Fix incorrect drag-event threshold when releasing modifiers early

db4313610cab18933c1b1b1348720ea241b9d91e added support for modifier
keys to be released while dragging.

The key release events set wmEvent.prev_type which is used select the
drag threshold, causing the wrong threshold to be used.

Add wmEvent.prev_click_type which is only set when the drag begins.

3 files changed, 14 insertions, 11 deletions

diff --git a/source/blender/windowmanager/WM_types.h b/source/blender/windowmanager/WM_types.h
index cdbaa2739ba..26462402e3d 100644
--- a/source/blender/windowmanager/WM_types.h
+++ b/source/blender/windowmanager/WM_types.h
@@ -636,6 +636,15 @@ typedef struct wmEvent {
   short prev_type;
   /** The previous value of `val`. */
   short prev_val;
+  /**
+   * The previous value of #wmEvent.xy,
+   * Unlike other previous state variables, this is set on any mouse motion.
+   * Use `prev_click` for the value at time of pressing.
+   */
+  int prev_xy[2];
+
+  /** The `type` at the point of the click action. */
+  short prev_click_type;
   /** The time when the key is pressed, see #PIL_check_seconds_timer. */
   double prev_click_time;
   /** The location when the key is pressed (used to enforce drag thresholds). */
@@ -646,13 +655,6 @@ typedef struct wmEvent {
   short prev_click_keymodifier;
 
   /**
-   * The previous value of #wmEvent.xy,
-   * Unlike other previous state variables, this is set on any mouse motion.
-   * Use `prev_click` for the value at time of pressing.
-   */
-  int prev_xy[2];
-
-  /**
    * Modifier states.
    * #KM_SHIFT, #KM_CTRL, #KM_ALT & #KM_OSKEY is apple or windows-key.
    */
diff --git a/source/blender/windowmanager/intern/wm_event_query.c b/source/blender/windowmanager/intern/wm_event_query.c
index 0d42d0a44c7..5e8b9b945c9 100644
--- a/source/blender/windowmanager/intern/wm_event_query.c
+++ b/source/blender/windowmanager/intern/wm_event_query.c
@@ -260,8 +260,8 @@ bool WM_cursor_test_motion_and_update(const int mval[2])
 int WM_event_drag_threshold(const struct wmEvent *event)
 {
   int drag_threshold;
-  if (ISMOUSE(event->prev_type)) {
-    BLI_assert(event->prev_type != MOUSEMOVE);
+  if (ISMOUSE(event->prev_click_type)) {
+    BLI_assert(event->prev_click_type != MOUSEMOVE);
     /* Using the previous type is important is we want to check the last pressed/released button,
      * The `event->type` would include #MOUSEMOVE which is always the case when dragging
      * and does not help us know which threshold to use. */
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index 4e9a430b380..ee07e90f4de 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -4705,10 +4705,11 @@ static void wm_event_prev_values_set(wmEvent *event, wmEvent *event_state)
 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_type = event_state->prev_click_type = event_state->type;
   event->prev_click_modifier = event_state->prev_click_modifier = event_state->modifier;
   event->prev_click_keymodifier = event_state->prev_click_keymodifier = event_state->keymodifier;
+  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];
 }
 
 static wmEvent *wm_event_add_mousemove(wmWindow *win, const wmEvent *event)