Automatically raise windows

.gitignore

@@ -26,10 +26,14 @@ object_script.*.Debug
 *.pro.user.*
 *.qbs.user
 *.qbs.user.*
+.objs/
+.mocs/
 *.moc
 moc_*.cpp
 moc_*.h
+.qrcs/
 qrc_*.cpp
+.uis/
 ui_*.h
 *.qmlc
 *.jsc

inc/liquidappwindow.hpp

@@ -10,6 +10,8 @@
 #include <QWebEngineView>
 #include <QWebEngineFullScreenRequest>
 
+#include "singleinstance.hpp"
+
 #include "liquidappwebpage.hpp"
 
 class LiquidAppWebPage;
@@ -22,6 +24,8 @@ class LiquidAppWindow : public QWebEngineView
     explicit LiquidAppWindow(const QString* name);
     ~LiquidAppWindow(void);
 
+    bool isAlreadyRunning(void);
+    void run(void);
     void setForgiveNextPageLoadError(const bool ok);
 
     QSettings* liquidAppConfig;
@@ -60,6 +64,7 @@ public slots:
 
     QString liquidAppWindowTitle;
     QIcon iconToSave;
+    SingleInstance *singleInstance;
 
     LiquidAppWebPage* liquidAppWebPage = Q_NULLPTR;
     QWebEngineProfile* liquidAppWebProfile = Q_NULLPTR;

inc/mainwindow.hpp

@@ -6,12 +6,17 @@
 #include <QScrollArea>
 #include <QTableWidget>
 
+#include "singleinstance.hpp"
+
 class MainWindow : public QScrollArea
 {
 public:
     MainWindow();
     ~MainWindow();
 
+    bool isAlreadyRunning(void);
+    void run(void);
+
 protected:
     void closeEvent(QCloseEvent *event) override;
 
@@ -24,7 +29,7 @@ class MainWindow : public QScrollArea
 
     QTableWidget* appListTable;
     QPushButton* createNewLiquidAppButton;
-    QSettings* settings;
-
     QAction* quitAction;
+    QSettings* settings;
+    SingleInstance *singleInstance;
 };

liquid.pro

@@ -1,3 +1,7 @@
+include($${PWD}/modules/modules.pri)
+
+PROG_NAME     = liquid
+
 VERSION_MAJOR = 0
 VERSION_MINOR = 7
 VERSION_PATCH = 11
@@ -9,10 +13,9 @@ CONFIG      += c++11
 TEMPLATE     = app
 
 DESTDIR      = build
-PROG_NAME    = liquid
 
-SRC_DIR      = src
 INC_DIR      = inc
+SRC_DIR      = src
 FORMS_DIR    = ui
 
 OBJECTS_DIR  = .objs
@@ -22,21 +25,21 @@ RCC_DIR      = .qrcs
 
 INCLUDEPATH += $${INC_DIR}
 
-SOURCES     += src/liquid.cpp \
-               src/liquidappcookiejar.cpp \
-               src/liquidappconfigwindow.cpp \
-               src/liquidappwebpage.cpp \
-               src/liquidappwindow.cpp \
-               src/main.cpp \
-               src/mainwindow.cpp \
-
-HEADERS     += inc/lqd.h \
-               inc/liquid.hpp \
-               inc/liquidappcookiejar.hpp \
-               inc/liquidappconfigwindow.hpp \
-               inc/liquidappwebpage.hpp \
-               inc/liquidappwindow.hpp \
-               inc/mainwindow.hpp \
+HEADERS     += $${INC_DIR}/lqd.h \
+               $${INC_DIR}/liquid.hpp \
+               $${INC_DIR}/liquidappcookiejar.hpp \
+               $${INC_DIR}/liquidappconfigwindow.hpp \
+               $${INC_DIR}/liquidappwebpage.hpp \
+               $${INC_DIR}/liquidappwindow.hpp \
+               $${INC_DIR}/mainwindow.hpp \
+
+SOURCES     += $${SRC_DIR}/liquid.cpp \
+               $${SRC_DIR}/liquidappcookiejar.cpp \
+               $${SRC_DIR}/liquidappconfigwindow.cpp \
+               $${SRC_DIR}/liquidappwebpage.cpp \
+               $${SRC_DIR}/liquidappwindow.cpp \
+               $${SRC_DIR}/main.cpp \
+               $${SRC_DIR}/mainwindow.cpp \
 
 RESOURCES    = res/resources.qrc
 

modules/modules.pri

@@ -0,0 +1 @@
+include($${PWD}/singleinstance/singleinstance.pri)

modules/singleinstance/inc/singleinstance.hpp

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <QSharedMemory>
+#include <QSystemSemaphore>
+#include <QWidget>
+
+class SingleInstance : public QObject
+{
+    Q_OBJECT
+
+public:
+    explicit SingleInstance(QWidget *parent = Q_NULLPTR, QString *instanceId = new QString());
+    ~SingleInstance();
+
+    bool isAlreadyRunning(const bool raiseExisting = false);
+    static void raiseWindow(QWidget *window);
+
+private:
+    struct SharedData
+    {
+        bool needToRaiseExistingWindow = false;
+    };
+
+    QSharedMemory *shMem;
+    QString shmemName;
+    QString smphorName;
+};

modules/singleinstance/singleinstance.pri

@@ -0,0 +1,16 @@
+!win:!mac {
+    LIBS += -lX11 -lXfixes -lXinerama -lXext -lXcomposite
+}
+
+QT           += core
+CONFIG       += c++11
+TEMPLATE      = lib
+
+INC_DIR       = inc
+SRC_DIR       = src
+
+INCLUDEPATH  += $${PWD}/$${INC_DIR}
+
+HEADERS      += $${PWD}/inc/singleinstance.hpp
+
+SOURCES      += $${PWD}/src/singleinstance.cpp

modules/singleinstance/src/singleinstance.cpp

@@ -0,0 +1,118 @@
+#include <QTimer>
+
+#include "singleinstance.hpp"
+
+#if defined(Q_OS_WIN)
+#include <windows.h>
+#elif !defined(Q_OS_MACOS)
+#include <X11/Xlib.h>
+#endif
+
+SingleInstance::SingleInstance(QWidget *parent, QString *instanceId) : QObject(parent)
+{
+    shmemName = instanceId + QString("_shrdmmr");
+    smphorName = instanceId + QString("_smphr");
+}
+
+SingleInstance::~SingleInstance()
+{
+}
+
+bool SingleInstance::isAlreadyRunning(const bool raiseExisting)
+{
+    QSystemSemaphore sem(smphorName, 1);
+
+    // Fix danging memory on Linux
+    {
+        QSharedMemory fix(shmemName);
+        fix.attach();
+    }
+
+    shMem = new QSharedMemory(shmemName);
+    if (shMem->create(sizeof(SharedData))) { // This is the first instance
+        shMem->attach();
+
+        sem.acquire();
+        memset(shMem->data(), 0, shMem->size());
+        sem.release();
+
+        QTimer* t = new QTimer(this);
+        connect(t, &QTimer::timeout, this, [this]() {
+            QSystemSemaphore sem(smphorName, 1);
+            sem.acquire();
+            SharedData* data = reinterpret_cast<SharedData*>(shMem->data());
+            if (data->needToRaiseExistingWindow) {
+                SingleInstance::raiseWindow((QWidget*)parent());
+                data->needToRaiseExistingWindow = false;
+            }
+            sem.release();
+        });
+        t->start(0);
+    } else { // Another instance is already running
+        shMem->attach();
+
+        sem.acquire();
+        SharedData* data = reinterpret_cast<SharedData*>(shMem->data());
+        data->needToRaiseExistingWindow = raiseExisting;
+
+        return true;
+    }
+
+    return false;
+}
+
+void SingleInstance::raiseWindow(QWidget *window)
+{
+#if defined(Q_OS_WIN) // Windows
+    Window winId = window->effectiveWinId();
+
+    SetWindowPos(winId, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW);
+    SetWindowPos(winId, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW);
+#elif defined(Q_OS_MACOS) // macOS
+    window->show();
+    window->raise();
+    window->activateWindow();
+#else // GNU/Linux, FreeBSD, etc
+    Window winId = window->effectiveWinId();
+
+    if (winId > 0) {
+        Display* disp = XOpenDisplay(nullptr);
+
+        if (disp) {
+            XWindowAttributes attributes;
+
+            if (XGetWindowAttributes(disp, winId, &attributes)) {
+                XSetInputFocus(disp, winId, RevertToPointerRoot, CurrentTime);
+                XRaiseWindow(disp, winId);
+
+                // Show window if minimized, instead of just highlighting its icon
+                {
+                    const Atom atom = XInternAtom(disp, "_NET_ACTIVE_WINDOW", True);
+
+                    if (atom != None) {
+                        XEvent xev;
+
+                        xev.xclient.type = ClientMessage;
+                        xev.xclient.serial = 0;
+                        xev.xclient.send_event = True;
+                        xev.xclient.message_type = atom;
+                        xev.xclient.display = disp;
+                        xev.xclient.window = winId;
+                        xev.xclient.format = 32;
+                        xev.xclient.data.l[0] = 1;
+                        xev.xclient.data.l[1] = 0;
+                        xev.xclient.data.l[2] = None;
+                        xev.xclient.data.l[3] = 0;
+                        xev.xclient.data.l[4] = 0;
+
+                        XSendEvent(disp, DefaultRootWindow(disp), False, SubstructureRedirectMask | SubstructureNotifyMask, &xev);
+                    }
+                }
+            }
+
+            XFlush(disp);
+            XCloseDisplay(disp);
+        }
+    }
+#endif
+}