edu.princeton.cs.introcs

Class Picture

java.lang.Object

edu.princeton.cs.introcs.Picture

All Implemented Interfaces:

ActionListener, EventListener

public final class Picture
extends Object
implements ActionListener

This class provides methods for manipulating individual pixels of an image. The original image can be read from a .jpg, .gif, or .png file or the user can create a blank image of a given size. This class includes methods for displaying the image in a window on the screen or saving it to a file.

Pixel (x, y) is column x and row y. By default, the origin (0, 0) is upper left, which is a common convention in image processing. The method setOriginLowerLeft() change the origin to the lower left.

For additional documentation, see Section 3.1 of Introduction to Programming in Java: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne.

Author:

Robert Sedgewick, Kevin Wayne

Constructor Summary

Constructors

Constructor and Description
Picture(File file) Initializes a picture by reading in a .png, .gif, or .jpg from a File.
Picture(int w, int h) Initializes a blank w-by-h picture, where each pixel is black.
Picture(Picture pic) Initializes a new picture that is a deep copy of pic.
Picture(String filename) Initializes a picture by reading in a .png, .gif, or .jpg from the given filename or URL name.

Method Summary

Modifier and Type	Method and Description
void	actionPerformed(ActionEvent e) Opens a save dialog box when the user selects "Save As" from the menu.
boolean	equals(Object obj) Is this Picture equal to obj?
Color	get(int x, int y) Returns the color of pixel (x, y).
JLabel	getJLabel() Returns a JLabel containing this picture, for embedding in a JPanel, JFrame or other GUI widget.
int	height() Returns the height of the picture (in pixels).
static void	main(String[] args) Tests this Picture data type.
void	save(File file) Saves the picture to a file in a standard image format.
void	save(String name) Saves the picture to a file in a standard image format.
void	set(int x, int y, Color color) Sets the color of pixel (x, y) to given color.
void	setOriginLowerLeft() Sets the origin to be the lower left pixel.
void	setOriginUpperLeft() Sets the origin to be the upper left pixel.
void	show() Displays the picture in a window on the screen.
int	width() Returns the width of the picture (in pixels).

Methods inherited from class java.lang.Object

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

Constructor Detail

Picture

public Picture(int w,
               int h)

Initializes a blank w-by-h picture, where each pixel is black.

Picture

public Picture(Picture pic)

Initializes a new picture that is a deep copy of pic.

Picture

public Picture(String filename)

Initializes a picture by reading in a .png, .gif, or .jpg from the given filename or URL name.

Picture

public Picture(File file)

Initializes a picture by reading in a .png, .gif, or .jpg from a File.

Method Detail

getJLabel

public JLabel getJLabel()

Returns a JLabel containing this picture, for embedding in a JPanel, JFrame or other GUI widget.

setOriginUpperLeft

public void setOriginUpperLeft()

Sets the origin to be the upper left pixel.

setOriginLowerLeft

public void setOriginLowerLeft()

Sets the origin to be the lower left pixel.

show

public void show()

Displays the picture in a window on the screen.

height

public int height()

Returns the height of the picture (in pixels).

width

public int width()

Returns the width of the picture (in pixels).

get

public Color get(int x,
                 int y)

Returns the color of pixel (x, y).

set

public void set(int x,
                int y,
                Color color)

Sets the color of pixel (x, y) to given color.

equals

public boolean equals(Object obj)

Is this Picture equal to obj?

Overrides:

equals in class Object

save

public void save(String name)

Saves the picture to a file in a standard image format. The filetype must be .png or .jpg.

save

public void save(File file)

Saves the picture to a file in a standard image format.

actionPerformed

public void actionPerformed(ActionEvent e)

Opens a save dialog box when the user selects "Save As" from the menu.

Specified by:

actionPerformed in interface ActionListener

main

public static void main(String[] args)

Tests this Picture data type. Reads a picture specified by the command-line argument, and shows it in a window on the screen.