QWindowsMimeConverter Class

The QWindowsMimeConverter class maps open-standard MIME to Window Clipboard formats. More...

Header:	#include <QWindowsMimeConverter>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Gui) target_link_libraries(mytarget PRIVATE Qt6::Gui)
qmake:	QT += gui

List of all members, including inherited members

Public Functions

	QWindowsMimeConverter()
virtual	~QWindowsMimeConverter()
virtual bool	canConvertFromMime(const FORMATETC &formatetc, const QMimeData *mimeData) const = 0
virtual bool	canConvertToMime(const QString &mimeType, IDataObject *pDataObj) const = 0
virtual bool	convertFromMime(const FORMATETC &formatetc, const QMimeData *mimeData, STGMEDIUM *pmedium) const = 0
virtual QVariant	convertToMime(const QString &mimeType, IDataObject *pDataObj, QMetaType preferredType) const = 0
virtual QList<FORMATETC>	formatsForMime(const QString &mimeType, const QMimeData *mimeData) const = 0
virtual QString	mimeForFormat(const FORMATETC &formatetc) const = 0

Static Public Members

int	registerMimeType(const QString &mimeType)

Detailed Description

Qt's drag-and-drop and clipboard facilities use the MIME standard. On X11, this maps trivially to the Xdnd protocol, but on Windows although some applications use MIME types to describe clipboard formats, others use arbitrary non-standardized naming conventions, or unnamed built-in formats of Windows.

By instantiating subclasses of QWindowsMimeConverter that provide conversions between Windows Clipboard and MIME formats, you can convert proprietary clipboard formats to MIME formats.

Construct an instance of your converter implementation after instantiating QGuiApplication:

int main(int argc, char **argv)
{
    QGuiApplication app(argc, argv);
    JsonMimeConverter jsonConverter;
}

Destroying the instance will unregister the converter and remove support for the conversion. It is also valid to heap-allocate the converter instance; Qt takes ownership and will delete the converter object during QGuiApplication shut-down.

Qt has predefined support for the following Windows Clipboard formats:

Windows Format	Equivalent MIME type
`CF_UNICODETEXT`	`text/plain`
`CF_TEXT`	`text/plain`
`CF_DIB`	`image/xyz`, where `xyz` is a Qt image format
`CF_HDROP`	`text/uri-list`
`CF_INETURL`	`text/uri-list`
`CF_HTML`	`text/html`

An example use of this class would be to map the Windows Metafile clipboard format (CF_METAFILEPICT) to and from the MIME type image/x-wmf. This conversion might simply be adding or removing a header, or even just passing on the data. See Drag and Drop for more information on choosing and definition MIME types.

You can check if a MIME type is convertible using canConvertFromMime() and can perform conversions with convertToMime() and convertFromMime().

Member Function Documentation

QWindowsMimeConverter::QWindowsMimeConverter()

Constructs a QWindowsMimeConverter instance.

The instance is automatically registered, and will be called to convert data during clipboard or drag'n'drop operations.

Call this constructor after QGuiApplication has been created.

`[virtual noexcept]` QWindowsMimeConverter::~QWindowsMimeConverter()

Constructs a QWindowsMimeConverter instance.

The instance is automatically unregistered.

`[pure virtual]` bool QWindowsMimeConverter::canConvertFromMime(const FORMATETC &formatetc, const QMimeData **mimeData*) const

Returns true if the converter can convert from the mimeData to the format specified in formatetc.