Introduction¶

py_gd is a set of “Pythonic” bindings to the libgd rendering library

py_gd aims to provide nice Pythonic wrappers around libgd – a robust, fast, and simple drawing lib:

https://github.com/libgd/libgd/

Why gd?¶

For the project at hand we needed fast and simple drawing – 8-bit color, no anti-aliasing. We also wanted a nice simple API to work with. There are a number of newer drawing libs (AGG, Skia) that produce some pretty results, but are not as simple to use, and are focused on 32 bit fully anti-aliased drawing. If you want the prettiest rendering possible, I encourage you to check those out.

If you want something fast and simple – py_gd may be for you.

General Structure¶

py_gd provides an Object-Oriented interface for rendering.

At the core is the Image class – it gets created with a given set of parameters, at least the size of the image:

img = Image(width=400, height=400)

once created, you can draw to with a variety of drawing functions:

img.draw_line((1, 1), (350, 200), color='red', line_width=3)

Drawing of an object is usually accomplished with a single call – you can set the properties of the object you want to draw all at once: color, line width, etc.

The image can be saved out in various formats:

img.save('my_image.png', 'png')

Parameters of Drawing¶

Depending on the object being drawn, there are a number of parameters that can be set:

For Lines:¶

color: string color name

line_width: integer pixels

For Solid Color Objects:¶

color: string color name

For Objects with a Line and Fill:¶

line_color: string color name
fill_color: string color name
line_width: integer pixels

For Objects Defined at a Single Point¶

point: (x, y) tuple (or other 2-sequence)

For Objects Defined at a Multiple Points¶

Polygon, Polyline

points: sequence of points: [(x1, y1), (x2, y2), (x3, y3), ...] (Nx2 numpy array)

For Objects with a Width or Height:¶

width: integer pixels

height: integer pixels