LibGUI: Make ScrollBar track the currently pressed component

And remove the now-redundant members m_scrubbing, m_scrubber_in_use,
and m_automatic_scrolling_kind.

This also made it clear that we weren't canceling the autoscroll
timer if the scrollbar got disabled while it was scrolling, so
this fixes that too.

Libraries/LibGUI/ScrollBar.cpp

@@ -237,8 +237,8 @@ void ScrollBar::paint_event(PaintEvent& event)
 
     painter.fill_rect_with_dither_pattern(rect(), palette().button().lightened(1.3f), palette().button());
 
-    bool decrement_pressed = m_automatic_scrolling_kind == AutomaticScrollingKind::DecrementButton;
-    bool increment_pressed = m_automatic_scrolling_kind == AutomaticScrollingKind::IncrementButton;
+    bool decrement_pressed = m_pressed_component == Component::DecrementButton;
+    bool increment_pressed = m_pressed_component == Component::IncrementButton;
 
     Gfx::StylePainter::paint_button(painter, decrement_button_rect(), palette(), Gfx::ButtonStyle::Normal, decrement_pressed, m_hovered_component == Component::DecrementButton);
     Gfx::StylePainter::paint_button(painter, increment_button_rect(), palette(), Gfx::ButtonStyle::Normal, increment_pressed, m_hovered_component == Component::IncrementButton);
@@ -256,20 +256,20 @@ void ScrollBar::paint_event(PaintEvent& event)
     }
 
     if (has_scrubber())
-        Gfx::StylePainter::paint_button(painter, scrubber_rect(), palette(), Gfx::ButtonStyle::Normal, false, m_hovered_component == Component::Scrubber || m_scrubber_in_use);
+        Gfx::StylePainter::paint_button(painter, scrubber_rect(), palette(), Gfx::ButtonStyle::Normal, false, m_hovered_component == Component::Scrubber || m_pressed_component == Component::Scrubber);
 }
 
 void ScrollBar::on_automatic_scrolling_timer_fired()
 {
-    if (m_automatic_scrolling_kind == AutomaticScrollingKind::DecrementButton && component_at_position(m_last_mouse_position) == Component::DecrementButton) {
+    if (m_pressed_component == Component::DecrementButton && component_at_position(m_last_mouse_position) == Component::DecrementButton) {
         set_value(value() - m_step);
         return;
     }
-    if (m_automatic_scrolling_kind == AutomaticScrollingKind::IncrementButton && component_at_position(m_last_mouse_position) == Component::IncrementButton) {
+    if (m_pressed_component == Component::IncrementButton && component_at_position(m_last_mouse_position) == Component::IncrementButton) {
         set_value(value() + m_step);
         return;
     }
-    if (m_automatic_scrolling_kind == AutomaticScrollingKind::Gutter && component_at_position(m_last_mouse_position) == Component::Gutter) {
+    if (m_pressed_component == Component::Gutter && component_at_position(m_last_mouse_position) == Component::Gutter) {
         scroll_by_page(m_last_mouse_position);
         return;
     }
@@ -283,27 +283,25 @@ void ScrollBar::mousedown_event(MouseEvent& event)
         return;
 
     m_last_mouse_position = event.position();
-    Component clicked_component = component_at_position(m_last_mouse_position);
+    m_pressed_component = component_at_position(m_last_mouse_position);
 
-    if (clicked_component == Component::DecrementButton) {
-        set_automatic_scrolling_active(true, AutomaticScrollingKind::DecrementButton);
+    if (m_pressed_component == Component::DecrementButton) {
+        set_automatic_scrolling_active(true, Component::DecrementButton);
         update();
         return;
     }
-    if (clicked_component == Component::IncrementButton) {
-        set_automatic_scrolling_active(true, AutomaticScrollingKind::IncrementButton);
+    if (m_pressed_component == Component::IncrementButton) {
+        set_automatic_scrolling_active(true, Component::IncrementButton);
         update();
         return;
     }
 
     if (event.shift()) {
         scroll_to_position(event.position());
-        clicked_component = component_at_position(event.position());
-        ASSERT(clicked_component == Component::Scrubber);
+        m_pressed_component = component_at_position(event.position());
+        ASSERT(m_pressed_component == Component::Scrubber);
     }
-    if (clicked_component == Component::Scrubber) {
-        m_scrubber_in_use = true;
-        m_scrubbing = true;
+    if (m_pressed_component == Component::Scrubber) {
         m_scrub_start_value = value();
         m_scrub_origin = event.position();
         update();
@@ -311,8 +309,8 @@ void ScrollBar::mousedown_event(MouseEvent& event)
     }
     ASSERT(!event.shift());
 
-    ASSERT(clicked_component == Component::Gutter);
-    set_automatic_scrolling_active(true, AutomaticScrollingKind::Gutter);
+    ASSERT(m_pressed_component == Component::Gutter);
+    set_automatic_scrolling_active(true, Component::Gutter);
     update();
 }
 
@@ -320,9 +318,7 @@ void ScrollBar::mouseup_event(MouseEvent& event)
 {
     if (event.button() != MouseButton::Left)
         return;
-    m_scrubber_in_use = false;
-    set_automatic_scrolling_active(false, AutomaticScrollingKind::None);
-    m_scrubbing = false;
+    set_automatic_scrolling_active(false, Component::None);
     update();
 }
 
@@ -334,10 +330,10 @@ void ScrollBar::mousewheel_event(MouseEvent& event)
     Widget::mousewheel_event(event);
 }
 
-void ScrollBar::set_automatic_scrolling_active(bool active, AutomaticScrollingKind kind)
+void ScrollBar::set_automatic_scrolling_active(bool active, Component pressed_component)
 {
-    m_automatic_scrolling_kind = kind;
-    if (m_automatic_scrolling_kind == AutomaticScrollingKind::Gutter)
+    m_pressed_component = pressed_component;
+    if (m_pressed_component == Component::Gutter)
         m_automatic_scrolling_timer->set_interval(200);
     else
         m_automatic_scrolling_timer->set_interval(100);
@@ -383,7 +379,7 @@ ScrollBar::Component ScrollBar::component_at_position(const Gfx::IntPoint& posit
         return Component::IncrementButton;
     if (rect().contains(position))
         return Component::Gutter;
-    return Component::Invalid;
+    return Component::None;
 }
 
 void ScrollBar::mousemove_event(MouseEvent& event)
@@ -395,7 +391,7 @@ void ScrollBar::mousemove_event(MouseEvent& event)
     if (old_hovered_component != m_hovered_component) {
         update();
     }
-    if (!m_scrubbing)
+    if (m_pressed_component != Component::Scrubber)
         return;
     float delta = orientation() == Orientation::Vertical ? (event.y() - m_scrub_origin.y()) : (event.x() - m_scrub_origin.x());
     float scrubbable_range = scrubbable_range_in_pixels();
@@ -406,8 +402,8 @@ void ScrollBar::mousemove_event(MouseEvent& event)
 
 void ScrollBar::leave_event(Core::Event&)
 {
-    if (m_hovered_component != Component::Invalid) {
-        m_hovered_component = Component::Invalid;
+    if (m_hovered_component != Component::None) {
+        m_hovered_component = Component::None;
         update();
     }
 }
@@ -416,7 +412,7 @@ void ScrollBar::change_event(Event& event)
 {
     if (event.type() == Event::Type::EnabledChange) {
         if (!is_enabled())
-            m_scrubbing = false;
+            set_automatic_scrolling_active(false, Component::None);
     }
     return Widget::change_event(event);
 }

Libraries/LibGUI/ScrollBar.h

@@ -60,7 +60,7 @@ public:
     Function<void(int)> on_change;
 
     enum Component {
-        Invalid,
+        None,
         DecrementButton,
         IncrementButton,
         Gutter,
@@ -78,13 +78,6 @@ private:
     virtual void leave_event(Core::Event&) override;
     virtual void change_event(Event&) override;
 
-    enum class AutomaticScrollingKind {
-        None = 0,
-        DecrementButton,
-        IncrementButton,
-        Gutter,
-    };
-
     int default_button_size() const { return 16; }
     int button_size() const { return length(orientation()) <= (default_button_size() * 2) ? length(orientation()) / 2 : default_button_size(); }
     int button_width() const { return orientation() == Orientation::Vertical ? width() : button_size(); }
@@ -98,7 +91,7 @@ private:
     int visible_scrubber_size() const;
     int scrubbable_range_in_pixels() const;
     void on_automatic_scrolling_timer_fired();
-    void set_automatic_scrolling_active(bool, AutomaticScrollingKind);
+    void set_automatic_scrolling_active(bool, Component);
 
     void scroll_to_position(const Gfx::IntPoint&);
     void scroll_by_page(const Gfx::IntPoint&);
@@ -112,16 +105,14 @@ private:
     int m_step { 1 };
     int m_big_step { 5 };
 
-    bool m_scrubbing { false };
     int m_scrub_start_value { 0 };
     Gfx::IntPoint m_scrub_origin;
 
     Gfx::Orientation m_orientation { Gfx::Orientation::Vertical };
-    Component m_hovered_component { Component::Invalid };
+    Component m_hovered_component { Component::None };
+    Component m_pressed_component { Component::None };
     Gfx::IntPoint m_last_mouse_position;
-    bool m_scrubber_in_use { false };
 
-    AutomaticScrollingKind m_automatic_scrolling_kind { AutomaticScrollingKind::None };
     RefPtr<Core::Timer> m_automatic_scrolling_timer;
 };