The QMimeData class provides a container for data that records information about its MIME type. 更多...
继承 QObject .
The 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 应用程序。
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 formats () 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 Types |
|---|---|---|---|
| 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 object:
QByteArray csvData = ...; QMimeData *mimeData = new QMimeData; mimeData->setData("text/csv", csvData);
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) } }
在 Windows， formats () 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"
value declaration of each format describes the way in which the data is encoded.
On Windows, the MIME format does not always map directly to the clipboard formats. Qt provides QWindowsMime to map clipboard formats to open-standard MIME formats. Similarly, the QMacPasteboardMime maps MIME to Mac flavors.
Constructs a new MIME data object with no data in it.
Removes all the MIME type and data entries in the object.
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 QtCore library, whereas QColor belongs to QtGui . 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 ().
Returns the data stored in the object in the format described by the MIME type specified by mimeType .
另请参阅 setData ().
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 函数 hasText (), hasHtml (), hasUrls (), hasImage ()，和 hasColor () 代替。
另请参阅 hasFormat (), setData ()，和 data ().
Returns true if the object can return a color (MIME type application/x-color ); otherwise returns false.
另请参阅 setColorData (), colorData ()，和 hasFormat ().
Returns true if the object can return data for the MIME type 指定通过 mimeType ；否则返回 false。
For the most common types of data, you can call the higher-level 函数 hasText (), hasHtml (), hasUrls (), hasImage ()，和 hasColor () 代替。
另请参阅 formats (), setData ()，和 data ().
Returns true if the object can return HTML (MIME type text/html ); otherwise returns false.
另请参阅 setHtml (), html ()，和 hasFormat ().
Returns true if the object can return an image; otherwise returns false.
另请参阅 setImageData (), imageData ()，和 hasFormat ().
Returns true if the object can return plain text (MIME type text/plain ); otherwise returns false.
另请参阅 setText (), text (), hasHtml ()，和 hasFormat ().
Returns 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 ().
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 ().
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 QtCore library, whereas QImage belongs to QtGui . 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 ().
Removes the data entry for mimeType in the object.
该函数在 Qt 4.4 引入。
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 formats ().
另请参阅 data ().
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 ().
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 函数 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 ().
集 html as the HTML (MIME type text/html ) used to represent the data.
另请参阅 html (), hasHtml (), setText ()，和 setData ().
Sets the data in the object to the given image .
A QVariant is used because QMimeData belongs to the QtCore library, whereas QImage belongs to QtGui . The conversion from QImage to QVariant is implicit. For example:
mimeData->setImageData(QImage("beautifulfjord.png"));
另请参阅 imageData (), hasImage ()，和 setData ().
集 text as the plain text (MIME type text/plain ) used to represent the data.
另请参阅 text (), hasText (), setHtml ()，和 setData ().
Sets the URLs stored in the MIME data object to those specified by urls .
URLs correspond to the MIME type text/uri-list .
另请参阅 urls (), hasUrls ()，和 setData ().
Returns a plain text (MIME type text/plain ) representation of the data.
另请参阅 setText (), hasText (), html ()，和 data ().
Returns a list of URLs contained within the MIME data 对象。
URLs correspond to the MIME type text/uri-list .
