Taskbar: More bringup work. We now see a basic window list.

Applications/Taskbar/Makefile

@@ -1,6 +1,7 @@
 OBJS = \
     TaskbarWindow.o \
     TaskbarWidget.o \
+    WindowList.o \
     main.o
 
 APP = Taskbar

Applications/Taskbar/TaskbarWidget.cpp

@@ -5,13 +5,14 @@
 #include <LibGUI/GPainter.h>
 #include <stdio.h>
 
-TaskbarWidget::TaskbarWidget(GWidget* parent)
+TaskbarWidget::TaskbarWidget(WindowList& window_list, GWidget* parent)
     : GFrame(parent)
+    , m_window_list(window_list)
 {
     set_fill_with_background_color(true);
     set_layout(make<GBoxLayout>(Orientation::Horizontal));
-    layout()->set_margins({ 0, 8, 0, 8 });
-    layout()->set_spacing(8);
+    layout()->set_margins({ 0, 3, 0, 3 });
+    layout()->set_spacing(3);
 
     set_frame_thickness(1);
     set_frame_shape(GFrame::Shape::Panel);

Applications/Taskbar/TaskbarWidget.h

@@ -1,8 +1,10 @@
 #include <LibGUI/GFrame.h>
 
+class WindowList;
+
 class TaskbarWidget final : public GFrame {
 public:
-    TaskbarWidget(GWidget* parent = nullptr);
+    TaskbarWidget(WindowList&, GWidget* parent = nullptr);
     virtual ~TaskbarWidget() override;
 
     virtual const char* class_name() const override { return "TaskbarWidget"; }
@@ -10,4 +12,5 @@ public:
 private:
     virtual void paint_event(GPaintEvent&) override;
 
+    WindowList& m_window_list;
 };

Applications/Taskbar/TaskbarWindow.cpp

@@ -3,6 +3,7 @@
 #include <LibGUI/GWindow.h>
 #include <LibGUI/GDesktop.h>
 #include <LibGUI/GEventLoop.h>
+#include <LibGUI/GButton.h>
 #include <WindowServer/WSAPITypes.h>
 #include <stdio.h>
 
@@ -16,7 +17,7 @@ TaskbarWindow::TaskbarWindow()
 
     GDesktop::the().on_rect_change = [this] (const Rect& rect) { on_screen_rect_change(rect); };
 
-    auto* widget = new TaskbarWidget;
+    auto* widget = new TaskbarWidget(m_window_list);
     set_main_widget(widget);
 }
 
@@ -32,10 +33,51 @@ void TaskbarWindow::on_screen_rect_change(const Rect& rect)
 
 void TaskbarWindow::wm_event(GWMEvent& event)
 {
-#if 0
+    WindowIdentifier identifier { event.client_id(), event.window_id() };
     switch (event.type()) {
-    case GEvent::WM_WindowAdded:
-        m_window_list.append({})
+    case GEvent::WM_WindowAdded: {
+        auto& added_event = static_cast<GWMWindowAddedEvent&>(event);
+        printf("WM_WindowAdded: client_id=%d, window_id=%d, title=%s, rect=%s\n",
+            added_event.client_id(),
+            added_event.window_id(),
+            added_event.title().characters(),
+            added_event.rect().to_string().characters()
+        );
+        auto& window = m_window_list.ensure_window(identifier);
+        window.set_title(added_event.title());
+        window.set_rect(added_event.rect());
+        window.set_button(new GButton(main_widget()));
+        window.button()->set_size_policy(SizePolicy::Fixed, SizePolicy::Fixed);
+        window.button()->set_preferred_size({ 100, 22 });
+        window.button()->set_caption(window.title());
+        update();
+        break;
+    }
+    case GEvent::WM_WindowRemoved: {
+        auto& removed_event = static_cast<GWMWindowRemovedEvent&>(event);
+        printf("WM_WindowRemoved: client_id=%d, window_id=%d\n",
+            removed_event.client_id(),
+            removed_event.window_id()
+        );
+        m_window_list.remove_window(identifier);
+        update();
+        break;
+    }
+    case GEvent::WM_WindowStateChanged: {
+        auto& changed_event = static_cast<GWMWindowStateChangedEvent&>(event);
+        printf("WM_WindowStateChanged: client_id=%d, window_id=%d, title=%s, rect=%s\n",
+            changed_event.client_id(),
+            changed_event.window_id(),
+            changed_event.title().characters(),
+            changed_event.rect().to_string().characters()
+        );
+        auto& window = m_window_list.ensure_window(identifier);
+        window.set_title(changed_event.title());
+        window.set_rect(changed_event.rect());
+        window.button()->set_caption(changed_event.title());
+        break;
+    }
+    default:
+        break;
     }
-#endif
 }

Applications/Taskbar/TaskbarWindow.h

@@ -1,12 +1,13 @@
 #include <LibGUI/GWindow.h>
 #include <LibGUI/GWidget.h>
+#include "WindowList.h"
 
 class TaskbarWindow final : public GWindow {
 public:
     TaskbarWindow();
     virtual ~TaskbarWindow() override;
 
-    int taskbar_height() const { return 20; }
+    int taskbar_height() const { return 28; }
 
     virtual const char* class_name() const override { return "TaskbarWindow"; }
 
@@ -14,4 +15,6 @@ private:
     void on_screen_rect_change(const Rect&);
 
     virtual void wm_event(GWMEvent&) override;
+
+    WindowList m_window_list;
 };

Applications/Taskbar/WindowList.cpp

@@ -0,0 +1,17 @@
+#include "WindowList.h"
+
+Window& WindowList::ensure_window(const WindowIdentifier& identifier)
+{
+    auto it = m_windows.find(identifier);
+    if (it != m_windows.end())
+        return *it->value;
+    auto window = make<Window>(identifier);
+    auto& window_ref = *window;
+    m_windows.set(identifier, move(window));
+    return window_ref;
+}
+
+void WindowList::remove_window(const WindowIdentifier& identifier)
+{
+    m_windows.remove(identifier);
+}

Applications/Taskbar/WindowList.h

@@ -0,0 +1,80 @@
+#pragma once
+
+#include <AK/AKString.h>
+#include <AK/HashMap.h>
+#include <AK/Traits.h>
+#include <SharedGraphics/Rect.h>
+#include <LibGUI/GButton.h>
+
+class WindowIdentifier {
+public:
+    WindowIdentifier(int client_id, int window_id)
+        : m_client_id(client_id)
+        , m_window_id(window_id)
+    {
+    }
+
+    int client_id() const { return m_client_id; }
+    int window_id() const { return m_window_id; }
+
+    bool operator==(const WindowIdentifier& other) const
+    {
+        return m_client_id == other.m_client_id && m_window_id == other.m_window_id;
+    }
+private:
+    int m_client_id { -1 };
+    int m_window_id { -1 };
+};
+
+namespace AK {
+template<>
+struct Traits<WindowIdentifier> {
+    static unsigned hash(const WindowIdentifier& w) { return pair_int_hash(w.client_id(), w.window_id()); }
+    static void dump(const WindowIdentifier& w) { kprintf("WindowIdentifier(%d, %d)", w.client_id(), w.window_id()); }
+};
+}
+
+class Window {
+public:
+    explicit Window(const WindowIdentifier& identifier)
+        : m_identifier(identifier)
+    {
+    }
+
+    ~Window()
+    {
+        delete m_button;
+    }
+
+    WindowIdentifier identifier() const { return m_identifier; }
+
+    String title() const { return m_title; }
+    void set_title(const String& title) { m_title = title; }
+
+    Rect rect() const { return m_rect; }
+    void set_rect(const Rect& rect) { m_rect = rect; }
+
+    GButton* button() { return m_button; }
+    void set_button(GButton* button) { m_button = button; }
+
+private:
+    WindowIdentifier m_identifier;
+    String m_title;
+    Rect m_rect;
+    GButton* m_button { nullptr };
+};
+
+class WindowList {
+public:
+    template<typename Callback> void for_each_window(Callback callback)
+    {
+        for (auto& it : m_windows)
+            callback(*it.value);
+    }
+
+    Window& ensure_window(const WindowIdentifier&);
+    void remove_window(const WindowIdentifier&);
+
+private:
+    HashMap<WindowIdentifier, OwnPtr<Window>> m_windows;
+};