From 9fe8c10aaf55a8aeea924f8f69de432f98256f89 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Mon, 22 Jun 2020 15:03:27 +0200
Subject: Make detection of virtual screen smarter; fall back to disconnected

We try to find a virtual output, set the desired resolution, and disable
all real outputs. If we don't find a virtual one, we pick a disconnected
output, set the resolution, and disable the remaining outputs. If we don't
have a disconnected output, we just take the first one.
---
 src/loginrpc.cpp | 64 ++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 55 insertions(+), 9 deletions(-)

diff --git a/src/loginrpc.cpp b/src/loginrpc.cpp
index 30534a0..6ad70ec 100644
--- a/src/loginrpc.cpp
+++ b/src/loginrpc.cpp
@@ -5,6 +5,7 @@
 #include <QtNetwork/QTcpSocket>
 #include <QDebug>
 #include <QProcess>
+#include <QRegularExpression>
 
 LoginRpc::LoginRpc(int port, QObject *parent)
     : QObject(parent)
@@ -65,17 +66,62 @@ void LoginRpc::handleCommandV1(const QString &command)
                                      << QString::number(mode->hr) << QString::number(mode->hss) << QString::number(mode->hse) << QString::number(mode->hfl)
                                      << QString::number(mode->vr) << QString::number(mode->vss) << QString::number(mode->vse) << QString::number(mode->vfl)
                                      << "-hsync" << "+vsync";
-            qDebug() << "Setting mode" << newmode;
-            p.setProcessChannelMode(QProcess::ForwardedChannels);
-            p.start("xrandr", newmode);
-            p.waitForFinished(2000);
-            p.kill();
-            p.start("xrandr", QStringList() << "--verbose" << "--addmode" << "VIRTUAL1" << name);
-            p.waitForFinished(2000);
-            p.kill();
-            p.start("xrandr", QStringList() << "--verbose" << "--output" << "VIRTUAL1" << "--mode" << name);
+            // Get all outputs
+            QStringList setMode("--verbose");
+            p.setProcessChannelMode(QProcess::MergedChannels);
+            p.start("xrandr");
             p.waitForFinished(2000);
+            QString out = QString::fromLocal8Bit(p.readAll());
+            QRegularExpression re("^(\\S+)\\s.*?(\\w+connected)", QRegularExpression::MultilineOption);
+            QRegularExpressionMatchIterator it = re.globalMatch(out);
+            QString disconnectedOut;
+            QString virtOut;
+            QStringList outputs;
+            while (it.hasNext()) {
+                QRegularExpressionMatch m = it.next();
+                QString output = m.captured(1);
+                if (virtOut.isEmpty() && (output == QLatin1String("VIRTUAL1") || output == QLatin1String("VIRTUAL-1")
+                        || output == QLatin1String("Virtual1") || output == QLatin1String("Virtual-1")
+                        || output == QLatin1String("default"))) {
+                    virtOut = output;
+                } else if (disconnectedOut.isEmpty() && m.captured(2) == "disconnected") {
+                    disconnectedOut = output;
+                } else {
+                    outputs << output;
+                }
+            }
+            if (virtOut.isEmpty() && !disconnectedOut.isEmpty()) {
+                virtOut = disconnectedOut;
+                disconnectedOut.clear();
+            }
+            if (!disconnectedOut.isEmpty()) {
+                outputs << disconnectedOut;
+            }
+            if (virtOut.isEmpty() && !outputs.isEmpty()) {
+                virtOut = outputs.takeFirst();
+            }
+            qDebug() << "Virtual output:" << virtOut << "unwanted additional outputs:" << outputs << "(First disconnected:" << disconnectedOut << ")";
             p.kill();
+            if (!virtOut.isEmpty()) {
+                setMode << "--output" << virtOut << "--mode" << name;
+                for (auto output : outputs) {
+                    setMode << "--output" << output << "--off";
+                }
+                qDebug() << "Setting mode" << newmode;
+                p.setProcessChannelMode(QProcess::ForwardedChannels);
+                // Create mode
+                p.start("xrandr", newmode);
+                p.waitForFinished(2000);
+                p.kill();
+                // Add to virtual output
+                p.start("xrandr", QStringList() << "--verbose" << "--addmode" << virtOut << name);
+                p.waitForFinished(2000);
+                p.kill();
+                // Set all outputs
+                p.start("xrandr", setMode);
+                p.waitForFinished(2000);
+                p.kill();
+            }
         }
     }
     emit loginRequest(lines[0], lines[1], lines[2]);
-- 
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