// Copyright 2002, FreeHEP.
package org.freehep.graphicsio.emf.gdi;

import java.io.IOException;
import com.google.code.appengine.awt.Image;

import org.freehep.graphicsio.emf.EMFConstants;
import org.freehep.graphicsio.emf.EMFInputStream;
import org.freehep.graphicsio.emf.EMFOutputStream;
import org.freehep.graphicsio.emf.EMFTag;
import org.freehep.graphicsio.emf.EMFRenderer;

/**
 * SetStretchBltMode TAG.
 * 
 * @author Mark Donszelmann
 * @version $Id: SetStretchBltMode.java 10367 2007-01-22 19:26:48Z duns $
 */
public class SetStretchBltMode extends EMFTag implements EMFConstants {

    private int mode;

    public SetStretchBltMode() {
        super(21, 1);
    }

    public SetStretchBltMode(int mode) {
        this();
        this.mode = mode;
    }

    public EMFTag read(int tagID, EMFInputStream emf, int len)
            throws IOException {

        return new SetStretchBltMode(emf.readDWORD());
    }

    public void write(int tagID, EMFOutputStream emf) throws IOException {
        emf.writeDWORD(mode);
    }

    public String toString() {
        return super.toString() + "\n  mode: " + mode;
    }

    /**
     * displays the tag using the renderer
     *
     * @param renderer EMFRenderer storing the drawing session data
     */
    public void render(EMFRenderer renderer) {
        // The stretching mode defines how the system combines rows or columns of a
        // bitmap with existing pixels on a display device when an application calls
        // the StretchBlt function.
        renderer.setScaleMode(
            getScaleMode(mode));
    }

    /**
     * converts a SetStretchBltMode to a TWIP_SCALE constat of class Image
     * @return e.g. {@link com.google.code.appengine.awt.Image#SCALE_FAST}
     * @param mode EMFTag SetStretchBltMode
     */
    private int getScaleMode(int mode) {
        //     COLORONCOLOR 	Deletes the pixels. This mode deletes all
        // eliminated lines of pixels without trying to preserve their information.
        if (
            mode == EMFConstants.COLORONCOLOR /*||
            mode == EMFConstants.STRETCH_DELETESCANS*/) {
            return Image.SCALE_FAST;
        }
        //     HALFTONE 	Maps pixels from the source rectangle into blocks
        // of pixels in the destination rectangle. The average color over the
        // destination block of pixels approximates the color of the source pixels.
        else if (
            mode == EMFConstants.HALFTONE /*||
            mode == EMFConstants.STRETCH_HALFTONE*/) {
            return Image.SCALE_SMOOTH;
        }
        //     BLACKONWHITE 	Performs a Boolean AND operation using the
        // color values for the eliminated and existing pixels. If the bitmap
        // is a monochrome bitmap, this mode preserves black pixels at the
        // expense of white pixels.
        else if (
            mode == EMFConstants.BLACKONWHITE /*||
            mode == EMFConstants.STRETCH_ANDSCANS*/) {
            // TODO not sure
            return Image.SCALE_REPLICATE;
        }
        //     WHITEONBLACK 	Performs a Boolean OR operation using the
        // color values for the eliminated and existing pixels. If the bitmap
        // is a monochrome bitmap, this mode preserves white pixels at the
        // expense of black pixels.
        else if (
            mode == EMFConstants.WHITEONBLACK /*||
            mode == EMFConstants.STRETCH_ORSCANS*/) {
            // TODO not sure
            return Image.SCALE_REPLICATE;
        } else {
            logger.warning("got unsupported SetStretchBltMode " + mode);
            return Image.SCALE_DEFAULT;
        }
    }
}