workwin.c

This source code has been tested under OpenWindows 2.0, Sun s X11/NeWS server. For Xlib programs th

/***********************************************************************
**                                                                    **
**  workwin.c                                                         **
**                                                                    **
**  Doodle -- Work Window Module                                      **
**                                                                    **
***********************************************************************/


#include <Xm/DrawingA.h>

#include "doodle.h"


/***********************************************************************
**                                                                    **
**               F O R W A R D   D E F I N I T I O N S                **
**                                                                    **
***********************************************************************/

static	void	InitGC();
static	void	DrawEvt();



/***********************************************************************
**                                                                    **
**                    L O C A L   V A R I A B L E S                   **
**                                                                    **
***********************************************************************/

static	GC	    the_gc;		/* Current GC for drawing     */
static	XGCValues   gc_values;		/* Values for allocating GCs  */
static	XtGCMask    gc_mask;		/* Mask for allocating GCs    */
static	int	    last_x, last_y;	/* Last pointer position      */



/***********************************************************************
**                                                                    **
**  InitWorkWindow()                                                  **
**                                                                    **
**  This function creates the drawing area used as the work window.   **
**  It also allocates the initial (default) GC for drawing in that    **
**  window, and attaches callbacks and event handlers.                **
**                                                                    **
***********************************************************************/

void InitWorkWindow()
{
    workwin = XmCreateDrawingArea( mainwin, "WorkWin", NULL, 0 );
    XtManageChild( workwin );

    InitGC();

    XtAddEventHandler( workwin, (ButtonPressMask | ButtonMotionMask),
                                FALSE, DrawEvt, NULL );
}



/***********************************************************************
**                                                                    **
**  InitGC()                                                          **
**                                                                    **
**  Initializes the graphics context used for drawing. This function  **
**  stores default values in the variable "gc_values", which is used  **
**  to tell the server about the GC we want. It also sets bits in     **
**  "gc_mask", which is used to tell the server what values we have   **
**  set. Finally, it gets the work window's color scheme, sets the    **
**  line width to 1, and allocates a GC.                              **
**                                                                    **
***********************************************************************/

static void InitGC()
{
    Pixel	foreground,
		background;

    XtSetArg( arglist[0], XmNforeground, &foreground );
    XtSetArg( arglist[1], XmNbackground, &background );
    XtGetValues( workwin, arglist, 2 );

    gc_values.foreground = foreground;
    gc_values.background = background;
    gc_values.line_width = 1;
    gc_values.line_style = LineSolid;
    gc_values.cap_style  = CapRound;
    gc_values.join_style = JoinRound;

    gc_mask = GCForeground | GCBackground | GCLineWidth |
              GCLineStyle  | GCCapStyle   | GCJoinStyle;

    the_gc = XtGetGC( workwin, gc_mask, &gc_values );
}



/***********************************************************************
**                                                                    **
**  DrawEvt( w, client_data, event )                                  **
**                                                                    **
**  This function is attached to button-press and button-motion       **
**  events. On button press, it initializes the stored position       **
**  variables. On buttton-motion, it draws a line from the stored     **
**  position to the new position, then stores the new position.       **
**                                                                    **
***********************************************************************/

static void DrawEvt( w, client_data, event )
    Widget	w;
    caddr_t	client_data;
    XEvent	*event;
{
    int		new_x, new_y;

    switch (event->type)
        {
	case ButtonPress :
		last_x = event->xbutton.x;
		last_y = event->xbutton.y;
		break;
	case MotionNotify :
		new_x = event->xmotion.x;
		new_y = event->xmotion.y;
		XDrawLine( XtDisplay(w), XtWindow(w), the_gc,
			   last_x, last_y, new_x, new_y );
		last_x = new_x;
		last_y = new_y;
		break;
	default :
		break;
	}
}



/***********************************************************************
**                                                                    **
**  ClearWin()                                                        **
**                                                                    **
**  This function clears the work window. It is attached to the       **
**  File/New menu choice.                                             **
**                                                                    **
***********************************************************************/

void ClearWin()
{
    XClearWindow( XtDisplay(workwin), XtWindow(workwin) );
}



/***********************************************************************
**                                                                    **
**  PenColorCB( w, client_data, call_data )                           **
**                                                                    **
**  This function is attached to each of the buttons in the Pen       **
**  menu's Color submenu. It takes the foreground color from the      **
**  invoking button, and allocates a GC using that color.             **
**                                                                    **
***********************************************************************/

void PenColorCB( w, client_data, call_data )
    Widget	w;
    caddr_t	client_data;
    caddr_t	call_data;
{
    Pixel	new_color;

    XtReleaseGC( workwin, the_gc );

    XtSetArg( arglist[0], XmNbackground, &new_color );
    XtGetValues( w, arglist, 1 );

    gc_values.foreground = new_color;
    the_gc = XtGetGC( workwin, gc_mask, &gc_values );
}



/***********************************************************************
**                                                                    **
**  PenSizeCB( w, client_data, call_data )                            **
**                                                                    **
**  This function is attached to each of the buttons in the Pen       **
**  menu's Size submenu. It is passed a string as its client data,    **
**  which specifies the new pen width. It then allocates a GC         **
**  that uses that width.                                             **
**                                                                    **
**  Note: A more elegant approach to line widths would use the        **
**        button's labelString resource to specify the width.         **
**                                                                    **
***********************************************************************/

void PenSizeCB( w, client_data, call_data )
    Widget	w;
    char	*client_data;
    caddr_t	call_data;
{
    XtReleaseGC( workwin, the_gc );

    if (!strcmp(client_data, "1"))
        gc_values.line_width = 1;
    else if (!strcmp(client_data, "2"))
        gc_values.line_width = 2;
    else if (!strcmp(client_data, "3"))
        gc_values.line_width = 3;
    else if (!strcmp(client_data, "4"))
        gc_values.line_width = 4;
    else if (!strcmp(client_data, "8"))
        gc_values.line_width = 8;

    the_gc = XtGetGC( workwin, gc_mask, &gc_values );
}