Put dropdown window on active screen under Wayland (#1196)

All complex problems in implementing this feature were caused by resizing the window programmatically on Wayland, as was done on X11. This patch sets 4 anchors instead, and then sets the left, right and bottom margins properly on showing the window.

Fixes #1142

src/mainwindow.cpp

@@ -69,7 +69,8 @@ MainWindow::MainWindow(TerminalConfig &cfg,
       presetsMenu(nullptr),
       m_config(cfg),
       m_dropLockButton(nullptr),
-      m_dropMode(dropMode)
+      m_dropMode(dropMode),
+      m_layerWindow(nullptr)
 {
 #ifdef HAVE_QDBUS
     registerAdapter<WindowAdaptor, MainWindow>(this);
@@ -176,12 +177,17 @@ void MainWindow::enableDropMode()
         winId();
         if (QWindow *win = windowHandle())
         {
-            if (LayerShellQt::Window* layershell = LayerShellQt::Window::get(win))
+            m_layerWindow = LayerShellQt::Window::get(win);
+            if (m_layerWindow)
             {
-                layershell->setLayer(LayerShellQt::Window::Layer::LayerOverlay);
-                layershell->setKeyboardInteractivity(LayerShellQt::Window::KeyboardInteractivityOnDemand);
-                LayerShellQt::Window::Anchors anchors = {LayerShellQt::Window::AnchorTop};
-                layershell->setAnchors(anchors);
+                m_layerWindow->setLayer(LayerShellQt::Window::Layer::LayerOverlay);
+                m_layerWindow->setKeyboardInteractivity(LayerShellQt::Window::KeyboardInteractivityOnDemand);
+                LayerShellQt::Window::Anchors anchors = {LayerShellQt::Window::AnchorTop
+                                                         | LayerShellQt::Window::AnchorBottom
+                                                         | LayerShellQt::Window::AnchorLeft
+                                                         | LayerShellQt::Window::AnchorRight};
+                m_layerWindow->setAnchors(anchors);
+                m_layerWindow->setScreenConfiguration(LayerShellQt::Window::ScreenConfiguration::ScreenFromCompositor);
             }
         }
     }
@@ -757,9 +763,15 @@ void MainWindow::realign()
 {
     if (m_dropMode)
     {
+        if (m_layerWindow)
+        {
+            return; // done in showEvent
+        }
         QScreen *appScreen = QGuiApplication::screenAt(QCursor::pos());
         if(appScreen == nullptr)
+        {
             appScreen = QGuiApplication::primaryScreen();
+        }
         const QRect desktop = appScreen->availableGeometry();
         QRect g = QRect(desktop.x(),
                         desktop.y(),
@@ -768,7 +780,8 @@ void MainWindow::realign()
         g.moveCenter(desktop.center());
         // do not use 0 here - we need to calculate with potential panel on top
         g.moveTop(desktop.top());
-        if (g != geometry()) {
+        if (g != geometry())
+        {
             setGeometry(g);
         }
     }
@@ -871,6 +884,18 @@ bool MainWindow::event(QEvent *event)
     return QMainWindow::event(event);
 }
 
+void MainWindow::showEvent(QShowEvent* event)
+{
+    if (m_dropMode && m_layerWindow)
+    {
+        const QRect desktop = windowHandle()->screen()->availableGeometry();
+        int hMargin = desktop.width() * (100 - Properties::Instance()->dropWidth) / 200;
+        int vMargin = desktop.height() * (100 - Properties::Instance()->dropHeight) / 100;
+        m_layerWindow->setMargins(QMargins(hMargin, 0, hMargin, vMargin));
+    }
+    QMainWindow::showEvent(event);
+}
+
 void MainWindow::newTerminalWindow()
 {
     TerminalConfig cfg;

src/mainwindow.h

@@ -28,6 +28,9 @@
 #include "terminalconfig.h"
 #include "dbusaddressable.h"
 
+namespace LayerShellQt {
+    class Window;
+}
 
 class QToolButton;
 
@@ -55,6 +58,7 @@ class MainWindow : public QMainWindow, private Ui::mainWindow, public DBusAddres
 
 protected:
      bool event(QEvent* event) override;
+     void showEvent(QShowEvent* event) override;
 
 private:
     QActionGroup *tabPosition, *scrollBarPosition, *keyboardCursorShape;
@@ -86,6 +90,7 @@ class MainWindow : public QMainWindow, private Ui::mainWindow, public DBusAddres
     void enableDropMode();
     QToolButton *m_dropLockButton;
     bool m_dropMode;
+    LayerShellQt::Window *m_layerWindow;
     QxtGlobalShortcut m_dropShortcut;
     void realign();
     void setDropShortcut(const QKeySequence& dropShortCut);