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

Applications/ProcessManager/main.cpp

@@ -6,6 +6,8 @@
 #include <LibGUI/GToolBar.h>
 #include <LibGUI/GMenuBar.h>
 #include <LibGUI/GAction.h>
+#include <LibGUI/GTabWidget.h>
+#include <LibGUI/GLabel.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <signal.h>
@@ -16,7 +18,15 @@ int main(int argc, char** argv)
 {
     GApplication app(argc, argv);
 
-    auto* widget = new GWidget;
+    auto* tabwidget = new GTabWidget(nullptr);
+
+    auto* widget = new GWidget(nullptr);
+    tabwidget->add_widget("Processes", widget);
+    auto* placeholder_label = new GLabel("Placeholder text");
+    placeholder_label->set_fill_with_background_color(true);
+    placeholder_label->set_background_color(Color::from_rgb(0xffc0c0));
+    tabwidget->add_widget("Placeholder", placeholder_label);
+
     widget->set_layout(make<GBoxLayout>(Orientation::Vertical));
 
     auto* toolbar = new GToolBar(widget);
@@ -90,7 +100,7 @@ int main(int argc, char** argv)
     auto* window = new GWindow;
     window->set_title("ProcessManager");
     window->set_rect(20, 200, 680, 400);
-    window->set_main_widget(widget);
+    window->set_main_widget(tabwidget);
     window->set_should_exit_event_loop_on_close(true);
     window->show();
 

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);
+    }
+}

LibGUI/GTabWidget.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <LibGUI/GWidget.h>
+
+class GTabWidget : public GWidget {
+public:
+    explicit GTabWidget(GWidget* parent);
+    virtual ~GTabWidget() override;
+
+    GWidget* active_widget() const { return m_active_widget; }
+    void set_active_widget(GWidget*);
+
+    int bar_height() const { return 22; }
+
+    void add_widget(const String&, GWidget*);
+
+    virtual const char* class_name() const override { return "GTabWidget"; }
+
+protected:
+    virtual void paint_event(GPaintEvent&) override;
+    virtual void child_event(CChildEvent&) override;
+    virtual void resize_event(GResizeEvent&) override;
+    virtual void mousedown_event(GMouseEvent&) override;
+
+private:
+    Rect child_rect_for_size(const Size&) const;
+    Rect button_rect(int index) const;
+    Rect bar_rect() const;
+
+    GWidget* m_active_widget { nullptr };
+
+    struct TabData {
+        Rect rect(const Font&) const;
+        int width(const Font&) const;
+        String title;
+        GWidget* widget { nullptr };
+    };
+    Vector<TabData> m_tabs;
+};

LibGUI/Makefile

@@ -54,6 +54,7 @@ LIBGUI_OBJS = \
     GGroupBox.o \
     GSlider.o \
     GResizeCorner.o \
+    GTabWidget.o \
     GWindow.o
 
 OBJS = $(SHAREDGRAPHICS_OBJS) $(LIBGUI_OBJS)