colorlib.java

来自「用applet实现很多应用小程序」· Java 代码 · 共 597 行 · 第 1/2 页

package prefuse.util;

import java.awt.Color;

import prefuse.util.collections.IntObjectHashMap;

/**
 * <p>Library routines for processing color values. The standard color
 * representation used by prefuse is to store each color as single
 * primitive integer value, using 32 bits to represent 4 8-bit color
 * channels: red, green, blue, and alpha (transparency). An alpha value
 * of 0 indicates complete transparency while a maximum value (255)
 * indicated complete opacity. The layout of the bit is as follows,
 * moving from most significant bit on the left to least significant
 * bit on the right:</p>
 * 
 * <pre>
 * AAAAAAAARRRRRRRRGGGGGGGBBBBBBBB
 * </pre>
 * 
 * <p>This class also maintains methods for mapping these values to actual
 * Java {@link java.awt.Color} instances; a cache is maintained for
 * quick-lookups, avoiding the need to continually allocate new Color
 * instances.</p>
 * 
 * <p>Finally, this class also contains routine for creating color
 * palettes for use in visualization.</p>
 *
 * @author <a href="http://jheer.org">jeffrey heer</a>
 */
public class ColorLib {

    public static final char HEX_PREFIX = '#';
    
    private static final IntObjectHashMap colorMap = new IntObjectHashMap();
    private static int misses = 0;
    private static int lookups = 0;
    
    // ------------------------------------------------------------------------
    // Color Code Methods
    
    /**
     * Get the color code for the given red, green, and blue values.
     * @param r the red color component (in the range 0-255)
     * @param g the green color component (in the range 0-255)
     * @param b the blue color component (in the range 0-255)
     * @return the integer color code
     */
    public static int rgb(int r, int g, int b) {
        return rgba(r, g, b, 255);
    }

    /**
     * Get the color code for the given grayscale value.
     * @param v the grayscale value (in the range 0-255, 0 is
     * black and 255 is white)
     * @return the integer color code
     */
    public static int gray(int v) {
        return rgba(v, v, v, 255);
    }

    /**
     * Get the color code for the given grayscale value.
     * @param v the grayscale value (in the range 0-255, 0 is
     * black and 255 is white)
     * @param a the alpha (transparency) value (in the range 0-255)
     * @return the integer color code
     */
    public static int gray(int v, int a) {
        return rgba(v, v, v, a);
    }
    
    /**
     * Parse a hexadecimal String as a color code. The color convention
     * is the same as that used in webpages, with two-decimal hexadecimal
     * numbers representing RGB color values in the range 0-255. A single
     * '#' character may be included at the beginning of the String, but
     * is not required. For example '#000000' is black, 'FFFFFF' is white,
     * '0000FF' is blue, and '#FFFF00' is orange. Color values may also
     * include transparency (alpha) values, ranging from 00 (fully transparent)
     * to FF (fully opaque). If included, alpha values should come first in
     * the string. For example, "#770000FF" is a translucent blue.
     * @param hex the color code value as a hexadecimal String
     * @return the integer color code for the input String
     */
    public static int hex(String hex) {
        if ( hex.charAt(0) == HEX_PREFIX )
            hex = hex.substring(1);
        
        if ( hex.length() > 6 ) {
			// break up number, as Integer will puke on a large unsigned int
			int rgb = Integer.parseInt(hex.substring(2), 16);
			int alpha = Integer.parseInt(hex.substring(0,2), 16);
			return ColorLib.setAlpha(rgb, alpha);
		} else {
			return setAlpha(Integer.parseInt(hex, 16), 255);
		}
    }
    
    /**
     * Get the color code for the given hue, saturation, and brightness
     * values, translating from HSB color space to RGB color space.
     * @param h the hue value (in the range 0-1.0). This represents the
     * actual color hue (blue, green, purple, etc). 
     * @param s the saturation value (in the range 0-1.0). This represents
     * "how much" of the color is included. Lower values can result in
     * more grayed out or pastel colors.
     * @param b the brightness value (in the range 0-1.0). This represents
     * how dark or light the color is.
     * @return the integer color code
     */
    public static int hsb(float h, float s, float b) {
        return Color.HSBtoRGB(h,s,b);
    }
    
    /**
     * Get the color code for the given hue, saturation, and brightness
     * values, translating from HSB color space to RGB color space.
     * @param h the hue value (in the range 0-1.0). This represents the
     * actual color hue (blue, green, purple, etc). 
     * @param s the saturation value (in the range 0-1.0). This represents
     * "how much" of the color is included. Lower values can result in
     * more grayed out or pastel colors.
     * @param b the brightness value (in the range 0-1.0). This represents
     * how dark or light the color is.
     * @param a the alpha value (in the range 0-1.0). This represents the
     * transparency of the color.
     * @return the integer color code
     */
    public static int hsba(float h, float s, float b, float a) {
        return setAlpha(Color.HSBtoRGB(h,s,b), (int)(a*255+0.5) & 0xFF);
    }
    
    /**
     * Get the color code for the given red, green, blue, and alpha values.
     * @param r the red color component (in the range 0-255)
     * @param g the green color component (in the range 0-255)
     * @param b the blue color component (in the range 0-255)
     * @param a the alpha (transparency) component (in the range 0-255)
     * @return the integer color code
     */
    public static int rgba(int r, int g, int b, int a) {
        return ((a & 0xFF) << 24) | ((r & 0xFF) << 16) |
               ((g & 0xFF) << 8)  | ((b & 0xFF) << 0);
    }
    
    /**
     * Get the color code for the given red, green, blue, and alpha values as
     * floating point numbers in the range 0-1.0.
     * @param r the red color component (in the range 0-1.0)
     * @param g the green color component (in the range 0-1.0)
     * @param b the blue color component (in the range 0-1.0)
     * @param a the alpha (transparency) component (in the range 0-1.0)
     * @return the integer color code
     */
    public static int rgba(float r, float g, float b, float a) {
        return ((((int)(a*255+0.5)) & 0xFF) << 24) |
               ((((int)(r*255+0.5)) & 0xFF) << 16) | 
               ((((int)(g*255+0.5)) & 0xFF) <<  8) |
               (((int)(b*255+0.5)) & 0xFF);
    }
    
    /**
     * Get the color code for the given Color instance.
     * @param c the Java Color instance
     * @return the integer color code
     */
    public static int color(Color c) {
        return c.getRGB();
    }
    
    /**
     * Get the red component of the given color.
     * @param color the color code
     * @return the red component of the color (in the range 0-255)
     */
    public static int red(int color) {
        return (color>>16) & 0xFF;
    }
    
    /**
     * Get the green component of the given color.
     * @param color the color code
     * @return the green component of the color (in the range 0-255)
     */
    public static int green(int color) {
        return (color>>8) & 0xFF;
    }
    
    /**
     * Get the blue component of the given color.
     * @param color the color code
     * @return the blue component of the color (in the range 0-255)
     */
    public static int blue(int color) {
        return color & 0xFF;
    }
    
    /**
     * Get the alpha component of the given color.
     * @param color the color code
     * @return the alpha component of the color (in the range 0-255)
     */
    public static int alpha(int color) {
        return (color>>24) & 0xFF;
    }
    
    /**
     * Set the alpha component of the given color.
     * @param c the color code
     * @param alpha the alpha value to set
     * @return the new color with updated alpha channel
     */
    public static int setAlpha(int c, int alpha) {
        return rgba(red(c), green(c), blue(c), alpha);
    }
    
    // ------------------------------------------------------------------------
    // java.awt.Color Lookup Methods
    
    /**
     * Get a Java Color object for the given red, green, blue, and alpha values
     * as floating point numbers in the range 0-1.0.
     * @param r the red color component (in the range 0-1.0)
     * @param g the green color component (in the range 0-1.0)
     * @param b the blue color component (in the range 0-1.0)
     * @param a the alpha (transparency) component (in the range 0-1.0)
     * @return a Java Color object
     */
    public static Color getColor(float r, float g, float b, float a) {
        return getColor(rgba(r,g,b,a));
    }

    /**
     * Get a Java Color object for the given red, green, and blue values
     * as floating point numbers in the range 0-1.0.
     * @param r the red color component (in the range 0-1.0)
     * @param g the green color component (in the range 0-1.0)
     * @param b the blue color component (in the range 0-1.0)
     * @return a Java Color object
     */
    public static Color getColor(float r, float g, float b) {
        return getColor(r,g,b,1.0f);
    }
    
    /**
     * Get a Java Color object for the given red, green, and blue values.
     * @param r the red color component (in the range 0-255)
     * @param g the green color component (in the range 0-255)
     * @param b the blue color component (in the range 0-255)
     * @param a the alpa (transparency) component (in the range 0-255)
     * @return a Java Color object
     */
    public static Color getColor(int r, int g, int b, int a) {
        return getColor(rgba(r,g,b,a));
    }
    
    /**
     * Get a Java Color object for the given red, green, and blue values.
     * @param r the red color component (in the range 0-255)
     * @param g the green color component (in the range 0-255)
     * @param b the blue color component (in the range 0-255)
     * @return a Java Color object
     */
    public static Color getColor(int r, int g, int b) {
        return getColor(r,g,b,255);
    }
    
    /**
     * Get a Java Color object for the given grayscale value.
     * @param v the grayscale value (in the range 0-255, 0 is
     * black and 255 is white)
     * @return a Java Color object
     */
    public static Color getGrayscale(int v) {
        return getColor(v,v,v,255);
    }
    
    /**
     * Get a Java Color object for the given color code value.
     * @param rgba the integer color code containing red, green,
     * blue, and alpha channel information
     * @return a Java Color object
     */
    public static Color getColor(int rgba) {
        Color c = null;
        if ( (c=(Color)colorMap.get(rgba)) == null ) {
            c = new Color(rgba,true);
            colorMap.put(rgba,c);
            misses++;
        }
        lookups++;
        return c;
    }
    
    // ------------------------------------------------------------------------
    // ColorLib Statistics and Cache Management