org.jdesktop.swingx.graphics
Class ShadowRenderer

java.lang.Object
  org.jdesktop.swingx.graphics.ShadowRenderer

public class ShadowRenderer
extends Object

A shadow renderer generates a drop shadow for any given picture, respecting the transparency channel if present. The resulting picture contains the shadow only and to create a drop shadow effect you will need to stack the original picture and the shadow generated by the renderer.

Shadow Properties

A shadow is defined by three properties:

• size: The size, in pixels, of the shadow. This property also defines the fuzzyness.
• opacity: The opacity, between 0.0 and 1.0, of the shadow.
• color: The color of the shadow. Shadows are not meant to be black only.

You can set these properties using the provided mutaters or the appropriate constructor. Here are two ways of creating a green shadow of size 10 and with an opacity of 50%:

 ShadowRenderer renderer = new ShadowRenderer(10, 0.5f, Color.GREEN);
 // ..
 renderer = new ShadowRenderer();
 renderer.setSize(10);
 renderer.setOpacity(0.5f);
 renderer.setColor(Color.GREEN);
 

The default constructor provides the following default values:

• size: 5 pixels
• opacity: 50%
• color: Black

Generating a Shadow

A shadow is generated as a BufferedImage from another BufferedImage. Once the renderer is set up, you must call createShadow(java.awt.image.BufferedImage) to actually generate the shadow:

 ShadowRenderer renderer = new ShadowRenderer();
 // renderer setup
 BufferedImage shadow = renderer.createShadow(bufferedImage);
 

The generated image dimensions are computed as following:

 width  = imageWidth  + 2 * shadowSize
 height = imageHeight + 2 * shadowSize
 

Properties Changes

This renderer allows to register property change listeners with addPropertyChangeListener(java.beans.PropertyChangeListener). Listening to properties changes is very useful when you emebed the renderer in a graphical component and give the API user the ability to access the renderer. By listening to properties changes, you can easily repaint the component when needed.

Threading Issues

ShadowRenderer is not guaranteed to be thread-safe.

Field Summary

static String	COLOR_CHANGED_PROPERTY Identifies a change to the color used to render the shadow.
static String	OPACITY_CHANGED_PROPERTY Identifies a change to the opacity used to render the shadow.
static String	SIZE_CHANGED_PROPERTY Identifies a change to the size used to render the shadow.

Constructor Summary

ShadowRenderer()
Creates a default good looking shadow generator.

ShadowRenderer(int size, float opacity, Color color)
A shadow renderer needs three properties to generate shadows.

Method Summary

void	addPropertyChangeListener(PropertyChangeListener listener) Add a PropertyChangeListener to the listener list.
BufferedImage	createShadow(BufferedImage image) Generates the shadow for a given picture and the current properties of the renderer.
Color	getColor() Gets the color used by the renderer to generate shadows.
float	getOpacity() Gets the opacity used by the renderer to generate shadows.
int	getSize() Gets the size in pixel used by the renderer to generate shadows.
void	removePropertyChangeListener(PropertyChangeListener listener) Remove a PropertyChangeListener from the listener list.
void	setColor(Color shadowColor) Sets the color used by the renderer to generate shadows.
void	setOpacity(float shadowOpacity) Sets the opacity used by the renderer to generate shadows.
void	setSize(int shadowSize) Sets the size, in pixels, used by the renderer to generate shadows.

Methods inherited from class java.lang.Object

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

Field Detail

SIZE_CHANGED_PROPERTY

public static final String SIZE_CHANGED_PROPERTY

Identifies a change to the size used to render the shadow.

When the property change event is fired, the old value and the new value are provided as Integer instances.

See Also:

Constant Field Values

OPACITY_CHANGED_PROPERTY

public static final String OPACITY_CHANGED_PROPERTY

Identifies a change to the opacity used to render the shadow.

When the property change event is fired, the old value and the new value are provided as Float instances.

See Also:

Constant Field Values

COLOR_CHANGED_PROPERTY

public static final String COLOR_CHANGED_PROPERTY

Identifies a change to the color used to render the shadow.

See Also:

Constant Field Values

Constructor Detail

ShadowRenderer

public ShadowRenderer()

Creates a default good looking shadow generator. The default shadow renderer provides the following default values:

• size: 5 pixels
• opacity: 50%
• color: Black

These properties provide a regular, good looking shadow.

ShadowRenderer

public ShadowRenderer(int size,
                      float opacity,
                      Color color)

A shadow renderer needs three properties to generate shadows. These properties are:

• size: The size, in pixels, of the shadow. This property also defines the fuzzyness.
• opacity: The opacity, between 0.0 and 1.0, of the shadow.
• color: The color of the shadow. Shadows are not meant to be black only.

Parameters:

size - the size of the shadow in pixels. Defines the fuzziness.

opacity - the opacity of the shadow.

color - the color of the shadow.

Method Detail

addPropertyChangeListener

public void addPropertyChangeListener(PropertyChangeListener listener)

Add a PropertyChangeListener to the listener list. The listener is registered for all properties. The same listener object may be added more than once, and will be called as many times as it is added. If listener is null, no exception is thrown and no action is taken.

Parameters:

listener - the PropertyChangeListener to be added

removePropertyChangeListener

public void removePropertyChangeListener(PropertyChangeListener listener)

Remove a PropertyChangeListener from the listener list. This removes a PropertyChangeListener that was registered for all properties. If listener was added more than once to the same event source, it will be notified one less time after being removed. If listener is null, or was never added, no exception is thrown and no action is taken.

Parameters:

listener - the PropertyChangeListener to be removed

getColor

public Color getColor()

Gets the color used by the renderer to generate shadows.

Returns:

this renderer's shadow color

setColor

public void setColor(Color shadowColor)

Sets the color used by the renderer to generate shadows.

Consecutive calls to createShadow(java.awt.image.BufferedImage) will all use this color until it is set again.

If the color provided is null, the previous color will be retained.

Parameters:

shadowColor - the generated shadows color

getOpacity

public float getOpacity()

Gets the opacity used by the renderer to generate shadows.

The opacity is comprised between 0.0f and 1.0f; 0.0f being fully transparent and 1.0f fully opaque.

Returns:

this renderer's shadow opacity

setOpacity

public void setOpacity(float shadowOpacity)

Sets the opacity used by the renderer to generate shadows.

Consecutive calls to createShadow(java.awt.image.BufferedImage) will all use this opacity until it is set again.

The opacity is comprised between 0.0f and 1.0f; 0.0f being fully transparent and 1.0f fully opaque. If you provide a value out of these boundaries, it will be restrained to the closest boundary.

Parameters:

shadowOpacity - the generated shadows opacity

getSize

public int getSize()

Gets the size in pixel used by the renderer to generate shadows.

Returns:

this renderer's shadow size

setSize

public void setSize(int shadowSize)

Sets the size, in pixels, used by the renderer to generate shadows.

The size defines the blur radius applied to the shadow to create the fuzziness.

There is virtually no limit to the size. The size cannot be negative. If you provide a negative value, the size will be 0 instead.

Parameters:

shadowSize - the generated shadows size in pixels (fuzziness)

createShadow

public BufferedImage createShadow(BufferedImage image)

Generates the shadow for a given picture and the current properties of the renderer.

The generated image dimensions are computed as following:

 width  = imageWidth  + 2 * shadowSize
 height = imageHeight + 2 * shadowSize
 

Parameters:

image - the picture from which the shadow must be cast

Returns:

the picture containing the shadow of image