Event System: drag events now use modifier state on drag start

Now drag & tweak can have modifier keys to be released while dragging.
without this, modifier keys needs to be held which is more noticeable
for tablet input or whenever the drag threshold is set to a large value.

Resolves T89989.

1 files changed, 24 insertions, 7 deletions

diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index 326b8c167b8..6753978eece 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -3161,21 +3161,27 @@ static int wm_handlers_do(bContext *C, wmEvent *event, ListBase *handlers)
         if (WM_event_drag_test(event, event->prev_click_xy)) {
           win->event_queue_check_drag_handled = true;
 
-          int xy[2] = {UNPACK2(event->xy)};
-          short val = event->val;
-          short type = event->type;
+          const int prev_xy[2] = {UNPACK2(event->xy)};
+          const short prev_val = event->val;
+          const short prev_type = event->type;
+          const uint8_t prev_modifier = event->modifier;
+          const short prev_keymodifier = event->keymodifier;
 
           copy_v2_v2_int(event->xy, event->prev_click_xy);
           event->val = KM_CLICK_DRAG;
           event->type = event->prev_type;
+          event->modifier = event->prev_click_modifier;
+          event->keymodifier = event->prev_click_keymodifier;
 
           CLOG_INFO(WM_LOG_HANDLERS, 1, "handling PRESS_DRAG");
 
           action |= wm_handlers_do_intern(C, win, event, handlers);
 
-          event->val = val;
-          event->type = type;
-          copy_v2_v2_int(event->xy, xy);
+          event->keymodifier = prev_keymodifier;
+          event->modifier = prev_modifier;
+          event->val = prev_val;
+          event->type = prev_type;
+          copy_v2_v2_int(event->xy, prev_xy);
 
           win->event_queue_check_click = false;
           if (!wm_action_not_handled(action)) {
@@ -3205,7 +3211,16 @@ static int wm_handlers_do(bContext *C, wmEvent *event, ListBase *handlers)
         }
       }
       else if (event->val == KM_RELEASE) {
-        win->event_queue_check_drag = false;
+        if (win->event_queue_check_drag) {
+          if ((event->prev_type != event->type) &&
+              (ISKEYMODIFIER(event->type) || (event->type == event->prev_click_keymodifier))) {
+            /* Support releasing modifier keys without canceling the drag event, see T89989.
+             * NOTE: this logic is replicated for tweak gestures. */
+          }
+          else {
+            win->event_queue_check_drag = false;
+          }
+        }
       }
 
       if (event->prev_type == event->type) {
@@ -4692,6 +4707,8 @@ static void wm_event_prev_click_set(wmEvent *event, wmEvent *event_state)
   event->prev_click_time = event_state->prev_click_time = PIL_check_seconds_timer();
   event->prev_click_xy[0] = event_state->prev_click_xy[0] = event_state->xy[0];
   event->prev_click_xy[1] = event_state->prev_click_xy[1] = event_state->xy[1];
+  event->prev_click_modifier = event_state->prev_click_modifier = event_state->modifier;
+  event->prev_click_keymodifier = event_state->prev_click_keymodifier = event_state->keymodifier;
 }
 
 static wmEvent *wm_event_add_mousemove(wmWindow *win, const wmEvent *event)