LibGUI: Add page_step setting to AbstractSlider and use it in Slider

This makes clicking on the track of a GUI::Slider actually move the
knob more than 1 value unit (assuming page_step > 1)

Author: awesomekling

Libraries/LibGUI/AbstractSlider.cpp

@@ -36,9 +36,11 @@ namespace GUI {
 AbstractSlider::AbstractSlider(Orientation orientation)
     : m_orientation(orientation)
 {
+    REGISTER_INT_PROPERTY("value", value, set_value);
     REGISTER_INT_PROPERTY("min", min, set_min);
     REGISTER_INT_PROPERTY("max", max, set_max);
     REGISTER_INT_PROPERTY("step", step, set_step);
+    REGISTER_INT_PROPERTY("page_step", page_step, set_page_step);
     REGISTER_ENUM_PROPERTY("orientation", this->orientation, set_orientation, Orientation,
         { Orientation::Horizontal, "Horizontal" },
         { Orientation::Vertical, "Vertical" });
@@ -56,6 +58,11 @@ void AbstractSlider::set_orientation(Orientation value)
     update();
 }
 
+void AbstractSlider::set_page_step(int page_step)
+{
+    m_page_step = AK::max(0, page_step);
+}
+
 void AbstractSlider::set_range(int min, int max)
 {
     ASSERT(min <= max);

Libraries/LibGUI/AbstractSlider.h

@@ -43,13 +43,15 @@ class AbstractSlider : public Widget {
     int min() const { return m_min; }
     int max() const { return m_max; }
     int step() const { return m_step; }
+    int page_step() const { return m_page_step; }
 
     void set_range(int min, int max);
     void set_value(int);
 
     void set_min(int min) { set_range(min, max()); }
     void set_max(int max) { set_range(min(), max); }
     void set_step(int step) { m_step = step; }
+    void set_page_step(int page_step);
 
     Function<void(int)> on_value_changed;
 
@@ -63,6 +65,7 @@ class AbstractSlider : public Widget {
     int m_min { 0 };
     int m_max { 100 };
     int m_step { 1 };
+    int m_page_step { 10 };
     Orientation m_orientation { Orientation::Horizontal };
 };
 

Libraries/LibGUI/Slider.cpp

@@ -105,9 +105,9 @@ void Slider::mousedown_event(MouseEvent& event)
             return;
         } else {
             if (event.position().primary_offset_for_orientation(orientation()) > knob_rect().last_edge_for_orientation(orientation()))
-                set_value(value() + 1);
+                set_value(value() + page_step());
             else if (event.position().primary_offset_for_orientation(orientation()) < knob_rect().first_edge_for_orientation(orientation()))
-                set_value(value() - 1);
+                set_value(value() - page_step());
         }
     }
     return Widget::mousedown_event(event);