Add DesktopThemeHandler class

app/src/handlers/desktopthemehandler.cpp

+#include "desktopthemehandler.h"
+
+#include <QStringList>
+
+#ifdef QTLIB_UNIX
+#include <QFileInfo>
+
+#include "desktopthemes/kdetheme.h"
+#include "desktopthemes/gnometheme.h"
+#include "desktopthemes/xfcetheme.h"
+#endif
+
+DesktopThemeHandler::DesktopThemeHandler(QObject *parent)
+    : QObject(parent)
+{}
+
+QString DesktopThemeHandler::desktopEnvironment() const
+{
+    QString desktop;
+    QString currentDesktop;
+
+    if (!qgetenv("XDG_CURRENT_DESKTOP").isEmpty()) {
+        currentDesktop = QString::fromLocal8Bit(qgetenv("XDG_CURRENT_DESKTOP").constData()).toLower();
+    }
+    else if (!qgetenv("XDG_SESSION_DESKTOP").isEmpty()) {
+        currentDesktop = QString::fromLocal8Bit(qgetenv("XDG_SESSION_DESKTOP").constData()).toLower();
+    }
+    else if (!qgetenv("DESKTOP_SESSION").isEmpty()) {
+        currentDesktop = QString::fromLocal8Bit(qgetenv("DESKTOP_SESSION").constData()).toLower();
+    }
+
+    if (currentDesktop.contains("kde") || currentDesktop.contains("plasma")) {
+        desktop = "kde";
+    }
+    else if (currentDesktop.contains("gnome") || currentDesktop.contains("unity")) {
+        desktop = "gnome";
+    }
+    else if (currentDesktop.contains("xfce")) {
+        desktop = "xfce";
+    }
+
+    return desktop;
+}
+
+bool DesktopThemeHandler::isApplicableType(const QString &installType) const
+{
+    auto desktop = desktopEnvironment();
+
+    QStringList applicableTypes;
+
+    if (desktop == "kde") {
+        applicableTypes << "wallpapers"
+                        << "icons"
+                        << "cursors"
+                        << "plasma5_desktopthemes"
+                        << "aurorae_themes";
+    }
+    else if (desktop == "gnome") {
+        applicableTypes << "wallpapers"
+                        << "icons"
+                        << "cursors"
+                        << "gtk3_themes"
+                        << "gnome_shell_themes";
+    }
+    else if (desktop == "xfce") {
+        applicableTypes << "wallpapers"
+                        << "icons"
+                        << "cursors"
+                        << "gtk2_themes"
+                        << "xfwm4_themes";
+    }
+
+    return applicableTypes.contains(installType);
+}
+
+#ifdef QTLIB_UNIX
+bool DesktopThemeHandler::applyTheme(const QString &path, const QString &installType) const
+{
+    if (QFileInfo::exists(path) && isApplicableType(installType)) {
+        auto desktop = desktopEnvironment();
+
+        if (desktop == "kde") {
+            KdeTheme kdeTheme(path);
+            if (installType == "wallpapers") {
+                return kdeTheme.applyAsWallpaper();
+            }
+            else if (installType == "icons") {
+                return kdeTheme.applyAsIcon();
+            }
+            else if (installType == "cursors") {
+                return kdeTheme.applyAsCursor();
+            }
+            else if (installType == "plasma5_desktopthemes") {
+                return kdeTheme.applyAsPlasma5Desktoptheme();
+            }
+            else if (installType == "aurorae_themes") {
+                return kdeTheme.applyAsAuroraeTheme();
+            }
+        }
+        else if (desktop == "gnome") {
+            GnomeTheme gnomeTheme(path);
+            if (installType == "wallpapers") {
+                return gnomeTheme.applyAsWallpaper();
+            }
+            else if (installType == "icons") {
+                return gnomeTheme.applyAsIcon();
+            }
+            else if (installType == "cursors") {
+                return gnomeTheme.applyAsCursor();
+            }
+            else if (installType == "gtk3_themes") {
+                return gnomeTheme.applyAsGtk3Theme();
+            }
+            else if (installType == "gnome_shell_themes") {
+                return gnomeTheme.applyAsGnomeShellTheme();
+            }
+        }
+        else if (desktop == "xfce") {
+            XfceTheme xfceTheme(path);
+            if (installType == "wallpapers") {
+                return xfceTheme.applyAsWallpaper();
+            }
+            else if (installType == "icons") {
+                return xfceTheme.applyAsIcon();
+            }
+            else if (installType == "cursors") {
+                return xfceTheme.applyAsCursor();
+            }
+            else if (installType == "gtk2_themes") {
+                return xfceTheme.applyAsGtk2Theme();
+            }
+            else if (installType == "xfwm4_themes") {
+                return xfceTheme.applyAsXfwm4Theme();
+            }
+        }
+    }
+
+    return false;
+}
+#endif

app/src/handlers/desktopthemehandler.h

+#pragma once
+
+#include <QObject>
+
+class DesktopThemeHandler : public QObject
+{
+    Q_OBJECT
+
+public:
+    explicit DesktopThemeHandler(QObject *parent = nullptr);
+
+public slots:
+    QString desktopEnvironment() const;
+    bool isApplicableType(const QString &installType) const;
+
+#ifdef QTLIB_UNIX
+    bool applyTheme(const QString &path, const QString &installType) const;
+#endif
+};