QMimeData Class

The https:// class provides a container for data that records information about its MIME type.

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Publié le 27 décembre 2024 - Mis à jour le 27 décembre 2024

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QMimeData Class▲

Header: QMimeData
CMake:

find_package(Qt6 REQUIRED COMPONENTS Core)

target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake: QT += core
Inherits: https://

Detailed Description▲

https:// is used to describe information that can be stored in the clipboard, and transferred via the drag and drop mechanism. https:// objects associate the data that they hold with the corresponding MIME types to ensure that information can be safely transferred between applications, and copied around within the same application.

https:// objects are usually created using new and supplied to QDrag or QClipboard objects. This is to enable Qt to manage the memory that they use.

A single https:// object can store the same data using several different formats at the same time. The https://() function returns a list of the available formats in order of preference. The https://() function returns the raw data associated with a MIME type, and https://() allows you to set the data for a MIME type.

For the most common MIME types, https:// provides convenience functions to access the data:

Tester	Getter	Setter	MIME Types
https://()	https://()	https://()	text/plain
https://()	https://()	https://()	text/html
https://()	https://()	https://()	text/uri-list
https://()	https://()	https://()	image/ *
https://()	https://()	https://()	application/x-color

For example, if your write a widget that accepts URL drags, you would end up writing code like this:

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void MyWidget::dragEnterEvent(QDragEnterEvent *event)
{
    if (event-&gt;mimeData()-&gt;hasUrls())
        event-&gt;acceptProposedAction();
}

void MyWidget::dropEvent(QDropEvent *event)
{
    if (event-&gt;mimeData()-&gt;hasUrls()) {
        foreach (QUrl url, event-&gt;mimeData()-&gt;urls()) {
            ...
        }
    }
}

There are three approaches for storing custom data in a https:// object:

Custom data can be stored directly in a https:// object as a https:// using https://(). For example:
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```
QByteArray csvData = ...;

QMimeData *mimeData = new QMimeData;
mimeData-&gt;setData("text/csv", csvData);
```
We can subclass https:// and reimplement https://(), https://(), and https://().

If the drag and drop operation occurs within a single application, we can subclass https:// and add extra data in it, and use a https://() in the receiver's drop event handler. For example:

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void MyWidget::dropEvent(QDropEvent *event)
{
    const MyMimeData *myData =
            qobject_cast&lt;const MyMimeData *&gt;(event-&gt;mimeData());
    if (myData) {
        // access myData's data directly (not through QMimeData's API)
    }
}

Platform-Specific MIME Types▲

On Windows, https://() will also return custom formats available in the MIME data, using the x-qt-windows-mime subtype to indicate that they represent data in non-standard formats. The formats will take the following form:

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application/x-qt-windows-mime;value="&lt;custom type&gt;"

The following are examples of custom MIME types:

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application/x-qt-windows-mime;value="FileGroupDescriptor"
application/x-qt-windows-mime;value="FileContents"

The value declaration of each format describes the way in which the data is encoded.

In some cases (e.g. dropping multiple email attachments), multiple data values are available. They can be accessed by adding an index value:

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application/x-qt-windows-mime;value="FileContents";index=0
application/x-qt-windows-mime;value="FileContents";index=1

On Windows, the MIME format does not always map directly to the clipboard formats. Qt provides QWinMime to map clipboard formats to open-standard MIME formats. Similarly, the QMacPasteboardMime maps MIME to Mac flavors.

Member Function Documentation▲

QMimeData::QMimeData()▲

Constructs a new MIME data object with no data in it.

[virtual] QMimeData::~QMimeData()▲

Destroys the MIME data object.

void QMimeData::clear()▲

Removes all the MIME type and data entries in the object.

QVariant QMimeData::colorData() const▲

Returns a color if the data stored in the object represents a color (MIME type application/x-color); otherwise returns a null variant.

A https:// is used because https:// belongs to the Qt Core module, whereas QColor belongs to Qt GUI. To convert the https:// to a QColor, simply use https://(). For example:

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if (event-&gt;mimeData()-&gt;hasColor()) {
    QColor color = qvariant_cast&lt;QColor&gt;(event-&gt;mimeData()-&gt;colorData());
    ...
}

QByteArray QMimeData::data(const QString &mimeType) const▲

Returns the data stored in the object in the format described by the MIME type specified by mimeType.

[virtual] QStringList QMimeData::formats() const▲

Returns a list of formats supported by the object. This is a list of MIME types for which the object can return suitable data. The formats in the list are in a priority order.

For the most common types of data, you can call the higher-level functions https://(), https://(), https://(), https://(), and https://() instead.

bool QMimeData::hasColor() const▲

Returns true if the object can return a color (MIME type application/x-color); otherwise returns false.

[virtual] bool QMimeData::hasFormat(const QString &mimeType) const▲

Returns true if the object can return data for the MIME type specified by mimeType; otherwise returns false.

For the most common types of data, you can call the higher-level functions https://(), https://(), https://(), https://(), and https://() instead.

bool QMimeData::hasHtml() const▲

Returns true if the object can return HTML (MIME type text/html); otherwise returns false.

bool QMimeData::hasImage() const▲

Returns true if the object can return an image; otherwise returns false.

bool QMimeData::hasText() const▲

Returns true if the object can return plain text (MIME type text/plain); otherwise returns false.

bool QMimeData::hasUrls() const▲

Returns true if the object can return a list of urls; otherwise returns false.

URLs correspond to the MIME type text/uri-list.

QString QMimeData::html() const▲

Returns a string if the data stored in the object is HTML (MIME type text/html); otherwise returns an empty string.

QVariant QMimeData::imageData() const▲

Returns a https:// storing a QImage if the object can return an image; otherwise returns a null variant.

A https:// is used because https:// belongs to the Qt Core module, whereas QImage belongs to Qt GUI. To convert the https:// to a QImage, simply use https://(). For example:

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if (event-&gt;mimeData()-&gt;hasImage()) {
    QImage image = qvariant_cast&lt;QImage&gt;(event-&gt;mimeData()-&gt;imageData());
    ...
}

void QMimeData::removeFormat(const QString &mimeType)▲

Removes the data entry for mimeType in the object.

[virtual protected] QVariant QMimeData::retrieveData(const QString &mimeType, QMetaType type) const▲

Returns a variant with the given type containing data for the MIME type specified by mimeType. If the object does not support the MIME type or variant type given, a null variant is returned instead.

This function is called by the general https://() getter and by the convenience getters (https://(), https://(), https://(), https://(), and https://()). You can reimplement it if you want to store your data using a custom data structure (instead of a https://, which is what https://() provides). You would then also need to reimplement https://() and https://().

void QMimeData::setColorData(const QVariant &color)▲

Sets the color data in the object to the given color.

Colors correspond to the MIME type application/x-color.

void QMimeData::setData(const QString &mimeType, const QByteArray &data)▲

Sets the data associated with the MIME type given by mimeType to the specified data.

For the most common types of data, you can call the higher-level functions https://(), https://(), https://(), https://(), and https://() instead.

Note that if you want to use a custom data type in an item view drag and drop operation, you must register it as a Qt https://, using the https://() macro, and implement stream operators for it.

void QMimeData::setHtml(const QString &html)▲

Sets html as the HTML (MIME type text/html) used to represent the data.

void QMimeData::setImageData(const QVariant &image)▲

Sets the data in the object to the given image.

A https:// is used because https:// belongs to the Qt Core module, whereas QImage belongs to Qt GUI. The conversion from QImage to https:// is implicit. For example:

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mimeData-&gt;setImageData(QImage("beautifulfjord.png"));

void QMimeData::setText(const QString &text)▲

Sets text as the plain text (MIME type text/plain) used to represent the data.

void QMimeData::setUrls(const QList<QUrl> &urls)▲

Sets the URLs stored in the MIME data object to those specified by urls.

URLs correspond to the MIME type text/uri-list.

Since Qt 5.0, setUrls also exports the urls as plain text, if https:// was not called before, to make it possible to drop them into any lineedit and text editor.

QString QMimeData::text() const▲

Returns a plain text (MIME type text/plain) representation of the data.

QList<QUrl> QMimeData::urls() const▲

Returns a list of URLs contained within the MIME data object.

URLs correspond to the MIME type text/uri-list.

QMimeData Class

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QMimeData Class▲

Detailed Description▲

Platform-Specific MIME Types▲

See Also▲

Member Function Documentation▲

QMimeData::QMimeData()▲

[virtual] QMimeData::~QMimeData()▲

void QMimeData::clear()▲

QVariant QMimeData::colorData() const▲

See Also▲

QByteArray QMimeData::data(const QString &mimeType) const▲

See Also▲

[virtual] QStringList QMimeData::formats() const▲

See Also▲

bool QMimeData::hasColor() const▲

See Also▲

[virtual] bool QMimeData::hasFormat(const QString &mimeType) const▲

See Also▲

bool QMimeData::hasHtml() const▲

See Also▲

bool QMimeData::hasImage() const▲

See Also▲

bool QMimeData::hasText() const▲

See Also▲

bool QMimeData::hasUrls() const▲

See Also▲

QString QMimeData::html() const▲

See Also▲

QVariant QMimeData::imageData() const▲

See Also▲

void QMimeData::removeFormat(const QString &mimeType)▲

[virtual protected] QVariant QMimeData::retrieveData(const QString &mimeType, QMetaType type) const▲

See Also▲

void QMimeData::setColorData(const QVariant &color)▲

See Also▲

void QMimeData::setData(const QString &mimeType, const QByteArray &data)▲

See Also▲

void QMimeData::setHtml(const QString &html)▲

See Also▲

void QMimeData::setImageData(const QVariant &image)▲

See Also▲

void QMimeData::setText(const QString &text)▲

See Also▲

void QMimeData::setUrls(const QList<QUrl> &urls)▲

See Also▲

QString QMimeData::text() const▲

See Also▲

QList<QUrl> QMimeData::urls() const▲

See Also▲