Ruby 2.3 program that simulates a basic interactive bitmap editor. Bitmaps are represented as an M x N matrix of pixels with each element representing a colour.

The input consists of a file containing a sequence of commands, where a command is represented by a single capital letter at the beginning of the line. Parameters of the command are separated by white spaces and they follow the command character.

Pixel coordinates are a pair of integers: a column number between 1 and 250, and a row number between 1 and 250. Bitmaps starts at coordinates 1,1. Colours are specified by capital letters.

There are 6 supported commands:

• I N M - Create a new M x N image with all pixels coloured white (O).
• C - Clears the table, setting all pixels to white (O).
• L X Y C - Colours the pixel (X,Y) with colour C.
• V X Y1 Y2 C - Draw a vertical segment of colour C in column X between rows Y1 and Y2 (inclusive).
• H X1 X2 Y C - Draw a horizontal segment of colour C in row Y between columns X1 and X2 (inclusive).
• S - Show the contents of the current image

To run the application you must supply a command file like so bin/bitmap_editor examples/show.txt

Input File:

I 5 6
L 1 3 A
V 2 3 6 W
H 3 5 2 Z
S

Expected Output:

OOOOO
OOZZZ
AWOOO
OWOOO
OWOOO
OWOOO

>bin/bitmap_editor examples/show.txt

1. If two I N M exists, the second will replace the first one and will receive all the succeeding commands.
2. Command on non-existing pixels will simply be ignored (silently)