QPicture Class

Detailed Description

A picture serializes painter commands to an IO device in a platform-independent format. They are sometimes referred to as meta-files.

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

QPicture is resolution independent, i.e. a QPicture can be displayed on different devices (for example svg, pdf, ps, printer and screen) looking the same. This is, for instance, needed for WYSIWYG print preview. QPicture runs in the default system dpi, and scales the painter to match differences in resolution depending on the window system.

Example of how to record a picture:

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

Note that the list of painter commands is reset on each call to the QPainter::begin() function.

Example of how to replay a picture:

         QPicture picture;
         picture.load("drawing.pic");           // load picture
         QPainter painter;
         painter.begin(&myImage);               // paint in myImage
         painter.drawPicture(0, 0, picture);    // draw the picture at (0,0)
         painter.end();                         // painting done

Pictures can also be drawn using play(). Some basic data about a picture is available, for example, size(), isNull() and boundingRect().