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

1 files changed, 39 insertions, 4 deletions

diff --git a/source/blender/editors/interface/view2d.c b/source/blender/editors/interface/view2d.c
index 4e53e59d7c0..096ea230bbe 100644
--- a/source/blender/editors/interface/view2d.c
+++ b/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 {