UI: ignore events in empty region overlap areas

- Resizable areas use 2D view bounds.
- Header uses the button bounds.
- A margin is added to avoid clicking between buttons.
- Region resize edges clamp to the 2D view bounds.

Resovles T61554

source/blender/editors/include/ED_screen.h

@@ -403,6 +403,18 @@ void ED_region_generic_tools_region_message_subscribe(const struct bContext *C,
                                                       struct wmMsgBus *mbus);
 int ED_region_generic_tools_region_snap_size(const struct ARegion *ar, int size, int axis);
 
+/* area_query.c */
+bool ED_region_overlap_isect_x(const ARegion *ar, const int event_x);
+bool ED_region_overlap_isect_y(const ARegion *ar, const int event_y);
+bool ED_region_overlap_isect_xy(const ARegion *ar, const int event_xy[2]);
+bool ED_region_overlap_isect_x_with_margin(const ARegion *ar, const int event_x, const int margin);
+bool ED_region_overlap_isect_y_with_margin(const ARegion *ar, const int event_y, const int margin);
+bool ED_region_overlap_isect_xy_with_margin(const ARegion *ar,
+                                            const int event_xy[2],
+                                            const int margin);
+
+bool ED_region_contains_xy(const struct ARegion *ar, const int event_xy[2]);
+
 /* interface_region_hud.c */
 struct ARegionType *ED_area_type_hud(int space_type);
 void ED_area_type_hud_clear(struct wmWindowManager *wm, ScrArea *sa_keep);

source/blender/editors/include/UI_interface.h

@@ -86,6 +86,14 @@ typedef struct uiPopupBlockHandle uiPopupBlockHandle;
 #define UI_MAX_NAME_STR 128
 #define UI_MAX_SHORTCUT_STR 64
 
+/**
+ * For #ARegion.overlap regions, pass events though if they don't overlap
+ * the regions contents (the usable part of the #View2D and buttons).
+ *
+ * The margin is needed so it's not possible to accidentally click inbetween buttons.
+ */
+#define UI_REGION_OVERLAP_MARGIN (U.widget_unit / 3)
+
 /* use for clamping popups within the screen */
 #define UI_SCREEN_MARGIN 10
 
@@ -2302,6 +2310,7 @@ void UI_context_active_but_prop_get_templateID(struct bContext *C,
 struct ID *UI_context_active_but_get_tab_ID(struct bContext *C);
 
 uiBut *UI_region_active_but_get(struct ARegion *ar);
+uiBut *UI_region_but_find_rect_over(const struct ARegion *ar, const struct rcti *isect);
 
 /* uiFontStyle.align */
 typedef enum eFontStyle_Align {

source/blender/editors/include/UI_view2d.h

@@ -117,6 +117,9 @@ enum eView2D_Gridlines {
 #define IN_2D_VERT_SCROLL(v2d, co) (BLI_rcti_isect_pt_v(&v2d->vert, co))
 #define IN_2D_HORIZ_SCROLL(v2d, co) (BLI_rcti_isect_pt_v(&v2d->hor, co))
 
+#define IN_2D_VERT_SCROLL_RECT(v2d, rct) (BLI_rcti_isect(&v2d->vert, rct, NULL))
+#define IN_2D_HORIZ_SCROLL_RECT(v2d, rct) (BLI_rcti_isect(&v2d->hor, rct, NULL))
+
 /* ------------------------------------------ */
 /* Type definitions:                          */
 
@@ -275,6 +278,13 @@ char UI_view2d_mouse_in_scrollers(const struct ARegion *ar,
                                   const struct View2D *v2d,
                                   int x,
                                   int y);
+char UI_view2d_rect_in_scrollers_ex(const struct ARegion *ar,
+                                    const struct View2D *v2d,
+                                    const struct rcti *rect,
+                                    int *r_scroll);
+char UI_view2d_rect_in_scrollers(const struct ARegion *ar,
+                                 const struct View2D *v2d,
+                                 const struct rcti *rect);
 
 /* cached text drawing in v2d, to allow pixel-aligned draw as post process */
 void UI_view2d_text_cache_add(

source/blender/editors/interface/interface_handlers.c

@@ -7692,6 +7692,11 @@ uiBut *UI_region_active_but_get(ARegion *ar)
   return ui_context_button_active(ar, NULL);
 }
 
+uiBut *UI_region_but_find_rect_over(const ARegion *ar, const rcti *rect_px)
+{
+  return ui_but_find_rect_over(ar, rect_px);
+}
+
 /**
  * Version of #UI_context_active_but_get that also returns RNA property info.
  * Helper function for insert keyframe, reset to default, etc operators.

source/blender/editors/interface/interface_intern.h

@@ -903,6 +903,7 @@ void ui_but_pie_dir(RadialDirection dir, float vec[2]);
 bool ui_but_is_cursor_warp(const uiBut *but) ATTR_WARN_UNUSED_RESULT;
 
 bool ui_but_contains_pt(const uiBut *but, float mx, float my) ATTR_WARN_UNUSED_RESULT;
+bool ui_but_contains_rect(const uiBut *but, const rctf *rect);
 bool ui_but_contains_point_px_icon(const uiBut *but,
                                    struct ARegion *ar,
                                    const struct wmEvent *event) ATTR_WARN_UNUSED_RESULT;
@@ -918,6 +919,8 @@ uiBut *ui_but_find_mouse_over_ex(struct ARegion *ar,
                                  const bool labeledit) ATTR_WARN_UNUSED_RESULT;
 uiBut *ui_but_find_mouse_over(struct ARegion *ar,
                               const struct wmEvent *event) ATTR_WARN_UNUSED_RESULT;
+uiBut *ui_but_find_rect_over(const struct ARegion *ar,
+                             const rcti *rect_px) ATTR_WARN_UNUSED_RESULT;
 
 uiBut *ui_list_find_mouse_over_ex(struct ARegion *ar, int x, int y) ATTR_WARN_UNUSED_RESULT;
 
@@ -936,6 +939,7 @@ bool ui_block_is_popup_any(const uiBlock *block) ATTR_WARN_UNUSED_RESULT;
 uiBut *ui_region_find_first_but_test_flag(struct ARegion *ar, int flag_include, int flag_exclude);
 uiBut *ui_region_find_active_but(struct ARegion *ar) ATTR_WARN_UNUSED_RESULT;
 bool ui_region_contains_point_px(const struct ARegion *ar, int x, int y) ATTR_WARN_UNUSED_RESULT;
+bool ui_region_contains_rect_px(const struct ARegion *ar, const rcti *rect_px);
 
 /* interface_context_menu.c */
 bool ui_popup_context_menu_for_button(struct bContext *C, uiBut *but);

source/blender/editors/interface/interface_query.c

@@ -201,6 +201,11 @@ bool ui_but_contains_pt(const uiBut *but, float mx, float my)
   return BLI_rctf_isect_pt(&but->rect, mx, my);
 }
 
+bool ui_but_contains_rect(const uiBut *but, const rctf *rect)
+{
+  return BLI_rctf_isect(&but->rect, rect, NULL);
+}
+
 bool ui_but_contains_point_px(const uiBut *but, const ARegion *ar, int x, int y)
 {
   uiBlock *block = but->block;
@@ -301,6 +306,44 @@ uiBut *ui_but_find_mouse_over(ARegion *ar, const wmEvent *event)
   return ui_but_find_mouse_over_ex(ar, event->x, event->y, event->ctrl != 0);
 }
 
+uiBut *ui_but_find_rect_over(const struct ARegion *ar, const rcti *rect_px)
+{
+  if (!ui_region_contains_rect_px(ar, rect_px)) {
+    return NULL;
+  }
+
+  /* Currently no need to expose this at the moment. */
+  bool labeledit = true;
+  rctf rect_px_fl;
+  BLI_rctf_rcti_copy(&rect_px_fl, rect_px);
+  uiBut *butover = NULL;
+
+  for (uiBlock *block = ar->uiblocks.first; block; block = block->next) {
+    rctf rect_block;
+    ui_window_to_block_rctf(ar, block, &rect_block, &rect_px_fl);
+
+    for (uiBut *but = block->buttons.last; but; but = but->prev) {
+      if (ui_but_is_interactive(but, labeledit)) {
+        /* No pie menu support. */
+        BLI_assert(but->pie_dir == UI_RADIAL_NONE);
+        if (ui_but_contains_rect(but, &rect_block)) {
+          butover = but;
+          break;
+        }
+      }
+    }
+
+    /* CLIP_EVENTS prevents the event from reaching other blocks */
+    if (block->flag & UI_BLOCK_CLIP_EVENTS) {
+      /* check if mouse is inside block */
+      if (BLI_rctf_isect(&block->rect, &rect_block, NULL)) {
+        break;
+      }
+    }
+  }
+  return butover;
+}
+
 uiBut *ui_list_find_mouse_over_ex(ARegion *ar, int x, int y)
 {
   uiBlock *block;
@@ -485,17 +528,13 @@ uiBut *ui_region_find_first_but_test_flag(ARegion *ar, int flag_include, int fla
 /** \} */
 
 /* -------------------------------------------------------------------- */
-/** \name Region (#ARegion) State
+/** \name Region (#ARegion) Spatial
  * \{ */
 
 bool ui_region_contains_point_px(const ARegion *ar, int x, int y)
 {
   rcti winrct;
-
-  /* scale down area rect to exclude shadow */
   ui_region_winrct_get_no_margin(ar, &winrct);
-
-  /* check if the mouse is in the region */
   if (!BLI_rcti_isect_pt(&winrct, x, y)) {
     return false;
   }
@@ -507,14 +546,9 @@ bool ui_region_contains_point_px(const ARegion *ar, int x, int y)
    */
   if (ar->v2d.mask.xmin != ar->v2d.mask.xmax) {
     const View2D *v2d = &ar->v2d;
-    int mx, my;
+    int mx = x, my = y;
 
-    /* convert window coordinates to region coordinates */
-    mx = x;
-    my = y;
     ui_window_to_region(ar, &mx, &my);
-
-    /* check if in the rect */
     if (!BLI_rcti_isect_pt(&v2d->mask, mx, my) ||
         UI_view2d_mouse_in_scrollers(ar, &ar->v2d, x, y)) {
       return false;
@@ -524,4 +558,26 @@ bool ui_region_contains_point_px(const ARegion *ar, int x, int y)
   return true;
 }
 
+bool ui_region_contains_rect_px(const ARegion *ar, const rcti *rect_px)
+{
+  rcti winrct;
+  ui_region_winrct_get_no_margin(ar, &winrct);
+  if (!BLI_rcti_isect(&winrct, rect_px, NULL)) {
+    return false;
+  }
+
+  /* See comment in 'ui_region_contains_point_px' */
+  if (ar->v2d.mask.xmin != ar->v2d.mask.xmax) {
+    const View2D *v2d = &ar->v2d;
+    rcti rect_region;
+    ui_window_to_region_rcti(ar, &rect_region, rect_px);
+    if (!BLI_rcti_isect(&v2d->mask, &rect_region, NULL) ||
+        UI_view2d_rect_in_scrollers(ar, &ar->v2d, rect_px)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 /** \} */

source/blender/editors/interface/view2d.c

@@ -2626,13 +2626,14 @@ void UI_view2d_offset(struct View2D *v2d, float xfac, float yfac)
 char UI_view2d_mouse_in_scrollers_ex(
     const ARegion *ar, const View2D *v2d, int x, int y, int *r_scroll)
 {
-  int co[2];
-  int scroll = view2d_scroll_mapped(v2d->scroll);
+  const int scroll = view2d_scroll_mapped(v2d->scroll);
   *r_scroll = scroll;
 
   /* clamp x,y to region-coordinates first */
-  co[0] = x - ar->winrct.xmin;
-  co[1] = y - ar->winrct.ymin;
+  const int co[2] = {
+      x - ar->winrct.xmin,
+      y - ar->winrct.ymin,
+  };
 
   /* check if within scrollbars */
   if (scroll & V2D_SCROLL_HORIZONTAL) {
@@ -2650,12 +2651,46 @@ char UI_view2d_mouse_in_scrollers_ex(
   return 0;
 }
 
+char UI_view2d_rect_in_scrollers_ex(const ARegion *ar,
+                                    const View2D *v2d,
+                                    const rcti *rect,
+                                    int *r_scroll)
+{
+  const int scroll = view2d_scroll_mapped(v2d->scroll);
+  *r_scroll = scroll;
+
+  /* clamp x,y to region-coordinates first */
+  rcti rect_region = *rect;
+  BLI_rcti_translate(&rect_region, -ar->winrct.xmin, ar->winrct.ymin);
+
+  /* check if within scrollbars */
+  if (scroll & V2D_SCROLL_HORIZONTAL) {
+    if (IN_2D_HORIZ_SCROLL_RECT(v2d, &rect_region)) {
+      return 'h';
+    }
+  }
+  if (scroll & V2D_SCROLL_VERTICAL) {
+    if (IN_2D_VERT_SCROLL_RECT(v2d, &rect_region)) {
+      return 'v';
+    }
+  }
+
+  /* not found */
+  return 0;
+}
+
 char UI_view2d_mouse_in_scrollers(const ARegion *ar, const View2D *v2d, int x, int y)
 {
   int scroll_dummy = 0;
   return UI_view2d_mouse_in_scrollers_ex(ar, v2d, x, y, &scroll_dummy);
 }
 
+char UI_view2d_rect_in_scrollers(const ARegion *ar, const View2D *v2d, const rcti *rect)
+{
+  int scroll_dummy = 0;
+  return UI_view2d_rect_in_scrollers_ex(ar, v2d, rect, &scroll_dummy);
+}
+
 /* ******************* view2d text drawing cache ******************** */
 
 typedef struct View2DString {

source/blender/editors/screen/CMakeLists.txt

@@ -39,6 +39,7 @@ set(INC_SYS
 
 set(SRC
   area.c
+  area_query.c
   area_utils.c
   glutil.c
   screen_context.c

source/blender/editors/screen/area.c

@@ -901,33 +901,65 @@ static void fullscreen_azone_initialize(ScrArea *sa, ARegion *ar)
 #define AZONEPAD_ICON (0.45f * U.widget_unit)
 static void region_azone_edge(AZone *az, ARegion *ar)
 {
+  int clip_axis = -1;
   switch (az->edge) {
     case AE_TOP_TO_BOTTOMRIGHT:
       az->x1 = ar->winrct.xmin;
       az->y1 = ar->winrct.ymax - AZONEPAD_EDGE;
       az->x2 = ar->winrct.xmax;
       az->y2 = ar->winrct.ymax + AZONEPAD_EDGE;
+      if (ar->overlap) {
+        clip_axis = 0;
+      }
       break;
     case AE_BOTTOM_TO_TOPLEFT:
       az->x1 = ar->winrct.xmin;
       az->y1 = ar->winrct.ymin + AZONEPAD_EDGE;
       az->x2 = ar->winrct.xmax;
       az->y2 = ar->winrct.ymin - AZONEPAD_EDGE;
+      if (ar->overlap) {
+        clip_axis = 0;
+      }
       break;
     case AE_LEFT_TO_TOPRIGHT:
       az->x1 = ar->winrct.xmin - AZONEPAD_EDGE;
       az->y1 = ar->winrct.ymin;
       az->x2 = ar->winrct.xmin + AZONEPAD_EDGE;
       az->y2 = ar->winrct.ymax;
+      if (ar->overlap) {
+        clip_axis = 1;
+      }
       break;
     case AE_RIGHT_TO_TOPLEFT:
       az->x1 = ar->winrct.xmax + AZONEPAD_EDGE;
       az->y1 = ar->winrct.ymin;
       az->x2 = ar->winrct.xmax - AZONEPAD_EDGE;
       az->y2 = ar->winrct.ymax;
+      if (ar->overlap) {
+        clip_axis = 1;
+      }
       break;
   }
 
+  /* Constrain action zones to usable area of region.
+   * Needed so blank areas of the region are interactive and aciton zones don't get in the way. */
+  if (clip_axis == 0) {
+    az->x1 = max_ii(az->x1,
+                    (ar->winrct.xmin + UI_view2d_view_to_region_x(&ar->v2d, ar->v2d.tot.xmin)) -
+                        UI_REGION_OVERLAP_MARGIN);
+    az->x2 = min_ii(az->x2,
+                    (ar->winrct.xmin + UI_view2d_view_to_region_x(&ar->v2d, ar->v2d.tot.xmax)) +
+                        UI_REGION_OVERLAP_MARGIN);
+  }
+  else if (clip_axis == 1) {
+    az->y1 = max_ii(az->y1,
+                    (ar->winrct.ymin + UI_view2d_view_to_region_y(&ar->v2d, ar->v2d.tot.ymin)) -
+                        UI_REGION_OVERLAP_MARGIN);
+    az->y2 = min_ii(az->y2,
+                    (ar->winrct.ymin + UI_view2d_view_to_region_y(&ar->v2d, ar->v2d.tot.ymax)) +
+                        UI_REGION_OVERLAP_MARGIN);
+  }
+
   BLI_rcti_init(&az->rect, az->x1, az->x2, az->y1, az->y2);
 }
 

source/blender/editors/screen/area_query.c

@@ -0,0 +1,123 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup edscr
+ *
+ * Query functions for area/region.
+ */
+
+#include "DNA_userdef_types.h"
+
+#include "BLI_blenlib.h"
+#include "BLI_utildefines.h"
+
+#include "RNA_types.h"
+
+#include "WM_api.h"
+
+#include "ED_screen.h"
+
+#include "UI_interface.h"
+#include "UI_view2d.h"
+
+bool ED_region_overlap_isect_x(const ARegion *ar, const int event_x)
+{
+  BLI_assert(ar->overlap);
+  /* No contents, skip it. */
+  if (ar->v2d.mask.xmin == ar->v2d.mask.xmax) {
+    return false;
+  }
+  return BLI_rctf_isect_x(&ar->v2d.tot,
+                          UI_view2d_region_to_view_x(&ar->v2d, event_x - ar->winrct.xmin));
+}
+
+bool ED_region_overlap_isect_y(const ARegion *ar, const int event_y)
+{
+  BLI_assert(ar->overlap);
+  /* No contents, skip it. */
+  if (ar->v2d.mask.ymin == ar->v2d.mask.ymax) {
+    return false;
+  }
+  return BLI_rctf_isect_y(&ar->v2d.tot,
+                          UI_view2d_region_to_view_y(&ar->v2d, event_y - ar->winrct.ymin));
+}
+
+bool ED_region_overlap_isect_xy(const ARegion *ar, const int event_xy[2])
+{
+  return (ED_region_overlap_isect_x(ar, event_xy[0]) &&
+          ED_region_overlap_isect_y(ar, event_xy[1]));
+}
+
+bool ED_region_overlap_isect_x_with_margin(const ARegion *ar, const int event_x, const int margin)
+{
+  BLI_assert(ar->overlap);
+  /* No contents, skip it. */
+  if (ar->v2d.mask.xmin == ar->v2d.mask.xmax) {
+    return false;
+  }
+  int region_x = event_x - ar->winrct.xmin;
+  return ((ar->v2d.tot.xmin <= UI_view2d_region_to_view_x(&ar->v2d, region_x + margin)) &&
+          (ar->v2d.tot.xmax >= UI_view2d_region_to_view_x(&ar->v2d, region_x - margin)));
+}
+
+bool ED_region_overlap_isect_y_with_margin(const ARegion *ar, const int event_y, const int margin)
+{
+  BLI_assert(ar->overlap);
+  /* No contents, skip it. */
+  if (ar->v2d.mask.ymin == ar->v2d.mask.ymax) {
+    return false;
+  }
+  int region_y = event_y - ar->winrct.ymin;
+  return ((ar->v2d.tot.ymin <= UI_view2d_region_to_view_y(&ar->v2d, region_y + margin)) &&
+          (ar->v2d.tot.ymax >= UI_view2d_region_to_view_y(&ar->v2d, region_y - margin)));
+}
+
+bool ED_region_overlap_isect_xy_with_margin(const ARegion *ar,
+                                            const int event_xy[2],
+                                            const int margin)
+{
+  return (ED_region_overlap_isect_x_with_margin(ar, event_xy[0], margin) &&
+          ED_region_overlap_isect_y_with_margin(ar, event_xy[1], margin));
+}
+
+bool ED_region_contains_xy(const ARegion *ar, const int event_xy[2])
+{
+  /* Only use the margin when inside the region. */
+  if (BLI_rcti_isect_pt_v(&ar->winrct, event_xy)) {
+    if (ar->overlap) {
+      const int overlap_margin = UI_REGION_OVERLAP_MARGIN;
+      /* Note the View2D.tot isn't reliable for headers with spacers otherwise
+       * we'd check #ED_region_overlap_isect_xy_with_margin for both bases. */
+      if (ar->v2d.keeptot == V2D_KEEPTOT_STRICT) {
+        /* Header. */
+        rcti rect;
+        BLI_rcti_init_pt_radius(&rect, event_xy, overlap_margin);
+        if (UI_region_but_find_rect_over(ar, &rect) == NULL) {
+          return false;
+        }
+      }
+      else {
+        /* Side-bar & any other kind of overlapping region. */
+        if (!ED_region_overlap_isect_xy_with_margin(ar, event_xy, overlap_margin)) {
+          return false;
+        }
+      }
+    }
+    return true;
+  }
+  return false;
+}

source/blender/editors/screen/screen_edit.c

@@ -683,7 +683,7 @@ void ED_screen_set_active_region(bContext *C, wmWindow *win, const int xy[2])
     if (sa) {
       /* make overlap active when mouse over */
       for (ar = sa->regionbase.first; ar; ar = ar->next) {
-        if (BLI_rcti_isect_pt_v(&ar->winrct, xy)) {
+        if (ED_region_contains_xy(ar, xy)) {
           scr->active_region = ar;
           break;
         }

source/blender/windowmanager/intern/wm_event_system.c

@@ -69,6 +69,7 @@
 #include "RNA_access.h"
 
 #include "UI_interface.h"
+#include "UI_view2d.h"
 
 #include "PIL_time.h"
 
@@ -2951,15 +2952,23 @@ static int wm_handlers_do(bContext *C, wmEvent *event, ListBase *handlers)
   return action;
 }
 
-static int wm_event_inside_i(wmEvent *event, rcti *rect)
+static bool wm_event_inside_rect(const wmEvent *event, const rcti *rect)
 {
   if (wm_event_always_pass(event)) {
-    return 1;
+    return true;
   }
   if (BLI_rcti_isect_pt_v(rect, &event->x)) {
-    return 1;
+    return true;
   }
-  return 0;
+  return false;
+}
+
+static bool wm_event_inside_region(const wmEvent *event, const ARegion *ar)
+{
+  if (wm_event_always_pass(event)) {
+    return true;
+  }
+  return ED_region_contains_xy(ar, &event->x);
 }
 
 static ScrArea *area_event_inside(bContext *C, const int xy[2])
@@ -3246,12 +3255,13 @@ void wm_event_do_handlers(bContext *C)
             ED_area_azones_update(sa, &event->x);
           }
 
-          if (wm_event_inside_i(event, &sa->totrct)) {
+          if (wm_event_inside_rect(event, &sa->totrct)) {
             CTX_wm_area_set(C, sa);
 
             if ((action & WM_HANDLER_BREAK) == 0) {
               for (ar = sa->regionbase.first; ar; ar = ar->next) {
-                if (wm_event_inside_i(event, &ar->winrct)) {
+                if (wm_event_inside_region(event, ar)) {
+
                   CTX_wm_region_set(C, ar);
 
                   /* call even on non mouse events, since the */