LibGUI: Start working on a tabbed widget container: GTabWidget.

LibGUI/GTabWidget.cpp

@@ -0,0 +1,114 @@
+#include <LibGUI/GTabWidget.h>
+#include <LibGUI/GBoxLayout.h>
+#include <LibGUI/GPainter.h>
+#include <SharedGraphics/StylePainter.h>
+
+GTabWidget::GTabWidget(GWidget* parent)
+    : GWidget(parent)
+{
+}
+
+GTabWidget::~GTabWidget()
+{
+}
+
+void GTabWidget::add_widget(const String& 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_rect());
+}
+
+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 { { 0, bar_height() }, { size.width(), size.height() - bar_height() } };
+}
+
+void GTabWidget::child_event(CChildEvent& event)
+{
+    if (!event.child() || !event.child()->is_widget())
+        return GWidget::child_event(event);
+    auto& child = static_cast<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 (auto* new_child : children()) {
+                if (new_child->is_widget()) {
+                    new_active_widget = static_cast<GWidget*>(new_child);
+                    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());
+
+    painter.fill_rect(bar_rect(), Color::MidGray);
+
+    for (int i = 0; i < m_tabs.size(); ++i) {
+        auto button_rect = this->button_rect(i);
+        StylePainter::paint_button(painter, button_rect, ButtonStyle::Normal, m_tabs[i].widget == m_active_widget);
+        painter.draw_text(button_rect, m_tabs[i].title, TextAlignment::Center);
+    }
+}
+
+Rect GTabWidget::button_rect(int index) const
+{
+    int x_offset = 0;
+    for (int i = 0; i < index; ++i)
+        x_offset += m_tabs[i].width(font());
+    return { x_offset, 0, m_tabs[index].width(font()), bar_height() };
+}
+
+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);
+    }
+}