[cairo] cairo-trace error

Jennifer Adams jma at cola.iges.org
Fri May 31 09:02:12 PDT 2013

Dear Experts,
I would like to create a trace file in order to do some debugging. I am using cairo 1.12.8 on a mac running OS X 10.7.5. My sample C program (xopen.c, copied below) is supposed to open an X window and fill it with a red rectangle. I am invoking cairo-trace without any options. Here is the error output:

# ~/supplibs/src/cairo/bin/cairo-trace ./xopen
calling cairo_xlib_surface_create...
Assertion failed: (cairo_xlib_surface_create_real != NULL), function cairo_xlib_surface_create, file trace.c, line 4737.

No window pops up. After a pause, this second error message appears:

/Users/jma/supplibs/src/cairo/bin/cairo-trace: line 136: 33085 Abort trap: 6           (core dumped) CAIRO_TRACE_OUTDIR=`pwd` "$@"

The program does compile and run, except the rectangle drawn is not red, it is white. This is the problem I need to debug. 
Please help! I have run out of ideas. 
--Jennifer Adams

p.s. Here is my program:

#include <stdio.h>
#include <stdlib.h>
#include <cairo.h>
#include <cairo-xlib.h>

static void handle_events(Display *);

static Window win;
static Visual *visual;
static KeyCode quit;

int main () {
  Display *display = (Display *)NULL; 
  cairo_surface_t *surface;
  cairo_t *cr;
  int snum;

  /* Connect to X server */
  display = XOpenDisplay(0);
  /* Create window, size is 500x500 */
  snum = DefaultScreen(display);
  win = XCreateSimpleWindow(display, RootWindow(display,snum),
			    100, 0, 500, 500, 4,
			    BlackPixel(display,snum), WhitePixel(display,snum));

  /* Set event type 'Q' for quit */
  quit = XKeysymToKeycode(display, XStringToKeysym("Q"));
  XSelectInput(display, win, KeyPressMask|StructureNotifyMask|ExposureMask);
  /* Display Window */
  XMapWindow(display, win);

  /* open a cairo surface in the window */
  visual = DefaultVisual(display,snum);
  printf("calling cairo_xlib_surface_create...\n");
  surface = cairo_xlib_surface_create (display, win, visual, 500, 500);
  cr = cairo_create(surface);

  /* fill red background */

  /* clean up the window */
  cairo_surface_finish (surface);
  cairo_surface_destroy (surface);

  return 0;

static void handle_events(Display *display) {
  XEvent xev;
  while (1) {
    XNextEvent(display, &xev);
    switch(xev.type) {
    case KeyPress:
	XKeyEvent *kev = &xev.xkey;
	if (kev->keycode == quit) return;

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