LibWeb: Move mouse event and label logic from layout to painting tree

Input events have nothing to do with layout, so let's not send them to
layout nodes.

The job of Paintable starts to become clear. It represents a paintable
item that can be rendered into the viewport, which means it can also
be targeted by the mouse cursor.

1 files changed, 48 insertions, 0 deletions

diff --git a/Userland/Libraries/LibWeb/Painting/Paintable.cpp b/Userland/Libraries/LibWeb/Painting/Paintable.cpp
index 2e9eda8f9c..8747e80a16 100644
--- a/Userland/Libraries/LibWeb/Painting/Paintable.cpp
+++ b/Userland/Libraries/LibWeb/Painting/Paintable.cpp
@@ -287,4 +287,52 @@ void PaintableWithLines::paint(PaintContext& context, PaintPhase phase) const
     }
 }
 
+void Paintable::handle_mousedown(Badge<EventHandler>, Gfx::IntPoint const&, unsigned, unsigned)
+{
+}
+
+void Paintable::handle_mouseup(Badge<EventHandler>, Gfx::IntPoint const&, unsigned, unsigned)
+{
+}
+
+void Paintable::handle_mousemove(Badge<EventHandler>, Gfx::IntPoint const&, unsigned, unsigned)
+{
+}
+
+bool Paintable::handle_mousewheel(Badge<EventHandler>, Gfx::IntPoint const&, unsigned, unsigned, int wheel_delta_x, int wheel_delta_y)
+{
+    if (auto* containing_block = layout_node().containing_block()) {
+        if (!containing_block->is_scrollable())
+            return false;
+        auto new_offset = containing_block->scroll_offset();
+        new_offset.translate_by(wheel_delta_x, wheel_delta_y);
+        // FIXME: This const_cast is gross.
+        // FIXME: Scroll offset shouldn't live in the layout tree.
+        const_cast<Layout::BlockContainer*>(containing_block)->set_scroll_offset(new_offset);
+        return true;
+    }
+
+    return false;
+}
+
+bool PaintableWithLines::handle_mousewheel(Badge<EventHandler>, Gfx::IntPoint const&, unsigned, unsigned, int wheel_delta_x, int wheel_delta_y)
+{
+    if (!layout_box().is_scrollable())
+        return false;
+    auto new_offset = layout_box().scroll_offset();
+    new_offset.translate_by(wheel_delta_x, wheel_delta_y);
+    const_cast<Layout::BlockContainer&>(layout_box()).set_scroll_offset(new_offset);
+    return true;
+}
+
+Layout::BlockContainer const& PaintableWithLines::layout_box() const
+{
+    return static_cast<Layout::BlockContainer const&>(PaintableBox::layout_box());
+}
+
+Layout::BlockContainer& PaintableWithLines::layout_box()
+{
+    return static_cast<Layout::BlockContainer&>(PaintableBox::layout_box());
+}
+
 }