XLIB Programming Manual, Rel. 5, Third Edition

14.9 Processing Events

The routine in Example 14-12 processes events. The top portion of takeEvents converts key events to the corresponding button event, and then the bottom sets the colors and flags and draws the button in the new color. Key codes are mapped to ASCII with XLookupString(), and keyToWin is called to get the offset into windata that is represented by this key. When key events occur, the appropriate pad is flashed.

Example 14-12. basecalc — the takeEvents routine

takeEvents () { XEvent Event; register int win; register int Pressed = False; register int inWindow = False; char buffer[10]; register char *keyChars = buffer; register int keyDown = False; int i, nbytes; while (1) { /* Get event if key not down */ if (!keyDown) XNextEvent (display, &Event); else Event.type = KeyRelease; /* Map keyboard events to window events */ if (Event.type == KeyPress || Event.type == KeyRelease) { nbytes = XLookupString (&Event, buffer, sizeof(buffer), NULL, NULL); if (Event.type == KeyPress) { Event.type = ButtonPress; keyDown = True; } else { for (i=0; i<60000; i++) ; /* Wait */ Event.type = ButtonRelease; } if ((Event.xbutton.window = keyToWin (keyChars, nbytes)) == None){ keyDown = False; continue; } } for (win=0; win < NBUTTONS; win++) if (Buttons[win].ID == Event.xbutton.window) break; switch (Event.type) { case ButtonPress: if (windata[win].color == disabledColor) break; Pressed = win; if (!keyDown) inWindow = True; windata[win].color = pressedColor; drawButton (win, 0); break; ...