acm.graphics
Class GImage

java.lang.Object
  acm.graphics.GObject
      acm.graphics.GImage

public class GImage
extends GObject
implements GResizable, GScalable

The GImage class is a graphical object whose appearance is defined by an image.

Constructor Summary

GImage(Image image)

GImage(Image image, double x, double y)

GImage(int[][] array)

GImage(int[][] array, double x, double y)

GImage(String name)

GImage(String name, double x, double y)

Method Summary

int	createRGBPixel(int red, int green, int blue) Creates an opaque pixel value with the color components given by red, green, and blue.
int	createRGBPixel(int red, int green, int blue, int alpha) Creates a pixel value with the color components given by red, green, and blue and the transparency value alpha.
int	getAlpha(int pixel) Returns the alpha component from an RGB value.
int	getBlue(int pixel) Returns the blue component from an RGB value.
GRectangle	getBounds() Returns the bounding box of this object.
int	getGreen(int pixel) Returns the green component from an RGB value.
Image	getImage() Returns the image stored inside this GImage.
int[][]	getPixelArray() Returns a two-dimensional array of pixel values from the stored image.
int	getRed(int pixel) Returns the red component from an RGB value.
GDimension	getSize() Returns the size of this object as a GDimension.
void	saveImage(File file) Saves the image to the specified file.
void	saveImage(String filename) Saves the image to a file with the specified filename.
void	scale(double sf) Scales the object on the screen by the scale factor sf, which applies in both dimensions.
void	scale(double sx, double sy) Scales the object on the screen by the scale factors sx and sy.
void	setBounds(double x, double y, double width, double height) Changes the bounds of this object to the specified values.
void	setBounds(GRectangle bounds) Changes the bounds of this object to the values from the specified GRectangle.
void	setImage(Image image) Resets the image used by this GImage object to the new image specified as an argument.
void	setImage(String name) Resets the image used by this GImage object to the one identified by the argument name, which is processed exactly as described in the constructors.
void	setSize(double width, double height) Changes the size of this object to the specified width and height.

Inherited Method Summary

void	addMouseListener(MouseListener listener) Adds a mouse listener to this graphical object.
void	addMouseMotionListener(MouseMotionListener listener) Adds a mouse motion listener to this graphical object.
boolean	contains(GPoint pt) Checks to see whether a point is inside the object.
boolean	contains(double x, double y) Checks to see whether a point is inside the object.
double	getHeight() Returns the height of this object as a double-precision value, which is defined to be the height of the bounding box.
GPoint	getLocation() Returns the location of this object as a GPoint.
double	getWidth() Returns the width of this object as a double-precision value, which is defined to be the width of the bounding box.
double	getX() Returns the x-coordinate of the object.
double	getY() Returns the y-coordinate of the object.
boolean	isVisible() Checks to see whether this object is visible.
void	move(double dx, double dy) Moves the object on the screen using the displacements dx and dy.
void	movePolar(double r, double theta) Moves the object using displacements given in polar coordinates.
void	removeMouseListener(MouseListener listener) Removes a mouse listener from this graphical object.
void	removeMouseMotionListener(MouseMotionListener listener) Removes a mouse motion listener from this graphical object.
void	sendBackward() Moves this object one step toward the back in the z dimension.
void	sendForward() Moves this object one step toward the front in the z dimension.
void	sendToBack() Moves this object to the back of the display in the z dimension.
void	sendToFront() Moves this object to the front of the display in the z dimension.
void	setLocation(GPoint pt) Sets the location of this object to the specified point.
void	setLocation(double x, double y) Sets the location of this object to the point (x, y).
void	setVisible(boolean visible) Sets whether this object is visible.

Constructor Detail

public GImage(Image image)

Creates a new GImage object at the origin that displays the specified image.

Usage:

GImage gimage = new GImage(image);

Parameter:

image

The image to use as the contents of this GImage

public GImage(Image image, double x, double y)

Creates a new GImage object at the specified coordinates. The image parameter is used to initialize the appearance of the image.

Usage:

GImage gimage = new GImage(image, x, y);

Parameters:

image	The image to use as the contents of this GImage
x	The x-coordinate of the upper left corner of the image
y	The y-coordinate of the upper left corner of the image

public GImage(int[][] array)

Creates a new GImage object at the origin. The array parameter is a two-dimensional pixel array in which each pixel value consists of an integer that is subdivided into four eight-bit bytes, as follows: alpha << 24 | red << 16 | green << 8 | blue The alpha value indicates the transparency, and the other values are the red, green, and blue components of the color.

Usage:

GImage gimage = new GImage(array);

Parameter:

array

A two-dimensional pixel array

public GImage(int[][] array, double x, double y)

Creates a new GImage object at the specified coordinates. The array parameter is a two-dimensional pixel array in which each pixel value consists of an integer that is subdivided into four eight-bit bytes, as follows: alpha << 24 | red << 16 | green << 8 | blue The alpha value indicates the transparency, and the other values are the red, green, and blue components of the color.

Usage:

GImage gimage = new GImage(array, x, y);

Parameters:

array	A two-dimensional pixel array
x	The x-coordinate of the upper left corner of the image
y	The y-coordinate of the upper left corner of the image

public GImage(String name)

Creates a new GImage object by looking for an image with that name. The search for an image by name consists of the following steps:

1. Check to see if an image with that name has already been defined. If so, return that image.

2. Check to see if there is a resource available with that name whose contents can be read as an Image. If so, read the image from the resource file.

3. Load the image from a file with the specified name, relative to the application directory or the applet code base.

Usage:

GImage gimage = new GImage(name);

Parameter:

name	The name used to search for the contents of this image

public GImage(String name, double x, double y)

Creates a new GImage object at the specified coordinates. The name parameter is used to identify an image to display, as described in the single-argument version of the GImage constructor.

Usage:

GImage gimage = new GImage(image, x, y);

Parameters:

name	The name used to search for the contents of this image
x	The x-coordinate of the upper left corner of the image
y	The y-coordinate of the upper left corner of the image

Method Detail

public static int createRGBPixel(int red, int green, int blue)

Creates an opaque pixel value with the color components given by red, green, and blue.

Usage:

int pixel = GImage.createRGBPixel(red, green, blue);

Parameters:

red	The red component of the pixel (0 to 255)
green	The green component of the pixel (0 to 255)
blue	The blue component of the pixel (0 to 255)

Returns:

An opaque pixel value containing these components

public static int createRGBPixel(int red, int green, int blue, int alpha)

Creates a pixel value with the color components given by red, green, and blue and the transparency value alpha.

Usage:

int pixel = GImage.createRGBPixel(red, green, blue);

Parameters:

red	The red component of the pixel (0 to 255)
green	The green component of the pixel (0 to 255)
blue	The blue component of the pixel (0 to 255)
alpha	The transparency value of the pixel (0 to 255)

Returns:

A pixel value containing these components

public static int getAlpha(int pixel)

Returns the alpha component from an RGB value.

Usage:

int alpha = GImage.getAlpha(pixel);

Parameter:

pixel

An int containing a pixel value as alpha/red/green/blue.

Returns:

The alpha component of the pixel

public static int getBlue(int pixel)

Returns the blue component from an RGB value.

Usage:

int blue = GImage.getBlue(pixel);

Parameter:

pixel

An int containing a pixel value as alpha/red/green/blue.

Returns:

The blue component of the pixel

public GRectangle getBounds()

Returns the bounding box of this object.

Usage:	GRectangle bounds = gimage.getBounds();
Returns:	The bounding box for this object

Specified by:

getBounds in class GObject

public static int getGreen(int pixel)

Returns the green component from an RGB value.

Usage:

int green = GImage.getGreen(pixel);

Parameter:

pixel

An int containing a pixel value as alpha/red/green/blue.

Returns:

The green component of the pixel

public Image getImage()

Returns the image stored inside this GImage.

Usage:	Image image = gimage.getImage();
Returns:	The Image object stored inside this GImage

public int[][] getPixelArray()

Returns a two-dimensional array of pixel values from the stored image.

Usage:	int[][] array = gimage.getPixelArray();
Returns:	A two-dimensional array of pixel values from the stored image

public static int getRed(int pixel)

Returns the red component from an RGB value.

Usage:

int red = GImage.getRed(pixel);

Parameter:

pixel

An int containing a pixel value as alpha/red/green/blue.

Returns:

The red component of the pixel

public GDimension getSize()

Returns the size of this object as a GDimension.

Usage:	GDimension size = gimage.getSize();
Returns:	The size of this object

public void saveImage(File file)

Saves the image to the specified file. The data format for the image file is determined by the suffix of the filename. If the suffix of the file is not recognized as a supported image type, calling this method generates an error.

Usage:

gimage.saveImage(file);

Parameter:

file	The File to which the image is saved

public void saveImage(String filename)

Saves the image to a file with the specified filename. The data format for the image file is determined by the suffix of the filename. If the suffix of the file is not recognized as a supported image type, calling this method generates an error.

Usage:

gimage.saveImage(filename);

Parameter:

filename

The name of the file to which the image is saved

public final void scale(double sf)

Scales the object on the screen by the scale factor sf, which applies in both dimensions.

Usage:

gobj.scale(sf);

Parameter:

sf	The factor used to scale all coordinates in both dimensions

Specified by:

scale in interface GScalable

public void scale(double sx, double sy)

Scales the object on the screen by the scale factors sx and sy.

Usage:

gobj.scale(sx, sy);

Parameters:

sx	The factor used to scale all coordinates in the x direction
sy	The factor used to scale all coordinates in the y direction

Specified by:

scale in interface GScalable

public void setBounds(double x, double y, double width, double height)

Changes the bounds of this object to the specified values.

Usage:

gimage.setBounds(x, y, width, height);

Parameters:

x	The new x-coordinate for the object
y	The new y-coordinate for the object
width	The new width of the object
height	The new height of the object

Specified by:

setBounds in interface GResizable

public final void setBounds(GRectangle bounds)

Changes the bounds of this object to the values from the specified GRectangle.

Usage:

gimage.setBounds(bounds);

Parameter:

bounds

A GRectangle specifying the new bounds

Specified by:

setBounds in interface GResizable

public void setImage(Image image)

Resets the image used by this GImage object to the new image specified as an argument. Calling setImage automatically changes the size of the image to be equal to that of the image data.

Usage:

gimage.setImage(image);

Parameter:

image

The image to use as the contents of this GImage

public void setImage(String name)

Resets the image used by this GImage object to the one identified by the argument name, which is processed exactly as described in the constructors. Calling setImage automatically changes the size of the image to be equal to that of the image data.

Usage:

gimage.setImage(name);

Parameter:

name	The name used to search for the contents of this image

public void setSize(double width, double height)

Changes the size of this object to the specified width and height.

Usage:

gimage.setSize(width, height);

Parameters:

width	The new width of the object
height	The new height of the object

Specified by:

setSize in interface GResizable