linux-capture: Add helper to get xcb screen

Add a helper function to get a xcb screen from a screen id.

plugins/linux-capture/xhelpers.c

@@ -188,3 +188,15 @@ void xshm_xcb_detach(xcb_shm_t *shm)
 	bfree(shm);
 }
 
+xcb_screen_t *xcb_get_screen(xcb_connection_t *xcb, int screen)
+{
+	xcb_screen_iterator_t iter;
+
+	iter = xcb_setup_roots_iterator(xcb_get_setup(xcb));
+	for (; iter.rem; --screen, xcb_screen_next(&iter)) {
+		if (screen == 0)
+			return iter.data;
+	}
+
+	return NULL;
+}

plugins/linux-capture/xhelpers.h

@@ -24,6 +24,7 @@ extern "C" {
 #include <X11/Xlib.h>
 #include <X11/extensions/XShm.h>
 #include <xcb/shm.h>
+#include <xcb/xproto.h>
 #include <obs.h>
 
 typedef struct {
@@ -120,6 +121,15 @@ xcb_shm_t *xshm_xcb_attach(xcb_connection_t *xcb, const int w, const int h);
  */
 void xshm_xcb_detach(xcb_shm_t *shm);
 
+/**
+ * Get screen by id for a xcb connection
+ *
+ * @param xcb xcb connection
+ * @param screen id of the screen
+ * @return screen info structure
+ */
+xcb_screen_t *xcb_get_screen(xcb_connection_t *xcb, int screen);
+
 #ifdef __cplusplus
 }
 #endif