From cf6c11cfaa6be44a2ba69f814dc1a022e84e37c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20=C3=85dahl?= <jadahl@gmail.com>
Date: Sun, 27 Dec 2015 10:42:45 +0800
Subject: [PATCH] wayland: Only set surface buffer scale when supported

Although very unlikely, the wl_compositor version might not support
wl_surface.set_buffer_scale while the wl_output emits a wl_output.scale
that is larger than 1. So for correctness, bail on changing the buffer
scale if we won't be able to set it later.
---
 src/wl_init.c     | 3 ++-
 src/wl_platform.h | 2 ++
 src/wl_window.c   | 5 +++++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/wl_init.c b/src/wl_init.c
index cceef16b..90dc507b 100644
--- a/src/wl_init.c
+++ b/src/wl_init.c
@@ -385,9 +385,10 @@ static void registryHandleGlobal(void* data,
 {
     if (strcmp(interface, "wl_compositor") == 0)
     {
+        _glfw.wl.wl_compositor_version = min(3, version);
         _glfw.wl.compositor =
             wl_registry_bind(registry, name, &wl_compositor_interface,
-                             min(3, version));
+                             _glfw.wl.wl_compositor_version);
     }
     else if (strcmp(interface, "wl_shm") == 0)
     {
diff --git a/src/wl_platform.h b/src/wl_platform.h
index a734ec1e..2bfdbb4c 100644
--- a/src/wl_platform.h
+++ b/src/wl_platform.h
@@ -91,6 +91,8 @@ typedef struct _GLFWlibraryWayland
     struct wl_pointer*          pointer;
     struct wl_keyboard*         keyboard;
 
+    int                         wl_compositor_version;
+
     struct wl_cursor_theme*     cursorTheme;
     struct wl_surface*          cursorSurface;
     uint32_t                    pointerSerial;
diff --git a/src/wl_window.c b/src/wl_window.c
index 00ce7135..3a75daa4 100644
--- a/src/wl_window.c
+++ b/src/wl_window.c
@@ -79,6 +79,11 @@ static void checkScaleChange(_GLFWwindow* window)
     int i;
     int monitorScale;
 
+    // Check if we will be able to set the buffer scale or not.
+    if (_glfw.wl.wl_compositor_version <
+        WL_SURFACE_SET_BUFFER_SCALE_SINCE_VERSION)
+        return;
+
     // Get the scale factor from the highest scale monitor.
     for (i = 0; i < window->wl.monitorsCount; ++i)
     {