vaadin-framework/client/src/com/vaadin/client/ui/dd/DDUtil.java

/*
 * Copyright 2000-2013 Vaadin Ltd.
 * 
 * Licensed 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 com.vaadin.client.ui.dd;

import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.user.client.Window;
import com.vaadin.client.Util;
import com.vaadin.shared.ui.dd.HorizontalDropLocation;
import com.vaadin.shared.ui.dd.VerticalDropLocation;

public class DDUtil {

    public static VerticalDropLocation getVerticalDropLocation(
            com.google.gwt.user.client.Element element, NativeEvent event,
            double topBottomRatio) {
        int offsetHeight = element.getOffsetHeight();
        return getVerticalDropLocation(element, offsetHeight, event,
                topBottomRatio);
    }

    public static VerticalDropLocation getVerticalDropLocation(
            com.google.gwt.user.client.Element element, int offsetHeight,
            NativeEvent event, double topBottomRatio) {
        int clientY = Util.getTouchOrMouseClientY(event);
        return getVerticalDropLocation(element, offsetHeight, clientY,
                topBottomRatio);
    }

    public static VerticalDropLocation getVerticalDropLocation(
            com.google.gwt.user.client.Element element, int offsetHeight,
            int clientY, double topBottomRatio) {

        // Event coordinates are relative to the viewport, element absolute
        // position is relative to the document. Make element position relative
        // to viewport by adjusting for viewport scrolling. See #6021
        int elementTop = element.getAbsoluteTop() - Window.getScrollTop();
        int fromTop = clientY - elementTop;

        float percentageFromTop = (fromTop / (float) offsetHeight);
        if (percentageFromTop < topBottomRatio) {
            return VerticalDropLocation.TOP;
        } else if (percentageFromTop > 1 - topBottomRatio) {
            return VerticalDropLocation.BOTTOM;
        } else {
            return VerticalDropLocation.MIDDLE;
        }
    }

    public static HorizontalDropLocation getHorizontalDropLocation(
            com.google.gwt.user.client.Element element, NativeEvent event,
            double leftRightRatio) {
        int clientX = Util.getTouchOrMouseClientX(event);

        // Event coordinates are relative to the viewport, element absolute
        // position is relative to the document. Make element position relative
        // to viewport by adjusting for viewport scrolling. See #6021
        int elementLeft = element.getAbsoluteLeft() - Window.getScrollLeft();
        int offsetWidth = element.getOffsetWidth();
        int fromLeft = clientX - elementLeft;

        float percentageFromLeft = (fromLeft / (float) offsetWidth);
        if (percentageFromLeft < leftRightRatio) {
            return HorizontalDropLocation.LEFT;
        } else if (percentageFromLeft > 1 - leftRightRatio) {
            return HorizontalDropLocation.RIGHT;
        } else {
            return HorizontalDropLocation.CENTER;
        }
    }

}