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QPicture Class Reference

The QPicture class is a paint device that records and replays QPainter commands. More...

#include <qpicture.h>

Inherits QPaintDevice.

List of all member functions.

Public Members

• QPicture ( int formatVersion = 0 ) 
• ~QPicture () 
• bool isNull () const
• uint size () const
• const char* data () const
• virtual void setData ( const char * data, uint size ) 
• bool play ( QPainter * ) 
• bool load ( const QString & fileName ) 
• bool save ( const QString & fileName ) 
• QPicture& operator= ( const QPicture & ) 

Protected Members

• virtual bool cmd ( int, QPainter *, QPDevCmdParam * ) (internal)
• virtual int metric ( int ) const

Related Functions

• QDataStream & operator>> (QDataStream & s, QPicture & r)
• QDataStream & operator<< (QDataStream & s, const QPicture & r)

Detailed Description

A picture serializes painter commands to an IO device in a platform-independent format. A picture created under Windows can be read on a Sun SPARC.

Pictures are called meta-files on some platforms.

Qt pictures use a proprietary binary format. Unlike native picture (meta-file) formats on many window systems, Qt pictures have no limitations regarding the contents. Everything that can be painted can also be stored in a picture (fonts, pixmaps, regions, transformed graphics etc.)

Example of how to record a picture:

    QPicture  pic;
    QPainter  p;
    p.begin( &pic );                            // paint in picture
    p.drawEllipse( 10,20, 80,70 );              // draw an ellipse
    p.end();                                    // painting done
    pic.save( "drawing.pic" );                  // save picture

Example of how to replay a picture:

    QPicture  pic;
    pic.load( "drawing.pic" );                  // load picture
    QPainter  p;
    p.begin( &myWidget );                       // paint in myWidget
    p.drawPicture( pic );                       // draw the picture
    p.end();                                    // painting done

Examples: xform/xform.cpp picture/picture.cpp

Member Function Documentation

QPicture::QPicture ( int formatVer = 0 )

Constructs an empty picture.

The formatVersion parameter may be used to create a QPicture that can be read by applications that are compiled with earlier versions of Qt. Currently supported is formatVersion == 1, which will make a QPicture which is stored in a format that is binary compatible with Qt 1.x programs, and formatVersion == 2, for a format compatible with Qt 2.0.x programs.

Reading of pictures generated by earlier versions of Qt is supported and needs no special coding; the format is automatically detected.

QPicture::~QPicture ()

Destructs the picture.

const char* QPicture::data () const

Returns a pointer to the picture data. The returned pointer is null if the picture contains no data.

See also size() and isNull().

bool QPicture::isNull () const

Returns TRUE if the picture contains no data, otherwise FALSE.

bool QPicture::load ( const QString & fileName )

Loads a picture from the file specified by fileName and returns TRUE if successful, otherwise FALSE.

See also save().

Examples: xform/xform.cpp picture/picture.cpp

int QPicture::metric ( int m ) const [virtual protected]

Internal implementation of the virtual QPaintDevice::metric() function.

Use the QPaintDeviceMetrics class instead.

A picture has the following hard coded values: width=640, height=480, dpi = 72, numcolors=16777216 and depth=24.

Reimplemented from QPaintDevice.

QPicture& QPicture::operator= ( const QPicture & p )

Makes this picture be a deep copy of p.

bool QPicture::play ( QPainter * painter )

Replays the picture using painter and returns TRUE if successful, or FALSE if the internal picture data is inconsistent.

This function does exactly the same as QPainter::drawPicture().

bool QPicture::save ( const QString & fileName )

Saves a picture to the file specified by fileName and returns TRUE if successful, otherwise FALSE.

See also load().

Examples: picture/picture.cpp

void QPicture::setData ( const char * data, uint size ) [virtual]

Sets the picture data directly from data and size. This function copies the input data.

See also data() and size().

uint QPicture::size () const

Returns the size of the picture data.

See also data().

bool QPicture::cmd ( int c, QPainter *, QPDevCmdParam * p ) [virtual protected]

For internal use only.

Reimplemented from QPaintDevice.

Related Functions

QDataStream & operator>> (QDataStream & s, QPicture & r)

Reads a QPicture from the stream and returns a reference to the stream.

QDataStream & operator<< (QDataStream & s, const QPicture & r)

Writes a QPicture to the stream and returns a reference to the stream.

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