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
Constructor Summary
Modifier | Constructor | Description |
---|---|---|
protected | GraphicsEnvironment() | This is an abstract class and cannot be instantiated directly. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
abstract Graphics2D | createGraphics(BufferedImage img) | Returns a |
abstract Font[] | getAllFonts() | Returns an array containing a one-point size instance of all fonts available in this |
abstract String[] | getAvailableFontFamilyNames() | Returns an array containing the names of all font families in this |
abstract String[] | getAvailableFontFamilyNames(Locale l) | Returns an array containing the names of all font families in this |
Point | getCenterPoint() | Returns the Point where Windows should be centered. |
abstract GraphicsDevice | getDefaultScreenDevice() | Returns the default screen |
static GraphicsEnvironment | getLocalGraphicsEnvironment() | Returns the local |
Rectangle | getMaximumWindowBounds() | Returns the maximum bounds for centered Windows. |
abstract GraphicsDevice[] | getScreenDevices() | Returns an array of all of the screen |
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. |
void | preferLocaleFonts() | Indicates a preference for locale-specific fonts in the mapping of logical fonts to physical fonts. |
void | preferProportionalFonts() | Indicates a preference for proportional over non-proportional (e.g. |
boolean | registerFont(Font font) | Registers a created |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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
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 specifiedBufferedImage
- Returns:
- a
Graphics2D
to be used for rendering into the specifiedBufferedImage
- Throws:
-
NullPointerException
- ifimg
is null
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 chosen 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 in this GraphicsEnvironment
localized for the default locale, as returned by Locale.getDefault()
.
Typical usage would be for presentation to a user for selection of a particular family name. An application can then specify this name when creating a font, in conjunction with a style, such as bold or italic, giving the font system flexibility in choosing its own best match among multiple fonts in the same font family.
- Returns:
- an array of
String
containing font family names localized for the default locale, or a suitable alternative name if no name exists for this locale. - Since:
- 1.2
- See Also:
-
getAllFonts()
,Font
,Font.getFamily()
getAvailableFontFamilyNames
public abstract String[] getAvailableFontFamilyNames(Locale l)
Returns an array containing the names of all font families in this GraphicsEnvironment
localized for the specified locale.
Typical usage would be for presentation to a user for selection of a particular family name. An application can then specify this name when creating a font, in conjunction with a style, such as bold or italic, giving the font system flexibility in choosing its own best match among multiple fonts in the same font family.
- Parameters:
-
l
- aLocale
object that represents a particular geographical, political, or cultural region. Specifyingnull
is equivalent to specifyingLocale.getDefault()
. - Returns:
- an array of
String
containing font family names localized for the specifiedLocale
, or a suitable alternative name if no name exists for the specified locale. - Since:
- 1.2
- See Also:
-
getAllFonts()
,Font
,Font.getFamily()
registerFont
public boolean registerFont(Font font)
Registers a created Font
in this GraphicsEnvironment
. A created font is one that was returned from calling Font.createFont(int, java.io.InputStream)
, or derived from a created font by calling Font.deriveFont(int, float)
. After calling this method for such a font, it is available to be used in constructing new Font
s by name or family name, and is enumerated by getAvailableFontFamilyNames()
and getAllFonts()
within the execution context of this application or applet. This means applets cannot register fonts in a way that they are visible to other applets.
Reasons that this method might not register the font and therefore return false
are:
- The font is not a created
Font
. - The font conflicts with a non-created
Font
already in thisGraphicsEnvironment
. For example if the name is that of a system font, or a logical font as described in the documentation of theFont
class. It is implementation dependent whether a font may also conflict if it has the same family name as a system font.Notice that an application can supersede the registration of an earlier created font with a new one.
- Parameters:
-
font
- the font to be registered - Returns:
- true if the
font
is successfully registered in thisGraphicsEnvironment
. - Throws:
-
NullPointerException
- iffont
is null - Since:
- 1.6
preferLocaleFonts
public void preferLocaleFonts()
Indicates a preference for locale-specific fonts in the mapping of logical fonts to physical fonts. Calling this method indicates that font rendering should primarily use fonts specific to the primary writing system (the one indicated by the default encoding and the initial default locale). For example, if the primary writing system is Japanese, then characters should be rendered using a Japanese font if possible, and other fonts should only be used for characters for which the Japanese font doesn't have glyphs.
The actual change in font rendering behavior resulting from a call to this method is implementation dependent; it may have no effect at all, or the requested behavior may already match the default behavior. The behavior may differ between font rendering in lightweight and peered components. Since calling this method requests a different font, clients should expect different metrics, and may need to recalculate window sizes and layout. Therefore this method should be called before user interface initialisation.
- Since:
- 1.5
preferProportionalFonts
public void preferProportionalFonts()
Indicates a preference for proportional over non-proportional (e.g. dual-spaced CJK fonts) fonts in the mapping of logical fonts to physical fonts. If the default mapping contains fonts for which proportional and non-proportional variants exist, then calling this method indicates the mapping should use a proportional variant.
The actual change in font rendering behavior resulting from a call to this method is implementation dependent; it may have no effect at all. The behavior may differ between font rendering in lightweight and peered components. Since calling this method requests a different font, clients should expect different metrics, and may need to recalculate window sizes and layout. Therefore this method should be called before user interface initialisation.
- Since:
- 1.5
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)