org.eclipse.rwt.graphics
Class Graphics

java.lang.Object
  org.eclipse.rwt.graphics.Graphics

public final class Graphics
extends java.lang.Object

This is a helper class for operations with text, fonts, colors and images. As RAP needs to handle with multiple clients simultaneously there are no constructors for these objects to share them between different sessions in order to have a much smaller memory footprint.

Since:

1.0

Method Summary

static float	getAvgCharWidth(Font font) Returns the average character width of the specified font, measured in pixels.
static int	getCharHeight(Font font) Returns the height of the specified font, measured in pixels.
static Color	getColor(int red, int green, int blue) Returns a Color given the desired red, green and blue values expressed as ints in the range 0 to 255 (where 0 is black and 255 is full brightness).
static Color	getColor(RGB rgb) Returns an instance of Color given an RGB describing the desired red, green and blue values.
static Font	getFont(FontData data) Returns a new font given a font data which describes the desired font's appearance.
static Font	getFont(java.lang.String name, int height, int style) Returns a Font object given a font name, the height of the desired font in points, and a font style.
static Image	getImage(java.lang.String path) Deprecated. Use getImage(String, ClassLoader) or getImage(String, InputStream) instead.
static Image	getImage(java.lang.String path, java.lang.ClassLoader imageLoader) Returns an instance of Image based on the specified image path.
static Image	getImage(java.lang.String path, java.io.InputStream inputStream) Returns an instance of Image based on the specified image path.
static Point	stringExtent(Font font, java.lang.String string) Returns the extent of the given string.
static Point	textExtent(Font font, java.lang.String string, int wrapWidth) Returns the extent of the given string.

Methods inherited from class java.lang.Object

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

Method Detail

getColor

public static Color getColor(RGB rgb)

Returns an instance of Color given an RGB describing the desired red, green and blue values.

Note: it is considered an error to attempt to dispose of colors that were created by this method. An IllegalStateException is thrown in this case.

Parameters:

rgb - the RGB values of the desired color - must not be null

Returns:

the color

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the rgb argument is null
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

See Also:

RGB, Device.getSystemColor(int)

getColor

public static Color getColor(int red,
                             int green,
                             int blue)

Returns a Color given the desired red, green and blue values expressed as ints in the range 0 to 255 (where 0 is black and 255 is full brightness).

Note: it is considered an error to attempt to dispose of colors that were created by this method. An IllegalStateException is thrown in this case.

Parameters:

red - the amount of red in the color

green - the amount of green in the color

blue - the amount of blue in the color

Returns:

the color

Throws:

java.lang.IllegalArgumentException -

• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

getFont

public static Font getFont(FontData data)

Returns a new font given a font data which describes the desired font's appearance.

Note: it is considered an error to attempt to dispose of fonts that were created by this method. An IllegalStateException is thrown in this case.

Parameters:

data - the FontData to use - must not be null

Returns:

the font

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the data argument is null
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

getFont

public static Font getFont(java.lang.String name,
                           int height,
                           int style)

Returns a Font object given a font name, the height of the desired font in points, and a font style.

Note: it is considered an error to attempt to dispose of fonts that were created by this method. An IllegalStateException is thrown in this case.

Parameters:

name - the name of the font (must not be null)

height - the font height in points

style - a bit or combination of NORMAL, BOLD, ITALIC

Returns:

the font

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the name argument is null
• ERROR_INVALID_ARGUMENT - if the height is negative
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

getImage

@Deprecated
public static Image getImage(java.lang.String path)

Deprecated. Use getImage(String, ClassLoader) or getImage(String, InputStream) instead.

Returns an instance of Image based on the specified image path. The image has to be on the applications class-path.

Parameters:

path - the path to the image

Returns:

the image

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the path is null
• ERROR_ILLEGAL_ARGUMENT - if the path is invalid

java.lang.IllegalArgumentException -

• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

SWTException -

• ERROR_IO - if an IO error occurs while reading from the stream
• ERROR_INVALID_IMAGE - if the image stream contains invalid data
• ERROR_UNSUPPORTED_FORMAT - if the image stream contains an unrecognized format

getImage

public static Image getImage(java.lang.String path,
                             java.lang.ClassLoader imageLoader)

Returns an instance of Image based on the specified image path. The image has to be on the applications class-path. Uses the specified classloader to load the image.

Parameters:

path - the path to the image

imageLoader - the classloader to use

Returns:

the image

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the path is null
• ERROR_ILLEGAL_ARGUMENT - if the path is invalid
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

SWTException -

• ERROR_IO - if an IO error occurs while reading from the stream
• ERROR_INVALID_IMAGE - if the image stream contains invalid data
• ERROR_UNSUPPORTED_FORMAT - if the image stream contains an unrecognized format

getImage

public static Image getImage(java.lang.String path,
                             java.io.InputStream inputStream)

Returns an instance of Image based on the specified image path. The image will be read from the provided InputStream.

Parameters:

path - the path the image resource is registered at

inputStream - the input stream for the image

Returns:

the image

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the path is null
• ERROR_NULL_ARGUMENT - if the inputStream is null
• ERROR_INVALID_ARGUMENT - if the path is invalid
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

SWTException -

• ERROR_IO - if an IO error occurs while reading from the stream
• ERROR_INVALID_IMAGE - if the image stream contains invalid data
• ERROR_UNSUPPORTED_FORMAT - if the image stream contains an unrecognized format

textExtent

public static Point textExtent(Font font,
                               java.lang.String string,
                               int wrapWidth)

Returns the extent of the given string. Tab expansion and carriage return processing are performed.

The extent of a string is the width and height of the rectangular area it would cover if drawn in a particular font.

Parameters:

font - the font for which the result is valid

string - the string to measure

wrapWidth - the maximum width of the text. The text will be wrapped to match this width. If set to 0, no wrapping will be performed.

Returns:

a point containing the extent of the string

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the font or string argument is null
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

stringExtent

public static Point stringExtent(Font font,
                                 java.lang.String string)

Returns the extent of the given string. No tab expansion or carriage return processing will be performed.

The extent of a string is the width and height of the rectangular area it would cover if drawn in a particular font.

Parameters:

font - the font for which the result is valid

string - the string to measure

Returns:

a point containing the extent of the string

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the font or string arguemnt is null
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

getCharHeight

public static int getCharHeight(Font font)

Returns the height of the specified font, measured in pixels.

Parameters:

font - the font for which the result is valid

Returns:

the height of the font

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the font argument is null
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread

getAvgCharWidth

public static float getAvgCharWidth(Font font)

Returns the average character width of the specified font, measured in pixels.

Parameters:

font - the font for which the result is valid

Returns:

the average character width of the font

Throws:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the font argument is null
• ERROR_THREAD_INVALID_ACCESS - if not called from the current display's UI thread