Fix redraws from non-existing scrollbars

Cursor motion was often causing redraws.

Distance to scrollbars that don't exist in hidden regions
caused redraws (for alpha fading).

Check if scrollbars are used before calculating fade.

4 files changed, 30 insertions, 8 deletions

diff --git a/source/blender/editors/include/UI_view2d.h b/source/blender/editors/include/UI_view2d.h
index 92aca0a707e..8581e5d4a93 100644
--- a/source/blender/editors/include/UI_view2d.h
+++ b/source/blender/editors/include/UI_view2d.h
@@ -225,7 +225,11 @@ void UI_view2d_center_set(struct View2D *v2d, float x, float y);
 
 void UI_view2d_offset(struct View2D *v2d, float xfac, float yfac);
 
-short UI_view2d_mouse_in_scrollers(const struct ARegion *ar, struct View2D *v2d, int x, int y);
+char UI_view2d_mouse_in_scrollers_ex(
+        const struct ARegion *ar, struct View2D *v2d, int x, int y,
+        int *r_scroll);
+char UI_view2d_mouse_in_scrollers(
+        const struct ARegion *ar, struct View2D *v2d, int x, int y);
 
 /* cached text drawing in v2d, to allow pixel-aligned draw as post process */
 void UI_view2d_text_cache_add(struct View2D *v2d, float x, float y,
diff --git a/source/blender/editors/interface/view2d.c b/source/blender/editors/interface/view2d.c
index 20ca492c8d1..72f5a75904b 100644
--- a/source/blender/editors/interface/view2d.c
+++ b/source/blender/editors/interface/view2d.c
@@ -2429,16 +2429,20 @@ void UI_view2d_offset(struct View2D *v2d, float xfac, float yfac)
  * Check if mouse is within scrollers
  *
  * \param x, y: Mouse coordinates in screen (not region) space.
+ * \param r_scroll: Mapped view2d scroll flag.
  *
  * \return appropriate code for match.
  * - 'h' = in horizontal scroller.
  * - 'v' = in vertical scroller.
  * - 0 = not in scroller.
  */
-short UI_view2d_mouse_in_scrollers(const ARegion *ar, View2D *v2d, int x, int y)
+char UI_view2d_mouse_in_scrollers_ex(
+        const ARegion *ar, View2D *v2d, int x, int y,
+        int *r_scroll)
 {
 	int co[2];
 	int scroll = view2d_scroll_mapped(v2d->scroll);
+	*r_scroll = scroll;
 
 	/* clamp x,y to region-coordinates first */
 	co[0] = x - ar->winrct.xmin;
@@ -2456,6 +2460,13 @@ short UI_view2d_mouse_in_scrollers(const ARegion *ar, View2D *v2d, int x, int y)
 	return 0;
 }
 
+char UI_view2d_mouse_in_scrollers(
+        const ARegion *ar, View2D *v2d, int x, int y)
+{
+	int scroll_dummy = 0;
+	return UI_view2d_mouse_in_scrollers_ex(ar, v2d, x, y, &scroll_dummy);
+}
+
 /* ******************* view2d text drawing cache ******************** */
 
 typedef struct View2DString {
diff --git a/source/blender/editors/interface/view2d_ops.c b/source/blender/editors/interface/view2d_ops.c
index 0ec6e3d5fd2..8df786b2a7f 100644
--- a/source/blender/editors/interface/view2d_ops.c
+++ b/source/blender/editors/interface/view2d_ops.c
@@ -1587,7 +1587,7 @@ typedef struct v2dScrollerMove {
 	View2D *v2d;            /* View2D data that this operation affects */
 	ARegion *ar;            /* region that the scroller is in */
 
-	short scroller;         /* scroller that mouse is in ('h' or 'v') */
+	char scroller;          /* scroller that mouse is in ('h' or 'v') */
 	short zone; /* -1 is min zoomer, 0 is bar, 1 is max zoomer */             // XXX find some way to provide visual feedback of this (active color?)
 
 	float fac;              /* view adjustment factor, based on size of region */
@@ -1694,7 +1694,7 @@ static bool scroller_activate_poll(bContext *C)
 }
 
 /* initialize customdata for scroller manipulation operator */
-static void scroller_activate_init(bContext *C, wmOperator *op, const wmEvent *event, short in_scroller)
+static void scroller_activate_init(bContext *C, wmOperator *op, const wmEvent *event, const char in_scroller)
 {
 	v2dScrollerMove *vsm;
 	View2DScrollers *scrollers;
@@ -1928,10 +1928,9 @@ static int scroller_activate_invoke(bContext *C, wmOperator *op, const wmEvent *
 {
 	ARegion *ar = CTX_wm_region(C);
 	View2D *v2d = &ar->v2d;
-	short in_scroller = 0;
 
 	/* check if mouse in scrollbars, if they're enabled */
-	in_scroller = UI_view2d_mouse_in_scrollers(ar, v2d, event->x, event->y);
+	const char in_scroller = UI_view2d_mouse_in_scrollers(ar, v2d, event->x, event->y);
 
 	/* if in a scroller, init customdata then set modal handler which will catch mousedown to start doing useful stuff */
 	if (in_scroller) {
diff --git a/source/blender/editors/screen/screen_ops.c b/source/blender/editors/screen/screen_ops.c
index 5377ccb5a44..8c28d73f44b 100644
--- a/source/blender/editors/screen/screen_ops.c
+++ b/source/blender/editors/screen/screen_ops.c
@@ -740,8 +740,16 @@ static AZone *area_actionzone_refresh_xy(ScrArea *sa, const int xy[2], const boo
 			else if (az->type == AZONE_REGION_SCROLL) {
 				ARegion *ar = az->ar;
 				View2D *v2d = &ar->v2d;
-				const short isect_value = UI_view2d_mouse_in_scrollers(ar, v2d, xy[0], xy[1]);
-				if (test_only) {
+				int scroll_flag = 0;
+				const int isect_value = UI_view2d_mouse_in_scrollers_ex(ar, v2d, xy[0], xy[1], &scroll_flag);
+
+				/* Check if we even have scroll bars. */
+				if (((az->direction == AZ_SCROLL_HOR)  && !(scroll_flag & V2D_SCROLL_HORIZONTAL)) ||
+				    ((az->direction == AZ_SCROLL_VERT) && !(scroll_flag & V2D_SCROLL_VERTICAL)))
+				{
+					/* no scrollbars, do nothing. */
+				}
+				else if (test_only) {
 					if (isect_value != 0) {
 						break;
 					}