[wayland] Add support for initial output count for nested compositors

Added to x11 backend which creates one window per output.

New command line option is called --output-count=<int>.

abstract_backend.h

@@ -107,6 +107,12 @@ public:
     void setOutputsEnabled(bool enabled) {
         m_outputsEnabled = enabled;
     }
+    int initialOutputCount() const {
+        return m_initialOutputCount;
+    }
+    void setInitialOutputCount(int count) {
+        m_initialOutputCount = count;
+    }
 
 public Q_SLOTS:
     void pointerMotion(const QPointF &position, quint32 time);
@@ -170,6 +176,7 @@ private:
     QByteArray m_deviceIdentifier;
     bool m_pointerWarping = false;
     bool m_outputsEnabled = true;
+    int m_initialOutputCount = 1;
 };
 
 }

backends/x11/x11windowed_backend.cpp

@@ -106,6 +106,7 @@ void X11WindowedBackend::createWindow()
 {
     Xcb::Atom protocolsAtom(QByteArrayLiteral("WM_PROTOCOLS"), false, m_connection);
     Xcb::Atom deleteWindowAtom(QByteArrayLiteral("WM_DELETE_WINDOW"), false, m_connection);
+    for (int i = 0; i < initialOutputCount(); ++i) {
         Output o;
         o.window = xcb_generate_id(m_connection);
         uint32_t mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
@@ -155,6 +156,7 @@ void X11WindowedBackend::createWindow()
         xcb_change_property(m_connection, XCB_PROP_MODE_REPLACE, o.window, m_protocols, XCB_ATOM_ATOM, 32, 1, &m_deleteWindowProtocol);
 
         m_windows << o;
+    }
 
     updateWindowTitle();
 

main_wayland.cpp

@@ -426,6 +426,7 @@ int main(int argc, char * argv[])
     };
     const bool hasWindowedOption = hasPlugin(KWin::s_x11Plugin) || hasPlugin(KWin::s_waylandPlugin);
     const bool hasSizeOption = hasPlugin(KWin::s_x11Plugin) || hasPlugin(KWin::s_virtualPlugin);
+    const bool hasOutputCountOption = hasPlugin(KWin::s_x11Plugin);
     const bool hasX11Option = hasPlugin(KWin::s_x11Plugin);
     const bool hasVirtualOption = hasPlugin(KWin::s_virtualPlugin);
     const bool hasWaylandOption = hasPlugin(KWin::s_waylandPlugin);
@@ -465,6 +466,10 @@ int main(int argc, char * argv[])
                                     i18n("The height for windowed mode. Default height is 768."),
                                     QStringLiteral("height"));
     heightOption.setDefaultValue(QString::number(768));
+    QCommandLineOption outputCountOption(QStringLiteral("output-count"),
+                                    i18n("The number of windows to open as outputs in windowed mode. Default value is 1"),
+                                    QStringLiteral("height"));
+    outputCountOption.setDefaultValue(QString::number(1));
 
     QCommandLineParser parser;
     a.setupCommandLine(&parser);
@@ -490,6 +495,9 @@ int main(int argc, char * argv[])
         parser.addOption(widthOption);
         parser.addOption(heightOption);
     }
+    if (hasOutputCountOption) {
+        parser.addOption(outputCountOption);
+    }
 #if HAVE_LIBHYBRIS
     QCommandLineOption hwcomposerOption(QStringLiteral("hwcomposer"), i18n("Use libhybris hwcomposer"));
     if (hasHwcomposerOption) {
@@ -551,6 +559,7 @@ int main(int argc, char * argv[])
     QString pluginName;
     QSize initialWindowSize;
     QByteArray deviceIdentifier;
+    int outputCount = 1;
 
 #if HAVE_DRM
     if (hasDrmOption && parser.isSet(drmOption)) {
@@ -573,6 +582,14 @@ int main(int argc, char * argv[])
         initialWindowSize = QSize(width, height);
     }
 
+    if (hasOutputCountOption) {
+        bool ok = false;
+        const int count = parser.value(outputCountOption).toInt(&ok);
+        if (ok) {
+            outputCount = qMax(1, count);
+        }
+    }
+
     if (hasWindowedOption && parser.isSet(windowedOption)) {
         if (hasX11Option && parser.isSet(x11DisplayOption)) {
             deviceIdentifier = parser.value(x11DisplayOption).toUtf8();
@@ -655,6 +672,7 @@ int main(int argc, char * argv[])
     if (initialWindowSize.isValid()) {
         server->backend()->setInitialWindowSize(initialWindowSize);
     }
+    server->backend()->setInitialOutputCount(outputCount);
 
     QObject::connect(&a, &KWin::Application::workspaceCreated, server, &KWin::WaylandServer::initWorkspace);
     environment.insert(QStringLiteral("WAYLAND_DISPLAY"), server->display()->socketName());