Draw

Running Draw

$ bundle
$ ruby run.rb

Commands

1. Draw a canvas, giving x and y dimensions:

enter command: C 20 4

______________________
|                    |
|                    |
|                    |
|                    |
----------------------

2. Draw a line, giving xy coordinates of start and finish.

enter command: L 1 2 6 2

______________________
|                    |
|xxxxxx              |
|                    |
|                    |
----------------------

3. Draw a rectangle, giving xy coordinates of top-left and bottom-right.

enter command: R 16 1 20 3

______________________
|               xxxxx|
|xxxxxx         x   x|
|               xxxxx|
|                    |
----------------------

4. Fill with a given 'colour' from an xy coordinate.

enter command: B 10 3 o

______________________
|oooooooooooooooxxxxx|
|xxxxxxooooooooox   x|
|oooooooooooooooxxxxx|
|oooooooooooooooooooo|
----------------------

5. Quit.

enter command: Q

Tests

$ rspec

Design

Modelling the grid

At the outset I chose to model the grid as a 2D array. This worked well until I wanted to implement the fill tool, which seemed to require a more graph-like data structure where each node is able to query the nodes around it. I briefly experimented with such a data structure but ultimately decided against it. Unfortunately this meant that the Fill shape needs to have access to the canvas to ensure it doesn't modify already-filled points.

CLI

I wanted to entirely decouple the Draw program from the means by which the user would enter input. I have done this using a CLI class that parses commands and arguments and calls the Draw program.