Add support for propagating palettes

Change-Id: Icd965d8a79f022f4375e2134621cbc3897014015
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 182 insertions, 0 deletions

diff --git a/src/quicktemplates2/qquickcontrol.cpp b/src/quicktemplates2/qquickcontrol.cpp
index d285fdd2..e866a9a3 100644
--- a/src/quicktemplates2/qquickcontrol.cpp
+++ b/src/quicktemplates2/qquickcontrol.cpp
@@ -421,6 +421,111 @@ void QQuickControlPrivate::updateFontRecur(QQuickItem *item, const QFont &font)
     }
 }
 
+/*!
+    \internal
+
+    Returns the palette that the item inherits from its ancestors and
+    QGuiApplication::palette.
+*/
+QPalette QQuickControlPrivate::parentPalette(const QQuickItem *item)
+{
+    QQuickItem *p = item->parentItem();
+    while (p) {
+        if (QQuickControl *control = qobject_cast<QQuickControl *>(p))
+            return control->palette();
+        else if (QQuickLabel *label = qobject_cast<QQuickLabel *>(p))
+            return label->palette();
+        else if (QQuickTextField *textField = qobject_cast<QQuickTextField *>(p))
+            return textField->palette();
+        else if (QQuickTextArea *textArea = qobject_cast<QQuickTextArea *>(p))
+            return textArea->palette();
+
+        p = p->parentItem();
+    }
+
+    if (QQuickApplicationWindow *window = qobject_cast<QQuickApplicationWindow *>(item->window()))
+        return window->palette();
+
+    return themePalette(QPlatformTheme::SystemPalette);
+}
+
+QPalette QQuickControlPrivate::themePalette(QPlatformTheme::Palette type)
+{
+    if (QPlatformTheme *theme = QGuiApplicationPrivate::platformTheme()) {
+        if (const QPalette *palette = theme->palette(type)) {
+            QPalette p = *palette;
+            if (type == QPlatformTheme::SystemPalette)
+                p.resolve(0);
+            return p;
+        }
+    }
+
+    return QPalette();
+}
+
+/*!
+    \internal
+
+    Determine which palette is implicitly imposed on this control by its ancestors
+    and QGuiApplication::palette, resolve this against its own palette (attributes from
+    the implicit palette are copied over). Then propagate this palette to this
+    control's children.
+*/
+void QQuickControlPrivate::resolvePalette()
+{
+    Q_Q(QQuickControl);
+    inheritPalette(parentPalette(q));
+}
+
+void QQuickControlPrivate::inheritPalette(const QPalette &palette)
+{
+    Q_Q(QQuickControl);
+    QPalette parentPalette = extra.isAllocated() ? extra->requestedPalette.resolve(palette) : palette;
+    parentPalette.resolve(extra.isAllocated() ? extra->requestedPalette.resolve() | palette.resolve() : palette.resolve());
+
+    const QPalette defaultPalette = q->defaultPalette();
+    const QPalette resolvedPalette = parentPalette.resolve(defaultPalette);
+
+    setPalette_helper(resolvedPalette);
+}
+
+/*!
+    \internal
+
+    Assign \a palette to this control, and propagate it to all children.
+*/
+void QQuickControlPrivate::updatePalette(const QPalette &palette)
+{
+    Q_Q(QQuickControl);
+    QPalette oldPalette = resolvedPalette;
+    resolvedPalette = palette;
+
+    if (oldPalette != palette)
+        q->paletteChange(palette, oldPalette);
+
+    QQuickControlPrivate::updatePaletteRecur(q, palette);
+
+    if (oldPalette != palette)
+        emit q->paletteChanged();
+}
+
+void QQuickControlPrivate::updatePaletteRecur(QQuickItem *item, const QPalette &palette)
+{
+    const auto childItems = item->childItems();
+    for (QQuickItem *child : childItems) {
+        if (QQuickControl *control = qobject_cast<QQuickControl *>(child))
+            QQuickControlPrivate::get(control)->inheritPalette(palette);
+        else if (QQuickLabel *label = qobject_cast<QQuickLabel *>(child))
+            QQuickLabelPrivate::get(label)->inheritPalette(palette);
+        else if (QQuickTextArea *textArea = qobject_cast<QQuickTextArea *>(child))
+            QQuickTextAreaPrivate::get(textArea)->inheritPalette(palette);
+        else if (QQuickTextField *textField = qobject_cast<QQuickTextField *>(child))
+            QQuickTextFieldPrivate::get(textField)->inheritPalette(palette);
+        else
+            QQuickControlPrivate::updatePaletteRecur(child, palette);
+    }
+}
+
 QLocale QQuickControlPrivate::calcLocale(const QQuickItem *item)
 {
     const QQuickItem *p = item;
@@ -556,11 +661,15 @@ void QQuickControlPrivate::destroyDelegate(QObject *delegate, QObject *parent)
 QQuickControl::QQuickControl(QQuickItem *parent)
     : QQuickItem(*(new QQuickControlPrivate), parent)
 {
+    // ### TODO: ItemEnabledChanged?
+    connect(this, &QQuickItem::enabledChanged, this, &QQuickControl::paletteChanged);
 }
 
 QQuickControl::QQuickControl(QQuickControlPrivate &dd, QQuickItem *parent)
     : QQuickItem(dd, parent)
 {
+    // ### TODO: ItemEnabledChanged?
+    connect(this, &QQuickItem::enabledChanged, this, &QQuickControl::paletteChanged);
 }
 
 void QQuickControl::itemChange(QQuickItem::ItemChange change, const QQuickItem::ItemChangeData &value)
@@ -577,6 +686,7 @@ void QQuickControl::itemChange(QQuickItem::ItemChange change, const QQuickItem::
     case ItemParentHasChanged:
         if (value.item) {
             d->resolveFont();
+            d->resolvePalette();
             if (!d->hasLocale)
                 d->updateLocale(QQuickControlPrivate::calcLocale(d->parentItem), false); // explicit=false
 #if QT_CONFIG(quicktemplates2_hover)
@@ -1208,11 +1318,72 @@ void QQuickControl::setContentItem(QQuickItem *item)
     d->setContentItem_helper(item, true);
 }
 
+/*!
+    \since QtQuick.Controls 2.3
+    \qmlproperty palette QtQuick.Controls::Control::palette
+
+    This property holds the palette currently set for the control.
+
+    This property describes the control's requested palette. The palette is used by the control's
+    style when rendering standard components, and is available as a means to ensure that custom
+    controls can maintain consistency with the native platform's native look and feel. It's common
+    that different platforms, or different styles, define different palettes for an application.
+
+    The default palette depends on the system environment. ApplicationWindow maintains a system/theme
+    palette which serves as a default for all controls. There may also be special palette defaults for
+    certain types of controls. You can also set the default palette for controls by passing a custom
+    palette to QGuiApplication::setPalette(), before loading any QML.
+
+    Control propagates explicit palette properties from parent to children. If you change a specific
+    property on a control's palette, that property propagates to all of the control's children,
+    overriding any system defaults for that property.
+
+    \code
+    Page {
+        palette.text: "red"
+
+        Column {
+            Label {
+                text: qsTr("This will use red color...")
+            }
+
+            Switch {
+                text: qsTr("... and so will this")
+            }
+        }
+    }
+    \endcode
+*/
+QPalette QQuickControl::palette() const
+{
+    Q_D(const QQuickControl);
+    QPalette palette = d->resolvedPalette;
+    if (!isEnabled())
+        palette.setCurrentColorGroup(QPalette::Disabled);
+    return palette;
+}
+
+void QQuickControl::setPalette(const QPalette &palette)
+{
+    Q_D(QQuickControl);
+    if (d->extra.value().requestedPalette.resolve() == palette.resolve() && d->extra.value().requestedPalette == palette)
+        return;
+
+    d->extra.value().requestedPalette = palette;
+    d->resolvePalette();
+}
+
+void QQuickControl::resetPalette()
+{
+    setPalette(QPalette());
+}
+
 void QQuickControl::classBegin()
 {
     Q_D(QQuickControl);
     QQuickItem::classBegin();
     d->resolveFont();
+    d->resolvePalette();
 }
 
 void QQuickControl::componentComplete()
@@ -1237,6 +1408,11 @@ QFont QQuickControl::defaultFont() const
     return QQuickControlPrivate::themeFont(QPlatformTheme::SystemFont);
 }
 
+QPalette QQuickControl::defaultPalette() const
+{
+    return QQuickControlPrivate::themePalette(QPlatformTheme::SystemPalette);
+}
+
 void QQuickControl::focusInEvent(QFocusEvent *event)
 {
     QQuickItem::focusInEvent(event);
@@ -1420,6 +1596,12 @@ void QQuickControl::localeChange(const QLocale &newLocale, const QLocale &oldLoc
     Q_UNUSED(oldLocale);
 }
 
+void QQuickControl::paletteChange(const QPalette &newPalette, const QPalette &oldPalette)
+{
+    Q_UNUSED(newPalette);
+    Q_UNUSED(oldPalette);
+}
+
 #if QT_CONFIG(accessibility)
 QAccessible::Role QQuickControl::accessibleRole() const
 {