colormodel.java

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     * separate spatial bands.  If the <code>boolean</code>
     * is <code>true</code>, color samples are assumed to have been
     * multiplied by the alpha sample.  The <code>transparency</code> 
     * specifies what alpha values can be represented by this color model.
     * The transfer type is the type of primitive array used to represent
     * pixel values.  Note that the bits array contains the number of
     * significant bits per color/alpha component after the translation
     * from pixel values.  For example, for an
     * <code>IndexColorModel</code> with <code>pixel_bits</code> equal to
     * 16, the bits array might have four elements with each element set
     * to 8.
     * @param pixel_bits the number of bits in the pixel values
     * @param bits array that specifies the number of significant bits
     *		per color and alpha component
     * @param cspace the specified <code>ColorSpace</code>
     * @param hasAlpha <code>true</code> if alpha information is present;
     *		<code>false</code> otherwise
     * @param isAlphaPremultiplied <code>true</code> if color samples are
     *		assumed to be premultiplied by the alpha samples;
     *		<code>false</code> otherwise
     * @param transparency what alpha values can be represented by this
     *		color model
     * @param transferType the type of the array used to represent pixel
     *		values
     * @throws IllegalArgumentException if the length of
     *		the bit array is less than the number of color or alpha
     *		components in this <code>ColorModel</code>, or if the
     *          transparency is not a valid value.
     * @throws IllegalArgumentException if the sum of the number
     * 		of bits in <code>bits</code> is less than 1 or if
     *          any of the elements in <code>bits</code> is less than 0.
     * @see java.awt.Transparency
     */
    protected ColorModel(int pixel_bits, int[] bits, ColorSpace cspace,
                         boolean hasAlpha,
                         boolean isAlphaPremultiplied,
                         int transparency,
                         int transferType) {
        colorSpace                = cspace;
        colorSpaceType            = cspace.getType();
        numColorComponents        = cspace.getNumComponents();
        numComponents             = numColorComponents + (hasAlpha ? 1 : 0);
        supportsAlpha             = hasAlpha;
        if (bits.length < numComponents) {
            throw new IllegalArgumentException("Number of color/alpha "+
                                               "components should be "+
                                               numComponents+
                                               " but length of bits array is "+
                                               bits.length);
        }

        // 4186669
        if (transparency < Transparency.OPAQUE ||
            transparency > Transparency.TRANSLUCENT)
        {
            throw new IllegalArgumentException("Unknown transparency: "+
                                               transparency);
        }
        
        if (supportsAlpha == false) {
            this.isAlphaPremultiplied = false;
            this.transparency = Transparency.OPAQUE;
        }
        else {
            this.isAlphaPremultiplied = isAlphaPremultiplied;
            this.transparency         = transparency;
        }

        nBits = (int[]) bits.clone();
        this.pixel_bits = pixel_bits;
        if (pixel_bits <= 0) {
            throw new IllegalArgumentException("Number of pixel bits must "+
                                               "be > 0");
        }
        // Check for bits < 0
        maxBits = 0;
        for (int i=0; i < bits.length; i++) {
            // bug 4304697
            if (bits[i] < 0) {
                throw new
                    IllegalArgumentException("Number of bits must be >= 0");
            }
            if (maxBits < bits[i]) {
                maxBits = bits[i];
            }
        }

        // Make sure that we don't have all 0-bit components
        if (maxBits == 0) {
            throw new IllegalArgumentException("There must be at least "+
                                               "one component with > 0 "+
                                              "pixel bits.");
        }

        // Save this since we always need to check if it is the default CS
        if (cspace != ColorSpace.getInstance(ColorSpace.CS_sRGB)) {
            is_sRGB = false;
        }

        // Save the transfer type
        this.transferType = transferType;
    }

    /**
     * Returns whether or not alpha is supported in this 
     * <code>ColorModel</code>.
     * @return <code>true</code> if alpha is supported in this
     * <code>ColorModel</code>; <code>false</code> otherwise.
     */
    final public boolean hasAlpha() {
        return supportsAlpha;
    }
    
    /**
     * Returns whether or not the alpha has been premultiplied in the
     * pixel values to be translated by this <code>ColorModel</code>.  
     * If the boolean is <code>true</code>, this <code>ColorModel</code> 
     * is to be used to interpret pixel values in which color and alpha
     * information are represented as separate spatial bands, and color
     * samples are assumed to have been multiplied by the
     * alpha sample.
     * @return <code>true</code> if the alpha values are premultiplied
     *		in the pixel values to be translated by this
     *		<code>ColorModel</code>; <code>false</code> otherwise.
     */
    final public boolean isAlphaPremultiplied() {
        return isAlphaPremultiplied;
    }

    /**
     * Returns the transfer type of this <code>ColorModel</code>.
     * The transfer type is the type of primitive array used to represent
     * pixel values as arrays.
     * @return the transfer type.
     */
    final public int getTransferType() {
        return transferType;
    }
    
    /**
     * Returns the number of bits per pixel described by this 
     * <code>ColorModel</code>.
     * @return the number of bits per pixel.
     */
    public int getPixelSize() {
	return pixel_bits;
    }

    /**
     * Returns the number of bits for the specified color/alpha component.
     * Color components are indexed in the order specified by the 
     * <code>ColorSpace</code>.  Typically, this order reflects the name
     * of the color space type. For example, for TYPE_RGB, index 0
     * corresponds to red, index 1 to green, and index 2
     * to blue.  If this <code>ColorModel</code> supports alpha, the alpha
     * component corresponds to the index following the last color
     * component.
     * @param componentIdx the index of the color/alpha component
     * @return the number of bits for the color/alpha component at the
     *		specified index.
     * @throws ArrayIndexOutOfBoundsException if <code>componentIdx</code> 
     *         is greater than the number of components or
     *         less than zero
     * @throws NullPointerException if the number of bits array is 
     *         <code>null</code>
     */
    public int getComponentSize(int componentIdx) {
        // REMIND:
        if (nBits == null) {
            throw new NullPointerException("Number of bits array is null.");
        }
        
        return nBits[componentIdx];
    }
    
    /**
     * Returns an array of the number of bits per color/alpha component.  
     * The array contains the color components in the order specified by the
     * <code>ColorSpace</code>, followed by the alpha component, if
     * present.
     * @return an array of the number of bits per color/alpha component
     */
    public int[] getComponentSize() {
        if (nBits != null) {
            return (int[]) nBits.clone();
        }

        return null;
    }

    /**
     * Returns the transparency.  Returns either OPAQUE, BITMASK,
     * or TRANSLUCENT.
     * @return the transparency of this <code>ColorModel</code>.
     * @see Transparency#OPAQUE
     * @see Transparency#BITMASK
     * @see Transparency#TRANSLUCENT
     */
    public int getTransparency() {
        return transparency;
    }

    /**
     * Returns the number of components, including alpha, in this
     * <code>ColorModel</code>.  This is equal to the number of color
     * components, optionally plus one, if there is an alpha component.
     * @return the number of components in this <code>ColorModel</code>
     */
    public int getNumComponents() {
        return numComponents;
    }
    
    /**
     * Returns the number of color components in this
     * <code>ColorModel</code>.
     * This is the number of components returned by
     * {@link ColorSpace#getNumComponents}.
     * @return the number of color components in this
     * <code>ColorModel</code>.
     * @see ColorSpace#getNumComponents
     */
    public int getNumColorComponents() {
        return numColorComponents;
    }

    /**
     * Returns the red color component for the specified pixel, scaled
     * from 0 to 255 in the default RGB ColorSpace, sRGB.  A color conversion
     * is done if necessary.  The pixel value is specified as an int.
     * An <code>IllegalArgumentException</code> is thrown if pixel
     * values for this <code>ColorModel</code> are not conveniently
     * representable as a single int.  The returned value is not a
     * pre-multiplied value.  For example, if the
     * alpha is premultiplied, this method divides it out before returning
     * the value.  If the alpha value is 0, the red value is 0.
     * @param pixel a specified pixel
     * @return the value of the red component of the specified pixel.
     */
    public abstract int getRed(int pixel);

    /**
     * Returns the green color component for the specified pixel, scaled
     * from 0 to 255 in the default RGB ColorSpace, sRGB.  A color conversion
     * is done if necessary.  The pixel value is specified as an int.
     * An <code>IllegalArgumentException</code> is thrown if pixel
     * values for this <code>ColorModel</code> are not conveniently
     * representable as a single int.  The returned value is a non
     * pre-multiplied value.  For example, if the alpha is premultiplied,
     * this method divides it out before returning
     * the value.  If the alpha value is 0, the green value is 0.
     * @param pixel the specified pixel
     * @return the value of the green component of the specified pixel.
     */
    public abstract int getGreen(int pixel);

    /**
     * Returns the blue color component for the specified pixel, scaled
     * from 0 to 255 in the default RGB ColorSpace, sRGB.  A color conversion
     * is done if necessary.  The pixel value is specified as an int.
     * An <code>IllegalArgumentException</code> is thrown if pixel values
     * for this <code>ColorModel</code> are not conveniently representable
     * as a single int.  The returned value is a non pre-multiplied
     * value, for example, if the alpha is premultiplied, this method
     * divides it out before returning the value.  If the alpha value is
     * 0, the blue value is 0.
     * @param pixel the specified pixel
     * @return the value of the blue component of the specified pixel.
     */
    public abstract int getBlue(int pixel);

    /**
     * Returns the alpha component for the specified pixel, scaled
     * from 0 to 255.  The pixel value is specified as an int.