color.java

《移动Agent技术》一书的所有章节源代码。

	int b = getBlue();

	/* From 2D group:
         * 1. black.brighter() should return grey
	 * 2. applying brighter to blue will always return blue, brighter
         * 3. non pure color (non zero rgb) will eventually return white
         */
	int i = (int)(1.0/(1.0-FACTOR));
	if ( r == 0 && g == 0 && b == 0) {
	   return new Color(i, i, i);
        }
	if ( r > 0 && r < i ) r = i;
	if ( g > 0 && g < i ) g = i;
	if ( b > 0 && b < i ) b = i;

	return new Color(Math.min((int)(r/FACTOR), 255), 
			 Math.min((int)(g/FACTOR), 255),
			 Math.min((int)(b/FACTOR), 255));
    }

    /**
     * Creates a darker version of this color.
     * <p>
     * This method applies an arbitrary scale factor to each of the three RGB 
     * components of the color to create a darker version of the same 
     * color. Although <code>brighter</code> and <code>darker</code> are 
     * inverse operations, the results of a series of invocations of 
     * these two methods may be inconsistent because of rounding errors. 
     * @return  a new <code>Color</code> object, 
     *                              a darker version of this color.
     * @see        java.awt.Color#brighter
     * @since      JDK1.0
     */
    public Color darker() {
	return new Color(Math.max((int)(getRed()  *FACTOR), 0), 
			 Math.max((int)(getGreen()*FACTOR), 0),
			 Math.max((int)(getBlue() *FACTOR), 0));
    }

    /**
     * Computes the hash code for this color.
     * @return     a hash code value for this object.
     * @since      JDK1.0
     */
    public int hashCode() {
	return value;
    }

    /**
     * Determines whether another object is equal to this color.
     * <p>
     * The result is <code>true</code> if and only if the argument is not 
     * <code>null</code> and is a <code>Color</code> object that has the same 
     * red, green, and blue values as this object. 
     * @param       obj   the object to compare with.
     * @return      <code>true</code> if the objects are the same; 
     *                             <code>false</code> otherwise.
     * @since   JDK1.0
     */
    public boolean equals(Object obj) {
        return obj instanceof Color && ((Color)obj).value == this.value;
    }

    /**
     * Creates a string that represents this color and indicates the 
     * values of its RGB components. 
     * @return     a representation of this color as a 
     *                           <code>String</code> object.
     * @since      JDK1.0
     */
    public String toString() {
        return getClass().getName() + "[r=" + getRed() + ",g=" + getGreen() + ",b=" + getBlue() + "]";
    }

    /**
     * Converts a string to an integer and returns the 
     * specified color. This method handles string formats that 
     * are used to represent octal and hexidecimal numbers.
     * @param      nm a string that represents 
     *                            a color as a 24-bit integer.
     * @return     the new color
     * @see        java.lang.Integer#decode
     * @exception  NumberFormatException  if the specified string cannot
     *                      be interpreted as a decimal, 
     *                      octal, or hexidecimal integer.
     * @since      JDK1.1
     */
    public static Color decode(String nm) throws NumberFormatException {
	Integer intval = Integer.decode(nm);
	int i = intval.intValue();
	return new Color((i >> 16) & 0xFF, (i >> 8) & 0xFF, i & 0xFF);
    }

    /**
     * Finds a color in the system properties. 
     * <p>
     * The argument is treated as the name of a system property to 
     * be obtained. The string value of this property is then interpreted 
     * as an integer which is then converted to a color. 
     * <p>
     * If the specified property is not found, or could not be parsed as 
     * an integer, then <code>null</code> is returned. 
     * @param    nm the name of the color property
     * @return   the color value of the property.
     * @see      java.lang.System#getProperty(java.lang.String)
     * @see      java.lang.Integer#getInteger(java.lang.String)
     * @see      java.awt.Color#Color(int)
     * @since    JDK1.0
     */
    public static Color getColor(String nm) {
	return getColor(nm, null);
    }

    /**
     * Finds a color in the system properties. 
     * <p>
     * The first argument is treated as the name of a system property to 
     * be obtained. The string value of this property is then interpreted 
     * as an integer which is then converted to a color. 
     * <p>
     * If the specified property is not found, or cannot be parsed as 
     * an integer, then the color specified by the second argument is 
     * returned instead. 
     * @param    nm the name of the color property
     * @param    v    the default color value.
     * @return   the color value of the property.
     * @see      java.lang.System#getProperty(java.lang.String)
     * @see      java.lang.Integer#getInteger(java.lang.String)
     * @see      java.awt.Color#Color(int)
     * @since    JDK1.0
     */
    public static Color getColor(String nm, Color v) {
	Integer intval = Integer.getInteger(nm);
	if (intval == null) {
	    return v;
	}
	int i = intval.intValue();
	return new Color((i >> 16) & 0xFF, (i >> 8) & 0xFF, i & 0xFF);
    }

    /**
     * Finds a color in the system properties. 
     * <p>
     * The first argument is treated as the name of a system property to 
     * be obtained. The string value of this property is then interpreted 
     * as an integer which is then converted to a color. 
     * <p>
     * If the specified property is not found, or could not be parsed as 
     * an integer, then the integer value <code>v</code> is used instead, 
     * and is converted to a color.
     * @param    nm  the name of the color property.
     * @param    v   the default color value, as an integer.
     * @return   the color value of the property.
     * @see      java.lang.System#getProperty(java.lang.String)
     * @see      java.lang.Integer#getInteger(java.lang.String)
     * @see      java.awt.Color#Color(int)
     * @since    JDK1.0
     */
    public static Color getColor(String nm, int v) {
	Integer intval = Integer.getInteger(nm);
	int i = (intval != null) ? intval.intValue() : v;
	return new Color((i >> 16) & 0xFF, (i >> 8) & 0xFF, (i >> 0) & 0xFF);
    }

    /**
     * Converts the components of a color, as specified by the HSB 
     * model, to an equivalent set of values for the RGB model. 
     * <p>
     * The integer that is returned by <code>HSBtoRGB</code> encodes the 
     * value of a color in bits 0&endash;23 of an integer value, the same 
     * format used by the method <code>getRGB</code>. This integer can be 
     * supplied as an argument to the <code>Color</code> constructor that 
     * takes a single integer argument. 
     * @param     hue   the hue component of the color.
     * @param     saturation   the saturation of the color.
     * @param     brightness   the brightness of the color.
     * @return    the RGB value of the color with the indicated hue, 
     *                            saturation, and brightness.
     * @see       java.awt.Color#getRGB()
     * @see       java.awt.Color#Color(int)
     * @since     JDK1.0
     */
    public static int HSBtoRGB(float hue, float saturation, float brightness) {
	int r = 0, g = 0, b = 0;
    	if (saturation == 0) {
	    r = g = b = (int) (brightness * 255);
	} else {
	    double h = (hue - Math.floor(hue)) * 6.0;
	    double f = h - java.lang.Math.floor(h);
	    double p = brightness * (1.0 - saturation);
	    double q = brightness * (1.0 - saturation * f);
	    double t = brightness * (1.0 - (saturation * (1.0 - f)));
	    switch ((int) h) {
	    case 0:
		r = (int) (brightness * 255);
		g = (int) (t * 255);
		b = (int) (p * 255);
		break;
	    case 1:
		r = (int) (q * 255);
		g = (int) (brightness * 255);
		b = (int) (p * 255);
		break;
	    case 2:
		r = (int) (p * 255);
		g = (int) (brightness * 255);
		b = (int) (t * 255);
		break;
	    case 3:
		r = (int) (p * 255);
		g = (int) (q * 255);
		b = (int) (brightness * 255);
		break;
	    case 4:
		r = (int) (t * 255);
		g = (int) (p * 255);
		b = (int) (brightness * 255);
		break;
	    case 5:
		r = (int) (brightness * 255);
		g = (int) (p * 255);
		b = (int) (q * 255);
		break;
	    }
	}
	return 0xff000000 | (r << 16) | (g << 8) | (b << 0);
    }

    /**
     * Converts the components of a color, as specified by the RGB 
     * model, to an equivalent set of values for hue, saturation, and 
     * brightness, the three components of the HSB model. 
     * <p>
     * If the <code>hsbvals</code> argument is <code>null</code>, then a 
     * new array is allocated to return the result. Otherwise, the method 
     * returns the array <code>hsbvals</code>, with the values put into 
     * that array. 
     * @param     r   the red component of the color.
     * @param     g   the green component of the color.
     * @param     b   the blue component of the color.
     * @param     hsbvals  the array to be used to return the 
     *                     three HSB values, or <code>null</code>.
     * @return    an array of three elements containing the hue, saturation, 
     *                     and brightness (in that order), of the color with 
     *                     the indicated red, green, and blue components.
     * @see       java.awt.Color#getRGB()
     * @see       java.awt.Color#Color(int)
     * @since     JDK1.0
     */
    public static float[] RGBtoHSB(int r, int g, int b, float[] hsbvals) {
	float hue, saturation, brightness;
	if (hsbvals == null) {
	    hsbvals = new float[3];
	}
    	int cmax = (r > g) ? r : g;
	if (b > cmax) cmax = b;
	int cmin = (r < g) ? r : g;
	if (b < cmin) cmin = b;

	brightness = ((float) cmax) / 255.0f;
	if (cmax != 0)
	    saturation = ((float) (cmax - cmin)) / ((float) cmax);
	else
	    saturation = 0;
	if (saturation == 0)
	    hue = 0;
	else {
	    float redc = ((float) (cmax - r)) / ((float) (cmax - cmin));
	    float greenc = ((float) (cmax - g)) / ((float) (cmax - cmin));
	    float bluec = ((float) (cmax - b)) / ((float) (cmax - cmin));
	    if (r == cmax)
		hue = bluec - greenc;
	    else if (g == cmax)
	        hue = 2.0f + redc - bluec;
            else
		hue = 4.0f + greenc - redc;
	    hue = hue / 6.0f;
	    if (hue < 0)
		hue = hue + 1.0f;
	}
	hsbvals[0] = hue;
	hsbvals[1] = saturation;
	hsbvals[2] = brightness;
	return hsbvals;
    }

    /**
     * Creates a <code>Color</code> object based on values supplied 
     * for the HSB color model. 
     * <p>
     * Each of the three components should be a floating-point 
     * value between zero and one (a number in the range 
     * <code>0.0</code>&nbsp;&le;&nbsp;<code>h</code>, <code>s</code>, 
     * <code>b</code>&nbsp;&le;&nbsp;<code>1.0). </code> 
     * @param  h   the hue component.
     * @param  s   the saturation of the color.
     * @param  b   the brightness of the color.
     * @return  a <code>Color</code> object with the specified hue, 
     *                                 saturation, and brightness.
     * @since   JDK1.0
     */
    public static Color getHSBColor(float h, float s, float b) {
	return new Color(HSBtoRGB(h, s, b));
    }
}