内容

• 公共函数
• 保护函数
• 详细描述
• 特定平台 MIME 类型

QMimeData 类

QMimeData class provides a container for data that records information about its MIME type. 更多...

头：	#include <QMimeData>
qmake:	QT += core
继承：	QObject

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公共函数

	QMimeData ()
	~QMimeData ()
void	clear ()
QVariant	colorData () const
QByteArray	data (const QString & mimeType ) const
virtual QStringList	格式 () const
bool	hasColor () const
virtual bool	hasFormat (const QString & mimeType ) const
bool	hasHtml () const
bool	hasImage () const
bool	hasText () const
bool	hasUrls () const
QString	html () const
QVariant	imageData () const
void	removeFormat (const QString & mimeType )
void	setColorData (const QVariant & color )
void	setData (const QString & mimeType , const QByteArray & data )
void	setHtml (const QString & html )
void	setImageData (const QVariant & image )
void	setText (const QString & text )
void	setUrls (const QList<QUrl> & urls )
QString	text () const
QList<QUrl>	urls () const

• 32 公共函数继承自 QObject

保护函数

virtual QVariant

retrieveData (const QString & mimeType , QVariant::Type type ) const

• 9 保护函数继承自 QObject

额外继承成员

• 1 特性继承自 QObject
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详细描述

QMimeData class provides a container for data that records information about its MIME type.

QMimeData is used to describe information that can be stored in the clipboard , and transferred via the 拖放 mechanism. QMimeData 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.

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

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

Tester	Getter	Setter	MIME (多用途 Internet 邮件扩展) 类型
hasText ()	text ()	setText ()	text/plain
hasHtml ()	html ()	setHtml ()	text/html
hasUrls ()	urls ()	setUrls ()	text/uri-list
hasImage ()	imageData ()	setImageData ()	image/ *
hasColor ()	colorData ()	setColorData ()	application/x-color

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

void MyWidget::dragEnterEvent(QDragEnterEvent *event)
{
    if (event->mimeData()->hasUrls())
        event->acceptProposedAction();
}
void MyWidget::dropEvent(QDropEvent *event)
{
    if (event->mimeData()->hasUrls()) {
        foreach (QUrl url, event->mimeData()->urls()) {
            ...
        }
    }
}
					

There are three approaches for storing custom data in a QMimeData 对象：

1. Custom data can be stored directly in a QMimeData object as a QByteArray 使用 setData ()。例如：

   QByteArray csvData = ...;
   QMimeData *mimeData = new QMimeData;
   mimeData->setData("text/csv", csvData);
   							

2. We can subclass QMimeData and reimplement hasFormat (), 格式 ()，和 retrieveData ().
3. If the drag and drop operation occurs within a single application, we can subclass QMimeData and add extra data in it, and use a qobject_cast () in the receiver's drop event handler. For example:

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

特定平台 MIME 类型

在 Windows， 格式 () 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:

application/x-qt-windows-mime;value="<custom type>"
					

The following are examples of custom MIME types:

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

值 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 值：

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.

另请参阅 QClipboard , QDragEnterEvent , QDragMoveEvent , QDropEvent , QDrag , QMacPasteboardMime ，和 拖放 .

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QMimeData:: QMimeData ()

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

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 QVariant is used because QMimeData belongs to the Qt Core module, whereas QColor belongs to Qt GUI. To convert the QVariant 到 QColor , simply use qvariant_cast ()。例如：

if (event->mimeData()->hasColor()) {
    QColor color = qvariant_cast<QColor>(event->mimeData()->colorData());
    ...
}
					

另请参阅 hasColor (), setColorData ()，和 data ().

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 .

另请参阅 setData ().

[virtual] QStringList QMimeData:: 格式 () 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 hasText (), hasHtml (), hasUrls (), hasImage ()，和 hasColor () 代替。

另请参阅 hasFormat (), setData ()，和 data ().

bool QMimeData:: hasColor () const

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

另请参阅 setColorData (), colorData ()，和 hasFormat ().

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

返回 true if the object can return data for the MIME type specified by mimeType ；否则返回 false .

For the most common types of data, you can call the higher-level functions hasText (), hasHtml (), hasUrls (), hasImage ()，和 hasColor () 代替。

另请参阅 格式 (), setData ()，和 data ().

bool QMimeData:: hasHtml () const

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

另请参阅 setHtml (), html ()，和 hasFormat ().

bool QMimeData:: hasImage () const

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

另请参阅 setImageData (), imageData ()，和 hasFormat ().

bool QMimeData:: hasText () const

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

另请参阅 setText (), text (), hasHtml ()，和 hasFormat ().

bool QMimeData:: hasUrls () const

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

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

另请参阅 setUrls (), urls ()，和 hasFormat ().

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.

另请参阅 setHtml (), hasHtml ()，和 setData ().

QVariant QMimeData:: imageData () const

返回 QVariant storing a QImage if the object can return an image; otherwise returns a null variant.

A QVariant is used because QMimeData belongs to the Qt Core module, whereas QImage belongs to Qt GUI. To convert the QVariant 到 QImage , simply use qvariant_cast ()。例如：

if (event->mimeData()->hasImage()) {
    QImage image = qvariant_cast<QImage>(event->mimeData()->imageData());
    ...
}
					

另请参阅 setImageData () 和 hasImage ().

void QMimeData:: removeFormat (const QString & mimeType )

Removes the data entry for mimeType in the object.

该函数在 Qt 4.4 引入。

[virtual protected] QVariant QMimeData:: retrieveData (const QString & mimeType , QVariant::Type 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 data () getter and by the convenience getters ( text (), html (), urls (), imageData ()，和 colorData ()). You can reimplement it if you want to store your data using a custom data structure (instead of a QByteArray , which is what setData () provides). You would then also need to reimplement hasFormat () 和 格式 ().

另请参阅 data ().

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 .

另请参阅 colorData (), hasColor ()，和 setData ().

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

Sets the data associated with the MIME type given by mimeType 到指定 data .

For the most common types of data, you can call the higher-level functions setText (), setHtml (), setUrls (), setImageData ()，和 setColorData () 代替。

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 meta type ，使用 Q_DECLARE_METATYPE () macro, and implement stream operators for it. The stream operators must then be registered with the qRegisterMetaTypeStreamOperators () 函数。

另请参阅 data (), hasFormat (), QMetaType ，和 qRegisterMetaTypeStreamOperators ().

void QMimeData:: setHtml (const QString & html )

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

另请参阅 html (), hasHtml (), setText ()，和 setData ().

void QMimeData:: setImageData (const QVariant & image )

Sets the data in the object to the given image .

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

mimeData->setImageData(QImage("beautifulfjord.png"));
					

另请参阅 imageData (), hasImage ()，和 setData ().

void QMimeData:: setText (const QString & text )

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

另请参阅 text (), hasText (), setHtml ()，和 setData ().

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 setText was not called before, to make it possible to drop them into any lineedit and text editor.

另请参阅 urls (), hasUrls ()，和 setData ().

QString QMimeData:: text () const

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

另请参阅 setText (), hasText (), html ()，和 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 .

另请参阅 setUrls (), hasUrls ()，和 data ().