Undo.java

package ij;
import ij.process.*;
import java.awt.*;
import java.awt.image.*;
import ij.gui.*;

public class Undo {

    public static final int NOTHING = 0;
    public static final int FILTER = 1;
    public static final int TYPE_CONVERSION = 2;
    public static final int PASTE = 3;
    public static final int COMPOUND_FILTER = 4;
    public static final int COMPOUND_FILTER_DONE = 5;
    public static final int TRANSFORM = 6;
    
    private static int whatToUndo = NOTHING;
    private static int imageID;
    private static ImageProcessor ipCopy = null;
    private static ImagePlus impCopy;
    
    public static void setup(int what, ImagePlus imp) {
        if (imp==null)
            {reset(); return;}
        //IJ.log(imp.getTitle() + ": set up undo (" + what + ")");
        if (what==FILTER && whatToUndo==COMPOUND_FILTER)
                return;
        if (what==COMPOUND_FILTER_DONE) {
            if (whatToUndo==COMPOUND_FILTER)
                whatToUndo = what;
            return;
        }
        whatToUndo = what;
        imageID = imp.getID();
        if (what==TYPE_CONVERSION)
            ipCopy = imp.getProcessor();
        else if (what==TRANSFORM) {         
            impCopy = new ImagePlus(imp.getTitle(), imp.getProcessor().duplicate());
            Object fht  = imp.getProperty("FHT");
            if (fht!=null) {
                fht = new FHT((ImageProcessor)fht); // duplicate
                impCopy.setProperty("FHT", fht);
            }
        } else if (what==COMPOUND_FILTER) {
            ImageProcessor ip = imp.getProcessor();
            if (ip!=null)
                ipCopy = ip.duplicate();
            else
                ipCopy = null;
        } else
            ipCopy = null;
    }
    
    
    public static void reset() {
        if (whatToUndo==COMPOUND_FILTER)
            return;
        whatToUndo = NOTHING;
        imageID = 0;
        ipCopy = null;
        impCopy = null;
        //IJ.log("Undo: reset");
    }
    

    public static void undo() {
        ImagePlus imp = IJ.getInstance().getImagePlus();
        //IJ.log(imp.getTitle() + ": undo (" + whatToUndo + ")  "+(imageID!=imp.getID()));
        if (imageID!=imp.getID()) {
            reset();
            return;
        }
        switch (whatToUndo) {
            case FILTER:
                ImageProcessor ip = imp.getProcessor();
                if (ip!=null) {
                    ip.reset();
                    imp.updateAndDraw();
                }
                break;
            case TYPE_CONVERSION:
            case COMPOUND_FILTER:
            case COMPOUND_FILTER_DONE:
                if (ipCopy!=null)
                    imp.setProcessor(null, ipCopy);
                break;
            case TRANSFORM:
                if (impCopy!=null) {
                    imp.setProcessor(impCopy.getTitle(), impCopy.getProcessor());
                    Object fht  = impCopy.getProperty("FHT");
                    if (fht!=null)
                        imp.setProperty("FHT", fht);
                    else if (imp.getProperty("FHT")!=null)
                            imp.getProperties().remove("FHT");
                }
                break;
            case PASTE:
                Roi roi = imp.getRoi();
                if (roi!=null)
                    roi.abortPaste();
                break;
        }
        reset();
    }
    
}