QTextObjectInterface Class Reference
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QtGui

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The QTextObjectInterface class allows drawing of custom text objects in QTextDocument s. 更多...

方法

__init__ ( self )
__init__ ( self , QTextObjectInterface)
drawObject ( self , QPainter painter , QRectF rect , QTextDocument doc , int posInDocument , QTextFormat format )
QSizeF intrinsicSize ( self , QTextDocument doc , int posInDocument , QTextFormat format )

详细描述

The QTextObjectInterface class allows drawing of custom text objects in QTextDocument s.

A text object describes the structure of one or more elements in a text document; for instance, images imported from HTML are implemented using text objects. A text object knows how to lay out and draw its elements when a document is being rendered.

Qt allows custom text objects to be inserted into a document by registering a custom object type with QTextCharFormat . A QTextObjectInterface must also be implemented for this type and be registered 采用 QAbstractTextDocumentLayout of the document. When the object type is encountered while rendering a QTextDocument ， intrinsicSize () 和 drawObject () functions of the interface are called.

The following list explains the required steps of inserting a custom text object into a document:

Choose an objectType 。 objectType 是 integer with a value greater or equal to QTextFormat.UserObject .
创建 QTextCharFormat object and set the object type to the chosen type using the setObjectType() function.
Implement the QTextObjectInterface class.
调用 QAbstractTextDocumentLayout.registerHandler () with an instance of your QTextObjectInterface subclass to register your object type.
Insert QChar.ObjectReplacementCharacter with the aforementioned QTextCharFormat of the chosen object type into the document. As mentioned, the functions of QTextObjectInterface intrinsicSize() and drawObject() will then be called with the QTextFormat as parameter whenever the replacement character is encountered.

A class implementing a text object needs to inherit both QObject and QTextObjectInterface. QObject must be the first class inherited. For instance:

 class SvgTextObject : public QObject, public QTextObjectInterface
 {
     Q_OBJECT
     Q_INTERFACES(QTextObjectInterface)

The data of a text object is usually stored in the QTextCharFormat 使用 QTextCharFormat.setProperty (), and then retrieved with QTextCharFormat.property ().

警告： Copy and Paste operations ignore custom text 对象。

方法文档编制

QTextObjectInterface.init ( self )

QTextObjectInterface.init ( self , QTextObjectInterface )

QTextObjectInterface.drawObject ( self , QPainter painter , QRectF rect , QTextDocument doc , int posInDocument , QTextFormat format )

This method is abstract and should be reimplemented in any sub-class.

绘制此文本对象使用指定 painter .

The size of the rectangle, rect , to draw in is the size previously calculated by intrinsicSize ()。 rectangles position is relative to the painter .

You also get the document ( doc ) and the position ( posInDocument ) of the format in that document.

另请参阅 intrinsicSize ().

QSizeF QTextObjectInterface.intrinsicSize ( self , QTextDocument doc , int posInDocument , QTextFormat format )

This method is abstract and should be reimplemented in any sub-class.

The intrinsicSize() function returns the size of the text object represented by format in the given document ( doc ) at the given position ( posInDocument ).

The size calculated will be used for subsequent calls to drawObject () for this format .

另请参阅 drawObject ().

QTextObjectInterface Class Reference [ QtGui module]

方法