/text-draw

A text console drawing application with few simple commands

Primary LanguageScalaApache License 2.0Apache-2.0

Text Draw

A text console drawing application with few simple commands.

The objective for making this application is to show what is the difference of a purely functional style application from an OOP designed application in terms of implementation. The second objective is sharing an example of using GraalVM native-image to compile a non-trivial Scala project to native code.

The importance of Cats Effect or other similar libraries cannot be emphasized enough. Without using any one of these libraries, it is extremely tedious if not impossible to create a pure functional style application.

How to Build

This project uses SBT 1.5.x to build and runs on Scala 3.0.x. Please install these software before proceeding.

  1. sbt to start the build tool. Steps (2) and (3) must be executed in the SBT console.
  2. app/run to run the application.
  3. test to run the all test spec.
  4. nativeImage to compile project to native code. This might not be straight forward because it requires GraalVM. Please refer to sbt-native-image and (GraalVM)[https://www.graalvm.org/reference-manual/native-image/] documentations for details

Commands

Command Description
C w h Should create a new canvas of width w and height h.
L x1 y1 x2 y2 Should create a new line from (x1,y1) to (x2,y2). Currently only horizontal or vertical lines are supported. Horizontal and vertical lines will be drawn using the 'x' character.
R x1 y1 x2 y2 Should create a new rectangle, whose upper left corner is (x1,y1) and lower right corner is (x2,y2). Horizontal and vertical lines will be drawn using the 'x' character.
B x1 y1 c Should fill the entire area connected to (x,y) with "colour" c. The behaviour of this is the same as that of the "bucket fill" tool in paint programs.
Q Should quit the program.

Sample Output

Below is a sample run of the program. User input is prefixed with enter command:

enter command: C 20 4
----------------------
|                    |
|                    |
|                    |
|                    |
----------------------

enter command: L 1 2 6 2
----------------------
|                    |
|xxxxxx              |
|                    |
|                    |
----------------------

enter command: L 6 3 6 4
----------------------
|                    |
|xxxxxx              |
|     x              |
|     x              |
----------------------

enter command: R 14 1 18 3
----------------------
|             xxxxx  |
|xxxxxx       x   x  |
|     x       xxxxx  |
|     x              |
----------------------

enter command: B 10 3 o
----------------------
|oooooooooooooxxxxxoo|
|xxxxxxooooooox   xoo|
|     xoooooooxxxxxoo|
|     xoooooooooooooo|
----------------------

enter command: Q
Quit