LibGUI: Add callbacks for Slider drags starting and ending

2 files changed, 11 insertions, 1 deletions

diff --git a/Userland/Libraries/LibGUI/Slider.cpp b/Userland/Libraries/LibGUI/Slider.cpp
index ce4c14217e..0f9a641c64 100644
--- a/Userland/Libraries/LibGUI/Slider.cpp
+++ b/Userland/Libraries/LibGUI/Slider.cpp
@@ -82,6 +82,8 @@ void Slider::start_drag(Gfx::IntPoint start_position)
     m_dragging = true;
     m_drag_origin = start_position;
     m_drag_origin_value = value();
+    if (on_drag_start)
+        on_drag_start();
 }
 
 void Slider::mousedown_event(MouseEvent& event)
@@ -98,8 +100,11 @@ void Slider::mousedown_event(MouseEvent& event)
             }
 
             int new_value = static_cast<int>(min() + ((max() - min()) * normalized_mouse_offset));
-            set_value(new_value);
+            set_value(new_value, AllowCallback::No);
             start_drag(event.position());
+            // Delay the callback to make it aware that a drag has started.
+            if (on_change)
+                on_change(new_value);
             return;
         }
 
@@ -136,6 +141,8 @@ void Slider::end_drag()
 {
     if (m_dragging) {
         m_dragging = false;
+        if (on_drag_end)
+            on_drag_end();
     }
 }
 
diff --git a/Userland/Libraries/LibGUI/Slider.h b/Userland/Libraries/LibGUI/Slider.h
index 56be2641eb..a2f3cfd800 100644
--- a/Userland/Libraries/LibGUI/Slider.h
+++ b/Userland/Libraries/LibGUI/Slider.h
@@ -40,6 +40,9 @@ public:
         return rect().shrunken(0, track_margin() * 2);
     }
 
+    Function<void()> on_drag_start;
+    Function<void()> on_drag_end;
+
 protected:
     explicit Slider(Orientation = Orientation::Vertical);