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13.1 Introduction

Graphics Ports allow you to write source-compatible applications which draw text, lines, shapes and images, for different host window systems. Graphics Ports are the destinations for the drawing primitives. They are implemented with a generic host-independent part and a small host-specific part.

All Graphics Ports symbols are interned in and exported from the graphics-ports package, nicknamed gp .

Graphics Ports implement a set of drawing functions and a mechanism for specifying the graphics state to be used in each drawing function call. There are four categories of graphics ports:

On-screen ports

These correspond to visible windows. They are instances of capi:output-pane or a subclass, and are integral part of the CAPI panes system.

Pixmap ports

These are used for off-screen drawing. Once the drawing is completed they can be copied to another port (typically the screen, with copy-area ), or converted to an image.

Printer ports

These are used for drawing to a printer.

Metafile ports

These are used for recording drawing operations so that the drawing can be realized later.

13.1.1 Creating instances

CAPI User Guide (Unix version) - 30 Aug 2011