Applets: Add DesktopPicker applet

This applet displays a grid of desktops, and shows the user what virtual
desktop they are on. When clicked, the desktop will be changed.

Base/etc/SystemServer.ini

@@ -94,6 +94,11 @@ SocketPermissions=600
 Priority=low
 User=anon
 
+[DesktopPicker.Applet]
+Priority=low
+KeepAlive=1
+User=anon
+
 [ResourceGraph.Applet]
 Arguments=--cpu=CPUGraph,#00bb00 --memory=MemoryGraph,#00bbbb
 Priority=low

Userland/Applets/CMakeLists.txt

@@ -2,3 +2,4 @@ add_subdirectory(Audio)
 add_subdirectory(ClipboardHistory)
 add_subdirectory(Network)
 add_subdirectory(ResourceGraph)
+add_subdirectory(DesktopPicker)

Userland/Applets/DesktopPicker/CMakeLists.txt

@@ -0,0 +1,13 @@
+serenity_component(
+    DesktopPicker.Applet
+    REQUIRED
+    TARGETS DesktopPicker.Applet
+)
+
+set(SOURCES
+    DesktopStatusWindow.cpp
+    main.cpp
+)
+
+serenity_bin(DesktopPicker.Applet)
+target_link_libraries(DesktopPicker.Applet LibGUI LibCore LibGfx)

Userland/Applets/DesktopPicker/DesktopStatusWindow.cpp

@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2021, Peter Elliott <pelliott@ualberta.ca>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "DesktopStatusWindow.h"
+#include <LibGUI/Desktop.h>
+#include <LibGUI/Painter.h>
+#include <LibGUI/Widget.h>
+#include <LibGUI/WindowManagerServerConnection.h>
+#include <LibGfx/Palette.h>
+
+class DesktopStatusWidget : public GUI::Widget {
+    C_OBJECT(DesktopStatusWidget);
+
+public:
+    virtual ~DesktopStatusWidget() override
+    {
+    }
+
+    Gfx::IntRect rect_for_desktop(unsigned row, unsigned col) const
+    {
+        auto& desktop = GUI::Desktop::the();
+
+        auto vcols = desktop.virtual_desktop_columns();
+        auto vrows = desktop.virtual_desktop_rows();
+
+        auto desktop_width = (width() - gap() * (vcols - 1)) / vcols;
+        auto desktop_height = (height() - gap() * (vrows - 1)) / vrows;
+
+        return {
+            col * (desktop_width + gap()), row * (desktop_height + gap()),
+            desktop_width, desktop_height
+        };
+    }
+
+    virtual void paint_event(GUI::PaintEvent& event) override
+    {
+        GUI::Widget::paint_event(event);
+
+        GUI::Painter painter(*this);
+        painter.add_clip_rect(event.rect());
+        painter.fill_rect({ 0, 0, width(), height() }, palette().button());
+
+        auto& desktop = GUI::Desktop::the();
+
+        auto active_color = palette().active_window_border1();
+        auto inactive_color = palette().inactive_window_border1();
+
+        for (unsigned row = 0; row < desktop.virtual_desktop_rows(); ++row) {
+            for (unsigned col = 0; col < desktop.virtual_desktop_columns(); ++col) {
+                painter.fill_rect(rect_for_desktop(row, col),
+                    (row == current_row() && col == current_col()) ? active_color : inactive_color);
+            }
+        }
+    }
+
+    virtual void mousedown_event(GUI::MouseEvent& event) override
+    {
+        auto base_rect = rect_for_desktop(0, 0);
+        auto row = event.y() / (base_rect.height() + gap());
+        auto col = event.x() / (base_rect.width() + gap());
+
+        // Handle case where divider is clicked.
+        if (rect_for_desktop(row, col).contains(event.position()))
+            GUI::WindowManagerServerConnection::the().async_set_virtual_desktop(row, col);
+    }
+
+    unsigned current_row() const { return m_current_row; }
+    void set_current_row(unsigned row) { m_current_row = row; }
+    unsigned current_col() const { return m_current_col; }
+    void set_current_col(unsigned col) { m_current_col = col; }
+
+    unsigned gap() const { return m_gap; }
+
+private:
+    DesktopStatusWidget()
+    {
+    }
+
+    unsigned m_gap { 1 };
+
+    unsigned m_current_row;
+    unsigned m_current_col;
+};
+
+DesktopStatusWindow::DesktopStatusWindow()
+{
+    GUI::Desktop::the().on_receive_screen_rects([&](GUI::Desktop&) {
+        update();
+    });
+    set_window_type(GUI::WindowType::Applet);
+    set_has_alpha_channel(true);
+    m_widget = &set_main_widget<DesktopStatusWidget>();
+}
+
+DesktopStatusWindow::~DesktopStatusWindow()
+{
+}
+
+void DesktopStatusWindow::wm_event(GUI::WMEvent& event)
+{
+    if (event.type() == GUI::Event::WM_VirtualDesktopChanged) {
+        auto& changed_event = static_cast<GUI::WMVirtualDesktopChangedEvent&>(event);
+        m_widget->set_current_row(changed_event.current_row());
+        m_widget->set_current_col(changed_event.current_column());
+        update();
+    }
+}

Userland/Applets/DesktopPicker/DesktopStatusWindow.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2021, Peter Elliott <pelliott@ualberta.ca>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibGUI/Window.h>
+
+class DesktopStatusWidget;
+
+class DesktopStatusWindow : public GUI::Window {
+    C_OBJECT(DesktopStatusWindow);
+
+public:
+    virtual ~DesktopStatusWindow() override;
+
+    virtual void wm_event(GUI::WMEvent&) override;
+
+private:
+    DesktopStatusWindow();
+
+    DesktopStatusWidget* m_widget;
+};

Userland/Applets/DesktopPicker/main.cpp

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2021, Peter Elliott <pelliott@ualberta.ca>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "DesktopStatusWindow.h"
+#include <LibGUI/Application.h>
+#include <LibGUI/Frame.h>
+#include <LibGUI/Painter.h>
+#include <LibGUI/Window.h>
+#include <LibGUI/WindowManagerServerConnection.h>
+#include <WindowServer/Window.h>
+#include <serenity.h>
+#include <stdio.h>
+
+int main(int argc, char** argv)
+{
+    if (pledge("stdio recvfd sendfd rpath unix", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    auto app = GUI::Application::construct(argc, argv);
+
+    // We need to obtain the WM connection here as well before the pledge shortening.
+    GUI::WindowManagerServerConnection::the();
+
+    if (pledge("stdio recvfd sendfd rpath", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    auto window = DesktopStatusWindow::construct();
+    window->resize(28, 16);
+    window->show();
+    window->make_window_manager(WindowServer::WMEventMask::VirtualDesktopChanges);
+
+    return app->exec();
+}