Re: Bug 50372: Setting stipple to NULL = X error

[Owen Taylor <otaylor redhat com>]

Jamie Strachan <frostfreek yahoo com> writes:

> http://bugzilla.gnome.org/show_bug.cgi?id=50372
> 
> Alright, I have patched this to clear the X GC stipple/tile when a NULL is specified.

Hmmm, a neat trick.

But if we are going this route, wouldn't it be better to simply
do, instead of:

===
  if (copyclear_mask)
    {
      GC temp;
      temp = XCreateGC(GDK_GC_XDISPLAY(gc), GDK_ROOT_WINDOW(), 0, &xvalues);
      g_return_if_fail(temp != NULL);

      /* Copy everything except Null-stipple and/or null-tile */
      XCopyGC(GDK_GC_XDISPLAY(gc), GDK_GC_XGC (gc), ~copyclear_mask, temp);

      /* overwrite the GC with the stipple-less copy... */
      XCopyGC(GDK_GC_XDISPLAY(gc), temp, ~0, GDK_GC_XGC (gc));

      XFreeGC(GDK_GC_XDISPLAY(gc), temp);
      xvalues_mask &= ~copyclear_mask;
  }
=== 

Simply:

===
  if (copyclear_mask)
    {
      GC temp;
      temp = XCreateGC(GDK_GC_XDISPLAY(gc), GDK_ROOT_WINDOW(), 0, &xvalues);

      XCopyGC(GDK_GC_XDISPLAY(gc), temp, copyclear_mask, GDK_GC_XGC(gc));

      XFreeGC(GDK_GC_XDISPLAY(gc), temp);
      xvalues_mask &= ~copyclear_mask;
  }
===

(I'd avoid the g_return_if_fail() here - g_return_if_fail() is
supposed to be used for catching programmer errors. 

Either you should you do nothing/g_assert() if you think the failure
will never ever happen, or you should handle it.

In this case, we assume throughout GDK that calls like XCreateGC
will always succeed.)

Regards,
                                        Owen