Item delegates: show localized detailed tooltips and "What's this?" texts

Extract the common part from QItemDelegate and QStyledItemDelegate
which uses QLocale to convert a value for Qt::DisplayRole to a string.
Use this code to get the text for tooltips and "What's this?".

[ChangeLog][QtWidgets][QAbstractItemDelegate] Show localized detailed
tooltips and "What's this?" texts.

Task-number: QTBUG-16469
Change-Id: I8618763d45b8cfddafc2f263d658ba256be60a15
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

4 files changed, 58 insertions, 78 deletions

diff --git a/src/widgets/itemviews/qabstractitemdelegate.cpp b/src/widgets/itemviews/qabstractitemdelegate.cpp
index c2dd1ec8fd..00f2b87f93 100644
--- a/src/widgets/itemviews/qabstractitemdelegate.cpp
+++ b/src/widgets/itemviews/qabstractitemdelegate.cpp
@@ -370,6 +370,7 @@ bool QAbstractItemDelegate::helpEvent(QHelpEvent *event,
                                       const QStyleOptionViewItem &option,
                                       const QModelIndex &index)
 {
+    Q_D(QAbstractItemDelegate);
     Q_UNUSED(option);
 
     if (!event || !view)
@@ -378,9 +379,10 @@ bool QAbstractItemDelegate::helpEvent(QHelpEvent *event,
 #ifndef QT_NO_TOOLTIP
     case QEvent::ToolTip: {
         QHelpEvent *he = static_cast<QHelpEvent*>(event);
-        QVariant tooltip = index.data(Qt::ToolTipRole);
-        if (tooltip.canConvert<QString>()) {
-            QToolTip::showText(he->globalPos(), tooltip.toString(), view);
+        const int precision = inherits("QItemDelegate") ? 10 : 6; // keep in sync with DBL_DIG in qitemdelegate.cpp
+        const QString tooltip = d->textForRole(Qt::ToolTipRole, index.data(Qt::ToolTipRole), option.locale, precision);
+        if (!tooltip.isEmpty()) {
+            QToolTip::showText(he->globalPos(), tooltip, view);
             return true;
         }
         break;}
@@ -392,9 +394,10 @@ bool QAbstractItemDelegate::helpEvent(QHelpEvent *event,
         break; }
     case QEvent::WhatsThis: {
         QHelpEvent *he = static_cast<QHelpEvent*>(event);
-        QVariant whatsthis = index.data(Qt::WhatsThisRole);
-        if (whatsthis.canConvert<QString>()) {
-            QWhatsThis::showText(he->globalPos(), whatsthis.toString(), view);
+        const int precision = inherits("QItemDelegate") ? 10 : 6; // keep in sync with DBL_DIG in qitemdelegate.cpp
+        const QString whatsthis = d->textForRole(Qt::WhatsThisRole, index.data(Qt::WhatsThisRole), option.locale, precision);
+        if (!whatsthis.isEmpty()) {
+            QWhatsThis::showText(he->globalPos(), whatsthis, view);
             return true;
         }
         break ; }
@@ -537,6 +540,46 @@ bool QAbstractItemDelegatePrivate::tryFixup(QWidget *editor)
     return true;
 }
 
+QString QAbstractItemDelegatePrivate::textForRole(Qt::ItemDataRole role, const QVariant &value, const QLocale &locale, int precision) const
+{
+    const QLocale::FormatType formatType = (role == Qt::DisplayRole) ? QLocale::ShortFormat : QLocale::LongFormat;
+    QString text;
+    switch (value.userType()) {
+    case QMetaType::Float:
+        text = locale.toString(value.toFloat());
+        break;
+    case QVariant::Double:
+        text = locale.toString(value.toDouble(), 'g', precision);
+        break;
+    case QVariant::Int:
+    case QVariant::LongLong:
+        text = locale.toString(value.toLongLong());
+        break;
+    case QVariant::UInt:
+    case QVariant::ULongLong:
+        text = locale.toString(value.toULongLong());
+        break;
+    case QVariant::Date:
+        text = locale.toString(value.toDate(), formatType);
+        break;
+    case QVariant::Time:
+        text = locale.toString(value.toTime(), formatType);
+        break;
+    case QVariant::DateTime: {
+        const QDateTime dateTime = value.toDateTime();
+        text = locale.toString(dateTime.date(), formatType)
+             + QLatin1Char(' ')
+             + locale.toString(dateTime.time(), formatType);
+        break; }
+    default:
+        text = value.toString();
+        if (role == Qt::DisplayRole)
+            text.replace(QLatin1Char('\n'), QChar::LineSeparator);
+        break;
+    }
+    return text;
+}
+
 void QAbstractItemDelegatePrivate::_q_commitDataAndCloseEditor(QWidget *editor)
 {
     Q_Q(QAbstractItemDelegate);
diff --git a/src/widgets/itemviews/qabstractitemdelegate_p.h b/src/widgets/itemviews/qabstractitemdelegate_p.h
index 05f1bd138c..1796290ba9 100644
--- a/src/widgets/itemviews/qabstractitemdelegate_p.h
+++ b/src/widgets/itemviews/qabstractitemdelegate_p.h
@@ -52,7 +52,7 @@
 
 QT_BEGIN_NAMESPACE
 
-class QAbstractItemDelegatePrivate : public QObjectPrivate
+class Q_AUTOTEST_EXPORT QAbstractItemDelegatePrivate : public QObjectPrivate
 {
     Q_DECLARE_PUBLIC(QAbstractItemDelegate)
 public:
@@ -60,6 +60,7 @@ public:
 
     bool editorEventFilter(QObject *object, QEvent *event);
     bool tryFixup(QWidget *editor);
+    QString textForRole(Qt::ItemDataRole role, const QVariant &value, const QLocale &locale, int precision = 6) const;
     void _q_commitDataAndCloseEditor(QWidget *editor);
 };
 
diff --git a/src/widgets/itemviews/qitemdelegate.cpp b/src/widgets/itemviews/qitemdelegate.cpp
index cd952737dd..2b6e1210ca 100644
--- a/src/widgets/itemviews/qitemdelegate.cpp
+++ b/src/widgets/itemviews/qitemdelegate.cpp
@@ -61,6 +61,7 @@
 
 #include <limits.h>
 
+// keep in sync with QAbstractItemDelegate::helpEvent()
 #ifndef DBL_DIG
 #  define DBL_DIG 10
 #endif
@@ -96,7 +97,7 @@ public:
             return text;
         }
 
-    static QString valueToText(const QVariant &value, const QStyleOptionViewItem &option);
+    QString valueToText(const QVariant &value, const QStyleOptionViewItem &option) const;
 
     QItemEditorFactory *f;
     bool clipPainting;
@@ -326,40 +327,9 @@ void QItemDelegate::setClipping(bool clip)
     d->clipPainting = clip;
 }
 
-QString QItemDelegatePrivate::valueToText(const QVariant &value, const QStyleOptionViewItem &option)
+QString QItemDelegatePrivate::valueToText(const QVariant &value, const QStyleOptionViewItem &option) const
 {
-    QString text;
-    switch (value.userType()) {
-        case QMetaType::Float:
-            text = option.locale.toString(value.toFloat(), 'g');
-            break;
-        case QVariant::Double:
-            text = option.locale.toString(value.toDouble(), 'g', DBL_DIG);
-            break;
-        case QVariant::Int:
-        case QVariant::LongLong:
-            text = option.locale.toString(value.toLongLong());
-            break;
-        case QVariant::UInt:
-        case QVariant::ULongLong:
-            text = option.locale.toString(value.toULongLong());
-            break;
-        case QVariant::Date:
-            text = option.locale.toString(value.toDate(), QLocale::ShortFormat);
-            break;
-        case QVariant::Time:
-            text = option.locale.toString(value.toTime(), QLocale::ShortFormat);
-            break;
-        case QVariant::DateTime:
-            text = option.locale.toString(value.toDateTime().date(), QLocale::ShortFormat);
-            text += QLatin1Char(' ');
-            text += option.locale.toString(value.toDateTime().time(), QLocale::ShortFormat);
-            break;
-        default:
-            text = replaceNewLine(value.toString());
-            break;
-    }
-    return text;
+    return textForRole(Qt::DisplayRole, value, option.locale, DBL_DIG);
 }
 
 /*!
@@ -428,7 +398,7 @@ void QItemDelegate::paint(QPainter *painter,
     QRect displayRect;
     value = index.data(Qt::DisplayRole);
     if (value.isValid() && !value.isNull()) {
-        text = QItemDelegatePrivate::valueToText(value, opt);
+        text = d->valueToText(value, opt);
         displayRect = textRectangle(painter, d->textLayoutBounds(opt), opt.font, text);
     }
 
@@ -1055,7 +1025,7 @@ QRect QItemDelegate::rect(const QStyleOptionViewItem &option,
             return QRect(QPoint(0, 0), option.decorationSize);
         case QVariant::String:
         default: {
-            QString text = QItemDelegatePrivate::valueToText(value, option);
+            const QString text = d->valueToText(value, option);
             value = index.data(Qt::FontRole);
             QFont fnt = qvariant_cast<QFont>(value).resolve(option.font);
             return textRectangle(0, d->textLayoutBounds(option), fnt, text); }
diff --git a/src/widgets/itemviews/qstyleditemdelegate.cpp b/src/widgets/itemviews/qstyleditemdelegate.cpp
index f02f98cb31..483cfbdc36 100644
--- a/src/widgets/itemviews/qstyleditemdelegate.cpp
+++ b/src/widgets/itemviews/qstyleditemdelegate.cpp
@@ -255,41 +255,7 @@ QStyledItemDelegate::~QStyledItemDelegate()
 */
 QString QStyledItemDelegate::displayText(const QVariant &value, const QLocale& locale) const
 {
-    QString text;
-    switch (value.userType()) {
-    case QMetaType::Float:
-    case QVariant::Double:
-        text = locale.toString(value.toReal());
-        break;
-    case QVariant::Int:
-    case QVariant::LongLong:
-        text = locale.toString(value.toLongLong());
-        break;
-    case QVariant::UInt:
-    case QVariant::ULongLong:
-        text = locale.toString(value.toULongLong());
-        break;
-    case QVariant::Date:
-        text = locale.toString(value.toDate(), QLocale::ShortFormat);
-        break;
-    case QVariant::Time:
-        text = locale.toString(value.toTime(), QLocale::ShortFormat);
-        break;
-    case QVariant::DateTime:
-        text = locale.toString(value.toDateTime().date(), QLocale::ShortFormat);
-        text += QLatin1Char(' ');
-        text += locale.toString(value.toDateTime().time(), QLocale::ShortFormat);
-        break;
-    default:
-        // convert new lines into line separators
-        text = value.toString();
-        for (int i = 0; i < text.count(); ++i) {
-            if (text.at(i) == QLatin1Char('\n'))
-                text[i] = QChar::LineSeparator;
-        }
-        break;
-    }
-    return text;
+    return d_func()->textForRole(Qt::DisplayRole, value, locale);
 }
 
 /*!