Introduce a KWin internal on-screen-notification service

Summary:
Recently we noticed that there are multiple areas where KWin needs to
inform the user about how to operate. Examples are:
* Screenshot
* ColorPicker
* Pointer constraint enabled
* Pointer constraint about to be removed
* Kill Window

For Screenshot and ColorPicker we used an EffectFrame to render it. But
this is not an optimal solution as it's lacking many features we would
need. We cannot properly use it from within KWin core, we cannot
implement features like hide on mouse over, etc. etc.

This change introduces an OnScreenNotification which supports:
* showing an icon
* showing a message
* timeout

It is Qml styled, so that it can be easily adjusted. This is a big
improvement over the EffectFrame solution. The Qml file creates a Plasma
Dialog of type OSD. Thus KWin places it like the normal OSD windows and
also looks kind of similar. In the case of KWin the focus is more on the
message, than an icon, so the icon is placed left of the text.

While the OnScreenNotification is supposed to be used like a singleton,
it doesn't use the KWin singleton pattern. Instead a small wrapper
namespace OSD is introduced which provides a convenient API for KWin
internal areas to show/hide the notification. By not using the KWin
singleton pattern, the OnScreenNotification does not depend on any other
parts of KWin and can be easily unit-tested.

A few features are still missing and will be added in further commits:
* hide-out on mouse over
* optional skip close animation (needed for screenshot)
* X11 support (not that important as it's mostly for Wayland features)

Reviewers: #kwin, #plasma

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D3723

CMakeLists.txt

@@ -409,6 +409,8 @@ set(kwin_KDEINIT_SRCS
    xcbutils.cpp
    x11eventfilter.cpp
    logind.cpp
+   onscreennotification.cpp
+   osd.cpp
     screenedge.cpp
     scripting/scripting.cpp
     scripting/workspace_wrapper.cpp

autotests/CMakeLists.txt

@@ -313,3 +313,21 @@ target_link_libraries(testScreenEdges
 
 add_test(kwin_testScreenEdges testScreenEdges)
 ecm_mark_as_test(testScreenEdges)
+
+########################################################
+# Test OnScreenNotification
+########################################################
+set( testOnScreenNotification_SRCS
+    onscreennotificationtest.cpp
+    ../onscreennotification.cpp
+)
+add_executable( testOnScreenNotification ${testOnScreenNotification_SRCS})
+
+target_link_libraries(testOnScreenNotification
+    Qt5::Test
+    Qt5::Quick
+    KF5::ConfigCore
+)
+
+add_test(kwin-testOnScreenNotification testOnScreenNotification)
+ecm_mark_as_test(testOnScreenNotification)

autotests/onscreennotificationtest.cpp

@@ -0,0 +1,118 @@
+/*
+ * Copyright 2016  Martin Graesslin <mgraesslin@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "onscreennotificationtest.h"
+#include "../onscreennotification.h"
+
+#include <KSharedConfig>
+
+#include <QQmlEngine>
+#include <QSignalSpy>
+#include <QTest>
+
+QTEST_MAIN(OnScreenNotificationTest);
+
+using KWin::OnScreenNotification;
+
+void OnScreenNotificationTest::show()
+{
+    OnScreenNotification notification;
+    notification.setConfig(KSharedConfig::openConfig(QString(), KSharedConfig::SimpleConfig));
+    notification.setEngine(new QQmlEngine(&notification));
+    notification.setMessage(QStringLiteral("Some text so that we see it in the test"));
+
+    QSignalSpy visibleChangedSpy(&notification, &OnScreenNotification::visibleChanged);
+    QCOMPARE(notification.isVisible(), false);
+    notification.setVisible(true);
+    QCOMPARE(notification.isVisible(), true);
+    QCOMPARE(visibleChangedSpy.count(), 1);
+
+    // show again should not trigger
+    notification.setVisible(true);
+    QCOMPARE(visibleChangedSpy.count(), 1);
+
+    // timer should not have hidden
+    QTest::qWait(500);
+    QCOMPARE(notification.isVisible(), true);
+
+    // hide again
+    notification.setVisible(false);
+    QCOMPARE(notification.isVisible(), false);
+    QCOMPARE(visibleChangedSpy.count(), 2);
+
+    // now show with timer
+    notification.setTimeout(250);
+    notification.setVisible(true);
+    QCOMPARE(notification.isVisible(), true);
+    QCOMPARE(visibleChangedSpy.count(), 3);
+    QVERIFY(visibleChangedSpy.wait());
+    QCOMPARE(notification.isVisible(), false);
+    QCOMPARE(visibleChangedSpy.count(), 4);
+}
+
+void OnScreenNotificationTest::timeout()
+{
+    OnScreenNotification notification;
+    QSignalSpy timeoutChangedSpy(&notification, &OnScreenNotification::timeoutChanged);
+    QCOMPARE(notification.timeout(), 0);
+    notification.setTimeout(1000);
+    QCOMPARE(notification.timeout(), 1000);
+    QCOMPARE(timeoutChangedSpy.count(), 1);
+    notification.setTimeout(1000);
+    QCOMPARE(timeoutChangedSpy.count(), 1);
+    notification.setTimeout(0);
+    QCOMPARE(notification.timeout(), 0);
+    QCOMPARE(timeoutChangedSpy.count(), 2);
+}
+
+void OnScreenNotificationTest::iconName()
+{
+    OnScreenNotification notification;
+    QSignalSpy iconNameChangedSpy(&notification, &OnScreenNotification::iconNameChanged);
+    QVERIFY(iconNameChangedSpy.isValid());
+    QCOMPARE(notification.iconName(), QString());
+    notification.setIconName(QStringLiteral("foo"));
+    QCOMPARE(notification.iconName(), QStringLiteral("foo"));
+    QCOMPARE(iconNameChangedSpy.count(), 1);
+    notification.setIconName(QStringLiteral("foo"));
+    QCOMPARE(iconNameChangedSpy.count(), 1);
+    notification.setIconName(QStringLiteral("bar"));
+    QCOMPARE(notification.iconName(), QStringLiteral("bar"));
+    QCOMPARE(iconNameChangedSpy.count(), 2);
+}
+
+void OnScreenNotificationTest::message()
+{
+    OnScreenNotification notification;
+    QSignalSpy messageChangedSpy(&notification, &OnScreenNotification::messageChanged);
+    QVERIFY(messageChangedSpy.isValid());
+    QCOMPARE(notification.message(), QString());
+    notification.setMessage(QStringLiteral("foo"));
+    QCOMPARE(notification.message(), QStringLiteral("foo"));
+    QCOMPARE(messageChangedSpy.count(), 1);
+    notification.setMessage(QStringLiteral("foo"));
+    QCOMPARE(messageChangedSpy.count(), 1);
+    notification.setMessage(QStringLiteral("bar"));
+    QCOMPARE(notification.message(), QStringLiteral("bar"));
+    QCOMPARE(messageChangedSpy.count(), 2);
+}
+
+#include "onscreennotificationtest.moc"

autotests/onscreennotificationtest.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2016  Martin Graesslin <mgraesslin@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef ONSCREENNOTIFICATIONTEST_H
+#define ONSCREENNOTIFICATIONTEST_H
+
+#include <QObject>
+
+class OnScreenNotificationTest : public QObject
+{
+    Q_OBJECT
+private slots:
+
+    void show();
+    void timeout();
+    void iconName();
+    void message();
+};
+
+#endif // ONSCREENNOTIFICATIONTEST_H

onscreennotification.cpp

@@ -0,0 +1,170 @@
+/*
+ * Copyright 2016  Martin Graesslin <mgraesslin@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "onscreennotification.h"
+#include <config-kwin.h>
+
+#include <QStandardPaths>
+#include <QTimer>
+#include <QQmlComponent>
+#include <QQmlContext>
+#include <QQmlEngine>
+#include <QQuickWindow>
+
+#include <KConfigGroup>
+
+#include <functional>
+
+using namespace KWin;
+
+OnScreenNotification::OnScreenNotification(QObject *parent)
+    : QObject(parent)
+    , m_timer(new QTimer(this))
+{
+    m_timer->setSingleShot(true);
+    connect(m_timer, &QTimer::timeout, this, std::bind(&OnScreenNotification::setVisible, this, false));
+    connect(this, &OnScreenNotification::visibleChanged, this,
+        [this] {
+            if (m_visible) {
+                show();
+            } else {
+                m_timer->stop();
+            }
+        }
+    );
+}
+
+OnScreenNotification::~OnScreenNotification()
+{
+    if (QQuickWindow *w = qobject_cast<QQuickWindow*>(m_mainItem.data())) {
+        w->hide();
+        w->destroy();
+    }
+}
+
+void OnScreenNotification::setConfig(KSharedConfigPtr config)
+{
+    m_config = config;
+}
+
+void OnScreenNotification::setEngine(QQmlEngine *engine)
+{
+    m_qmlEngine = engine;
+}
+
+bool OnScreenNotification::isVisible() const
+{
+    return m_visible;
+}
+
+void OnScreenNotification::setVisible(bool visible)
+{
+    if (m_visible == visible) {
+        return;
+    }
+    m_visible = visible;
+    emit visibleChanged();
+}
+
+QString OnScreenNotification::message() const
+{
+    return m_message;
+}
+
+void OnScreenNotification::setMessage(const QString &message)
+{
+    if (m_message == message) {
+        return;
+    }
+    m_message = message;
+    emit messageChanged();
+}
+
+QString OnScreenNotification::iconName() const
+{
+    return m_iconName;
+}
+
+void OnScreenNotification::setIconName(const QString &iconName)
+{
+    if (m_iconName == iconName) {
+        return;
+    }
+    m_iconName = iconName;
+    emit iconNameChanged();
+}
+
+int OnScreenNotification::timeout() const
+{
+    return m_timer->interval();
+}
+
+void OnScreenNotification::setTimeout(int timeout)
+{
+    if (m_timer->interval() == timeout) {
+        return;
+    }
+    m_timer->setInterval(timeout);
+    emit timeoutChanged();
+}
+
+void OnScreenNotification::show()
+{
+    Q_ASSERT(m_visible);
+    ensureQmlContext();
+    ensureQmlComponent();
+    if (m_timer->interval() != 0) {
+        m_timer->start();
+    }
+}
+
+void OnScreenNotification::ensureQmlContext()
+{
+    Q_ASSERT(m_qmlEngine);
+    if (!m_qmlContext.isNull()) {
+        return;
+    }
+    m_qmlContext.reset(new QQmlContext(m_qmlEngine));
+    m_qmlContext->setContextProperty(QStringLiteral("osd"), this);
+}
+
+void OnScreenNotification::ensureQmlComponent()
+{
+    Q_ASSERT(m_config);
+    Q_ASSERT(m_qmlEngine);
+    if (!m_qmlComponent.isNull()) {
+        return;
+    }
+    m_qmlComponent.reset(new QQmlComponent(m_qmlEngine));
+    const QString fileName = QStandardPaths::locate(QStandardPaths::GenericDataLocation,
+                                                m_config->group(QStringLiteral("OnScreenNotification")).readEntry("QmlPath", QStringLiteral(KWIN_NAME "/onscreennotification/plasma/main.qml")));
+    if (fileName.isEmpty()) {
+        return;
+    }
+    m_qmlComponent->loadUrl(QUrl::fromLocalFile(fileName));
+    if (!m_qmlComponent->isError()) {
+        m_mainItem.reset(m_qmlComponent->create(m_qmlContext.data()));
+    } else {
+        m_qmlComponent.reset();
+    }
+}
+
+#include "onscreennotification.moc"

onscreennotification.h

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2016  Martin Graesslin <mgraesslin@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef KWIN_ONSCREENNOTIFICATION_H
+#define KWIN_ONSCREENNOTIFICATION_H
+
+#include <QObject>
+
+#include <KSharedConfig>
+
+class QTimer;
+class QQmlContext;
+class QQmlComponent;
+class QQmlEngine;
+
+namespace KWin {
+
+class OnScreenNotification : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(bool visible READ isVisible WRITE setVisible NOTIFY visibleChanged)
+    Q_PROPERTY(QString message READ message WRITE setMessage NOTIFY messageChanged)
+    Q_PROPERTY(QString iconName READ iconName WRITE setIconName NOTIFY iconNameChanged)
+    Q_PROPERTY(int timeout READ timeout WRITE setTimeout NOTIFY timeoutChanged)
+
+public:
+    explicit OnScreenNotification(QObject *parent = nullptr);
+    ~OnScreenNotification() override;
+    bool isVisible() const;
+    QString message() const;
+    QString iconName() const;
+    int timeout() const;
+
+    void setVisible(bool m_visible);
+    void setMessage(const QString &message);
+    void setIconName(const QString &iconName);
+    void setTimeout(int timeout);
+
+    void setConfig(KSharedConfigPtr config);
+    void setEngine(QQmlEngine *engine);
+
+Q_SIGNALS:
+    void visibleChanged();
+    void messageChanged();
+    void iconNameChanged();
+    void timeoutChanged();
+
+private:
+    void show();
+    void ensureQmlContext();
+    void ensureQmlComponent();
+    bool m_visible = false;
+    QString m_message;
+    QString m_iconName;
+    QTimer *m_timer;
+    KSharedConfigPtr m_config;
+    QScopedPointer<QQmlContext> m_qmlContext;
+    QScopedPointer<QQmlComponent> m_qmlComponent;
+    QQmlEngine *m_qmlEngine = nullptr;
+    QScopedPointer<QObject> m_mainItem;
+};
+}
+
+#endif // KWIN_ONSCREENNOTIFICATION_H

osd.cpp

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2016  Martin Graesslin <mgraesslin@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#include "osd.h"
+#include "onscreennotification.h"
+#include "main.h"
+#include "workspace.h"
+#include "scripting/scripting.h"
+
+#include <QQmlEngine>
+
+namespace KWin
+{
+namespace OSD
+{
+
+static OnScreenNotification *create()
+{
+    auto osd = new OnScreenNotification(workspace());
+    osd->setConfig(kwinApp()->config());
+    osd->setEngine(Scripting::self()->qmlEngine());
+    return osd;
+}
+
+static OnScreenNotification *osd()
+{
+    static OnScreenNotification *s_osd = create();
+    return s_osd;
+}
+
+void show(const QString &message, const QString &iconName, int timeout)
+{
+    if (!kwinApp()->shouldUseWaylandForCompositing()) {
+        // FIXME: only supported on Wayland
+        return;
+    }
+    auto notification = osd();
+    notification->setIconName(iconName);
+    notification->setMessage(message);
+    notification->setTimeout(timeout);
+    notification->setVisible(true);
+}
+
+void show(const QString &message, int timeout)
+{
+    show(message, QString(), timeout);
+}
+
+void show(const QString &message, const QString &iconName)
+{
+    show(message, iconName, 0);
+}
+
+void hide()
+{
+    if (!kwinApp()->shouldUseWaylandForCompositing()) {
+        // FIXME: only supported on Wayland
+        return;
+    }
+    osd()->setVisible(false);
+}
+
+}
+}

osd.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2016  Martin Graesslin <mgraesslin@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef KWIN_OSD_H
+#define KWIN_OSD_H
+
+#include <QString>
+
+namespace KWin
+{
+namespace OSD
+{
+
+void show(const QString &message, const QString &iconName = QString());
+void show(const QString &message, int timeout);
+void show(const QString &message, const QString &iconName, int timeout);
+void hide();
+
+}
+}
+
+#endif

qml/CMakeLists.txt

@@ -1,2 +1,3 @@
 install( DIRECTORY outline/plasma   DESTINATION ${DATA_INSTALL_DIR}/${KWIN_NAME}/outline )
+install( DIRECTORY onscreennotification/plasma DESTINATION ${DATA_INSTALL_DIR}/${KWIN_NAME}/onscreennotification )
 install( DIRECTORY virtualkeyboard   DESTINATION ${DATA_INSTALL_DIR}/${KWIN_NAME} )

qml/onscreennotification/plasma/dummydata/osd.qml

@@ -0,0 +1,7 @@
+import QtQuick 2.3
+
+QtObject {
+    property bool visible: true
+    property string message: "This is an example message.\nUsing multiple lines"
+    property string iconName: "kwin"
+}

qml/onscreennotification/plasma/main.qml

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2016  Martin Graesslin <mgraesslin@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+import QtQuick 2.0;
+import QtQuick.Window 2.0;
+import org.kde.plasma.core 2.0 as PlasmaCore;
+import org.kde.plasma.components 2.0 as Plasma;
+import QtQuick.Layouts 1.3;
+
+PlasmaCore.Dialog {
+    id: dialog
+    location: PlasmaCore.Types.Floating
+    visible: osd.visible
+    flags: Qt.X11BypassWindowManagerHint | Qt.FramelessWindowHint
+    type: PlasmaCore.Dialog.OnScreenDisplay
+    outputOnly: true
+
+    mainItem: RowLayout {
+        PlasmaCore.IconItem {
+            Layout.minimumWidth: 64
+            Layout.minimumHeight: 64
+            source: osd.iconName
+            visible: osd.iconName != ""
+        }
+        Plasma.Label {
+            text: osd.message
+        }
+    }
+}