screenbrightnessplugin: Extract from initialstart and use in shell

This is partially an emergency fix also for
https://invent.kde.org/plasma/plasma-mobile/-/issues/404, which was
potentially introduced by https://invent.kde.org/plasma/plasma-mobile/-/merge_requests/582

This MR extracts the screen brightness implementation from initialstart
to a QML plugin, and also ports the action drawer brightness slider
implementation to it. This avoids importing the powerdevil screen
brightness plugin on the lockscreen, which apparently has a race
condition that causes it to sometimes segfault.

components/CMakeLists.txt

@@ -11,3 +11,4 @@ add_subdirectory(windowplugin)
 add_subdirectory(shellsettingsplugin)
 add_subdirectory(wallpaperimageplugin)
 add_subdirectory(dpmsplugin)
+add_subdirectory(screenbrightnessplugin)

components/mobileshell/qml/actiondrawer/quicksettings/BrightnessItem.qml

@@ -12,16 +12,15 @@ import org.kde.kirigami 2.20 as Kirigami
 
 import org.kde.plasma.core as PlasmaCore
 import org.kde.plasma.components 3.0 as PC3
+import org.kde.plasma.private.mobileshell.screenbrightnessplugin as ScreenBrightness
 
 Item {
     id: root
-
     implicitHeight: brightnessRow.implicitHeight
 
-    property alias value: brightnessSlider.value
+    ScreenBrightness.ScreenBrightnessUtil {
-    property alias maximumValue: brightnessSlider.to
+        id: screenBrightness
-
+    }
-    signal moved()
 
     RowLayout {
         id: brightnessRow
@@ -42,10 +41,18 @@ Item {
         PC3.Slider {
             id: brightnessSlider
             Layout.fillWidth: true
-            Layout.alignment: Qt.AlignVCenter
             from: 1
+            to: screenBrightness.maxBrightness
+            value: screenBrightness.brightness
+            onMoved: screenBrightness.brightness = value;
 
-            onMoved: root.moved()
+            // HACK: for some reason, the slider initial value doesn't set without being done after the component completes loading
+            Timer {
+                interval: 0
+                running: true
+                repeat: false
+                onTriggered: brightnessSlider.value = Qt.binding(() => screenBrightness.brightness)
+            }
         }
 
         Kirigami.Icon {

components/mobileshell/qml/actiondrawer/quicksettings/QuickSettings.qml

@@ -14,7 +14,6 @@ import org.kde.plasma.private.mobileshell as MobileShell
 import org.kde.plasma.components 3.0 as PlasmaComponents
 import org.kde.plasma.private.mobileshell.quicksettingsplugin as QS
 import org.kde.kirigami 2.20 as Kirigami
-import org.kde.plasma.private.brightnesscontrolplugin as BC
 
 /**
  * Quick settings elements layout, change the height to clip.
@@ -107,29 +106,11 @@ Item {
             sourceComponent: root.mode === QuickSettings.Pages ? swipeViewComponent : scrollViewComponent
         }
 
-        BC.ScreenBrightnessControl {
+        BrightnessItem {
-            id: screenBrightnessControl
+            Layout.bottomMargin: Kirigami.Units.smallSpacing * 2
-        }
+            Layout.leftMargin: Kirigami.Units.smallSpacing
-
+            Layout.rightMargin: Kirigami.Units.smallSpacing
-        Repeater {
+            Layout.fillWidth: true
-            id: brightnessRepeater
-            model: screenBrightnessControl.displays
-
-            BrightnessItem {
-                required property string displayName
-                required property int brightness
-                required property int maxBrightness
-
-                Layout.bottomMargin: Kirigami.Units.smallSpacing * 2
-                Layout.leftMargin: Kirigami.Units.smallSpacing
-                Layout.rightMargin: Kirigami.Units.smallSpacing
-                Layout.fillWidth: true
-
-                value: brightness
-                maximumValue: maxBrightness
-
-                onMoved: screenBrightnessControl.setBrightness(displayName, value)
-            }
         }
     }
 

components/screenbrightnessplugin/CMakeLists.txt

@@ -0,0 +1,25 @@
+# SPDX-FileCopyrightText: 2024 Devin Lin <devin@kde.org>
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+ecm_add_qml_module(screenbrightnessplugin URI org.kde.plasma.private.mobileshell.screenbrightnessplugin GENERATE_PLUGIN_SOURCE)
+
+qt_add_dbus_interfaces(DBUS_SRCS dbus/org.kde.Solid.PowerManagement.Actions.BrightnessControl.xml)
+
+target_sources(screenbrightnessplugin PRIVATE
+    screenbrightnessutil.cpp
+    ${DBUS_SRCS}
+)
+
+target_link_libraries(screenbrightnessplugin PRIVATE
+    Qt::Qml
+    Qt::DBus
+    Qt::Gui
+    Qt::Quick
+    KF6::CoreAddons
+    KF6::ConfigCore
+    KF6::ConfigGui
+    KF6::I18n
+    KF6::Screen
+)
+
+ecm_finalize_qml_module(screenbrightnessplugin)

components/screenbrightnessplugin/screenbrightnessutil.cpp

@@ -0,0 +1,97 @@
+// SPDX-FileCopyrightText: 2024 Devin Lin <devin@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "screenbrightnessutil.h"
+
+#include <QDBusPendingCallWatcher>
+#include <QDBusPendingReply>
+
+ScreenBrightnessUtil::ScreenBrightnessUtil(QObject *parent)
+    : QObject{parent}
+{
+    m_brightnessInterface =
+        new org::kde::Solid::PowerManagement::Actions::BrightnessControl(QStringLiteral("org.kde.Solid.PowerManagement"),
+                                                                         QStringLiteral("/org/kde/Solid/PowerManagement/Actions/BrightnessControl"),
+                                                                         QDBusConnection::sessionBus(),
+                                                                         this);
+
+    fetchBrightness();
+    fetchMaxBrightness();
+
+    connect(m_brightnessInterface,
+            &org::kde::Solid::PowerManagement::Actions::BrightnessControl::brightnessChanged,
+            this,
+            &ScreenBrightnessUtil::fetchBrightness);
+    connect(m_brightnessInterface,
+            &org::kde::Solid::PowerManagement::Actions::BrightnessControl::brightnessMaxChanged,
+            this,
+            &ScreenBrightnessUtil::fetchMaxBrightness);
+
+    // watch for brightness interface
+    m_brightnessInterfaceWatcher = new QDBusServiceWatcher(QStringLiteral("org.kde.Solid.PowerManagement.Actions.BrightnessControl"),
+                                                           QDBusConnection::sessionBus(),
+                                                           QDBusServiceWatcher::WatchForOwnerChange,
+                                                           this);
+
+    connect(m_brightnessInterfaceWatcher, &QDBusServiceWatcher::serviceRegistered, this, [this]() -> void {
+        Q_EMIT brightnessAvailableChanged();
+    });
+
+    connect(m_brightnessInterfaceWatcher, &QDBusServiceWatcher::serviceUnregistered, this, [this]() -> void {
+        Q_EMIT brightnessAvailableChanged();
+    });
+}
+
+int ScreenBrightnessUtil::brightness() const
+{
+    return m_brightness;
+}
+
+void ScreenBrightnessUtil::setBrightness(int brightness)
+{
+    m_brightnessInterface->setBrightness(brightness);
+}
+
+int ScreenBrightnessUtil::maxBrightness() const
+{
+    return m_maxBrightness;
+}
+
+bool ScreenBrightnessUtil::brightnessAvailable() const
+{
+    return m_brightnessInterface->isValid();
+}
+
+void ScreenBrightnessUtil::fetchBrightness()
+{
+    QDBusPendingReply<int> reply = m_brightnessInterface->brightness();
+    QDBusPendingCallWatcher *watcher = new QDBusPendingCallWatcher(reply, this);
+
+    connect(watcher, &QDBusPendingCallWatcher::finished, this, [this](QDBusPendingCallWatcher *watcher) {
+        QDBusPendingReply<int> reply = *watcher;
+        if (reply.isError()) {
+            qWarning() << "Getting brightness failed:" << reply.error().name() << reply.error().message();
+        } else if (m_brightness != reply.value()) {
+            m_brightness = reply.value();
+            Q_EMIT brightnessChanged();
+        }
+        watcher->deleteLater();
+    });
+}
+
+void ScreenBrightnessUtil::fetchMaxBrightness()
+{
+    QDBusPendingReply<int> reply = m_brightnessInterface->brightnessMax();
+    QDBusPendingCallWatcher *watcher = new QDBusPendingCallWatcher(reply, this);
+
+    connect(watcher, &QDBusPendingCallWatcher::finished, this, [this](QDBusPendingCallWatcher *watcher) {
+        QDBusPendingReply<int> reply = *watcher;
+        if (reply.isError()) {
+            qWarning() << "Getting max brightness failed:" << reply.error().name() << reply.error().message();
+        } else if (m_maxBrightness != reply.value()) {
+            m_maxBrightness = reply.value();
+            Q_EMIT maxBrightnessChanged();
+        }
+        watcher->deleteLater();
+    });
+}

components/screenbrightnessplugin/screenbrightnessutil.h

@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: 2024 Devin Lin <devin@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <QDBusServiceWatcher>
+#include <QObject>
+#include <qqmlregistration.h>
+
+#include "brightnesscontrolinterface.h"
+
+/**
+ * Utility class that provides useful functions related to screen brightness.
+ *
+ * @author Devin Lin <devin@kde.org>
+ **/
+class ScreenBrightnessUtil : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(int brightness READ brightness WRITE setBrightness NOTIFY brightnessChanged);
+    Q_PROPERTY(int maxBrightness READ maxBrightness NOTIFY maxBrightnessChanged)
+    Q_PROPERTY(bool brightnessAvailable READ brightnessAvailable NOTIFY brightnessAvailableChanged)
+    QML_ELEMENT
+
+public:
+    ScreenBrightnessUtil(QObject *parent = nullptr);
+
+    int brightness() const;
+    void setBrightness(int brightness);
+
+    int maxBrightness() const;
+
+    bool brightnessAvailable() const;
+
+Q_SIGNALS:
+    void brightnessChanged();
+    void maxBrightnessChanged();
+    void brightnessAvailableChanged();
+
+private Q_SLOTS:
+    void fetchBrightness();
+    void fetchMaxBrightness();
+
+private:
+    int m_brightness;
+    int m_maxBrightness;
+
+    org::kde::Solid::PowerManagement::Actions::BrightnessControl *m_brightnessInterface;
+    QDBusServiceWatcher *m_brightnessInterfaceWatcher;
+};

initialstart/modules/prepare/CMakeLists.txt

@@ -1,12 +1,9 @@
 # SPDX-FileCopyrightText: 2023 Devin Lin <devin@kde.org>
 # SPDX-License-Identifier: GPL-2.0-or-later
 
-qt_add_dbus_interfaces(DBUS_SRCS dbus/org.kde.Solid.PowerManagement.Actions.BrightnessControl.xml)
-
 set(prepareplugin_SRCS
     prepareplugin.cpp
     prepareutil.cpp
-    ${DBUS_SRCS}
 )
 
 kconfig_add_kcfg_files(prepareplugin_SRCS colorssettings.kcfgc GENERATE_MOC)

initialstart/modules/prepare/package/contents/ui/main.qml

@@ -8,6 +8,7 @@ import QtQuick.Layouts 1.15
 import org.kde.kirigami 2.20 as Kirigami
 import org.kde.kirigamiaddons.formcard 1.0 as FormCard
 import org.kde.plasma.mobileinitialstart.prepare 1.0 as Prepare
+import org.kde.plasma.private.mobileshell.screenbrightnessplugin as ScreenBrightness
 
 Item {
     id: root
@@ -15,6 +16,10 @@ Item {
 
     readonly property real cardWidth: Math.min(Kirigami.Units.gridUnit * 30, root.width - Kirigami.Units.gridUnit * 2)
 
+    ScreenBrightness.ScreenBrightnessUtil {
+        id: screenBrightness
+    }
+
     ScrollView {
         anchors {
             fill: parent
@@ -34,7 +39,7 @@ Item {
                 Layout.alignment: Qt.AlignTop
                 Layout.fillWidth: true
 
-                visible: Prepare.PrepareUtil.brightnessAvailable
+                visible: screenBrightness.brightnessAvailable
                 wrapMode: Text.Wrap
                 horizontalAlignment: Text.AlignHCenter
                 text: i18n("Adjust the screen brightness to be comfortable for the installation process.")
@@ -42,7 +47,7 @@ Item {
 
             FormCard.FormCard {
                 id: brightnessCard
-                visible: Prepare.PrepareUtil.brightnessAvailable
+                visible: screenBrightness.brightnessAvailable
                 maximumWidth: root.cardWidth
 
                 Layout.alignment: Qt.AlignTop | Qt.AlignHCenter
@@ -63,16 +68,16 @@ Item {
                             id: brightnessSlider
                             Layout.fillWidth: true
                             from: 1
-                            to: Prepare.PrepareUtil.maxBrightness
+                            to: screenBrightness.maxBrightness
-                            value: Prepare.PrepareUtil.brightness
+                            value: screenBrightness.brightness
-                            onMoved: Prepare.PrepareUtil.brightness = value;
+                            onMoved: screenBrightness.brightness = value;
 
                             // HACK: for some reason, the slider initial value doesn't set without being done after the component completes loading
                             Timer {
                                 interval: 0
                                 running: true
                                 repeat: false
-                                onTriggered: brightnessSlider.value = Qt.binding(() => Prepare.PrepareUtil.brightness)
+                                onTriggered: brightnessSlider.value = Qt.binding(() => screenBrightness.brightness)
                             }
                         }
 

initialstart/modules/prepare/prepareutil.cpp

@@ -10,23 +10,12 @@
 
 #include <QDBusPendingCallWatcher>
 #include <QDBusPendingReply>
+#include <QProcess>
 
 PrepareUtil::PrepareUtil(QObject *parent)
     : QObject{parent}
     , m_colorsSettings{new ColorsSettings(this)}
 {
-    m_brightnessInterface =
-        new org::kde::Solid::PowerManagement::Actions::BrightnessControl(QStringLiteral("org.kde.Solid.PowerManagement"),
-                                                                         QStringLiteral("/org/kde/Solid/PowerManagement/Actions/BrightnessControl"),
-                                                                         QDBusConnection::sessionBus(),
-                                                                         this);
-
-    fetchBrightness();
-    fetchMaxBrightness();
-
-    connect(m_brightnessInterface, &org::kde::Solid::PowerManagement::Actions::BrightnessControl::brightnessChanged, this, &PrepareUtil::fetchBrightness);
-    connect(m_brightnessInterface, &org::kde::Solid::PowerManagement::Actions::BrightnessControl::brightnessMaxChanged, this, &PrepareUtil::fetchMaxBrightness);
-
     connect(new KScreen::GetConfigOperation(), &KScreen::GetConfigOperation::finished, this, [this](auto *op) {
         m_config = qobject_cast<KScreen::GetConfigOperation *>(op)->config();
 
@@ -45,20 +34,6 @@ PrepareUtil::PrepareUtil(QObject *parent)
         Q_EMIT scalingChanged();
     });
 
-    // watch for brightness interface
-    m_brightnessInterfaceWatcher = new QDBusServiceWatcher(QStringLiteral("org.kde.Solid.PowerManagement.Actions.BrightnessControl"),
-                                                           QDBusConnection::sessionBus(),
-                                                           QDBusServiceWatcher::WatchForOwnerChange,
-                                                           this);
-
-    connect(m_brightnessInterfaceWatcher, &QDBusServiceWatcher::serviceRegistered, this, [this]() -> void {
-        Q_EMIT brightnessAvailableChanged();
-    });
-
-    connect(m_brightnessInterfaceWatcher, &QDBusServiceWatcher::serviceUnregistered, this, [this]() -> void {
-        Q_EMIT brightnessAvailableChanged();
-    });
-
     // set property initially
     m_usingDarkTheme = m_colorsSettings->colorScheme() == "BreezeDark";
 }
@@ -93,26 +68,6 @@ QStringList PrepareUtil::scalingOptions()
     return {"50%", "75%", "100%", "125%", "150%", "175%", "200%", "225%", "250%", "275%", "300%"};
 }
 
-int PrepareUtil::brightness() const
-{
-    return m_brightness;
-}
-
-void PrepareUtil::setBrightness(int brightness)
-{
-    m_brightnessInterface->setBrightness(brightness);
-}
-
-int PrepareUtil::maxBrightness() const
-{
-    return m_maxBrightness;
-}
-
-bool PrepareUtil::brightnessAvailable() const
-{
-    return m_brightnessInterface->isValid();
-}
-
 bool PrepareUtil::usingDarkTheme() const
 {
     return m_usingDarkTheme;
@@ -130,37 +85,3 @@ void PrepareUtil::setUsingDarkTheme(bool usingDarkTheme)
     m_usingDarkTheme = usingDarkTheme;
     Q_EMIT usingDarkThemeChanged();
 }
-
-void PrepareUtil::fetchBrightness()
-{
-    QDBusPendingReply<int> reply = m_brightnessInterface->brightness();
-    QDBusPendingCallWatcher *watcher = new QDBusPendingCallWatcher(reply, this);
-
-    connect(watcher, &QDBusPendingCallWatcher::finished, this, [this](QDBusPendingCallWatcher *watcher) {
-        QDBusPendingReply<int> reply = *watcher;
-        if (reply.isError()) {
-            qWarning() << "Getting brightness failed:" << reply.error().name() << reply.error().message();
-        } else if (m_brightness != reply.value()) {
-            m_brightness = reply.value();
-            Q_EMIT brightnessChanged();
-        }
-        watcher->deleteLater();
-    });
-}
-
-void PrepareUtil::fetchMaxBrightness()
-{
-    QDBusPendingReply<int> reply = m_brightnessInterface->brightnessMax();
-    QDBusPendingCallWatcher *watcher = new QDBusPendingCallWatcher(reply, this);
-
-    connect(watcher, &QDBusPendingCallWatcher::finished, this, [this](QDBusPendingCallWatcher *watcher) {
-        QDBusPendingReply<int> reply = *watcher;
-        if (reply.isError()) {
-            qWarning() << "Getting max brightness failed:" << reply.error().name() << reply.error().message();
-        } else if (m_maxBrightness != reply.value()) {
-            m_maxBrightness = reply.value();
-            Q_EMIT maxBrightnessChanged();
-        }
-        watcher->deleteLater();
-    });
-}

initialstart/modules/prepare/prepareutil.h

@@ -8,7 +8,6 @@
 
 #include <kscreen/config.h>
 
-#include "brightnesscontrolinterface.h"
 #include "colorssettings.h"
 
 class PrepareUtil : public QObject
@@ -16,9 +15,6 @@ class PrepareUtil : public QObject
     Q_OBJECT
     Q_PROPERTY(int scaling READ scaling WRITE setScaling NOTIFY scalingChanged);
     Q_PROPERTY(QStringList scalingOptions READ scalingOptions CONSTANT);
-    Q_PROPERTY(int brightness READ brightness WRITE setBrightness NOTIFY brightnessChanged);
-    Q_PROPERTY(int maxBrightness READ maxBrightness NOTIFY maxBrightnessChanged)
-    Q_PROPERTY(bool brightnessAvailable READ brightnessAvailable NOTIFY brightnessAvailableChanged)
     Q_PROPERTY(bool usingDarkTheme READ usingDarkTheme WRITE setUsingDarkTheme NOTIFY usingDarkThemeChanged)
 
 public:
@@ -29,35 +25,17 @@ public:
 
     QStringList scalingOptions();
 
-    int brightness() const;
-    void setBrightness(int brightness);
-
-    int maxBrightness() const;
-
-    bool brightnessAvailable() const;
-
     bool usingDarkTheme() const;
     void setUsingDarkTheme(bool usingDarkTheme);
 
 Q_SIGNALS:
     void scalingChanged();
-    void brightnessChanged();
-    void maxBrightnessChanged();
-    void brightnessAvailableChanged();
     void usingDarkThemeChanged();
 
-private Q_SLOTS:
-    void fetchBrightness();
-    void fetchMaxBrightness();
-
 private:
     int m_scaling;
-    int m_brightness;
-    int m_maxBrightness;
     bool m_usingDarkTheme;
 
     ColorsSettings *m_colorsSettings;
     KScreen::ConfigPtr m_config;
-    org::kde::Solid::PowerManagement::Actions::BrightnessControl *m_brightnessInterface;
-    QDBusServiceWatcher *m_brightnessInterfaceWatcher;
 };