org.kuali.student.common.ui.client.util.Elements.java Source code

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Here is the source code for org.kuali.student.common.ui.client.util.Elements.java

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/**
 * Copyright 2010 The Kuali Foundation Licensed under the
 * Educational Community 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.osedu.org/licenses/ECL-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 org.kuali.student.common.ui.client.util;

import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Style;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.DeferredCommand;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.ui.UIObject;

/**
 * Utility class for DOM element manipulations, UIObject effects, etc.
 * 
 */
public class Elements {

    public interface FadeCallback {
        public void onFadeComplete();

        public void onFadeStart();
    }

    public static class EmptyFadeCallback implements FadeCallback {
        public void onFadeComplete() {
        }

        public void onFadeStart() {
        }
    }

    /**
     * Causes an element to "fade in" via opacity. Make sure that element to
     * fade is not visible before calling this method. When the callback is
     * invoked with onFadeStart, the element can be set to visible as it is
     * entirely transparent. When onFadeComplete is called, the element will be
     * entirely opaque.
     * 
     * @param target
     *            the UIObject to be faded in
     * @param milliseconds
     *            how long the fade effect should take to process
     * @param maxOpacity
     *            final opacity
     * @param callback
     *            the callback to be invoked on fade progress
     */
    public static void fadeIn(final UIObject target, final int milliseconds, final int maxOpacity,
            final FadeCallback callback) {
        fadeIn(target.getElement(), milliseconds, maxOpacity, callback);
    }

    public static void fadeIn(final Element e, final int milliseconds, final int maxOpacity,
            final FadeCallback callback) {

        final int interval = milliseconds / 50;
        setOpacity(e, 0);
        DeferredCommand.addCommand(new Command() {

            @Override
            public void execute() {
                callback.onFadeStart();

                final Timer t = new Timer() {
                    int pct = 0;

                    @Override
                    public void run() {
                        pct += 2;
                        pct = Math.min(pct, maxOpacity);
                        setOpacity(e, pct);
                        if (pct == maxOpacity) {
                            this.cancel();
                            callback.onFadeComplete();
                        }
                    }
                };
                t.scheduleRepeating(interval);

            }
        });
    }

    /**
     * Causes an element to "fade out" via opacity. When onFadeComplete is
     * called, the element will be entirely transparent.
     * 
     * @param target
     *            the UIObject to be faded out
     * @param milliseconds
     *            how long the fade effect should take to process
     * @param minOpacity
     *            final opacity
     * @param callback
     *            the callback to be invoked on fade progress
     */
    public static void fadeOut(final UIObject target, final int milliseconds, final int minOpacity,
            final FadeCallback callback) {
        fadeOut(target.getElement(), milliseconds, minOpacity, callback);
    }

    public static void fadeOut(final Element e, final int milliseconds, final int minOpacity,
            final FadeCallback callback) {

        final int interval = milliseconds / 50;
        DeferredCommand.addCommand(new Command() {

            @Override
            public void execute() {
                callback.onFadeStart();

                final Timer t = new Timer() {
                    int pct = 100;

                    @Override
                    public void run() {
                        pct -= 2;
                        pct = Math.max(pct, minOpacity);
                        setOpacity(e, pct);
                        if (pct == minOpacity) {
                            this.cancel();
                            callback.onFadeComplete();
                        }
                    }
                };
                t.scheduleRepeating(interval);

            }
        });
    }

    /**
      * Sets a UIObject's opacity
      * 
      * @param u
      * @param percent
      */
    public static void setOpacity(final UIObject u, final int percent) {
        setOpacity(u.getElement(), percent);
    }

    /**
     * Sets a DOM element's opacity
     * 
     * @param e
     * @param percent
     */
    public static void setOpacity(final Element e, final int percent) {
        final Style s = e.getStyle();
        final double d = ((double) percent / (double) 100);
        s.setProperty("opacity", String.valueOf(d));
        s.setProperty("MozOpacity", String.valueOf(d));
        s.setProperty("KhtmlOpacity", String.valueOf(d));
        s.setProperty("filter", "alpha(opacity=" + percent + ")");
    }

    /**
     * Enables/disables text selection for the specified element.
     * 
     * @param e
     * @param selectable
     */
    public static native void setTextSelectable(Element e, boolean selectable)/*-{
                                                                              if (selectable) {
                                                                              e.ondrag = null;
                                                                              e.onselectstart = null;
                                                                              e.style.MozUserSelect="text";
                                                                              } else {
                                                                              e.ondrag = function () { return false; };
                                                                              e.onselectstart = function () { return false; };
                                                                              e.style.MozUserSelect="none";
                                                                              }
                                                                              }-*/;
}