Add setting to disable smooth scrolling

builtin/settingtypes.txt

@@ -694,6 +694,9 @@ language (Language) enum   ,be,bg,ca,cs,da,de,el,en,eo,es,et,eu,fi,fr,gd,gl,hu,i
 #    edge pixels when images are scaled by non-integer sizes.
 gui_scaling (GUI scaling) float 1.0 0.5 20
 
+#    Enables smooth scrolling.
+smooth_scrolling (Smooth scrolling) bool true
+
 #    Enables animation of inventory items.
 inventory_items_animations (Inventory items animations) bool false
 

src/defaultsettings.cpp

@@ -299,6 +299,7 @@ void set_default_settings()
 	settings->setDefault("gui_scaling", "1.0");
 	settings->setDefault("gui_scaling_filter", "false");
 	settings->setDefault("gui_scaling_filter_txr2img", "true");
+	settings->setDefault("smooth_scrolling", "true");
 	settings->setDefault("desynchronize_mapblock_texture_animation", "false");
 	settings->setDefault("hud_hotbar_max_width", "1.0");
 	settings->setDefault("enable_local_map_saving", "false");

src/gui/guiScrollBar.cpp

@@ -13,6 +13,7 @@ the arrow buttons where there is insufficient space.
 #include "guiScrollBar.h"
 #include "guiButton.h"
 #include "porting.h"
+#include "settings.h"
 #include <IGUISkin.h>
 
 GUIScrollBar::GUIScrollBar(IGUIEnvironment *environment, IGUIElement *parent, s32 id,
@@ -101,19 +102,9 @@ bool GUIScrollBar::OnEvent(const SEvent &event)
 					tray_clicked = !dragged_by_slider;
 					if (tray_clicked) {
 						const s32 new_pos = getPosFromMousePos(p);
-						const s32 old_pos = scroll_pos;
+						setPosAndSend(new_pos);
-						setPos(new_pos);
 						// drag in the middle
 						drag_offset = thumb_size / 2;
-						// report the scroll event
-						if (scroll_pos != old_pos && Parent) {
-							SEvent e;
-							e.EventType = EET_GUI_EVENT;
-							e.GUIEvent.Caller = this;
-							e.GUIEvent.Element = nullptr;
-							e.GUIEvent.EventType = EGET_SCROLL_BAR_CHANGED;
-							Parent->OnEvent(e);
-						}
 					}
 					Environment->setFocus(this);
 					return true;
@@ -147,18 +138,8 @@ bool GUIScrollBar::OnEvent(const SEvent &event)
 				}
 
 				const s32 new_pos = getPosFromMousePos(p);
-				const s32 old_pos = scroll_pos;
+				setPosAndSend(new_pos);
 
-				setPos(new_pos);
-
-				if (scroll_pos != old_pos && Parent) {
-					SEvent e;
-					e.EventType = EET_GUI_EVENT;
-					e.GUIEvent.Caller = this;
-					e.GUIEvent.Element = nullptr;
-					e.GUIEvent.EventType = EGET_SCROLL_BAR_CHANGED;
-					Parent->OnEvent(e);
-				}
 				return is_inside;
 			}
 			default:
@@ -300,8 +281,27 @@ void GUIScrollBar::setPos(const s32 &pos)
 	target_pos = std::nullopt;
 }
 
+void GUIScrollBar::setPosAndSend(const s32 &pos)
+{
+	const s32 old_pos = scroll_pos;
+	setPos(pos);
+	if (scroll_pos != old_pos && Parent) {
+		SEvent e;
+		e.EventType = EET_GUI_EVENT;
+		e.GUIEvent.Caller = this;
+		e.GUIEvent.Element = nullptr;
+		e.GUIEvent.EventType = EGET_SCROLL_BAR_CHANGED;
+		Parent->OnEvent(e);
+	}
+}
+
 void GUIScrollBar::setPosInterpolated(const s32 &pos)
 {
+	if (!g_settings->getBool("smooth_scrolling")) {
+		setPosAndSend(pos);
+		return;
+	}
+
 	s32 clamped = core::s32_clamp(pos, min_pos, max_pos);
 	if (scroll_pos != clamped) {
 		target_pos = clamped;

src/gui/guiScrollBar.h

@@ -53,6 +53,8 @@ public:
 	//! Sets a position immediately, aborting any ongoing interpolation.
 	// setPos does not send EGET_SCROLL_BAR_CHANGED events for you.
 	void setPos(const s32 &pos);
+	//! The same as setPos, but it takes care of sending EGET_SCROLL_BAR_CHANGED events.
+	void setPosAndSend(const s32 &pos);
 	//! Sets a target position for interpolation.
 	// If you want to do an interpolated addition, use
 	// setPosInterpolated(getTargetPos() + x).