Presentation Spaces for Graphic Output Foundation

A presentation space is the central element for graphic output. Xbase++ uses the class XbpPresSpace() to provide a simple mechanism to access presentation spaces on the Xbase++ language level. The essential elements of a presentation space have already been described in the section "Basics for graphic output". As discussed, a presentation space makes an abstract drawing area available that contains all the device-independent information about a drawing. The output of a drawing on the physical output device depends on the device context associated with the presentation space. A device context manages an output device and is accessed in Xbase++ using instances of classes, like XbpPrinter() or XbpFileDev(). The interaction between the presentation space and various device contexts is described in the next section. This chapter discusses different presentation spaces. It begins with a description of the features common to all presentation spaces.

Coordinate system and view port

The intelligent presentation space - XbpCrt:presSpace()

The high speed presentation space - XbpWindow:lockPS()

The complete presentation space - XbpPresSpace()