kcm/decorations: Simplify border selection

Use a single combobox instead of checkbox + combobox.
Adds a new property that acts as a proxy for the configuration value,
while internal configuration properties are kept unchanged.

BUG: 426157
BUG: 417430
FIXED-IN: 5.21

kcmkwin/kwindecoration/kcm.cpp

@@ -68,6 +68,10 @@ KCMKWinDecoration::KCMKWinDecoration(QObject *parent, const QVariantList &argume
     connect(m_data->settings(), &KWinDecorationSettings::themeChanged, this, &KCMKWinDecoration::themeChanged);
     connect(m_data->settings(), &KWinDecorationSettings::borderSizeChanged, this, &KCMKWinDecoration::borderSizeChanged);
 
+    connect(m_data->settings(), &KWinDecorationSettings::borderSizeAutoChanged, this, &KCMKWinDecoration::borderIndexChanged);
+    connect(this, &KCMKWinDecoration::borderSizeChanged, this, &KCMKWinDecoration::borderIndexChanged);
+    connect(this, &KCMKWinDecoration::themeChanged, this, &KCMKWinDecoration::borderIndexChanged);
+
     connect(m_leftButtonsModel, &QAbstractItemModel::rowsInserted, this, &KCMKWinDecoration::onLeftButtonsChanged);
     connect(m_leftButtonsModel, &QAbstractItemModel::rowsMoved, this, &KCMKWinDecoration::onLeftButtonsChanged);
     connect(m_leftButtonsModel, &QAbstractItemModel::rowsRemoved, this, &KCMKWinDecoration::onLeftButtonsChanged);
@@ -188,7 +192,24 @@ QAbstractListModel *KCMKWinDecoration::availableButtonsModel() const
 
 QStringList KCMKWinDecoration::borderSizesModel() const
 {
-    return Utils::getBorderSizeNames().values();
+    // Use index 0 for borderSizeAuto == true
+    // The rest of indexes get offset by 1
+    QStringList model = Utils::getBorderSizeNames().values();
+    model.insert(0, i18nc("%1 is the name of a border size",
+                          "Theme's default (%1)", model.at(recommendedBorderSize())));
+    return model;
+}
+
+int KCMKWinDecoration::borderIndex() const
+{
+    return settings()->borderSizeAuto() ? 0 : m_borderSizeIndex + 1;
+}
+
+void KCMKWinDecoration::setBorderIndex(int index)
+{
+    const bool borderAuto = (index == 0);
+    settings()->setBorderSizeAuto(borderAuto);
+    setBorderSize(borderAuto ? recommendedBorderSize() : index - 1);
 }
 
 int KCMKWinDecoration::borderSize() const

kcmkwin/kwindecoration/kcm.h

@@ -43,8 +43,9 @@ class KCMKWinDecoration : public KQuickAddons::ManagedConfigModule
     Q_OBJECT
     Q_PROPERTY(KWinDecorationSettings *settings READ settings CONSTANT)
     Q_PROPERTY(QSortFilterProxyModel *themesModel READ themesModel CONSTANT)
-    Q_PROPERTY(QStringList borderSizesModel READ borderSizesModel CONSTANT)
+    Q_PROPERTY(QStringList borderSizesModel READ borderSizesModel NOTIFY themeChanged)
-    Q_PROPERTY(int borderSize READ borderSize WRITE setBorderSize NOTIFY borderSizeChanged)
+    Q_PROPERTY(int borderIndex READ borderIndex WRITE setBorderIndex NOTIFY borderIndexChanged)
+    Q_PROPERTY(int borderSize READ borderSize NOTIFY borderSizeChanged)
     Q_PROPERTY(int recommendedBorderSize READ recommendedBorderSize CONSTANT)
     Q_PROPERTY(int theme READ theme WRITE setTheme NOTIFY themeChanged)
     Q_PROPERTY(QAbstractListModel *leftButtonsModel READ leftButtonsModel NOTIFY buttonsChanged)
@@ -60,10 +61,12 @@ public:
     QAbstractListModel *rightButtonsModel();
     QAbstractListModel *availableButtonsModel() const;
     QStringList borderSizesModel() const;
+    int borderIndex() const;
     int borderSize() const;
     int recommendedBorderSize() const;
     int theme() const;
 
+    void setBorderIndex(int index);
     void setBorderSize(int index);
     void setBorderSize(KDecoration2::BorderSize size);
     void setTheme(int index);
@@ -73,6 +76,7 @@ public:
 Q_SIGNALS:
     void themeChanged();
     void buttonsChanged();
+    void borderIndexChanged();
     void borderSizeChanged();
 
 public Q_SLOTS:

kcmkwin/kwindecoration/package/contents/ui/main.qml

@@ -7,7 +7,7 @@
 import QtQuick 2.7
 import QtQuick.Layouts 1.3
 import QtQuick.Controls 2.4 as Controls
-import org.kde.kcm 1.3 as KCM
+import org.kde.kcm 1.5 as KCM
 import org.kde.kconfig 1.0 // for KAuthorized
 import org.kde.kirigami 2.4 as Kirigami
 
@@ -81,49 +81,18 @@ Kirigami.Page {
                         }
 
                         RowLayout {
-                            Controls.CheckBox {
+                            Controls.Label {
-                                id: borderSizeAutoCheckbox
+                                text: i18nc("Selector label", "Window border size:")
-                                // Let it elide but don't make it push the ComboBox away from it
-                                Layout.fillWidth: true
-                                Layout.maximumWidth: implicitWidth
-                                text: i18nc("checkbox label", "Use theme's default window border size")
-                                checked: kcm.settings.borderSizeAuto
-                                onToggled: {
-                                    kcm.settings.borderSizeAuto = checked;
-                                    borderSizeComboBox.autoBorderUpdate()
-                                }
-
-                                KCM.SettingStateBinding {
-                                    configObject: kcm.settings
-                                    settingName: "borderSizeAuto"
-                                }
-
                             }
                             Controls.ComboBox {
                                 id: borderSizeComboBox
                                 model: kcm.borderSizesModel
-                                currentIndex: kcm.borderSize
+                                currentIndex: kcm.borderIndex
                                 onActivated: {
-                                    kcm.borderSize = currentIndex
+                                    kcm.borderIndex = currentIndex
-                                }
-
-                                KCM.SettingStateBinding {
-                                    configObject: kcm.settings
-                                    settingName: "borderSize"
-                                    extraEnabledConditions: !borderSizeAutoCheckbox.checked
-                                }
-
-                                function autoBorderUpdate() {
-                                    if (borderSizeAutoCheckbox.checked) {
-                                        kcm.borderSize = kcm.recommendedBorderSize
-                                    }
-                                }
-
-                                Connections {
-                                    target: kcm
-                                    function onThemeChanged() {
-                                        borderSizeComboBox.autoBorderUpdate()
                                 }
+                                KCM.SettingHighlighter {
+                                    highlight: kcm.borderIndex != 0
                                 }
                             }
                             Item {