Tortoise

open class Tortoise : CustomPlaygroundDisplayConvertible

Abstraction layer to allow drawing on a Canvas instance with a “LOGO turtle” metaphor

  • Creates a tortoise object that you can use to drive drawing upon an instance of the Canvas class.

    Declaration

    Swift

    public init(drawingUpon: Canvas)

    Parameters

    drawingUpon

    The canvas instance that the turtle should draw on.

Conformance with adopted protocols

  • Returns the bitmap image used for Xcode Playground quick looks; represents current state of the canvas at any given time.

    Declaration

    Swift

    public var playgroundDescription: Any { get }

Change state

  • Put the pen down. When the turtle moves, a line will be drawn.

    Declaration

    Swift

    open func penDown()

  • Lift the pen up. When the turtle moves, no line is drawn.

    Declaration

    Swift

    open func penUp()

  • Rotate the turtle to the right (clockwise).

    Declaration

    Swift

    open func right(by angle: Degrees)

    Parameters

    angle

    How far to rotate the turtle to the right, in degrees.

  • Rotate the turtle to the left (counter-clockwise).

    Declaration

    Swift

    open func left(by angle: Degrees)

    Parameters

    angle

    How far to rotate the turtle to the left, in degrees.

  • Move the turtle forward.

    Declaration

    Swift

    open func forward(steps: Int)

    Parameters

    steps

    How many steps forward the turtle should take.

  • Move the turtle backward.

    Declaration

    Swift

    open func backward(steps: Int)

    Parameters

    steps

    How many steps backward the turtle should take.

  • Point the turtle in a given direction. 0 = right, 90 = up, 180 = left, 270 = down.

    Declaration

    Swift

    open func setHeading(to: Degrees)

    Parameters

    to

    What direction to point the turtle in; works the same way as a unit circle.

  • Move the turtle to a given location, relative to the origin (bottom left of the screen).

    Declaration

    Swift

    open func setPosition(to: Point)

    Parameters

    to

    The point to place the turtle at on the Cartesian plane.

  • Set the horizontal position of the turtle.

    Declaration

    Swift

    open func setX(to: CGFloat)

    Parameters

    to

    The horizontal position, relative to 0 which is the left side of the canvas.

  • Set the horizontal position of the turtle.

    Declaration

    Swift

    open func setX(to: Double)

    Parameters

    to

    The horizontal position, relative to 0 which is the left side of the canvas.

  • Set the horizontal position of the turtle.

    Declaration

    Swift

    open func setX(to: Int)

    Parameters

    to

    The horizontal position, relative to 0 which is the left side of the canvas.

  • Set the vertical position of the turtle.

    Declaration

    Swift

    open func setY(to: CGFloat)

    Parameters

    to

    The vertical position, relative to 0 which is the bottom side of the canvas.

  • Set the vertical position of the turtle.

    Declaration

    Swift

    open func setY(to: Double)

    Parameters

    to

    The vertical position, relative to 0 which is the bottom side of the canvas.

  • Set the vertical position of the turtle.

    Declaration

    Swift

    open func setY(to: Int)

    Parameters

    to

    The vertical position, relative to 0 which is the bottom side of the canvas.

  • Set the turtle’s pen color.

    Declaration

    Swift

    open func setPenColor(to: Color)

    Parameters

    to

    The desired color.

  • What color to fill closed polygons drawn by the turtle with.

    Declaration

    Swift

    open func setFillColor(to: Color)

    Parameters

    to

    The desired color.

  • What size of stroke the turtle should make

    Declaration

    Swift

    open func setPenSize(to: Int)

    Parameters

    to

    The desired stroke size, with 1 as the smallest possible value. Values lower than 1 will be ignored.

  • Move the turtle to the origin (bottom left corner of canvas).

    Declaration

    Swift

    open func goToHome()

  • Start tracking turtle locations to mark the vertices of a closed polygon.

    Declaration

    Swift

    open func beginFill()

  • Stop tracking turtle locations to mark the vertices of a closed polygon. The shape will be filled at this point.

    Declaration

    Swift

    open func endFill()

  • Draw a triangle representing the turtle. The forward vertex of the triangle indicates the position of the turtle. The rear portion of the triangle indicates the heading of the turtle. For example, a triangle pointing to the right means the turtle has a heading of 0 degrees.

    Declaration

    Swift

    open func drawSelf()

  • When calling Tortoise methods within the a Processing-style draw() function, as with the Sketch class, be sure to invoke this method at the start of the draw() function to restore canvas state to where it left off after the last frame was animated.

    Declaration

    Swift

    open func restoreStateOnCanvas()

Interrogate state

  • The current heading of the turtle. 0 = right, 90 = up, 180 = left, 270 = down.

    Declaration

    Swift

    open func currentHeading() -> Degrees

  • The current position of the turtle on the Cartesian plane, relative to the origin (bottom left corner of canvas).

    Declaration

    Swift

    open func currentPosition() -> Point

  • Whether the pen is currently down, or not.

    Declaration

    Swift

    open func isPenDown() -> Bool

  • The color the turtle is drawing with right now.

    Declaration

    Swift

    open func currentPenColor() -> Color

  • The pen size the turtle is drawing with right now.

    Declaration

    Swift

    open func currentPenSize() -> Int

  • The color closed polygons will be filled with.

    Declaration

    Swift

    open func currentFillColor() -> Color

  • x-coordinate of the turtle’s current position.

    Declaration

    Swift

    public var xcor: CGFloat { get }

  • y-coordinate of the turtle’s current position

    Declaration

    Swift

    public var ycor: CGFloat { get }