com.sciencegadgets.client.algebra.WrapDragController.java Source code

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Here is the source code for com.sciencegadgets.client.algebra.WrapDragController.java

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/*******************************************************************************
 *     This file is part of ScienceGadgets, a collection of educational tools
 *     Copyright (C) 2012-2015 by John Gralyan
 *
 *     ScienceGadgets is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU Affero General Public License as
 *     published by the Free Software Foundation, either version 3 of
 *     the License, or (at your option) any later version.
 *
 *     ScienceGadgets is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU Affero General Public License for more details.
 *
 *     You should have received a copy of the GNU Affero General Public License
 *     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *     
 *     Contact us at info@sciencegadgets.org
 *******************************************************************************/
package com.sciencegadgets.client.algebra;

import java.util.LinkedList;

import com.allen_sauer.gwt.dnd.client.DragContext;
import com.allen_sauer.gwt.dnd.client.PickupDragController;
import com.allen_sauer.gwt.dnd.client.drop.DropController;
import com.allen_sauer.gwt.dnd.client.util.DragClientBundle;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Node;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.user.client.ui.AbsolutePanel;
import com.google.gwt.user.client.ui.SimplePanel;
import com.google.gwt.user.client.ui.Widget;
import com.sciencegadgets.client.ui.CSS;

public class WrapDragController extends PickupDragController {

    LinkedList<DropController> dropControllers = null;
    private SimplePanel proxy;
    private int moveCounter = 0;
    private boolean isDragging = false;

    public WrapDragController(AbsolutePanel boundaryPanel, boolean allowDroppingOnBoundaryPanel) {
        super(boundaryPanel, allowDroppingOnBoundaryPanel);

        this.setBehaviorDragStartSensitivity(2);
        this.setBehaviorDragProxy(true);
    }

    public boolean isDragging() {
        return isDragging;
    }

    @Override
    public void dragStart() {

        isDragging = true;

        ((Wrapper) context.draggable).moved = true;
        ((Wrapper) context.draggable).select();

        super.dragStart();

        proxy.getElement().getStyle().setOpacity(0);

        if (dropControllers != null) {
            for (DropController dropC : dropControllers) {
                dropC.getDropTarget().addStyleName(CSS.DROP_WRAPPER_DRAGGING);
            }
        }
    }

    @Override
    public void dragMove() {
        super.dragMove();

        // Wait a bit to avoid flicker
        if (moveCounter == 2) {
            proxy.getElement().getStyle().setOpacity(1);
            context.draggable.getElement().getStyle().setOpacity(0);
        }
        moveCounter++;
    }

    @Override
    public void dragEnd() {
        super.dragEnd();

        moveCounter = 0;

        proxy.getElement().getStyle().clearOpacity();
        context.draggable.getElement().getStyle().clearOpacity();

        isDragging = false;

        if (dropControllers != null) {
            for (DropController dropC : dropControllers) {
                dropC.getDropTarget().removeStyleName(CSS.DROP_WRAPPER_DRAGGING);
            }
        }
    }

    @Override
    protected Widget newDragProxy(DragContext context) {
        Widget drag = context.draggable;
        Element selectedElement = drag.getElement();
        Node dragEl = selectedElement.cloneNode(true);
        double pxPerEm = EquationHTML.getPxPerEm(selectedElement);

        proxy = new SimplePanel();
        proxy.getElement().getStyle().setWidth(drag.getOffsetWidth(), Unit.PX);
        proxy.getElement().getStyle().setHeight(drag.getOffsetHeight(), Unit.PX);
        proxy.addStyleName(DragClientBundle.INSTANCE.css().movablePanel());
        proxy.getElement().getStyle().setFontSize(pxPerEm, Unit.PX);
        proxy.getElement().appendChild(dragEl);

        return proxy;
    }

    public DragContext getContext() {
        return context;
    }

    @Override
    public void registerDropController(DropController dropC) {
        super.registerDropController(dropC);
        if (dropControllers == null) {
            dropControllers = new LinkedList<DropController>();
        }
        dropControllers.add(dropC);
    }

    @Override
    public void unregisterDropControllers() {
        super.unregisterDropControllers();
        if (dropControllers != null) {
            dropControllers.clear();
        }
    }

    @Override
    public void unregisterDropController(DropController dropC) {
        super.unregisterDropController(dropC);
        if (dropControllers != null) {
            dropControllers.remove(dropC);
        }
    }

}