Drawing and Interaction
The Enable project provides two related multi-platform packages for drawing GUI objects.
- Enable: An object drawing library that supports containment and event notification.
- Kiva: A multi-platform DisplayPDF vector drawing engine.
The Enable package is a multi-platform object drawing library built on top of Kiva. The core of Enable is a container/component model for drawing and event notification. The core concepts of Enable are:
- Events (mouse, drag, and key events)
Enable provides a high-level interface for creating GUI objects, while enabling a high level of control over user interaction. Enable is a supporting technology for the Chaco and BlockCanvas projects.
Kiva is a multi-platform DisplayPDF vector drawing engine that supports multiple output backends, including Windows, GTK, and Macintosh native windowing systems, a variety of raster image formats, PDF, and Postscript.
DisplayPDF is more of a convention than an actual specification. It is a path-based drawing API based on a subset of the Adobe PDF specification. Besides basic vector drawing concepts such as paths, rects, line sytles, and the graphics state stack, it also supports pattern fills, antialiasing, and transparency. Perhaps the most popular implementation of DisplayPDF is Apple's Quartz 2D graphics API in Mac OS X.
Kiva currently implements the following features:
- paths and compiled paths; arcs, bezier curves, rectangles
- graphics state stack
- clip stack, disjoint rectangular clip regions
- raster image blitting
- arbitrary affine transforms of the graphics context
- bevelled and mitered joins
- line width, line dash
- Freetype or native fonts
- RGB, RGBA, or grayscale color depths
ReportLab PDF: ReportLab Open source PDF library (needed for PDF backend support)