Libraries: Create top level directory for libraries.

Things were getting a little crowded in the project root, so this patch
moves the Lib*/ directories into Libraries/.

Libraries/LibGUI/GTabWidget.cpp

@@ -0,0 +1,176 @@
+#include <LibGUI/GBoxLayout.h>
+#include <LibGUI/GPainter.h>
+#include <LibGUI/GTabWidget.h>
+#include <SharedGraphics/StylePainter.h>
+
+GTabWidget::GTabWidget(GWidget* parent)
+    : GWidget(parent)
+{
+    set_fill_with_background_color(true);
+    set_background_color(Color::WarmGray);
+}
+
+GTabWidget::~GTabWidget()
+{
+}
+
+void GTabWidget::add_widget(const StringView& title, GWidget* widget)
+{
+    m_tabs.append({ title, widget });
+    add_child(*widget);
+}
+
+void GTabWidget::set_active_widget(GWidget* widget)
+{
+    if (widget == m_active_widget)
+        return;
+
+    if (m_active_widget)
+        m_active_widget->set_visible(false);
+    m_active_widget = widget;
+    if (m_active_widget) {
+        m_active_widget->set_relative_rect(child_rect_for_size(size()));
+        m_active_widget->set_visible(true);
+    }
+
+    update_bar();
+}
+
+void GTabWidget::resize_event(GResizeEvent& event)
+{
+    if (!m_active_widget)
+        return;
+    m_active_widget->set_relative_rect(child_rect_for_size(event.size()));
+}
+
+Rect GTabWidget::child_rect_for_size(const Size& size) const
+{
+    return { { container_padding(), bar_height() + container_padding() }, { size.width() - container_padding() * 2, size.height() - bar_height() - container_padding() * 2 } };
+}
+
+void GTabWidget::child_event(CChildEvent& event)
+{
+    if (!event.child() || !is<GWidget>(*event.child()))
+        return GWidget::child_event(event);
+    auto& child = to<GWidget>(*event.child());
+    if (event.type() == GEvent::ChildAdded) {
+        if (!m_active_widget)
+            set_active_widget(&child);
+        else if (m_active_widget != &child)
+            child.set_visible(false);
+    } else if (event.type() == GEvent::ChildRemoved) {
+        if (m_active_widget == &child) {
+            GWidget* new_active_widget = nullptr;
+            for_each_child_widget([&](auto& new_child) {
+                new_active_widget = &new_child;
+                return IterationDecision::Break;
+            });
+            set_active_widget(new_active_widget);
+        }
+    }
+    GWidget::child_event(event);
+}
+
+Rect GTabWidget::bar_rect() const
+{
+    return { 0, 0, width(), bar_height() };
+}
+
+void GTabWidget::paint_event(GPaintEvent& event)
+{
+    GPainter painter(*this);
+    painter.add_clip_rect(event.rect());
+
+    Rect container_rect { 0, bar_height(), width(), height() - bar_height() };
+    auto padding_rect = container_rect;
+    for (int i = 0; i < container_padding(); ++i) {
+        painter.draw_rect(padding_rect, background_color());
+        padding_rect.shrink(2, 2);
+    }
+
+    StylePainter::paint_frame(painter, container_rect, FrameShape::Container, FrameShadow::Raised, 2);
+
+    for (int i = 0; i < m_tabs.size(); ++i) {
+        if (m_tabs[i].widget == m_active_widget)
+            continue;
+        bool hovered = i == m_hovered_tab_index;
+        auto button_rect = this->button_rect(i);
+        StylePainter::paint_tab_button(painter, button_rect, false, hovered, m_tabs[i].widget->is_enabled());
+        painter.draw_text(button_rect.translated(0, 1), m_tabs[i].title, TextAlignment::Center);
+    }
+
+    for (int i = 0; i < m_tabs.size(); ++i) {
+        if (m_tabs[i].widget != m_active_widget)
+            continue;
+        bool hovered = i == m_hovered_tab_index;
+        auto button_rect = this->button_rect(i);
+        StylePainter::paint_tab_button(painter, button_rect, true, hovered, m_tabs[i].widget->is_enabled());
+        painter.draw_text(button_rect.translated(0, 1), m_tabs[i].title, TextAlignment::Center);
+        painter.draw_line(button_rect.bottom_left().translated(1, 1), button_rect.bottom_right().translated(-1, 1), background_color());
+        break;
+    }
+}
+
+Rect GTabWidget::button_rect(int index) const
+{
+    int x_offset = 2;
+    for (int i = 0; i < index; ++i)
+        x_offset += m_tabs[i].width(font());
+    Rect rect { x_offset, 0, m_tabs[index].width(font()), bar_height() };
+    if (m_tabs[index].widget != m_active_widget) {
+        rect.move_by(0, 2);
+        rect.set_height(rect.height() - 2);
+    } else {
+        rect.move_by(-2, 0);
+        rect.set_width(rect.width() + 4);
+    }
+    return rect;
+}
+
+int GTabWidget::TabData::width(const Font& font) const
+{
+    return 16 + font.width(title);
+}
+
+void GTabWidget::mousedown_event(GMouseEvent& event)
+{
+    for (int i = 0; i < m_tabs.size(); ++i) {
+        auto button_rect = this->button_rect(i);
+        if (!button_rect.contains(event.position()))
+            continue;
+        set_active_widget(m_tabs[i].widget);
+        return;
+    }
+}
+
+void GTabWidget::mousemove_event(GMouseEvent& event)
+{
+    int hovered_tab = -1;
+    for (int i = 0; i < m_tabs.size(); ++i) {
+        auto button_rect = this->button_rect(i);
+        if (!button_rect.contains(event.position()))
+            continue;
+        hovered_tab = i;
+        if (m_tabs[i].widget == m_active_widget)
+            break;
+    }
+    if (hovered_tab == m_hovered_tab_index)
+        return;
+    m_hovered_tab_index = hovered_tab;
+    update_bar();
+}
+
+void GTabWidget::leave_event(CEvent&)
+{
+    if (m_hovered_tab_index != -1) {
+        m_hovered_tab_index = -1;
+        update_bar();
+    }
+}
+
+void GTabWidget::update_bar()
+{
+    auto invalidation_rect = bar_rect();
+    invalidation_rect.set_height(invalidation_rect.height() + 1);
+    update(invalidation_rect);
+}