From b9718299ea509df2a3d563f0ac2639f01cad39ab Mon Sep 17 00:00:00 2001
From: Campbell Barton <ideasman42@gmail.com>
Date: Tue, 30 Jul 2019 21:40:42 +1000
Subject: Fix crash clicking in the 3D view on startup

Setting the 3D view cursor on startup could crash because the
viewport hasn't been assigned to the region.
---
 source/blender/windowmanager/WM_api.h         |  4 +++
 source/blender/windowmanager/intern/wm_draw.c | 35 ++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

(limited to 'source/blender/windowmanager')

diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index 04e3f7e88dc..fdf65d857fc 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -741,6 +741,10 @@ void *WM_draw_cb_activate(struct wmWindow *win,
 void WM_draw_cb_exit(struct wmWindow *win, void *handle);
 void WM_redraw_windows(struct bContext *C);
 
+void WM_draw_region_viewport_ensure(struct ARegion *ar, short space_type);
+void WM_draw_region_viewport_bind(struct ARegion *ar);
+void WM_draw_region_viewport_unbind(struct ARegion *ar);
+
 /* Region drawing */
 void WM_draw_region_free(struct ARegion *ar);
 struct GPUViewport *WM_draw_region_get_viewport(struct ARegion *ar, int view);
diff --git a/source/blender/windowmanager/intern/wm_draw.c b/source/blender/windowmanager/intern/wm_draw.c
index fc669c9543e..3bcb955c2b2 100644
--- a/source/blender/windowmanager/intern/wm_draw.c
+++ b/source/blender/windowmanager/intern/wm_draw.c
@@ -239,9 +239,14 @@ static void wm_region_test_render_do_draw(const Scene *scene,
   }
 }
 
+static bool wm_region_use_viewport_by_type(short space_type, short region_type)
+{
+  return (ELEM(space_type, SPACE_VIEW3D, SPACE_IMAGE) && region_type == RGN_TYPE_WINDOW);
+}
+
 static bool wm_region_use_viewport(ScrArea *sa, ARegion *ar)
 {
-  return (ELEM(sa->spacetype, SPACE_VIEW3D, SPACE_IMAGE) && ar->regiontype == RGN_TYPE_WINDOW);
+  return wm_region_use_viewport_by_type(sa->spacetype, ar->regiontype);
 }
 
 /********************** draw all **************************/
@@ -976,3 +981,31 @@ void WM_redraw_windows(bContext *C)
   CTX_wm_area_set(C, area_prev);
   CTX_wm_region_set(C, ar_prev);
 }
+
+/* -------------------------------------------------------------------- */
+/** \name Region Viewport Drawing
+ *
+ * This is needed for viewport drawing for operator use
+ * (where the viewport may not have drawn yet).
+ *
+ * Otherwise avoid using these sine they're exposing low level logic externally.
+ *
+ * \{ */
+
+void WM_draw_region_viewport_ensure(ARegion *ar, short space_type)
+{
+  bool use_viewport = wm_region_use_viewport_by_type(space_type, ar->regiontype);
+  wm_draw_region_buffer_create(ar, false, use_viewport);
+}
+
+void WM_draw_region_viewport_bind(ARegion *ar)
+{
+  wm_draw_region_bind(ar, 0);
+}
+
+void WM_draw_region_viewport_unbind(ARegion *ar)
+{
+  wm_draw_region_unbind(ar, 0);
+}
+
+/** \} */
-- 
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