libGLX: Add a function to check if a vendor library supports a given screen.

Add a new callback, __GLXvendorCallbacks::checkSupportsScreen to the vendor
library ABI. The callback is used to check if a vendor library can support a
given X screen.

If the vendor library reports that it doesn't support a screen, then libGLX
will use the indirect rendering library instead.

Issue #39.

1 files changed, 6 insertions, 0 deletions

diff --git a/tests/GLX_dummy/GLX_dummy.c b/tests/GLX_dummy/GLX_dummy.c
index a3d6191..c8f2380 100644
--- a/tests/GLX_dummy/GLX_dummy.c
+++ b/tests/GLX_dummy/GLX_dummy.c
@@ -439,6 +439,11 @@ static void dummyNopStub (void)
 }
 
 // XXX non-entry point ABI functions
+static Bool          dummyCheckSupportsScreen    (Display *dpy, int screen)
+{
+    return True;
+}
+
 static void         *dummyGetProcAddress         (const GLubyte *procName)
 {
     int i;
@@ -633,6 +638,7 @@ static const __GLXapiImports dummyImports =
 
     /* Non-entry points */
     .glxvc = {
+        .checkSupportsScreen = dummyCheckSupportsScreen,
         .getProcAddress = dummyGetProcAddress,
         .getDispatchAddress = dummyGetDispatchAddress,
         .setDispatchIndex = dummySetDispatchIndex,