qmacmime: add support for public.text

Copying a URL from Safari to Qt app does not work. The reason
is that it lies on the pasteboard as public.text, which we
don't support.

This patch will implement support for public.text.

The UTI public.text is documented as text with an unspecified
encoding. On iOS, this turns out to be UTF8 (which also matches
[UIPasteboard generalPasteboard].string).

Task-number: QTBUG-38551
Change-Id: I216dab206d3bff2dde99927ed7e5a3d85309f2a2
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>

src/platformsupport/clipboard/qmacmime.mm

@@ -115,6 +115,7 @@ const QStringList& qt_mac_enabledDraggedTypes()
   \list
     \i public.utf8-plain-text - converts to "text/plain"
     \i public.utf16-plain-text - converts to "text/plain"
+    \i public.text - converts to "text/plain"
     \i public.html - converts to "text/html"
     \i public.url - converts to "text/uri-list"
     \i public.file-url - converts to "text/uri-list"
@@ -343,6 +344,69 @@ QList<QByteArray> QMacPasteboardMimePlainText::convertFromMime(const QString &,
     return ret;
 }
 
+class QMacPasteboardMimePlainTextFallback : public QMacInternalPasteboardMime {
+public:
+    QMacPasteboardMimePlainTextFallback() : QMacInternalPasteboardMime(MIME_ALL) { }
+    QString convertorName();
+
+    QString flavorFor(const QString &mime);
+    QString mimeFor(QString flav);
+    bool canConvert(const QString &mime, QString flav);
+    QVariant convertToMime(const QString &mime, QList<QByteArray> data, QString flav);
+    QList<QByteArray> convertFromMime(const QString &mime, QVariant data, QString flav);
+};
+
+QString QMacPasteboardMimePlainTextFallback::convertorName()
+{
+    return QLatin1String("PlainText (public.text)");
+}
+
+QString QMacPasteboardMimePlainTextFallback::flavorFor(const QString &mime)
+{
+    if (mime == QLatin1String("text/plain"))
+        return QLatin1String("public.text");
+    return QString();
+}
+
+QString QMacPasteboardMimePlainTextFallback::mimeFor(QString flav)
+{
+    if (flav == QLatin1String("public.text"))
+        return QLatin1String("text/plain");
+    return QString();
+}
+
+bool QMacPasteboardMimePlainTextFallback::canConvert(const QString &mime, QString flav)
+{
+    return mime == mimeFor(flav);
+}
+
+QVariant QMacPasteboardMimePlainTextFallback::convertToMime(const QString &mimetype, QList<QByteArray> data, QString flavor)
+{
+    if (data.count() > 1)
+        qWarning("QMacPasteboardMimePlainTextFallback: Cannot handle multiple member data");
+
+    if (flavor == QLatin1String("public.text")) {
+        // Note that public.text is documented by Apple to have an undefined encoding. From
+        // testing it seems that utf8 is normally used, at least by Safari on iOS.
+        const QByteArray &firstData = data.first();
+        return QString::fromCFString(CFStringCreateWithBytes(kCFAllocatorDefault,
+                                             reinterpret_cast<const UInt8 *>(firstData.constData()),
+                                             firstData.size(), kCFStringEncodingUTF8, false));
+    } else {
+        qWarning("QMime::convertToMime: unhandled mimetype: %s", qPrintable(mimetype));
+    }
+    return QVariant();
+}
+
+QList<QByteArray> QMacPasteboardMimePlainTextFallback::convertFromMime(const QString &, QVariant data, QString flavor)
+{
+    QList<QByteArray> ret;
+    QString string = data.toString();
+    if (flavor == QLatin1String("public.text"))
+        ret.append(string.toUtf8());
+    return ret;
+}
+
 class QMacPasteboardMimeUnicodeText : public QMacInternalPasteboardMime {
 public:
     QMacPasteboardMimeUnicodeText() : QMacInternalPasteboardMime(MIME_ALL) { }
@@ -696,6 +760,7 @@ void QMacInternalPasteboardMime::initializeMimeTypes()
         new QMacPasteboardMimeAny;
 
         //standard types that we wrap
+        new QMacPasteboardMimePlainTextFallback;
         new QMacPasteboardMimeUnicodeText;
         new QMacPasteboardMimePlainText;
         new QMacPasteboardMimeHTMLText;