LibGUI: Improve IconView rubberband performance

Rather than invalidating the entire window, which is very expensive on
the transparent desktop widget, just invalidate the areas that actually
need updating.

Userland/Libraries/LibGUI/AbstractView.cpp

@@ -208,7 +208,8 @@ void AbstractView::notify_selection_changed(Badge<ModelSelection>)
     did_update_selection();
     if (on_selection_change)
         on_selection_change();
-    update();
+    if (!m_suppress_update_on_selection_change)
+        update();
 }
 
 NonnullRefPtr<Gfx::Font> AbstractView::font_for_index(const ModelIndex& index) const

Userland/Libraries/LibGUI/AbstractView.h

@@ -171,6 +171,8 @@ protected:
 
     void draw_item_text(Gfx::Painter&, const ModelIndex&, bool, const Gfx::IntRect&, const StringView&, const Gfx::Font&, Gfx::TextAlignment, Gfx::TextElision);
 
+    void set_suppress_update_on_selection_change(bool value) { m_suppress_update_on_selection_change = value; }
+
     virtual void did_scroll() override;
     void set_hovered_index(const ModelIndex&);
     void activate(const ModelIndex&);
@@ -215,6 +217,7 @@ private:
     bool m_tab_key_navigation_enabled { false };
     bool m_is_dragging { false };
     bool m_draw_item_text_with_shadow { false };
+    bool m_suppress_update_on_selection_change { false };
 };
 
 }

Userland/Libraries/LibGUI/IconView.cpp

@@ -258,7 +258,7 @@ void IconView::mouseup_event(MouseEvent& event)
         m_rubber_banding = false;
         if (m_out_of_view_timer)
             m_out_of_view_timer->stop();
-        update();
+        update(to_widget_rect(Gfx::IntRect::from_two_points(m_rubber_band_origin, m_rubber_band_current)));
     }
     AbstractView::mouseup_event(event);
 }
@@ -268,8 +268,15 @@ bool IconView::update_rubber_banding(const Gfx::IntPoint& position)
     auto adjusted_position = to_content_position(position);
     if (m_rubber_band_current != adjusted_position) {
         auto prev_rect = Gfx::IntRect::from_two_points(m_rubber_band_origin, m_rubber_band_current);
+        auto prev_rubber_band_fill_rect = prev_rect.shrunken(1, 1);
         m_rubber_band_current = adjusted_position;
         auto rubber_band_rect = Gfx::IntRect::from_two_points(m_rubber_band_origin, m_rubber_band_current);
+        auto rubber_band_fill_rect = rubber_band_rect.shrunken(1, 1);
+
+        for (auto& rect : prev_rubber_band_fill_rect.shatter(rubber_band_fill_rect))
+            update(to_widget_rect(rect.inflated(1, 1)));
+        for (auto& rect : rubber_band_fill_rect.shatter(prev_rubber_band_fill_rect))
+            update(to_widget_rect(rect.inflated(1, 1)));
 
         // If the rectangle width or height is 0, we still want to be able
         // to match the items in the path. An easy work-around for this
@@ -302,11 +309,16 @@ bool IconView::update_rubber_banding(const Gfx::IntPoint& position)
             return IterationDecision::Continue;
         });
 
+        // We're changing the selection and invalidating those items, so
+        // no need to trigger a full re-render for each item
+        set_suppress_update_on_selection_change(true);
+
         // Now toggle all items that are no longer in the selected area, once only
         for_each_item_intersecting_rects(deselect_area, [&](ItemData& item_data) -> IterationDecision {
             if (!item_data.selection_toggled && item_data.is_intersecting(prev_rect) && !item_data.is_intersecting(rubber_band_rect)) {
                 item_data.selection_toggled = true;
                 toggle_selection(item_data);
+                update(to_widget_rect(item_data.rect()));
             }
             return IterationDecision::Continue;
         });
@@ -315,11 +327,13 @@ bool IconView::update_rubber_banding(const Gfx::IntPoint& position)
             if (!item_data.selection_toggled && !item_data.is_intersecting(prev_rect) && item_data.is_intersecting(rubber_band_rect)) {
                 item_data.selection_toggled = true;
                 toggle_selection(item_data);
+                update(to_widget_rect(item_data.rect()));
             }
             return IterationDecision::Continue;
         });
 
-        update();
+        set_suppress_update_on_selection_change(false);
+
         return true;
     }
     return false;
@@ -491,8 +505,8 @@ void IconView::paint_event(PaintEvent& event)
     painter.add_clip_rect(widget_inner_rect());
     painter.add_clip_rect(event.rect());
 
-    if (fill_with_background_color())
+    painter.fill_rect(event.rect(), fill_with_background_color() ? widget_background_color : Color::Transparent);
-        painter.fill_rect(event.rect(), widget_background_color);
+
     painter.translate(frame_thickness(), frame_thickness());
     painter.translate(-horizontal_scrollbar().value(), -vertical_scrollbar().value());
 

Userland/Libraries/LibGUI/IconView.h

@@ -109,6 +109,11 @@ private:
             VERIFY(valid);
             return icon_rect.contains(point) || text_rect.contains(point);
         }
+
+        Gfx::IntRect rect() const
+        {
+            return text_rect.united(icon_rect);
+        }
     };
 
     template<typename Function>

Userland/Libraries/LibGfx/Painter.h

@@ -129,6 +129,8 @@ public:
         m_state_stack.take_last();
     }
 
+    IntRect clip_rect() const { return state().clip_rect; }
+
 protected:
     IntPoint translation() const { return state().translation; }
     IntRect to_physical(const IntRect& r) const { return r.translated(translation()) * scale(); }
@@ -139,7 +141,6 @@ protected:
     void fill_rect_with_draw_op(const IntRect&, Color);
     void blit_with_opacity(const IntPoint&, const Gfx::Bitmap&, const IntRect& src_rect, float opacity, bool apply_alpha = true);
     void draw_physical_pixel(const IntPoint&, Color, int thickness = 1);
-    IntRect clip_rect() const { return state().clip_rect; }
 
     struct State {
         const Font* font;