cases.

Event Classes

A X11TerminalStream object recognizes the following input event classes, and returns the following information in the xEventData instance variables, which are defined in InputEvent class. See InputEvent.

Event Class     xEventData1 xEventData2 xEventData3 xEventData4 xEventData5 xEventData6
BUTTONPRESS     x           y           state       button      root_x      root_y
BUTTONRELEASE   x           y           state       button      root_x      root_y
KEYPRESS        x           y           state       keycode     x_keycode[1]
KEYRELEASE      x           y           state       keycode     x_keycode[1]
CONFIGURENOTIFY x           y           height      width       border
MOVENOTIFY      x           y           height      width       border
RESIZENOTIFY    x           y           height      width       border
MOTIONNOTIFY    x           y           state       is_hint     -
MAPNOTIFY       event       window      -           -           -
EXPOSE          x           y           width       height      count
SELECTIONREQUEST -          -           -           -           -
SELECTIONCLEAR  -           -           -           -           -
WINDELETE       -           -           -           -           -

[1] The values of X keycodes are defined in X11/keysymdefs.h.

The x and y coordinates of the key and button events are relative to the window’s origin. The x and y coordinates of a CONFIGURENOTIFY event are relative to the origin of the root window, normally the upper left-hand corner of the display.

The MOVENOTIFY and RESIZENOTIFY events are both derived from CONFIGURENOTIFY events, depending on whether the receiver’s window was moved or resized.

Instance Variables

inputPID

The process ID of the X11TerminalStream event handler.

clientFD

The file descriptor that the X11TerminalStream event handler uses when communicating with the main window’s process.

eventMask

An Integer that contains the OR’d values of the window system events that the program wants to be notified of. The window system events are listed in the table above. If eventMask's value is zero, then the event handler assumes that the program wants to receiver all window system events. Any non-zero value, however, causes the program to receive only those events; for example:

myMainWindow inputStream eventMask = WINDELETE|KEYPRESS;

In this case the program only receives notice of key presses (KEYPRESS events) and requests from the GUI desktop to close the window (WINDELETE events) and exit the program.

Instance Methods

openInputClient (void)

Open the X input handler. This method is normally used by X11Pane class’s openEventStream method. See X11Pane.

parentPane (void)

Return the receiver’s X11Pane parent object if present.

queueInput (void)

Queue window system events as InputEvent objects in the receiver’s inputQueue instance variable. The inputQueue instance variable is inherited from TerminalStream class. See TerminalStream.