Image

The Image library is the easiest way to create pictures using Doodle. The tradeoff the Image library makes is that it only support a (large but limited) subset of operations that are supported across all the backends.

Imports

To use Image you'll need the following imports:

import doodle.image._
import doodle.image.syntax.all._
import doodle.core._

You'll also need to import a backend. Most people will be working on the JVM, and will use the Java2D backend:

import doodle.java2d._
import cats.effect.unsafe.implicits.global

Basic Concepts

Image is based on composition and the interpreter pattern.

Composition basically means that we build big Images out of small Images. For example, if we have an Image describing a red square and an Image describing a blue square

val redSquare = Image.square(100).fillColor(Color.red)
val blueSquare = Image.square(100).fillColor(Color.blue)

we can create an Image describing a red square next to a blue square by combining or composing them together.

val composition = redSquare.beside(blueSquare)

When draw this has the output shown below.

The interpreter pattern means that we separate describing the Image from rendering it. Writing Image.square(100) doesn't draw anything. To draw an image we need to call the draw() method. This separation is important for composition; if we were to immediately draw we would lose composition.

Shapes→