ado@elsie.UUCP (Arthur David Olson) (10/24/89)
I'm surprised that in the attached code, the X Server is giving me
expose events with x and y values of 100 for a 100x100 window--
but only if backing store is enabled.
If you can tell me what I've done wrong, I'd appreciate hearing from you
by electronic mail.
--
Arthur David Olson ado@alw.nih.gov ADO is a trademark of Ampex.
Script started on Mon Oct 23 13:02:09 1989
elsie$ cat try.c
#include <stdio.h>
#include <X11/Xlib.h>
Display * display;
int screen_number;
GC gc;
Window root;
Window first;
Window second;
XEvent xe;
static void
await_event(type, desc)
char * desc;
{
XSync(display, 0);
do {
XNextEvent(display, &xe);
(void) printf("got event type %d\n", xe.type);
} while (xe.type != type);
}
int
main(argc, argv)
int argc;
char * argv[];
{
XSetWindowAttributes xswa;
XExposeEvent * xeep;
xeep = (XExposeEvent *) &xe;
if (argc != 2)
return 1;
if (argv[1][0] == 'a' || argv[1][0] == 'A')
xswa.backing_store = Always;
else if (argv[1][0] == 'n' || argv[1][0] == 'N')
xswa.backing_store = NotUseful;
else if (argv[1][0] == 'w' || argv[1][0] == 'W')
xswa.backing_store = WhenMapped;
else return 1;
display = XOpenDisplay((char *) NULL);
screen_number = DefaultScreen(display);
gc = DefaultGC(display, screen_number);
root = DefaultRootWindow(display);
first = XCreateSimpleWindow(display, root,
1, 1, 100, 100, 1, 1, 0);
XSelectInput(display, first, ExposureMask);
XChangeWindowAttributes(display, first, CWBackingStore, &xswa);
XMapWindow(display, first);
await_event(Expose, "Expose");
second = XCreateSimpleWindow(display, first,
26, 26, 50, 50, 1, 1, 0);
XSelectInput(display, second, ExposureMask);
XMapWindow(display, second);
await_event(Expose, "Expose");
XFillRectangle(display, first, gc, 0, 0, 100, 100);
XSync(display, 0);
/*
** So much for preamble.
*/
XCopyArea(display, first, first, gc, 10, 20, 100, 100, 0, 0);
for ( ; ; ) {
await_event(GraphicsExpose, "GraphicsExpose");
(void) printf("x\t%d\ty\t%d\twidth\t%d\theight\t%d\n",
xeep->x, xeep->y, xeep->width, xeep->height);
}
}
elsie$ cc try.c -lX11 -o try
elsie$ try n
got event type 12
got event type 12
got event type 13
x 90 y 0 width 10 height 6
got event type 13
x 16 y 6 width 52 height 20
got event type 13
x 90 y 6 width 10 height 20
got event type 13
x 16 y 26 width 10 height 32
got event type 13
x 90 y 26 width 10 height 32
got event type 13
x 90 y 58 width 10 height 22
got event type 13
x 0 y 80 width 100 height 20
^Celsie$ try a
got event type 12
got event type 12
got event type 13
>>>>> x 100 y 20 width 10 height 80
got event type 13
>>>>> x 10 y 100 width 100 height 20
^Celsie$ exit
script done on Mon Oct 23 13:03:06 1989