WindowServer: Windows tile when moved onto the edge of the screen

Servers/WindowServer/WSWindow.cpp

@@ -340,3 +340,33 @@ void WSWindow::set_fullscreen(bool fullscreen)
     CEventLoop::current().post_event(*this, make<WSResizeEvent>(m_rect, new_window_rect));
     set_rect(new_window_rect);
 }
+
+void WSWindow::set_tiled(WindowTileType tiled)
+{
+    if (m_tiled == tiled)
+        return;
+    m_tiled = tiled;
+    auto old_rect = m_rect;
+
+    auto frame_width = m_frame.rect().width() - m_rect.width();
+    switch (tiled) {
+        case WindowTileType::None :
+        set_rect(m_untiled_rect);
+        break;
+    case WindowTileType::Left :
+        m_untiled_rect = m_rect;
+        set_rect(0,
+                WSWindowManager::the().maximized_window_rect(*this).y(),
+                WSScreen::the().width() / 2,
+                WSWindowManager::the().maximized_window_rect(*this).height());
+        break;
+    case WindowTileType::Right :
+        m_untiled_rect = m_rect;
+        set_rect(WSScreen::the().width() / 2 + frame_width,
+                WSWindowManager::the().maximized_window_rect(*this).y(),
+                (WSScreen::the().width() / 2),
+                WSWindowManager::the().maximized_window_rect(*this).height());
+        break;
+    }
+    CEventLoop::current().post_event(*this, make<WSResizeEvent>(old_rect, m_rect));
+}

Servers/WindowServer/WSWindow.h

@@ -21,6 +21,12 @@ enum WSWMEventMask {
     WindowRemovals = 1 << 3,
 };
 
+enum class WindowTileType {
+    None = 0,
+    Left,
+    Right,
+};
+
 class WSWindow final : public CObject
     , public InlineLinkedListNode<WSWindow> {
     C_OBJECT(WSWindow)
@@ -44,6 +50,9 @@ public:
     bool is_fullscreen() const { return m_fullscreen; }
     void set_fullscreen(bool);
 
+    WindowTileType tiled() const { return m_tiled; }
+    void set_tiled(WindowTileType);
+
     bool is_occluded() const { return m_occluded; }
     void set_occluded(bool);
 
@@ -194,6 +203,8 @@ private:
     bool m_minimized { false };
     bool m_maximized { false };
     bool m_fullscreen { false };
+    WindowTileType m_tiled { WindowTileType::None };
+    Rect m_untiled_rect;
     bool m_occluded { false };
     bool m_show_titlebar { true };
     RefPtr<GraphicsBitmap> m_backing_store;

Servers/WindowServer/WSWindowManager.cpp

@@ -543,6 +543,7 @@ bool WSWindowManager::process_ongoing_window_move(WSMouseEvent& event, WSWindow*
 #ifdef MOVE_DEBUG
         dbg() << "[WM] Finish moving WSWindow{" << m_move_window << "}";
 #endif
+
         invalidate(*m_move_window);
         if (m_move_window->rect().contains(event.position()))
             hovered_window = m_move_window;
@@ -565,7 +566,9 @@ bool WSWindowManager::process_ongoing_window_move(WSMouseEvent& event, WSWindow*
         if (m_move_window->is_maximized()) {
             dbg() << "  [!] The window is still maximized. Not moving yet.";
         }
+
 #endif
+
         if (m_move_window->is_maximized()) {
             auto pixels_moved_from_start = event.position().pixels_moved(m_move_origin);
             // dbg() << "[WM] " << pixels_moved_from_start << " moved since start of window move";
@@ -578,10 +581,20 @@ bool WSWindowManager::process_ongoing_window_move(WSMouseEvent& event, WSWindow*
                 m_move_window_origin = m_move_window->position();
             }
         } else {
-            Point pos = m_move_window_origin.translated(event.position() - m_move_origin);
+            auto pixels_moved_from_start = event.position().pixels_moved(m_move_origin);
-            m_move_window->set_position_without_repaint(pos);
+            const int tiling_deadzone = 5;
-            if (m_move_window->rect().contains(event.position()))
+
-                hovered_window = m_move_window;
+            if (event.x() <= tiling_deadzone) {
+                m_move_window->set_tiled(WindowTileType::Left);
+            } else if (event.x() >= WSScreen::the().width() - tiling_deadzone) {
+                m_move_window->set_tiled(WindowTileType::Right);
+            } else if (pixels_moved_from_start > 5 || m_move_window->tiled() == WindowTileType::None) {
+                m_move_window->set_tiled(WindowTileType::None);
+                Point pos = m_move_window_origin.translated(event.position() - m_move_origin);
+                m_move_window->set_position_without_repaint(pos);
+                if (m_move_window->rect().contains(event.position()))
+                    hovered_window = m_move_window;
+            }
             return true;
         }
     }