// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.GWT.client.widgets.nonpublic.external;

import com.google.gwt.user.client.*;
import com.google.gwt.user.client.ui.*;

/**
 * A controller which interprets drag events and delegates the mouse drag
 * operation to a delegate.
 * <p/>
 * see asquare.gwt.tk.client.ui.behavior.DragGesture
 */
public class DragController extends MouseController {
    private MouseEvent m_previousEvent;

    /**
     * Creates a new DragController which delegates to the specified
     * handler.
     *
     * @param handler a delegate object, or <code>null</code>
     */
    public DragController( MouseHandler handler ) {
        super( Event.ONMOUSEDOWN | Event.ONMOUSEMOVE | Event.ONMOUSEUP | Event.ONLOSECAPTURE, DragController.class, handler );
    }

    @Override
    public void onBrowserEvent( Widget widget, Event event ) {
        super.onBrowserEvent( widget, event );
        if ( DOM.eventGetType( event ) == Event.ONLOSECAPTURE ) {
            /*
                * Firefox loses the mouseup if released outside the client area.
                * But we do get an onlosecapture event. Not ideal, but it prevents
                * a invalid state (dragging while mouse is released).
                * http://code.google.com/p/google-web-toolkit/issues/detail?id=243
                */
            onMouseUp( m_previousEvent );
        }
    }

    @Override
    protected void onMouseDown( MouseEvent e ) {
        DOM.setCapture( e.getReceiver().getElement() );
        m_previousEvent = e;
        super.onMouseDown( e );
    }

    @Override
    protected void onMouseMove( MouseEvent e ) {
        m_previousEvent = e;
        super.onMouseMove( e );
    }

    @Override
    protected void onMouseUp( MouseEvent e ) {
        if ( m_previousEvent != null ) {
            // do last to prevent reentrancy via ONLOSECAPTURE
            DOM.releaseCapture( e.getReceiver().getElement() );
        }
        super.onMouseUp( e );
        m_previousEvent = null;
    }
}