Easy_Graphics Package

Easy_Graphics is a simple library for generating graphical output from your Ada program.

Typical use cases might be educational projects, prototyping, programming challenges, or simply when you want to visualise something quickly in a larger system.

The logo on the right is created with just a few lines of code, see this program

The package is free to use, with no warranty, under the MIT license.

Main Features

• Image output as portable PPM, PAM, and GIF files (other formats to follow)
• Images of any size using whatever (integer) coordinate ranges you like
• Simple set of graphics primitives provided
• Basic turtle graphics are supported
• Images are 24-bit colour + 8-bit alpha
• Basic (HTML/CSS) colours predefined as constants, as is TRANSPARENT

Utility Subprograms

• New_Image create a new image ("canvas"), prefilled with a colour or transparent
• Write_PPM create "raw" or "plain" NetPBM PPM file from image, Alpha is ignored
• Write_GIF create GIF file - only partially implemented at the moment
• Write_PAM create NetPBM PAM file from image, includes transparency. N.B. Convert to PNG with convert img.pam img.png or view directly with pqiv
• HSV_To_RGB convert colour values

Drawing Primitives

• Plot a point on the image
• Set_Alpha changes the transparency of a point
• Fill an entire image with a colour
• Line draw a line between two Points
• Rect (filled or outline)
• Triangle (filled or outline)
• Circle (filled or outline)
• Char draw a character using a simple built-in font
• Text draw a string

Turtle Graphics

• New_Turtle creates a virtual turtle for an image
• Home centres the turtle
• Go_To a specific coordinate
• Pen_Up, Pen_Down and Pen_Color
• Forward, Back
• Left and Right turn relative to the current heading
• Turn_To turns to an absolute heading

Example Code

There are several example programs using Easy_Graphics in the tests/src directory. The tests.adb file is intended to demonstrate all features that are currently implemented.