Package edu.macalester.graphics

Class CanvasWindow

java.lang.Object

edu.macalester.graphics.CanvasWindow

public class CanvasWindow
extends Object

A window frame that can contain graphical objects.

A CanvasWindow will not immediate draw GraphicsObjects you add to it. Instead, it waits until one of the following things happens:

1. Your main() method exits.
2. An event listener completes.
3. You explicitly call the CanvasWindow's draw() method.

You can use draw() to create animations using loops.

Constructor Summary

Constructors

Constructor	Description
CanvasWindow(String title, int windowWidth, int windowHeight)	Opens a new window for drawing.

Method Summary

Modifier and Type	Method	Description
void	add(GraphicsObject gObject)	Adds the given graphics object to the objects that will be drawn on the canvas.
void	add(GraphicsObject gObject, double x, double y)	Adds the graphical object to the list of objects drawn on the canvas at the position x, y.
void	animate(Runnable animation)	Call the given callback repeatedly forever, up to 60 times per second.
void	animate(DoubleConsumer animation)	Call the given callback repeatedly forever, up to 60 times per second, passing the time delta since the last time it was called.
void	closeWindow()	Closes the canvas window.
void	draw()	Immediately draws the currently added graphics objects to the screen.
Point	getCenter()	Returns the center of the window’s visible content area.
GraphicsObject	getElementAt(double x, double y)	Returns the topmost graphical object underneath position x, y.
GraphicsObject	getElementAt(Point position)	Returns the topmost graphical object underneath position x, y.
int	getHeight()	Returns the height of the window's visible content area, not including any title bar and border.
Set<Key>	getKeysPressed()	Returns all keys currently pressed on the keyboard.
int	getWidth()	Returns the width of the window's visible content area, not including any title bar and border.
JFrame	getWindowFrame()	Deprecated. Do not mix Swing and kilt-graphics APIs
void	onCharacterTyped(Consumer<Character> handler)	Adds a listener that will be notified when the use types a combination of keys that produce a character.
void	onClick(MouseButtonEventHandler handler)	Adds a listener that will receive an event when the mouse button goes down and then up inside the window without moving significantly (i.e.
void	onDrag(MouseMotionEventHandler handler)	Adds a listener that will receive an event when the mouse moves over the window with the button down.
void	onKeyDown(KeyboardEventHandler handler)	Adds a listener that will receive an event when a key on the keyboard is pressed.
void	onKeyUp(KeyboardEventHandler handler)	Adds a listener that will receive an event when a key on the keyboard is released.
void	onMouseDown(MouseButtonEventHandler handler)	Adds a listener that will receive an event when the mouse button goes down inside the window.
void	onMouseMove(MouseMotionEventHandler handler)	Adds a listener that will receive an event when the mouse moves over the window with the button up.
void	onMouseUp(MouseButtonEventHandler handler)	Adds a listener that will receive an event when the mouse button goes up inside the window.
void	pause(double milliseconds)	Pauses the program for the given time in milliseconds.
void	pause(long milliseconds)	Pauses the program for the given time in milliseconds.
void	performEventAction(Runnable action)	For internal use.
void	remove(GraphicsObject gObject)	Removes the object from being drawn
void	removeAll()	Removes all of the objects currently drawn on the canvas.
BufferedImage	screenShot()	Captures a screenshot of the currently drawn canvas' contents to an image.
void	screenShot(String filename)	Saves a screenshot of the currently drawn canvas' contents to the filename specified as a parameter
void	setBackground(Paint color)	Changes the background color of the window.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CanvasWindow

public CanvasWindow(String title,
 int windowWidth,
 int windowHeight)

Opens a new window for drawing.

Parameters:

title - The user-visible title of the window

windowWidth - The width of the window's content area

windowHeight - The height of the window's content area

Method Details

getWidth

public int getWidth()

Returns the width of the window's visible content area, not including any title bar and border.

getHeight

public int getHeight()

Returns the height of the window's visible content area, not including any title bar and border.

getCenter

public Point getCenter()

Returns the center of the window’s visible content area.

setBackground

public void setBackground(Paint color)

Changes the background color of the window.

add

public void add(GraphicsObject gObject)

Adds the given graphics object to the objects that will be drawn on the canvas.

add

public void add(GraphicsObject gObject,
 double x,
 double y)

Adds the graphical object to the list of objects drawn on the canvas at the position x, y.

Parameters:

gObject - the graphical object to be drawn

x - the x position of graphical object

y - the y position of graphical object

remove

public void remove(GraphicsObject gObject)

Removes the object from being drawn

Throws:

NoSuchElementException - if gObject has not been added to the canvas

removeAll

public void removeAll()

Removes all of the objects currently drawn on the canvas. Does not change the background color.

draw

public void draw()

Immediately draws the currently added graphics objects to the screen. This method is synchronous: it waits for the drawing to complete before proceeding.

pause

public void pause(long milliseconds)

Pauses the program for the given time in milliseconds.

pause

public void pause(double milliseconds)

Pauses the program for the given time in milliseconds.

getElementAt

public GraphicsObject getElementAt(double x,
 double y)

Returns the topmost graphical object underneath position x, y. If no such object exists it returns null.

getElementAt

public GraphicsObject getElementAt(Point position)

Returns the topmost graphical object underneath position x, y. If no such object exists it returns null.

screenShot

public BufferedImage screenShot()

Captures a screenshot of the currently drawn canvas' contents to an image.

screenShot

public void screenShot(String filename)

Saves a screenshot of the currently drawn canvas' contents to the filename specified as a parameter

Parameters:

filename - The filename for where you would like to save.

getWindowFrame

@Deprecated
public JFrame getWindowFrame()

Deprecated.

Do not mix Swing and kilt-graphics APIs

closeWindow

public void closeWindow()

Closes the canvas window.

onMouseDown

public void onMouseDown(MouseButtonEventHandler handler)

Adds a listener that will receive an event when the mouse button goes down inside the window.

onMouseUp

public void onMouseUp(MouseButtonEventHandler handler)

Adds a listener that will receive an event when the mouse button goes up inside the window.

onClick

public void onClick(MouseButtonEventHandler handler)

Adds a listener that will receive an event when the mouse button goes down and then up inside the window without moving significantly (i.e. not a drag).

onMouseMove

public void onMouseMove(MouseMotionEventHandler handler)

Adds a listener that will receive an event when the mouse moves over the window with the button up.

onDrag

public void onDrag(MouseMotionEventHandler handler)

Adds a listener that will receive an event when the mouse moves over the window with the button down.

onKeyDown

public void onKeyDown(KeyboardEventHandler handler)

Adds a listener that will receive an event when a key on the keyboard is pressed. Note that this reports actual keys on the keyboard, not which characters they produce. See onKeyUp() for more information. If you want to take some continuous action as long as a key is pressed, consider getKeysPressed() instead.

See Also:

• onKeyUp(KeyboardEventHandler)
• onCharacterTyped(Consumer)

onKeyUp

public void onKeyUp(KeyboardEventHandler handler)

Adds a listener that will receive an event when a key on the keyboard is released. Note that this reports actual keys on the keyboard, not any characters they produce. For example, if the user types a plus sign, you will receive the following events:

Example key event sequence

1.	keyDown	Key.SHIFT	modifiers=[ModifierKey.SHIFT]
2.	keyDown	Key.EQUALS	modifiers=[ModifierKey.SHIFT]
3.	keyUp	Key.EQUALS	modifiers=[ModifierKey.SHIFT]
4.	characterTyped	'+'
5.	keyUp	Key.SHIFT	modifiers=[]

If you want to know what character the user typed, taking keyboard layout and modifier keys into account (e.g. 'a' vs 'A'), consider onCharacterTyped() instead. If you want to take some continuous action as long as a key is pressed, consider getKeysPressed() instead.

See Also:

• onKeyDown(KeyboardEventHandler)
• onCharacterTyped(Consumer)

onCharacterTyped

public void onCharacterTyped(Consumer<Character> handler)

Adds a listener that will be notified when the use types a combination of keys that produce a character. Note that this only reports key combinations that produce characters; it does not report special keys such as arrow keys, backspace, modifiers, etc. See onKeyUp() for more information.

See Also:

• onKeyDown(KeyboardEventHandler)
• onKeyUp(KeyboardEventHandler)

getKeysPressed

public Set<Key> getKeysPressed()

Returns all keys currently pressed on the keyboard. You can poll this repeatedly (e.g. in an animate() callback) to continuously take some action as long as a key is held down. If instead you want to do something only at the moment a key goes down or comes back up, use onKeyDown and onKeyUp() instead.

animate

public void animate(Runnable animation)

Call the given callback repeatedly forever, up to 60 times per second. Automatically draws the canvas after each time the callback runs.

animate

public void animate(DoubleConsumer animation)

Call the given callback repeatedly forever, up to 60 times per second, passing the time delta since the last time it was called. Automatically draws the canvas after each time the callback runs.

performEventAction

public void performEventAction(Runnable action)

For internal use.