Package org.openstreetmap.josm.gui.draw

Class BlendComposite

java.lang.Object

org.openstreetmap.josm.gui.draw.BlendComposite

All Implemented Interfaces:

java.awt.Composite

public final class BlendComposite
extends java.lang.Object
implements java.awt.Composite

A Composite implementing the common "blend modes" of image editors (multiply, burn, hard light, difference, divide), which the standard AlphaComposite does not provide.

The source alpha (including the coverage produced by antialiasing) controls how strongly the blended color replaces the destination, following the "source over" rule of the W3C compositing model, so that a translucent destination is handled correctly as well. It works on any color model, but is implemented per pixel and thus only meant for drawing thin shapes such as grid lines. It must be used on BufferedImage backed graphics, since hardware accelerated pipelines do not support custom composites.

Since:

19640

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	BlendComposite.BlendContext
static class	BlendComposite.Mode	The supported blend modes.

Field Summary

Fields

Modifier and Type	Field	Description
private static java.util.Map<BlendComposite.Mode,BlendComposite>	INSTANCES
private BlendComposite.Mode	mode

Constructor Summary

Constructors

Modifier	Constructor	Description
private	BlendComposite(BlendComposite.Mode mode)

Method Summary

Modifier and Type	Method	Description
(package private) static int	blend(BlendComposite.Mode mode, int s, int d)	Blends one color channel.
private static int	composeChannel(BlendComposite.Mode mode, int cs, int cb, int sa, int da, int a)	Composes one color channel of a translucent destination, see the W3C compositing model: co = as*(1-ab)*Cs + as*ab*B(Cb,Cs) + (1-as)*ab*Cb and Co = co/ao.
(package private) static int	composePixel(BlendComposite.Mode mode, int s, int d)	Composes one pixel: blends the source color with the destination and combines the two with the "source over" rule, so that both the source alpha (including the coverage produced by antialiasing) and a translucent destination are handled correctly.
java.awt.CompositeContext	createContext(java.awt.image.ColorModel srcColorModel, java.awt.image.ColorModel dstColorModel, java.awt.RenderingHints hints)
static BlendComposite	getInstance(BlendComposite.Mode mode)	Returns the composite for the given mode.
BlendComposite.Mode	getMode()	Returns the blend mode of this composite.
private static int	mix(int s, int d, int alpha)	linear interpolation between d (alpha 0) and s (alpha 255)

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCES

private static final java.util.Map<BlendComposite.Mode,BlendComposite> INSTANCES

mode

private final BlendComposite.Mode mode

Constructor Detail

BlendComposite

private BlendComposite(BlendComposite.Mode mode)

Method Detail

getInstance

public static BlendComposite getInstance(BlendComposite.Mode mode)

Returns the composite for the given mode.

Parameters:

mode - the blend mode

Returns:

the composite

getMode

public BlendComposite.Mode getMode()

Returns the blend mode of this composite.

Returns:

the blend mode

createContext

public java.awt.CompositeContext createContext(java.awt.image.ColorModel srcColorModel,
                                               java.awt.image.ColorModel dstColorModel,
                                               java.awt.RenderingHints hints)

Specified by:

createContext in interface java.awt.Composite

blend

static int blend(BlendComposite.Mode mode,
                 int s,
                 int d)

Blends one color channel.

Parameters:

mode - blend mode

s - source channel value (0-255)

d - destination channel value (0-255)

Returns:

blended value (0-255)

composePixel

static int composePixel(BlendComposite.Mode mode,
                        int s,
                        int d)

Composes one pixel: blends the source color with the destination and combines the two with the "source over" rule, so that both the source alpha (including the coverage produced by antialiasing) and a translucent destination are handled correctly.

Parameters:

mode - blend mode

s - source color (ARGB, not premultiplied)

d - destination color (ARGB, not premultiplied)

Returns:

the resulting color (ARGB, not premultiplied)

composeChannel

private static int composeChannel(BlendComposite.Mode mode,
                                  int cs,
                                  int cb,
                                  int sa,
                                  int da,
                                  int a)

Composes one color channel of a translucent destination, see the W3C compositing model: co = as*(1-ab)*Cs + as*ab*B(Cb,Cs) + (1-as)*ab*Cb and Co = co/ao.

Parameters:

mode - blend mode

cs - source channel value (0-255)

cb - destination (backdrop) channel value (0-255)

sa - source alpha (0-255)

da - destination alpha (0-255)

a - the resulting alpha (0-255), must not be 0

Returns:

the resulting channel value (0-255)

mix

private static int mix(int s,
                       int d,
                       int alpha)

linear interpolation between d (alpha 0) and s (alpha 255)