/*

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

 */
package org.apache.batik.ext.awt.image.renderable;

import java.awt.image.RenderedImage;
import java.awt.image.renderable.RenderContext;

import org.apache.batik.ext.awt.image.ComponentTransferFunction;
import org.apache.batik.ext.awt.image.DiscreteTransfer;
import org.apache.batik.ext.awt.image.GammaTransfer;
import org.apache.batik.ext.awt.image.IdentityTransfer;
import org.apache.batik.ext.awt.image.LinearTransfer;
import org.apache.batik.ext.awt.image.TableTransfer;
import org.apache.batik.ext.awt.image.TransferFunction;
import org.apache.batik.ext.awt.image.rendered.ComponentTransferRed;

/**
 * This class implements the interface expected from a component
 * transfer operation.
 *
 * @author <a href="mailto:vincent.hardy@eng.sun.com">Vincent Hardy</a>
 * @version $Id: ComponentTransferRable8Bit.java 478276 2006-11-22 18:33:37Z dvholten $
 */
public class ComponentTransferRable8Bit
    extends    AbstractColorInterpolationRable
    implements ComponentTransferRable {

    public static final int ALPHA = 0;
    public static final int RED   = 1;
    public static final int GREEN = 2;
    public static final int BLUE  = 3;

    /**
     * Array of transfer functions. There are four
     * elements. Elements may be null.
     */
    private ComponentTransferFunction[]
        functions = new ComponentTransferFunction[4];

    /**
     * Array of transfer functions. Elements are computed
     * lazily.
     */
    private TransferFunction[]
        txfFunc = new TransferFunction[4];

    public ComponentTransferRable8Bit(Filter src,
                                      ComponentTransferFunction alphaFunction,
                                      ComponentTransferFunction redFunction,
                                      ComponentTransferFunction greenFunction,
                                      ComponentTransferFunction blueFunction){
        super(src, null);
        setAlphaFunction(alphaFunction);
        setRedFunction(redFunction);
        setGreenFunction(greenFunction);
        setBlueFunction(blueFunction);
    }

    /**
     * Sets the source of the blur operation
     */
    public void setSource(Filter src){
        init(src, null);
    }

    /**
     * Returns the source of the blur operation
     */
    public Filter getSource(){
        return (Filter)getSources().get(0);
    }

    /**
     * Returns the transfer function for the alpha channel
     */
    public ComponentTransferFunction getAlphaFunction(){
        return functions[ALPHA];
    }

    /**
     * Sets the transfer function for the alpha channel
     */
    public void setAlphaFunction(ComponentTransferFunction alphaFunction){
        touch();
        functions[ALPHA] = alphaFunction;
        txfFunc[ALPHA] = null;
    }

    /**
     * Returns the transfer function for the red channel
     */
    public ComponentTransferFunction getRedFunction(){
        return functions[RED];
    }

    /**
     * Sets the transfer function for the red channel
     */
    public void setRedFunction(ComponentTransferFunction redFunction){
        touch();
        functions[RED] = redFunction;
        txfFunc[RED] = null;
    }

    /**
     * Returns the transfer function for the green channel
     */
    public ComponentTransferFunction getGreenFunction(){
        return functions[GREEN];
    }

    /**
     * Sets the transfer function for the green channel
     */
    public void setGreenFunction(ComponentTransferFunction greenFunction){
        touch();
        functions[GREEN] = greenFunction;
        txfFunc[GREEN] = null;
    }

    /**
     * Returns the transfer function for the blue channel
     */
    public ComponentTransferFunction getBlueFunction(){
        return functions[BLUE];
    }

    /**
     * Sets the transfer function for the blue channel
     */
    public void setBlueFunction(ComponentTransferFunction blueFunction){
        touch();
        functions[BLUE] = blueFunction;
        txfFunc[BLUE] = null;
    }

    public RenderedImage createRendering(RenderContext rc){
        //
        // Get source's rendered image
        //
        RenderedImage srcRI = getSource().createRendering(rc);

        if(srcRI == null)
            return null;

        return new ComponentTransferRed(convertSourceCS(srcRI),
                                        getTransferFunctions(),
                                        rc.getRenderingHints());
    }

    /**
     * Builds an array of transfer functions for the
     * ComponentTransferOp.
     */
    private TransferFunction[] getTransferFunctions(){
        //
        // Copy array to avoid multi-thread conflicts on
        // array access.
        //
        TransferFunction[] txfFunc = new TransferFunction[4];
        System.arraycopy(this.txfFunc, 0, txfFunc, 0, 4);

        ComponentTransferFunction[] functions;
        functions = new ComponentTransferFunction[4];
        System.arraycopy(this.functions, 0, functions, 0, 4);

        for(int i=0; i<4; i++){
            if(txfFunc[i] == null){
                txfFunc[i] = getTransferFunction(functions[i]);
                synchronized(this.functions){
                    if(this.functions[i] == functions[i]){
                        this.txfFunc[i] = txfFunc[i];
                    }
                }
            }
        }

        return txfFunc;
    }

    /**
     * Converts a ComponentTransferFunction to a TransferFunction
     */
    private static TransferFunction getTransferFunction
        (ComponentTransferFunction function){

        TransferFunction txfFunc = null;
        if(function == null){
            txfFunc = new IdentityTransfer();
        }
        else{
            switch(function.getType()){
            case ComponentTransferFunction.IDENTITY:
                txfFunc = new IdentityTransfer();
                break;
            case ComponentTransferFunction.TABLE:
                txfFunc = new TableTransfer(tableFloatToInt(function.getTableValues()));
                break;
            case ComponentTransferFunction.DISCRETE:
                txfFunc = new DiscreteTransfer(tableFloatToInt(function.getTableValues()));
                break;
            case ComponentTransferFunction.LINEAR:
                txfFunc = new LinearTransfer(function.getSlope(),
                                             function.getIntercept());
                break;
            case ComponentTransferFunction.GAMMA:
                txfFunc = new GammaTransfer(function.getAmplitude(),
                                            function.getExponent(),
                                            function.getOffset());
                break;
            default:
                // Should never happen
                throw new Error();
            }
        }

        return txfFunc;
    }

    /**
     * Converts a intensity values (0-1) to code values (0-255)
     */
    private static int[] tableFloatToInt(float[] tableValues){
        int[] values = new int[tableValues.length];
        for(int i=0; i<tableValues.length; i++){
            values[i] = (int)(tableValues[i]*255f);
        }

        return values;
    }

}
