platforms/x11: Introduce X11PlaceholderOutput

It is useful in case the Xrandr extension is unavailable or no outputs
are connected.

plugins/platforms/x11/standalone/CMakeLists.txt

@@ -12,6 +12,7 @@ set(X11PLATFORM_SOURCES
     x11_output.cpp
     x11_platform.cpp
     x11cursor.cpp
+    x11placeholderoutput.cpp
     xfixes_cursor_event_filter.cpp
 )
 

plugins/platforms/x11/standalone/x11_platform.cpp

@@ -8,6 +8,7 @@
 */
 #include "x11_platform.h"
 #include "x11cursor.h"
+#include "x11placeholderoutput.h"
 #include "edge.h"
 #include "windowselector.h"
 #ifdef KWIN_HAVE_XRENDER_COMPOSITING
@@ -436,20 +437,17 @@ template <typename T>
 void X11StandalonePlatform::doUpdateOutputs()
 {
     auto fallback = [this]() {
-        auto *o = new X11Output(this);
-        o->setGammaRampSize(0);
-        o->setRefreshRate(60000);
-        o->setName(QStringLiteral("Xinerama"));
-        m_outputs << o;
-        emit outputAdded(o);
-        emit outputEnabled(o);
+        X11PlaceholderOutput *dummyOutput = new X11PlaceholderOutput();
+        m_outputs << dummyOutput;
+        emit outputAdded(dummyOutput);
+        emit outputEnabled(dummyOutput);
     };
 
     // TODO: instead of resetting all outputs, check if new output is added/removed
     //       or still available and leave still available outputs in m_outputs
     //       untouched (like in DRM backend)
     while (!m_outputs.isEmpty()) {
-        X11Output *output = m_outputs.takeLast();
+        AbstractOutput *output = m_outputs.takeLast();
         emit outputDisabled(output);
         emit outputRemoved(output);
         delete output;

plugins/platforms/x11/standalone/x11_platform.h

@@ -95,8 +95,7 @@ private:
     Display *m_x11Display;
     QScopedPointer<WindowSelector> m_windowSelector;
     QScopedPointer<X11EventFilter> m_screenEdgesFilter;
-
-    QVector<X11Output*> m_outputs;
+    QVector<AbstractOutput *> m_outputs;
 };
 
 }

plugins/platforms/x11/standalone/x11placeholderoutput.cpp

@@ -0,0 +1,42 @@
+/*
+    SPDX-FileCopyrightText: 2020 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#include "x11placeholderoutput.h"
+#include "main.h"
+
+namespace KWin
+{
+
+X11PlaceholderOutput::X11PlaceholderOutput(QObject *parent)
+    : AbstractOutput(parent)
+{
+}
+
+QString X11PlaceholderOutput::name() const
+{
+    return QStringLiteral("Placeholder-0");
+}
+
+QRect X11PlaceholderOutput::geometry() const
+{
+    xcb_screen_t *screen = kwinApp()->x11DefaultScreen();
+    if (screen) {
+        return QRect(0, 0, screen->width_in_pixels, screen->height_in_pixels);
+    }
+    return QRect();
+}
+
+int X11PlaceholderOutput::refreshRate() const
+{
+    return 60000;
+}
+
+QSize X11PlaceholderOutput::pixelSize() const
+{
+    return geometry().size();
+}
+
+} // namespace KWin

plugins/platforms/x11/standalone/x11placeholderoutput.h

@@ -0,0 +1,27 @@
+/*
+    SPDX-FileCopyrightText: 2020 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#pragma once
+
+#include "abstract_output.h"
+
+namespace KWin
+{
+
+class X11PlaceholderOutput : public AbstractOutput
+{
+    Q_OBJECT
+
+public:
+    explicit X11PlaceholderOutput(QObject *parent = nullptr);
+
+    QString name() const override;
+    QRect geometry() const override;
+    int refreshRate() const override;
+    QSize pixelSize() const override;
+};
+
+} // namespace KWin