From dcf5be92a3aede861909c08d06b114669bbe75e8 Mon Sep 17 00:00:00 2001
From: Ruslan Mustakov
Date: Tue, 27 Feb 2018 22:37:20 +0700
Subject: Make BaseButton not emit press when container is scrolled

This fixes the problem described in #13996 in a proper way.

This also adds "deadzone" property to ScrollContainer. It can be used
on mobile, where taps are not as precise as mouse clicks. Player could
slightly move their finger when tapping, in which case we still want
the button to be pressed rather than the container to be scrolled.
---
 scene/gui/scroll_container.cpp | 74 ++++++++++++++++++++++++++++--------------
 1 file changed, 50 insertions(+), 24 deletions(-)

(limited to 'scene/gui/scroll_container.cpp')

diff --git a/scene/gui/scroll_container.cpp b/scene/gui/scroll_container.cpp
index 33b3d4648..217df275b 100644
--- a/scene/gui/scroll_container.cpp
+++ b/scene/gui/scroll_container.cpp
@@ -75,6 +75,12 @@ void ScrollContainer::_cancel_drag() {
 	drag_accum = Vector2();
 	last_drag_accum = Vector2();
 	drag_from = Vector2();
+
+	if (beyond_deadzone) {
+		emit_signal("scroll_ended");
+		propagate_notification(NOTIFICATION_SCROLL_END);
+		beyond_deadzone = false;
+	}
 }
 
 void ScrollContainer::_gui_input(const Ref<InputEvent> &p_gui_input) {
@@ -122,13 +128,7 @@ void ScrollContainer::_gui_input(const Ref<InputEvent> &p_gui_input) {
 		if (mb->is_pressed()) {
 
 			if (drag_touching) {
-				set_physics_process(false);
-				drag_touching_deaccel = false;
-				drag_touching = false;
-				drag_speed = Vector2();
-				drag_accum = Vector2();
-				last_drag_accum = Vector2();
-				drag_from = Vector2();
+				_cancel_drag();
 			}
 
 			if (true) {
@@ -138,6 +138,7 @@ void ScrollContainer::_gui_input(const Ref<InputEvent> &p_gui_input) {
 				drag_from = Vector2(h_scroll->get_value(), v_scroll->get_value());
 				drag_touching = OS::get_singleton()->has_touchscreen_ui_hint();
 				drag_touching_deaccel = false;
+				beyond_deadzone = false;
 				time_since_motion = 0;
 				if (drag_touching) {
 					set_physics_process(true);
@@ -149,9 +150,7 @@ void ScrollContainer::_gui_input(const Ref<InputEvent> &p_gui_input) {
 			if (drag_touching) {
 
 				if (drag_speed == Vector2()) {
-					drag_touching_deaccel = false;
-					drag_touching = false;
-					set_physics_process(false);
+					_cancel_drag();
 				} else {
 
 					drag_touching_deaccel = true;
@@ -168,17 +167,27 @@ void ScrollContainer::_gui_input(const Ref<InputEvent> &p_gui_input) {
 
 			Vector2 motion = Vector2(mm->get_relative().x, mm->get_relative().y);
 			drag_accum -= motion;
-			Vector2 diff = drag_from + drag_accum;
-
-			if (scroll_h)
-				h_scroll->set_value(diff.x);
-			else
-				drag_accum.x = 0;
-			if (scroll_v)
-				v_scroll->set_value(diff.y);
-			else
-				drag_accum.y = 0;
-			time_since_motion = 0;
+
+			if (beyond_deadzone || scroll_h && Math::abs(drag_accum.x) > deadzone || scroll_v && Math::abs(drag_accum.y) > deadzone) {
+				if (!beyond_deadzone) {
+					propagate_notification(NOTIFICATION_SCROLL_BEGIN);
+					emit_signal("scroll_started");
+
+					beyond_deadzone = true;
+					// resetting drag_accum here ensures smooth scrolling after reaching deadzone
+					drag_accum = -motion;
+				}
+				Vector2 diff = drag_from + drag_accum;
+				if (scroll_h)
+					h_scroll->set_value(diff.x);
+				else
+					drag_accum.x = 0;
+				if (scroll_v)
+					v_scroll->set_value(diff.y);
+				else
+					drag_accum.y = 0;
+				time_since_motion = 0;
+			}
 		}
 	}
 
@@ -323,9 +332,7 @@ void ScrollContainer::_notification(int p_what) {
 				drag_speed = Vector2(sgn_x * val_x, sgn_y * val_y);
 
 				if (turnoff_h && turnoff_v) {
-					set_physics_process(false);
-					drag_touching = false;
-					drag_touching_deaccel = false;
+					_cancel_drag();
 				}
 
 			} else {
@@ -430,6 +437,14 @@ void ScrollContainer::set_h_scroll(int p_pos) {
 	_cancel_drag();
 }
 
+int ScrollContainer::get_deadzone() const {
+	return deadzone;
+}
+
+void ScrollContainer::set_deadzone(int p_deadzone) {
+	deadzone = p_deadzone;
+}
+
 String ScrollContainer::get_configuration_warning() const {
 
 	int found = 0;
@@ -466,12 +481,20 @@ void ScrollContainer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_h_scroll"), &ScrollContainer::get_h_scroll);
 	ClassDB::bind_method(D_METHOD("set_v_scroll", "value"), &ScrollContainer::set_v_scroll);
 	ClassDB::bind_method(D_METHOD("get_v_scroll"), &ScrollContainer::get_v_scroll);
+	ClassDB::bind_method(D_METHOD("set_deadzone", "deadzone"), &ScrollContainer::set_deadzone);
+	ClassDB::bind_method(D_METHOD("get_deadzone"), &ScrollContainer::get_deadzone);
+
+	ADD_SIGNAL(MethodInfo("scroll_started"));
+	ADD_SIGNAL(MethodInfo("scroll_ended"));
 
 	ADD_GROUP("Scroll", "scroll_");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "scroll_horizontal_enabled"), "set_enable_h_scroll", "is_h_scroll_enabled");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "scroll_horizontal"), "set_h_scroll", "get_h_scroll");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "scroll_vertical_enabled"), "set_enable_v_scroll", "is_v_scroll_enabled");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "scroll_vertical"), "set_v_scroll", "get_v_scroll");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "scroll_deadzone"), "set_deadzone", "get_deadzone");
+
+	GLOBAL_DEF("gui/common/default_scroll_deadzone", 0);
 };
 
 ScrollContainer::ScrollContainer() {
@@ -490,8 +513,11 @@ ScrollContainer::ScrollContainer() {
 	drag_speed = Vector2();
 	drag_touching = false;
 	drag_touching_deaccel = false;
+	beyond_deadzone = false;
 	scroll_h = true;
 	scroll_v = true;
 
+	deadzone = GLOBAL_GET("gui/common/default_scroll_deadzone");
+
 	set_clip_contents(true);
 };
-- 
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