clients & tests: use eglGetPlatformDisplayEXT when supported

Reviewed-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
diff --git a/shared/platform.h b/shared/platform.h
new file mode 100644
index 0000000..7f847fa
--- /dev/null
+++ b/shared/platform.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright © 2015 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef WESTON_PLATFORM_H
+#define WESTON_PLATFORM_H
+
+#include <string.h>
+
+#include <EGL/egl.h>
+#include <EGL/eglext.h>
+
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
+#ifdef EGL_EXT_platform_base
+static PFNEGLGETPLATFORMDISPLAYEXTPROC get_platform_display_ext = NULL;
+
+#ifndef EGL_PLATFORM_WAYLAND_KHR
+#define EGL_PLATFORM_WAYLAND_KHR 0x31D8
+#endif
+#endif /* EGL_EXT_platform_base */
+
+static inline void
+weston_platform_get_egl_proc_addresses(void)
+{
+#ifdef EGL_EXT_platform_base
+	if (!get_platform_display_ext) {
+		const char *extensions = eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
+
+		if (strstr(extensions, "EGL_EXT_platform_wayland")
+		    || strstr(extensions, "EGL_KHR_platform_wayland")) {
+			get_platform_display_ext =
+				(void *) eglGetProcAddress("eglGetPlatformDisplayEXT");
+		}
+	}
+#endif
+}
+
+static inline EGLDisplay
+weston_platform_get_egl_display(EGLenum platform, void *native_display,
+				const EGLint *attrib_list)
+{
+#ifdef EGL_EXT_platform_base
+	if (!get_platform_display_ext)
+		weston_platform_get_egl_proc_addresses();
+
+	if (get_platform_display_ext)
+		return get_platform_display_ext(platform,
+						native_display, attrib_list);
+	else
+#endif
+		return eglGetDisplay((EGLNativeDisplayType) native_display);
+}
+
+#ifdef  __cplusplus
+}
+#endif
+
+#endif /* WESTON_PLATFORM_H */