IPC socket, single instance, open in existing instance

notes

@@ -37,7 +37,7 @@ TODO {
             - quit (just trigger close on all sequentially)
             - if opening project already in other window, focus/flash that window
             - open project from command line
-            IPC to open/new window in existing instance
+            - IPC to open/new window in existing instance
             revert action
             
             xdg mime package + desktop file association

xybrid/main.cpp

@@ -9,9 +9,15 @@
 #include <QDebug>
 #include <QApplication>
 #include <QCommandLineParser>
+#include <QLocalServer>
+#include <QLocalSocket>
 #include <QSurfaceFormat>
 #include <QFontDatabase>
 
+namespace {
+    const QString socketName = QStringLiteral("Xybrid.IPC");
+}
+
 int main(int argc, char *argv[]) {
     qRegisterMetaType<Xybrid::Data::Port>();
     // enable antialiasing on accelerated graphicsview
@@ -24,11 +30,40 @@ int main(int argc, char *argv[]) {
     QCommandLineParser cl;
     cl.addHelpOption();
     cl.addVersionOption();
-    cl.addPositionalArgument("project", QApplication::translate("main", "Project file to open."));
+    cl.addPositionalArgument("[project]", QApplication::translate("main", "Project file to open."));
 
     cl.process(a);
     auto args = cl.positionalArguments();
     QString fileName = args.size() >= 1 ? args.at(0) : QString();
+    if (!fileName.isEmpty()) fileName = QFileInfo(fileName).absoluteFilePath(); // canonicize
+
+    QLocalSocket tryc;
+    tryc.connectToServer(socketName);
+    tryc.waitForConnected(1000); // wait for connection attempt (can't hang on local)
+    if (tryc.isOpen()) { // if server already exists, give it the signal and exit
+        tryc.write(fileName.toUtf8());
+        tryc.waitForBytesWritten();
+        tryc.close();
+        return 0;
+    }
+
+    QLocalServer srv;
+    srv.listen(socketName);
+    QObject::connect(&srv, &QLocalServer::newConnection, &srv, [&]() {
+        auto s = srv.nextPendingConnection();
+        s->waitForDisconnected();
+
+        auto fileName = QString::fromUtf8(s->readAll());
+
+        if (auto w = Xybrid::MainWindow::projectWindow(fileName); w) w->tryFocus();
+        else {
+            w = new Xybrid::MainWindow(nullptr, fileName);
+            if (w->getProject()) w->show();
+            else (w->deleteLater());
+        }
+
+        s->deleteLater();
+    });
 
     // make sure bundled fonts are loaded
     QFontDatabase::addApplicationFont(":/fonts/iosevka-term-light.ttf");

xybrid/mainwindow.cpp

@@ -523,6 +523,7 @@ MainWindow::~MainWindow() {
 }
 
 MainWindow* MainWindow::projectWindow(const QString &fileName) {
+    if (fileName.isEmpty()) return nullptr;
     for (auto w : openWindows) if (w->project && w->project->fileName == fileName) return w;
     return nullptr;
 }