LibGUI: Implement rubber band selection in table view

This patch implements rubber band selection in table view while clamping
the rubber band rect to the widget inner rect, matching the behavior of
IconView and ColumnsView.

Userland/Libraries/LibGUI/TableView.cpp

@@ -2,6 +2,7 @@
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2022, Glenford Williams <gw_dev@outlook.com>
  * Copyright (c) 2022, the SerenityOS developers.
+ * Copyright (c) 2022, Jakob-Niklas See <git@nwex.de>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -161,6 +162,25 @@ void TableView::paint_event(PaintEvent& event)
         painter.fill_rect(unpainted_rect, widget_background_color);
 }
 
+void TableView::second_paint_event(PaintEvent& event)
+{
+    if (!m_rubber_banding)
+        return;
+
+    Painter painter(*this);
+    painter.add_clip_rect(event.rect());
+    painter.add_clip_rect(widget_inner_rect());
+
+    // The rubber band rect always borders the widget inner to the left and right
+    auto rubber_band_left = widget_inner_rect().left();
+    auto rubber_band_right = widget_inner_rect().right() + 1;
+
+    auto rubber_band_rect = Gfx::IntRect::from_two_points({ rubber_band_left, m_rubber_band_origin }, { rubber_band_right, m_rubber_band_current });
+
+    painter.fill_rect(rubber_band_rect, palette().rubber_band_fill());
+    painter.draw_rect(rubber_band_rect, palette().rubber_band_border());
+}
+
 void TableView::keydown_event(KeyEvent& event)
 {
     if (!model())
@@ -196,6 +216,68 @@ void TableView::keydown_event(KeyEvent& event)
     }
 }
 
+void TableView::mousedown_event(MouseEvent& event)
+{
+    AbstractTableView::mousedown_event(event);
+
+    if (!model())
+        return;
+
+    if (event.button() != MouseButton::Primary)
+        return;
+
+    if (m_might_drag)
+        return;
+
+    if (selection_mode() == SelectionMode::MultiSelection) {
+        m_rubber_banding = true;
+        m_rubber_band_origin = event.position().y();
+        m_rubber_band_current = event.position().y();
+    }
+}
+
+void TableView::mouseup_event(MouseEvent& event)
+{
+    AbstractTableView::mouseup_event(event);
+
+    if (m_rubber_banding && event.button() == MouseButton::Primary) {
+        m_rubber_banding = false;
+        update();
+    }
+}
+
+void TableView::mousemove_event(MouseEvent& event)
+{
+    if (m_rubber_banding) {
+        // The rubber band rect cannot go outside the bounds of the rect enclosing all rows
+        m_rubber_band_current = clamp(event.position().y(), widget_inner_rect().top() + column_header().height(), widget_inner_rect().bottom() + 1);
+
+        int row_count = model()->row_count();
+
+        clear_selection();
+
+        set_suppress_update_on_selection_change(true);
+
+        for (int row = 0; row < row_count; ++row) {
+            auto index = model()->index(row);
+            VERIFY(index.is_valid());
+
+            int row_top = row * row_height() + column_header().height();
+            int row_bottom = row * row_height() + row_height() + column_header().height();
+
+            if ((m_rubber_band_origin > row_top && m_rubber_band_current < row_top) || (m_rubber_band_origin > row_bottom && m_rubber_band_current < row_bottom)) {
+                add_selection(index);
+            }
+        }
+
+        set_suppress_update_on_selection_change(false);
+
+        update();
+    }
+
+    AbstractTableView::mousemove_event(event);
+}
+
 void TableView::move_cursor(CursorMovement movement, SelectionUpdate selection_update)
 {
     if (!model())

Userland/Libraries/LibGUI/TableView.h

@@ -41,12 +41,20 @@ protected:
     TableView();
 
     virtual void keydown_event(KeyEvent&) override;
+    virtual void mousedown_event(MouseEvent&) override;
+    virtual void mouseup_event(MouseEvent&) override;
+    virtual void mousemove_event(MouseEvent&) override;
     virtual void paint_event(PaintEvent&) override;
+    virtual void second_paint_event(PaintEvent&) override;
 
 private:
     GridStyle m_grid_style { GridStyle::None };
 
     bool m_highlight_key_column { true };
+
+    bool m_rubber_banding { false };
+    int m_rubber_band_origin { 0 };
+    int m_rubber_band_current { 0 };
 };
 
 }