DrawingGizmo Class Specification

DrawingGizmo Class Diagram

Invariant

A DrawingGizmo object ...

Appears as an arrow within the Drawing Canvas window. (This window is 260 pixels wide and 160 pixels high.)

and is either in drawing mode or in moving mode.

Constructor Methods

public DrawingGizmo()

post: A new DrawingGizmo object is created and placed in the center of the Drawing Canvas

window. (Note that if two tools occupy the same location, only one will be visible.)

and This object is set to drawing mode (and therefore colored green).

and The arrow for this object is pointing up.

Update Methods

public void draw()

post: This object is set to drawing mode (and therefore colored green).

public void dontDraw()

post: This object is set to moving mode (and therefore colored red).

public void turnClockwise()

post: This object is rotated by 30 degrees clockwise from its previous direction.

public void turnCounterclockwise()

post: This object is rotated by 30 degrees counterclockwise from its previous direction.

public void moveForward()

pre: At least 20 pixels separate this object from the Drawing Canvas edge in its path

post: This object is moved in the arrow’s direction 20 pixels from its previous location.

and If this object is in drawing mode, a line segment is drawn across the 20 pixel path

just traversed

public void delay2Sec()

post: The DrawingGizmo delays all activity for 2 seconds, then resumes.

public void turnBy(int a)

post: This object is rotated by a degrees clockwise from its previous direction.

public void moveBy(int d)

pre: At least d pixels separate this object from the Drawing Canvas edge in its path

post: This object is moved in the arrow’s direction d pixels from its previous location.

and If this object is in drawing mode, a line segment is drawn across the d pixel path

just traversed

public void delayBy(int t)

post: The DrawingGizmo delays all activity for t milliseconds, then resumes.