WM: resolve transform triggering key-maps to be rebuilt

Since [0] modal transform in the 3D viewport caused key-maps to be
rebuilt by the event system. Creating a temporary copy for
ViewOpsData_Utility flagged the key-map as outdated.

This could crash (resolved by [1] - for the most-part), but would still
rebuild the whole key-map, adding unnecessary overhead.

This would also reset the KMI_EXPANDED flag, causing transform
to hide key-map items when using Blender with the key-map editor open.

Add a function to temporarily suppress key-map updates.
While not ideal, full support for temporary key-maps that behave
differently to user key-maps is a bigger project for something
that's only needed in one place.

[0]: 017d4912b2
[1]: 9a0eaa2062

source/blender/editors/space_view3d/view3d_navigate.cc

@@ -412,6 +412,9 @@ struct ViewOpsData_Utility : ViewOpsData {
 
     wmKeyMap *keymap = WM_keymap_find_all(
         CTX_wm_manager(C), "3D View", SPACE_VIEW3D, RGN_TYPE_WINDOW);
+
+    WM_keyconfig_update_suppress_begin();
+
     wmKeyMap keymap_tmp = {};
 
     LISTBASE_FOREACH (wmKeyMapItem *, kmi, &keymap->items) {
@@ -433,14 +436,20 @@ struct ViewOpsData_Utility : ViewOpsData {
 
     /* Weak, but only the keymap items from the #wmKeyMap struct are needed here. */
     this->keymap_items = keymap_tmp.items;
+
+    WM_keyconfig_update_suppress_end();
   }
 
   ~ViewOpsData_Utility()
   {
     /* Weak, but rebuild the struct #wmKeyMap to clear the keymap items. */
+    WM_keyconfig_update_suppress_begin();
+
     wmKeyMap keymap_tmp = {};
     keymap_tmp.items = this->keymap_items;
     WM_keymap_clear(&keymap_tmp);
+
+    WM_keyconfig_update_suppress_end();
   }
 
 #ifdef WITH_CXX_GUARDEDALLOC

source/blender/windowmanager/WM_keymap.hh

@@ -31,6 +31,9 @@ void WM_keyconfig_update(wmWindowManager *wm);
 void WM_keyconfig_update_tag(wmKeyMap *keymap, wmKeyMapItem *kmi);
 void WM_keyconfig_update_operatortype();
 
+void WM_keyconfig_update_suppress_begin();
+void WM_keyconfig_update_suppress_end();
+
 /* Keymap */
 
 /** Parameters for matching events, passed into functions that create key-map items. */

source/blender/windowmanager/intern/wm_keymap.cc

@@ -1795,6 +1795,11 @@ enum {
 
 static char wm_keymap_update_flag = 0;
 
+static char wm_keymap_update_suppress_flag = 0;
+#ifndef NDEBUG
+static int8_t wm_keymap_update_suppress_count = 0;
+#endif
+
 void WM_keyconfig_update_tag(wmKeyMap *keymap, wmKeyMapItem *kmi)
 {
   /* quick tag to do delayed keymap updates */
@@ -1813,6 +1818,33 @@ void WM_keyconfig_update_operatortype()
   wm_keymap_update_flag |= WM_KEYMAP_UPDATE_OPERATORTYPE;
 }
 
+/* NOTE(@ideasman42): regarding suppressing updates.
+ * If this becomes a common operation it would be better use something more general,
+ * a key-map flag for e.g. to signify that the key-map is stored outside of a #wmKeyConfig
+ * and should not receive updates on modification. At the moment this has the down-side of
+ * needing to be supported in quite a few places for something which isn't used much.
+ * Since the use case for this is limited, add functions to begin/end suppression.
+ * If these end up being used a lot we can consider alternatives. */
+
+void WM_keyconfig_update_suppress_begin()
+{
+#ifndef NDEBUG
+  BLI_assert(wm_keymap_update_suppress_count == 0);
+  wm_keymap_update_suppress_count += 1;
+#endif
+  wm_keymap_update_suppress_flag = wm_keymap_update_flag;
+}
+
+void WM_keyconfig_update_suppress_end()
+{
+#ifndef NDEBUG
+  BLI_assert(wm_keymap_update_suppress_count == 1);
+  wm_keymap_update_suppress_count -= 1;
+#endif
+  wm_keymap_update_flag = wm_keymap_update_suppress_flag;
+  wm_keymap_update_suppress_flag = 0;
+}
+
 static bool wm_keymap_test_and_clear_update(wmKeyMap *km)
 {
   int update = (km->flag & KEYMAP_UPDATE);