com.allen_sauer.gwt.dnd.client.util.WidgetLocation.java Source code

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Here is the source code for com.allen_sauer.gwt.dnd.client.util.WidgetLocation.java

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/*
 * Copyright 2009 Fred Sauer
 * 
 * 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.allen_sauer.gwt.dnd.client.util;

import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.Widget;

/*
 * * Class representing the location of one widget relative to another.
 */
public class WidgetLocation extends AbstractLocation {

    private int left;

    // private Widget reference;
    private int referenceAdjustLeft;

    private int referenceAdjustTop;

    private int top;

    // private Widget widget;
    private int widgetLeft;

    private int widgetTop;

    /**
     * Determine location of <code>widget</code> relative to <code>reference</code>, such that
     * <code>referencePanel.add(widget, location.getLeft(), location.getTop())</code> leaves the
     * widget in the exact same location on the screen. Note that <code>reference</code> need not be
     * the parent node, or even an ancestor of <code>widget</code>. Therefore coordinates returned may
     * be negative or may exceed the dimensions of <code>reference</code>.
     * 
     * @param widget the widget whose coordinates we seek
     * @param reference the widget relative to which we seek our coordinates
     */
    public WidgetLocation(Widget widget, Widget reference) {
        internalSetWidget(widget);
        internalSetReference(reference);
        recalculate();
    }

    /**
     * Constrain the widget location to the provided minimum and maximum values.
     * 
     * @param minLeft the minimum left value
     * @param minTop the minimum top value
     * @param maxLeft the maximum left value
     * @param maxTop the maximum top value
     */
    public void constrain(int minLeft, int minTop, int maxLeft, int maxTop) {
        left = Math.max(minLeft, Math.min(left, maxLeft));
        top = Math.max(minTop, Math.min(top, maxTop));
    }

    @Override
    public int getLeft() {
        return left;
    }

    // public Widget getReference() {
    // return reference;
    // }

    @Override
    public int getTop() {
        return top;
    }

    // public Widget getWidget() {
    // return widget;
    // }

    // public void setReference(Widget reference) {
    // internalSetReference(reference);
    // recalculate();
    // }
    //
    // public void setWidget(Widget widget) {
    // internalSetWidget(widget);
    // recalculate();
    // }

    @Override
    public String toString() {
        return "(" + left + ", " + top + ")";
    }

    private void internalSetReference(Widget reference) {
        // this.reference = reference;
        if (reference == null || reference == RootPanel.get()) {
            referenceAdjustLeft = 0;
            referenceAdjustTop = 0;
        } else {
            referenceAdjustLeft = reference.getAbsoluteLeft() + DOMUtil.getBorderLeft(reference.getElement());
            referenceAdjustTop = reference.getAbsoluteTop() + DOMUtil.getBorderTop(reference.getElement());
        }
    }

    private void internalSetWidget(Widget widget) {
        // this.widget = widget;
        if (widget == null || widget == RootPanel.get()) {
            widgetLeft = 0;
            widgetTop = 0;
        } else {
            widgetLeft = widget.getAbsoluteLeft() - widget.getElement().getScrollLeft();
            widgetTop = widget.getAbsoluteTop() - widget.getElement().getScrollTop();
        }
    }

    private void recalculate() {
        left = widgetLeft - referenceAdjustLeft;
        top = widgetTop - referenceAdjustTop;
    }
}