java.awt
Class GraphicsEnvironment

java.lang.Object
  java.awt.GraphicsEnvironment

public abstract class GraphicsEnvironment

extends Object

The GraphicsEnvironment class describes the collection of GraphicsDevice objects and Font objects available to a Java(tm) application on a particular platform. The resources in this GraphicsEnvironment might be local or on a remote machine. GraphicsDevice objects can be screens, printers or image buffers and are the destination of Graphics2D drawing methods. Each GraphicsDevice has a number of GraphicsConfiguration objects associated with it. These objects specify the different configurations in which the GraphicsDevice can be used.

See Also:

GraphicsDevice, GraphicsConfiguration

Field Summary

private static Boolean	headless The headless state of the Toolkit and GraphicsEnvironment
private static GraphicsEnvironment	localEnv

Constructor Summary

protected

GraphicsEnvironment() This is an abstract class and cannot be instantiated directly.

Method Summary

(package private) static void	checkHeadless() Check for headless state and throw HeadlessException if headless
abstract Graphics2D	createGraphics(BufferedImage img) Returns a Graphics2D object for rendering into the specified BufferedImage.
abstract Font[]	getAllFonts() Returns an array containing a one-point size instance of all fonts available in this GraphicsEnvironment.
abstract String[]	getAvailableFontFamilyNames() Returns an array containing the names of all font families available in this GraphicsEnvironment.
abstract String[]	getAvailableFontFamilyNames(Locale l) Returns an array containing the localized names of all font families available in this GraphicsEnvironment.
Point	getCenterPoint() Returns the Point where Windows should be centered.
abstract GraphicsDevice	getDefaultScreenDevice() Returns the default screen GraphicsDevice.
private static boolean	getHeadlessProperty()
static GraphicsEnvironment	getLocalGraphicsEnvironment() Returns the local GraphicsEnvironment.
Rectangle	getMaximumWindowBounds() Returns the maximum bounds for centered Windows.
abstract GraphicsDevice[]	getScreenDevices() Returns an array of all of the screen GraphicsDevice objects.
static boolean	isHeadless() Tests whether or not a display, keyboard, and mouse can be supported in this environment.
boolean	isHeadlessInstance() Returns whether or not a display, keyboard, and mouse can be supported in this graphics environment.

Methods inherited from class java.lang.Object

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

Field Detail

localEnv

private static GraphicsEnvironment localEnv

headless

private static Boolean headless

The headless state of the Toolkit and GraphicsEnvironment

Constructor Detail

GraphicsEnvironment

protected GraphicsEnvironment()

This is an abstract class and cannot be instantiated directly. Instances must be obtained from a suitable factory or query method.

Method Detail

getLocalGraphicsEnvironment

public static GraphicsEnvironment getLocalGraphicsEnvironment()

Returns the local GraphicsEnvironment.

Returns:

the local GraphicsEnvironment

isHeadless

public static boolean isHeadless()

Tests whether or not a display, keyboard, and mouse can be supported in this environment. If this method returns true, a HeadlessException is thrown from areas of the Toolkit and GraphicsEnvironment that are dependent on a display, keyboard, or mouse.

Returns:

true if this environment cannot support a display, keyboard, and mouse; false otherwise

Since:

1.4

See Also:

HeadlessException

getHeadlessProperty

private static boolean getHeadlessProperty()

Returns:

the value of the property "java.awt.headless"

Since:

1.4

checkHeadless

static void checkHeadless()
                   throws HeadlessException

Check for headless state and throw HeadlessException if headless

Throws:

HeadlessException

Since:

1.4

isHeadlessInstance

public boolean isHeadlessInstance()

Returns whether or not a display, keyboard, and mouse can be supported in this graphics environment. If this returns true, HeadlessException will be thrown from areas of the graphics environment that are dependent on a display, keyboard, or mouse.

Returns:

true if a display, keyboard, and mouse can be supported in this environment; false otherwise

Since:

1.4

See Also:

HeadlessException, isHeadless()

getScreenDevices

public abstract GraphicsDevice[] getScreenDevices()
                                           throws HeadlessException

Returns an array of all of the screen GraphicsDevice objects.

Returns:

an array containing all the GraphicsDevice objects that represent screen devices

Throws:

HeadlessException - if isHeadless() returns true

See Also:

isHeadless()

getDefaultScreenDevice

public abstract GraphicsDevice getDefaultScreenDevice()
                                               throws HeadlessException

Returns the default screen GraphicsDevice.

Returns:

the GraphicsDevice that represents the default screen device

Throws:

HeadlessException - if isHeadless() returns true

See Also:

isHeadless()

createGraphics

public abstract Graphics2D createGraphics(BufferedImage img)

Returns a Graphics2D object for rendering into the specified BufferedImage.

Parameters:

img - the specified BufferedImage

Returns:

a Graphics2D to be used for rendering into the specified BufferedImage

getAllFonts

public abstract Font[] getAllFonts()

Returns an array containing a one-point size instance of all fonts available in this GraphicsEnvironment. Typical usage would be to allow a user to select a particular font. Then, the application can size the font and set various font attributes by calling the deriveFont method on the choosen instance.

This method provides for the application the most precise control over which Font instance is used to render text. If a font in this GraphicsEnvironment has multiple programmable variations, only one instance of that Font is returned in the array, and other variations must be derived by the application.

If a font in this environment has multiple programmable variations, such as Multiple-Master fonts, only one instance of that font is returned in the Font array. The other variations must be derived by the application.

Returns:

an array of Font objects

Since:

1.2

See Also:

getAvailableFontFamilyNames(), Font, Font.deriveFont(int, float), Font.getFontName()

getAvailableFontFamilyNames

public abstract String[] getAvailableFontFamilyNames()

Returns an array containing the names of all font families available in this GraphicsEnvironment. Typical usage would be to allow a user to select a particular family name and allow the application to choose related variants of the same family when the user specifies style attributes such as Bold or Italic.

This method provides for the application some control over which Font instance is used to render text, but allows the Font object more flexibility in choosing its own best match among multiple fonts in the same font family.

Returns:

an array of String containing names of font families

Since:

1.2

See Also:

getAllFonts(), Font, Font.getFamily()

getAvailableFontFamilyNames

public abstract String[] getAvailableFontFamilyNames(Locale l)

Returns an array containing the localized names of all font families available in this GraphicsEnvironment. Typical usage would be to allow a user to select a particular family name and allow the application to choose related variants of the same family when the user specifies style attributes such as Bold or Italic.

This method provides for the application some control over which Font instance used to render text, but allows the Font object more flexibility in choosing its own best match among multiple fonts in the same font family. If l is null, this method returns an array containing all font family names available in this GraphicsEnvironment.

Parameters:

l - a Locale object that represents a particular geographical, political, or cultural region

Returns:

an array of String objects containing names of font families specific to the specified Locale

Since:

1.2

See Also:

getAllFonts(), Font, Font.getFamily()

getCenterPoint

public Point getCenterPoint()
                     throws HeadlessException

Returns the Point where Windows should be centered. It is recommended that centered Windows be checked to ensure they fit within the available display area using getMaximumWindowBounds().

Returns:

the point where Windows should be centered

Throws:

HeadlessException - if isHeadless() returns true

Since:

1.4

See Also:

getMaximumWindowBounds()

getMaximumWindowBounds

public Rectangle getMaximumWindowBounds()
                                 throws HeadlessException

Returns the maximum bounds for centered Windows. These bounds account for objects in the native windowing system such as task bars and menu bars. The returned bounds will reside on a single display with one exception: on multi-screen systems where Windows should be centered across all displays, this method returns the bounds of the entire display area.

To get the usable bounds of a single display, use GraphicsConfiguration.getBounds() and Toolkit.getScreenInsets().

Returns:

the maximum bounds for centered Windows

Throws:

HeadlessException - if isHeadless() returns true

Since:

1.4

See Also:

getCenterPoint(), GraphicsConfiguration.getBounds(), Toolkit.getScreenInsets(java.awt.GraphicsConfiguration)