Add support for the 'Present' extension. [v3]

This makes updating the eyes nicely vblank synchronized.

v2:
	Ensure extensions exist before calling query_version

	These calls add calls to xcb_get_extension_data before calling
	query_version calls, as those calls will mark the connection
	with an error if made against an X server without the
	extension present.

	Suggested-by: Uli Schlachter <psychon@znc.in>

v3:
	check the 'present' field in the return from
	xcb_get_extension_data; the xcb_get_extension_data call will
	always succeed (save for out of memory), the only way to tell
	if the extension is supported in the target X server is to
	test the 'present' field in the query extension reply value.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/xeyes.c b/xeyes.c
index c2f3a73..1c1f4b7 100644
--- a/xeyes.c
+++ b/xeyes.c
@@ -57,6 +57,10 @@ usage(void)
     fprintf(stderr,
 	    "       [-render | +render]\n");
 #endif
+#ifdef PRESENT
+    fprintf(stderr,
+	    "       [-present | +present]\n");
+#endif
     exit(1);
 }
 
@@ -73,6 +77,10 @@ static XrmOptionDescRec options[] = {
 {"-render",	"*eyes.render",		XrmoptionNoArg,		"TRUE"},
 {"+render",	"*eyes.render",		XrmoptionNoArg,		"FALSE"},
 #endif
+#ifdef PRESENT
+{"-present",	"*eyes.present",	XrmoptionNoArg,		"TRUE"},
+{"+present",	"*eyes.present",	XrmoptionNoArg,		"FALSE"},
+#endif
 {"-distance",	"*eyes.distance",	XrmoptionNoArg,		"TRUE"},
 };