Allow to set the available screen rect/region from outside through dbus

Summary:
I'm trying to implement the idea of @davidedmundson from this https://phabricator.kde.org/T10172 with my limited knowledge of C++/Qt/KDE/programming. This is the start of a new class so it could lack many things but it's usable.

- It allows clients to set the available screen rect/region from outside through dbus.
- The final available screen rect/region would be the intersection of all set values.
- When a client dies, its values would be removed automatically.

Test Plan:
+ qdbus-qt5 org.kde.plasmashell /StrutManager test org.kde.lattedock LVDS-1 0 24 1366 768
+ After killing latte-dock, the values are got only from plasmashellCorona.

{F7820969}

Reviewers: #plasma, mvourlakos, davidedmundson, mart, apol

Reviewed By: #plasma, davidedmundson

Subscribers: davidre, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D25807

shell/CMakeLists.txt

@@ -36,6 +36,7 @@ set (plasma_shell_SRCS
     standaloneappcorona
     osd.cpp
     coronatesthelper.cpp
+    strutmanager.cpp
     debug.cpp
     screenpool.cpp
     softwarerendernotifier.cpp

shell/shellcorona.cpp

@@ -21,6 +21,7 @@
  */
 
 #include "shellcorona.h"
+#include "strutmanager.h"
 
 #include <config-plasma.h>
 
@@ -107,7 +108,8 @@ ShellCorona::ShellCorona(QObject *parent)
       m_addPanelsMenu(nullptr),
       m_interactiveConsole(nullptr),
       m_waylandPlasmaShell(nullptr),
-      m_closingDown(false)
+      m_closingDown(false),
+      m_strutManager(new StrutManager(this))
 {
     setupWaylandIntegration();
     qmlRegisterUncreatableType<DesktopView>("org.kde.plasma.shell", 2, 0, "Desktop", QStringLiteral("It is not possible to create objects of type Desktop"));
@@ -1042,6 +1044,11 @@ QRect ShellCorona::screenGeometry(int id) const
 }
 
 QRegion ShellCorona::availableScreenRegion(int id) const
+{
+    return m_strutManager->availableScreenRegion(id);
+}
+
+QRegion ShellCorona::_availableScreenRegion(int id) const
 {
     DesktopView* view = m_desktopViewforId.value(id);
     if (!view) {
@@ -1062,6 +1069,11 @@ QRegion ShellCorona::availableScreenRegion(int id) const
 }
 
 QRect ShellCorona::availableScreenRect(int id) const
+{
+    return m_strutManager->availableScreenRect(id);
+}
+
+QRect ShellCorona::_availableScreenRect(int id) const
 {
     DesktopView *view = m_desktopViewforId.value(id);
     if (!view) {

shell/shellcorona.h

@@ -38,6 +38,7 @@ class PanelView;
 class QMenu;
 class QScreen;
 class ScreenPool;
+class StrutManager;
 
 namespace KActivities
 {
@@ -89,6 +90,10 @@ public:
     Q_INVOKABLE QRegion availableScreenRegion(int id) const override;
     Q_INVOKABLE QRect availableScreenRect(int id) const override;
 
+    // plasmashellCorona's value
+    QRegion _availableScreenRegion(int id) const;
+    QRect _availableScreenRect(int id) const;
+
     Q_INVOKABLE QStringList availableActivities() const;
 
     PanelView *panelView(Plasma::Containment *containment) const;
@@ -256,6 +261,8 @@ private:
     KWayland::Client::PlasmaShell *m_waylandPlasmaShell;
     bool m_closingDown : 1;
     QString m_testModeLayout;
+
+    StrutManager *m_strutManager;
 };
 
 #endif // SHELLCORONA_H

shell/strutmanager.cpp

@@ -0,0 +1,84 @@
+#include "strutmanager.h"
+#include "shellcorona.h"
+#include "screenpool.h"
+
+#include <QDBusMetaType>
+#include <QDBusConnection>
+#include <QDBusServiceWatcher>
+#include <QDBusConnectionInterface>
+
+StrutManager::StrutManager(ShellCorona *plasmashellCorona) : QObject(plasmashellCorona),
+    m_plasmashellCorona(plasmashellCorona),
+    m_serviceWatcher(new QDBusServiceWatcher(this))
+{
+    qDBusRegisterMetaType<QList<QRect>>();
+
+    QDBusConnection dbus = QDBusConnection::sessionBus();
+    dbus.registerObject("/StrutManager", this, QDBusConnection::ExportAllSlots);
+    m_serviceWatcher->setConnection(dbus);
+
+    connect(m_serviceWatcher, &QDBusServiceWatcher::serviceUnregistered, [=](const QString &service) {
+        m_availableScreenRects.remove(service);
+        m_availableScreenRegions.remove(service);
+        m_serviceWatcher->removeWatchedService(service);
+
+        emit m_plasmashellCorona->availableScreenRectChanged();
+    });
+}
+
+QRect StrutManager::availableScreenRect(int id) const
+{
+    QRect r = m_plasmashellCorona->_availableScreenRect(id);
+    QHash<int, QRect> service;
+    foreach (service, m_availableScreenRects) {
+        if (!service.value(id).isNull()) {
+            r &= service[id];
+        }
+    }
+    return r;
+}
+
+QRegion StrutManager::availableScreenRegion(int id) const
+{
+    QRegion r = m_plasmashellCorona->_availableScreenRegion(id);
+    QHash<int, QRegion> service;
+    foreach (service, m_availableScreenRegions) {
+        if (!service.value(id).isNull()) {
+            r &= service[id];
+        }
+    }
+    return r;
+}
+
+void StrutManager::setAvailableScreenRect(const QString &service, const QString &screenName, const QRect &rect) {
+    int id = m_plasmashellCorona->screenPool()->id(screenName);
+    if (id == -1 || m_availableScreenRects.value(service).value(id) == rect || !addWatchedService(service)) {
+        return;
+    }
+    m_availableScreenRects[service][id] = rect;
+    emit m_plasmashellCorona->availableScreenRectChanged();
+}
+
+void StrutManager::setAvailableScreenRegion(const QString &service, const QString &screenName, const QList<QRect> &rects) {
+    int id = m_plasmashellCorona->screenPool()->id(screenName);
+    QRegion region;
+    foreach(QRect rect, rects) {
+        region += rect;
+    }
+
+    if (id == -1 || m_availableScreenRegions.value(service).value(id) == region || !addWatchedService(service)) {
+        return;
+    }
+    m_availableScreenRegions[service][id] = region;
+    emit m_plasmashellCorona->availableScreenRegionChanged();
+}
+
+bool StrutManager::addWatchedService(const QString &service) {
+    if (!m_serviceWatcher->watchedServices().contains(service)) {
+        if (!QDBusConnection::sessionBus().interface()->isServiceRegistered(service)) {
+            return false;
+        }
+        m_serviceWatcher->addWatchedService(service);
+    }
+    return true;
+}

shell/strutmanager.h

@@ -0,0 +1,35 @@
+#ifndef STRUTMANAGER_H
+#define STRUTMANAGER_H
+
+#include <QObject>
+#include <QHash>
+
+class QDBusServiceWatcher;
+class ShellCorona;
+
+class StrutManager : public QObject
+{
+    Q_OBJECT
+    Q_CLASSINFO("D-Bus Interface","org.kde.PlasmaShell.StrutManager")
+
+    public:
+        explicit StrutManager(ShellCorona *plasmashellCorona);
+
+        QRect availableScreenRect(int id) const;
+        QRegion availableScreenRegion(int id) const;
+
+    public Q_SLOTS:
+        void setAvailableScreenRect(const QString &service, const QString &screenName, const QRect &rect);
+        void setAvailableScreenRegion(const QString &service, const QString &screenName, const QList<QRect> &rects);
+
+    private:
+        ShellCorona *m_plasmashellCorona;
+
+        QDBusServiceWatcher *m_serviceWatcher;
+        bool addWatchedService(const QString &service);
+
+        QHash <const QString, QHash<int, QRect>> m_availableScreenRects;
+        QHash <const QString, QHash<int, QRegion>> m_availableScreenRegions;
+};
+
+#endif