java.lang.Object
- edu.princeton.cs.algs4.GrayscalePicture

所有已实现的接口:

java.awt.event.ActionListener, java.util.EventListener
```
public final class GrayscalePicture
extends java.lang.Object
implements java.awt.event.ActionListener
```
This class provides methods for manipulating individual pixels of a grayscale image. The original image can be read from a PNG, GIF, or JPEG file or the user can create a blank image of a given dimension. This class includes methods for displaying the image in a window on the screen or saving it to a file.
Pixel (col, row) is column col and row row. By default, the origin (0, 0) is the pixel in the top-left corner, which is a common convention in image processing. The method setOriginLowerLeft() change the origin to the lower left.
The get() and set() methods use Color objects to get or set the color of the specified pixel. The Color objects are converted to grayscale if they have different values for the R, G, and B channels. The getGrayscale() and setGrayscale() methods use an 8-bit int to encode the grayscale value, thereby avoiding the need to create temporary Color objects.
A W-by-H picture uses ~ 4 W H bytes of memory, since the color of each pixel is encoded as a 32-bit int (even though, in principle, only ~ W H bytes are needed).
For additional documentation, see Section 3.1 of Computer Science: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne. See Picture for a version that supports 32-bit RGB color images.

构造器概要

构造器
构造器	说明
`GrayscalePicture(int width, int height)`	Creates a `width`-by-`height` picture, with `width` columns and `height` rows, where each pixel is black.
`GrayscalePicture(GrayscalePicture picture)`	Creates a new grayscale picture that is a deep copy of the argument picture.
`GrayscalePicture(java.lang.String filename)`	Creates a grayscale picture by reading an image from a file or URL.

方法概要

修饰符和类型	方法	说明
`void`	`actionPerformed(java.awt.event.ActionEvent e)`	Opens a save dialog box when the user selects "Save As" from the menu.
`boolean`	`equals(java.lang.Object other)`	Returns true if this picture is equal to the argument picture.
`java.awt.Color`	`get(int col, int row)`	Returns the grayscale value of pixel (`col`, `row`) as a `Color`.
`int`	`getGrayscale(int col, int row)`	Returns the grayscale value of pixel (`col`, `row`) as an `int` between 0 and 255.
`javax.swing.JLabel`	`getJLabel()`	Returns a `JLabel` containing this picture, for embedding in a `JPanel`, `JFrame` or other GUI widget.
`int`	`hashCode()`	This operation is not supported because pictures are mutable.
`int`	`height()`	Returns the height of the picture.
`static void`	`main(java.lang.String[] args)`	Unit tests this `Picture` data type.
`void`	`save(java.io.File file)`	Saves the picture to a file in a PNG or JPEG image format.
`void`	`save(java.lang.String name)`	Saves the picture to a file in either PNG or JPEG format.
`void`	`set(int col, int row, java.awt.Color color)`	Sets the color of pixel (`col`, `row`) to the given grayscale value.
`void`	`setGrayscale(int col, int row, int gray)`	Sets the color of pixel (`col`, `row`) to the given grayscale value between 0 and 255.
`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.
`java.lang.String`	`toString()`	Returns a string representation of this picture.
`int`	`width()`	Returns the width of the picture.

从类继承的方法 java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- 构造器详细资料
  - GrayscalePicture
```
public GrayscalePicture(int width,
                        int height)
```
    Creates a width-by-height picture, with width columns and height rows, where each pixel is black.
    
    参数:
    
    width - the width of the picture
    
    height - the height of the picture
    
    抛出:
    
    java.lang.IllegalArgumentException - if width is negative
    
    java.lang.IllegalArgumentException - if height is negative
  - GrayscalePicture
```
public GrayscalePicture(GrayscalePicture picture)
```
    Creates a new grayscale picture that is a deep copy of the argument picture.
    
    参数:
    
    picture - the picture to copy
    
    抛出:
    
    java.lang.IllegalArgumentException - if picture is null
  - GrayscalePicture
```
public GrayscalePicture(java.lang.String filename)
```
    Creates a grayscale picture by reading an image from a file or URL.
    
    参数:
    
    filename - the name of the file (.png, .gif, or .jpg) or URL.
    
    抛出:
    
    java.lang.IllegalArgumentException - if cannot read image
    
    java.lang.IllegalArgumentException - if filename is null
- 方法详细资料
  - getJLabel
```
public javax.swing.JLabel getJLabel()
```
    Returns a JLabel containing this picture, for embedding in a JPanel, JFrame or other GUI widget.
    
    返回:
    
    the JLabel
  - setOriginUpperLeft
```
public void setOriginUpperLeft()
```
    Sets the origin to be the upper left pixel. This is the default.
  - 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.
    
    返回:
    
    the height of the picture (in pixels)
  - width
```
public int width()
```
    Returns the width of the picture.
    
    返回:
    
    the width of the picture (in pixels)
  - get
```
public java.awt.Color get(int col,
                          int row)
```
    Returns the grayscale value of pixel (col, row) as a Color.
    
    参数:
    
    col - the column index
    
    row - the row index
    
    返回:
    
    the grayscale value of pixel (col, row)
    
    抛出:
    
    java.lang.IllegalArgumentException - unless both 0 <= col < width and 0 <= row < height
  - getGrayscale
```
public int getGrayscale(int col,
                        int row)
```
    Returns the grayscale value of pixel (col, row) as an int between 0 and 255. Using this method can be more efficient than get(int, int) because it does not create a Color object.
    
    参数:
    
    col - the column index
    
    row - the row index
    
    返回:
    
    the 8-bit integer representation of the grayscale value of pixel (col, row)
    
    抛出:
    
    java.lang.IllegalArgumentException - unless both 0 <= col < width and 0 <= row < height
  - set
```
public void set(int col,
                int row,
                java.awt.Color color)
```
    Sets the color of pixel (col, row) to the given grayscale value.
    
    参数:
    
    col - the column index
    
    row - the row index
    
    color - the color (converts to grayscale if color is not a shade of gray)
    
    抛出:
    
    java.lang.IllegalArgumentException - unless both 0 <= col < width and 0 <= row < height
    
    java.lang.IllegalArgumentException - if color is null
  - setGrayscale
```
public void setGrayscale(int col,
                         int row,
                         int gray)
```
    Sets the color of pixel (col, row) to the given grayscale value between 0 and 255.
    
    参数:
    
    col - the column index
    
    row - the row index
    
    gray - the 8-bit integer representation of the grayscale value
    
    抛出:
    
    java.lang.IllegalArgumentException - unless both 0 <= col < width and 0 <= row < height
  - equals
```
public boolean equals(java.lang.Object other)
```
    Returns true if this picture is equal to the argument picture.
    
    覆盖:
    
    equals 在类中 java.lang.Object
    
    参数:
    
    other - the other picture
    
    返回:
    
    true if this picture is the same dimension as other and if all pixels have the same color; false otherwise
  - toString
```
public java.lang.String toString()
```
    Returns a string representation of this picture. The result is a width-by-height matrix of pixels, where the grayscale value of a pixel is an integer between 0 and 255.
    
    覆盖:
    
    toString 在类中 java.lang.Object
    
    返回:
    
    a string representation of this picture
  - hashCode
```
public int hashCode()
```
    This operation is not supported because pictures are mutable.
    
    覆盖:
    
    hashCode 在类中 java.lang.Object
    
    返回:
    
    does not return a value
    
    抛出:
    
    java.lang.UnsupportedOperationException - if called
  - save
```
public void save(java.lang.String name)
```
    Saves the picture to a file in either PNG or JPEG format. The filetype extension must be either .png or .jpg.
    
    参数:
    
    name - the name of the file
    
    抛出:
    
    java.lang.IllegalArgumentException - if name is null
  - save
```
public void save(java.io.File file)
```
    Saves the picture to a file in a PNG or JPEG image format.
    
    参数:
    
    file - the file
    
    抛出:
    
    java.lang.IllegalArgumentException - if file is null
  - actionPerformed
```
public void actionPerformed(java.awt.event.ActionEvent e)
```
    Opens a save dialog box when the user selects "Save As" from the menu.
    
    指定者:
    
    actionPerformed 在接口中 java.awt.event.ActionListener
  - main
```
public static void main(java.lang.String[] args)
```
    Unit tests this Picture data type. Reads a picture specified by the command-line argument, and shows it in a window on the screen.
    
    参数:
    
    args - the command-line arguments

类 GrayscalePicture

构造器概要

方法概要

从类继承的方法 java.lang.Object

构造器详细资料

GrayscalePicture

GrayscalePicture

GrayscalePicture

方法详细资料

getJLabel

setOriginUpperLeft

setOriginLowerLeft

show

height

width

get

getGrayscale

set

setGrayscale

equals

toString

hashCode

save

save

actionPerformed

main