vaadin-framework/client/src/com/vaadin/client/Util.java

/*
 * Copyright 2000-2014 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;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import com.google.gwt.core.client.Scheduler;
import com.google.gwt.core.client.Scheduler.ScheduledCommand;
import com.google.gwt.dom.client.AnchorElement;
import com.google.gwt.dom.client.DivElement;
import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.dom.client.Node;
import com.google.gwt.dom.client.NodeList;
import com.google.gwt.dom.client.Style;
import com.google.gwt.dom.client.Style.Display;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.dom.client.Touch;
import com.google.gwt.event.dom.client.KeyEvent;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.EventListener;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.HasWidgets;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.Widget;
import com.vaadin.client.RenderInformation.FloatSize;
import com.vaadin.client.ui.VOverlay;
import com.vaadin.shared.AbstractComponentState;
import com.vaadin.shared.ApplicationConstants;
import com.vaadin.shared.communication.MethodInvocation;
import com.vaadin.shared.ui.ComponentStateUtil;
import com.vaadin.shared.util.SharedUtil;

public class Util {

    /**
     * Helper method for debugging purposes.
     * 
     * Stops execution on firefox browsers on a breakpoint.
     * 
     */
    public static native void browserDebugger()
    /*-{
        if($wnd.console)
            debugger;
    }-*/;

    /**
     * Helper method for a bug fix #14041. For mozilla getKeyCode return 0 for
     * space bar (because space is considered as char). If return 0 use
     * getCharCode.
     *
     * @param event
     * @return return key code
     * @since 7.2.4
     */
    public static int getKeyCode(KeyEvent<?> event) {
        int keyCode = event.getNativeEvent().getKeyCode();
        if (keyCode == 0) {
            keyCode = event.getNativeEvent().getCharCode();
        }
        return keyCode;
    }

    /**
     *
     * Returns the topmost element of from given coordinates.
     * 
     * TODO fix crossplat issues clientX vs pageX. See quircksmode. Not critical
     * for vaadin as we scroll div istead of page.
     * 
     * @param x
     * @param y
     * @return the element at given coordinates
     */
    public static native com.google.gwt.user.client.Element getElementFromPoint(
            int clientX, int clientY)
    /*-{
        var el = $wnd.document.elementFromPoint(clientX, clientY);
        // Call elementFromPoint two times to make sure IE8 also returns something sensible if the application is running in an iframe 
        el = $wnd.document.elementFromPoint(clientX, clientY);
        if(el != null && el.nodeType == 3) {
            el = el.parentNode;
        }
        return el;
    }-*/;

    /**
     * This helper method can be called if components size have been changed
     * outside rendering phase. It notifies components parent about the size
     * change so it can react.
     * 
     * When using this method, developer should consider if size changes could
     * be notified lazily. If lazy flag is true, method will save widget and
     * wait for a moment until it notifies parents in chunks. This may vastly
     * optimize layout in various situation. Example: if component have a lot of
     * images their onload events may fire "layout phase" many times in a short
     * period.
     * 
     * @param widget
     * @param lazy
     *            run componentSizeUpdated lazyly
     * 
     * @deprecated As of 7.0, use
     *             {@link LayoutManager#setNeedsMeasure(ComponentConnector)}
     *             instead
     */
    @Deprecated
    public static void notifyParentOfSizeChange(Widget widget, boolean lazy) {
        ComponentConnector connector = findConnectorFor(widget);
        if (connector != null) {
            connector.getLayoutManager().setNeedsMeasure(connector);
            if (!lazy) {
                connector.getLayoutManager().layoutNow();
            }
        }
    }

    public static ComponentConnector findConnectorFor(Widget widget) {
        List<ApplicationConnection> runningApplications = ApplicationConfiguration
                .getRunningApplications();
        for (ApplicationConnection applicationConnection : runningApplications) {
            ConnectorMap connectorMap = applicationConnection.getConnectorMap();
            ComponentConnector connector = connectorMap.getConnector(widget);
            if (connector == null) {
                continue;
            }
            if (connector.getConnection() == applicationConnection) {
                return connector;
            }
        }

        return null;
    }

    public static float parseRelativeSize(String size) {
        if (size == null || !size.endsWith("%")) {
            return -1;
        }

        try {
            return Float.parseFloat(size.substring(0, size.length() - 1));
        } catch (Exception e) {
            VConsole.log("Unable to parse relative size");
            return -1;
        }
    }

    private static final Element escapeHtmlHelper = DOM.createDiv();

    /**
     * Converts html entities to text.
     * 
     * @param html
     * @return escaped string presentation of given html
     */
    public static String escapeHTML(String html) {
        DOM.setInnerText(escapeHtmlHelper, html);
        String escapedText = DOM.getInnerHTML(escapeHtmlHelper);
        if (BrowserInfo.get().isIE8()) {
            // #7478 IE8 "incorrectly" returns "<br>" for newlines set using
            // setInnerText. The same for " " which is converted to "&nbsp;"
            escapedText = escapedText.replaceAll("<(BR|br)>", "\n");
            escapedText = escapedText.replaceAll("&nbsp;", " ");
        }
        return escapedText;
    }

    /**
     * Escapes the string so it is safe to write inside an HTML attribute.
     * 
     * @param attribute
     *            The string to escape
     * @return An escaped version of <literal>attribute</literal>.
     */
    public static String escapeAttribute(String attribute) {
        if (attribute == null) {
            return "";
        }
        attribute = attribute.replace("\"", "&quot;");
        attribute = attribute.replace("'", "&#39;");
        attribute = attribute.replace(">", "&gt;");
        attribute = attribute.replace("<", "&lt;");
        attribute = attribute.replace("&", "&amp;");
        return attribute;
    }

    /**
     * Clones given element as in JavaScript.
     * 
     * Deprecate this if there appears similar method into GWT someday.
     * 
     * @param element
     * @param deep
     *            clone child tree also
     * @return
     */
    public static native com.google.gwt.user.client.Element cloneNode(
            Element element, boolean deep)
    /*-{
        return element.cloneNode(deep);
    }-*/;

    public static int measureHorizontalPaddingAndBorder(Element element,
            int paddingGuess) {
        String originalWidth = DOM.getStyleAttribute(element, "width");

        int originalOffsetWidth = element.getOffsetWidth();
        int widthGuess = (originalOffsetWidth - paddingGuess);
        if (widthGuess < 1) {
            widthGuess = 1;
        }
        element.getStyle().setWidth(widthGuess, Unit.PX);
        int padding = element.getOffsetWidth() - widthGuess;

        element.getStyle().setProperty("width", originalWidth);

        return padding;
    }

    public static int measureVerticalPaddingAndBorder(Element element,
            int paddingGuess) {
        String originalHeight = DOM.getStyleAttribute(element, "height");
        int originalOffsetHeight = element.getOffsetHeight();
        int widthGuess = (originalOffsetHeight - paddingGuess);
        if (widthGuess < 1) {
            widthGuess = 1;
        }
        element.getStyle().setHeight(widthGuess, Unit.PX);
        int padding = element.getOffsetHeight() - widthGuess;

        element.getStyle().setProperty("height", originalHeight);
        return padding;
    }

    public static int measureHorizontalBorder(Element element) {
        int borders;

        if (BrowserInfo.get().isIE()) {
            String width = element.getStyle().getProperty("width");
            String height = element.getStyle().getProperty("height");

            int offsetWidth = element.getOffsetWidth();
            int offsetHeight = element.getOffsetHeight();
            if (offsetHeight < 1) {
                offsetHeight = 1;
            }
            if (offsetWidth < 1) {
                offsetWidth = 10;
            }
            element.getStyle().setPropertyPx("height", offsetHeight);
            element.getStyle().setPropertyPx("width", offsetWidth);

            borders = element.getOffsetWidth() - element.getClientWidth();

            element.getStyle().setProperty("width", width);
            element.getStyle().setProperty("height", height);
        } else {
            borders = element.getOffsetWidth()
                    - element.getPropertyInt("clientWidth");
        }
        assert borders >= 0;

        return borders;
    }

    public static int measureVerticalBorder(Element element) {
        int borders;
        if (BrowserInfo.get().isIE()) {
            String width = element.getStyle().getProperty("width");
            String height = element.getStyle().getProperty("height");

            int offsetWidth = element.getOffsetWidth();
            int offsetHeight = element.getOffsetHeight();
            if (offsetHeight < 1) {
                offsetHeight = 1;
            }
            if (offsetWidth < 1) {
                offsetWidth = 10;
            }
            element.getStyle().setPropertyPx("width", offsetWidth);

            element.getStyle().setPropertyPx("height", offsetHeight);

            borders = element.getOffsetHeight()
                    - element.getPropertyInt("clientHeight");

            element.getStyle().setProperty("height", height);
            element.getStyle().setProperty("width", width);
        } else {
            borders = element.getOffsetHeight()
                    - element.getPropertyInt("clientHeight");
        }
        assert borders >= 0;

        return borders;
    }

    public static int measureMarginLeft(Element element) {
        return element.getAbsoluteLeft()
                - element.getParentElement().getAbsoluteLeft();
    }

    public static int setHeightExcludingPaddingAndBorder(Widget widget,
            String height, int paddingBorderGuess) {
        if (height.equals("")) {
            setHeight(widget, "");
            return paddingBorderGuess;
        } else if (height.endsWith("px")) {
            int pixelHeight = Integer.parseInt(height.substring(0,
                    height.length() - 2));
            return setHeightExcludingPaddingAndBorder(widget.getElement(),
                    pixelHeight, paddingBorderGuess, false);
        } else {
            // Set the height in unknown units
            setHeight(widget, height);
            // Use the offsetWidth
            return setHeightExcludingPaddingAndBorder(widget.getElement(),
                    widget.getOffsetHeight(), paddingBorderGuess, true);
        }
    }

    private static void setWidth(Widget widget, String width) {
        widget.getElement().getStyle().setProperty("width", width);
    }

    private static void setHeight(Widget widget, String height) {
        widget.getElement().getStyle().setProperty("height", height);
    }

    public static int setWidthExcludingPaddingAndBorder(Widget widget,
            String width, int paddingBorderGuess) {
        if (width.equals("")) {
            setWidth(widget, "");
            return paddingBorderGuess;
        } else if (width.endsWith("px")) {
            int pixelWidth = Integer.parseInt(width.substring(0,
                    width.length() - 2));
            return setWidthExcludingPaddingAndBorder(widget.getElement(),
                    pixelWidth, paddingBorderGuess, false);
        } else {
            setWidth(widget, width);
            return setWidthExcludingPaddingAndBorder(widget.getElement(),
                    widget.getOffsetWidth(), paddingBorderGuess, true);
        }
    }

    public static int setWidthExcludingPaddingAndBorder(Element element,
            int requestedWidth, int horizontalPaddingBorderGuess,
            boolean requestedWidthIncludesPaddingBorder) {

        int widthGuess = requestedWidth - horizontalPaddingBorderGuess;
        if (widthGuess < 0) {
            widthGuess = 0;
        }

        element.getStyle().setWidth(widthGuess, Unit.PX);
        int captionOffsetWidth = DOM.getElementPropertyInt(element,
                "offsetWidth");

        int actualPadding = captionOffsetWidth - widthGuess;

        if (requestedWidthIncludesPaddingBorder) {
            actualPadding += actualPadding;
        }

        if (actualPadding != horizontalPaddingBorderGuess) {
            int w = requestedWidth - actualPadding;
            if (w < 0) {
                // Cannot set negative width even if we would want to
                w = 0;
            }
            element.getStyle().setWidth(w, Unit.PX);

        }

        return actualPadding;

    }

    public static int setHeightExcludingPaddingAndBorder(Element element,
            int requestedHeight, int verticalPaddingBorderGuess,
            boolean requestedHeightIncludesPaddingBorder) {

        int heightGuess = requestedHeight - verticalPaddingBorderGuess;
        if (heightGuess < 0) {
            heightGuess = 0;
        }

        element.getStyle().setHeight(heightGuess, Unit.PX);
        int captionOffsetHeight = DOM.getElementPropertyInt(element,
                "offsetHeight");

        int actualPadding = captionOffsetHeight - heightGuess;

        if (requestedHeightIncludesPaddingBorder) {
            actualPadding += actualPadding;
        }

        if (actualPadding != verticalPaddingBorderGuess) {
            int h = requestedHeight - actualPadding;
            if (h < 0) {
                // Cannot set negative height even if we would want to
                h = 0;
            }
            element.getStyle().setHeight(h, Unit.PX);

        }

        return actualPadding;

    }

    public static String getSimpleName(Object widget) {
        if (widget == null) {
            return "(null)";
        }

        String name = widget.getClass().getName();
        return name.substring(name.lastIndexOf('.') + 1);
    }

    public static void setFloat(Element element, String value) {
        if (BrowserInfo.get().isIE()) {
            element.getStyle().setProperty("styleFloat", value);
        } else {
            element.getStyle().setProperty("cssFloat", value);
        }
    }

    private static int detectedScrollbarSize = -1;

    public static int getNativeScrollbarSize() {
        if (detectedScrollbarSize < 0) {
            Element scroller = DOM.createDiv();
            scroller.getStyle().setProperty("width", "50px");
            scroller.getStyle().setProperty("height", "50px");
            scroller.getStyle().setProperty("overflow", "scroll");
            scroller.getStyle().setProperty("position", "absolute");
            scroller.getStyle().setProperty("marginLeft", "-5000px");
            RootPanel.getBodyElement().appendChild(scroller);
            detectedScrollbarSize = scroller.getOffsetWidth()
                    - scroller.getPropertyInt("clientWidth");

            RootPanel.getBodyElement().removeChild(scroller);
        }
        return detectedScrollbarSize;
    }

    /**
     * Defers the execution of {@link #runWebkitOverflowAutoFix(Element)}
     * 
     * @since
     * @param elem
     *            with overflow auto
     */
    public static void runWebkitOverflowAutoFixDeferred(final Element elem) {
        Scheduler.get().scheduleDeferred(new Command() {

            @Override
            public void execute() {
                Util.runWebkitOverflowAutoFix(elem);
            }
        });

    }

    /**
     * Run workaround for webkits overflow auto issue.
     * 
     * See: our bug #2138 and https://bugs.webkit.org/show_bug.cgi?id=21462
     * 
     * @param elem
     *            with overflow auto
     */
    public static void runWebkitOverflowAutoFix(final Element elem) {
        // Add max version if fix lands sometime to Webkit
        // Starting from Opera 11.00, also a problem in Opera
        if (BrowserInfo.get().requiresOverflowAutoFix()) {
            final String originalOverflow = elem.getStyle().getProperty(
                    "overflow");
            if ("hidden".equals(originalOverflow)) {
                return;
            }

            // check the scrolltop value before hiding the element
            final int scrolltop = elem.getScrollTop();
            final int scrollleft = elem.getScrollLeft();
            elem.getStyle().setProperty("overflow", "hidden");

            Scheduler.get().scheduleDeferred(new Command() {
                @Override
                public void execute() {
                    // Dough, Safari scroll auto means actually just a moped
                    elem.getStyle().setProperty("overflow", originalOverflow);

                    if (scrolltop > 0 || elem.getScrollTop() > 0) {
                        int scrollvalue = scrolltop;
                        if (scrollvalue == 0) {
                            // mysterious are the ways of webkits scrollbar
                            // handling. In some cases webkit reports bad (0)
                            // scrolltop before hiding the element temporary,
                            // sometimes after.
                            scrollvalue = elem.getScrollTop();
                        }
                        // fix another bug where scrollbar remains in wrong
                        // position
                        elem.setScrollTop(scrollvalue - 1);
                        elem.setScrollTop(scrollvalue);
                    }

                    // fix for #6940 : Table horizontal scroll sometimes not
                    // updated when collapsing/expanding columns
                    // Also appeared in Safari 5.1 with webkit 534 (#7667)
                    if ((BrowserInfo.get().isChrome() || (BrowserInfo.get()
                            .isSafari() && BrowserInfo.get().getWebkitVersion() >= 534))
                            && (scrollleft > 0 || elem.getScrollLeft() > 0)) {
                        int scrollvalue = scrollleft;

                        if (scrollvalue == 0) {
                            // mysterious are the ways of webkits scrollbar
                            // handling. In some cases webkit may report a bad
                            // (0) scrollleft before hiding the element
                            // temporary, sometimes after.
                            scrollvalue = elem.getScrollLeft();
                        }
                        // fix another bug where scrollbar remains in wrong
                        // position
                        elem.setScrollLeft(scrollvalue - 1);
                        elem.setScrollLeft(scrollvalue);
                    }
                }
            });
        }

    }

    /**
     * Parses shared state and fetches the relative size of the component. If a
     * dimension is not specified as relative it will return -1. If the shared
     * state does not contain width or height specifications this will return
     * null.
     * 
     * @param state
     * @return
     */
    public static FloatSize parseRelativeSize(AbstractComponentState state) {
        if (ComponentStateUtil.isUndefinedHeight(state)
                && ComponentStateUtil.isUndefinedWidth(state)) {
            return null;
        }

        float relativeWidth = Util.parseRelativeSize(state.width);
        float relativeHeight = Util.parseRelativeSize(state.height);

        FloatSize relativeSize = new FloatSize(relativeWidth, relativeHeight);
        return relativeSize;

    }

    @Deprecated
    public static boolean isCached(UIDL uidl) {
        return uidl.getBooleanAttribute("cached");
    }

    public static void alert(String string) {
        if (true) {
            Window.alert(string);
        }
    }

    /**
     * Checks if a and b are equals using {@link #equals(Object)}. Handles null
     * values as well. Does not ensure that objects are of the same type.
     * Assumes that the first object's equals method handle equals properly.
     * 
     * @param a
     *            The first value to compare
     * @param b
     *            The second value to compare
     * @return
     * @deprecated As of 7.1 use {@link SharedUtil#equals(Object)} instead
     */
    @Deprecated
    public static boolean equals(Object a, Object b) {
        return SharedUtil.equals(a, b);
    }

    public static void updateRelativeChildrenAndSendSizeUpdateEvent(
            ApplicationConnection client, HasWidgets container, Widget widget) {
        notifyParentOfSizeChange(widget, false);
    }

    /**
     * Gets the border-box width for the given element, i.e. element width +
     * border + padding. Always rounds up to nearest integer.
     * 
     * @param element
     *            The element to check
     * @return The border-box width for the element
     */
    public static int getRequiredWidth(com.google.gwt.dom.client.Element element) {
        int reqWidth = getRequiredWidthBoundingClientRect(element);
        if (BrowserInfo.get().isIE() && !BrowserInfo.get().isIE8()) {
            int csSize = getRequiredWidthComputedStyle(element);
            if (csSize == reqWidth + 1) {
                // If computed style reports one pixel larger than requiredWidth
                // we would be rounding in the wrong direction in IE9. Round up
                // instead.
                // We do not always use csSize as it e.g. for 100% wide Labels
                // in GridLayouts produces senseless values (see e.g.
                // ThemeTestUI with Runo).
                return csSize;
            }
        }
        return reqWidth;
    }

    /**
     * Gets the border-box height for the given element, i.e. element height +
     * border + padding. Always rounds up to nearest integer.
     * 
     * @param element
     *            The element to check
     * @return The border-box height for the element
     */
    public static int getRequiredHeight(
            com.google.gwt.dom.client.Element element) {
        int reqHeight = getRequiredHeightBoundingClientRect(element);
        if (BrowserInfo.get().isIE() && !BrowserInfo.get().isIE8()) {
            int csSize = getRequiredHeightComputedStyle(element);
            if (csSize == reqHeight + 1) {
                // If computed style reports one pixel larger than
                // requiredHeight we would be rounding in the wrong direction in
                // IE9. Round up instead.
                // We do not always use csSize as it e.g. for 100% wide Labels
                // in GridLayouts produces senseless values (see e.g.
                // ThemeTestUI with Runo).
                return csSize;
            }
        }
        return reqHeight;
    }

    public static native int getRequiredWidthBoundingClientRect(
            com.google.gwt.dom.client.Element element)
    /*-{
        if (element.getBoundingClientRect) {
          var rect = element.getBoundingClientRect();
          return Math.ceil(rect.right - rect.left);
        } else {
          return element.offsetWidth;
        }
    }-*/;

    public static native int getRequiredHeightComputedStyle(
            com.google.gwt.dom.client.Element element)
    /*-{
         var cs = element.ownerDocument.defaultView.getComputedStyle(element);
         var heightPx = cs.height;
         if(heightPx == 'auto'){
             // Fallback for when IE reports auto
             heightPx = @com.vaadin.client.Util::getRequiredHeightBoundingClientRect(Lcom/google/gwt/dom/client/Element;)(element) + 'px';
         }
         var borderTopPx = cs.borderTop;
         var borderBottomPx = cs.borderBottom;
         var paddingTopPx = cs.paddingTop;
         var paddingBottomPx = cs.paddingBottom;
         
         var height = heightPx.substring(0,heightPx.length-2);
         var border = borderTopPx.substring(0,borderTopPx.length-2)+borderBottomPx.substring(0,borderBottomPx.length-2);
         var padding = paddingTopPx.substring(0,paddingTopPx.length-2)+paddingBottomPx.substring(0,paddingBottomPx.length-2);
         return Math.ceil(height+border+padding);
     }-*/;

    public static native int getRequiredWidthComputedStyle(
            com.google.gwt.dom.client.Element element)
    /*-{
         var cs = element.ownerDocument.defaultView.getComputedStyle(element);
         var widthPx = cs.width;
         if(widthPx == 'auto'){
             // Fallback for when IE reports auto
             widthPx = @com.vaadin.client.Util::getRequiredWidthBoundingClientRect(Lcom/google/gwt/dom/client/Element;)(element) + 'px';
         }
         var borderLeftPx = cs.borderLeft;
         var borderRightPx = cs.borderRight;
         var paddingLeftPx = cs.paddingLeft;
         var paddingRightPx = cs.paddingRight;
         
         var width = widthPx.substring(0,widthPx.length-2);
         var border = borderLeftPx.substring(0,borderLeftPx.length-2)+borderRightPx.substring(0,borderRightPx.length-2);
         var padding = paddingLeftPx.substring(0,paddingLeftPx.length-2)+paddingRightPx.substring(0,paddingRightPx.length-2);
         return Math.ceil(width+border+padding);
     }-*/;

    public static native int getRequiredHeightBoundingClientRect(
            com.google.gwt.dom.client.Element element)
    /*-{
        var height;
        if (element.getBoundingClientRect != null) {
          var rect = element.getBoundingClientRect();
          height = Math.ceil(rect.bottom - rect.top);
        } else {
          height = element.offsetHeight;
        }
        return height;
    }-*/;

    public static int getRequiredWidth(Widget widget) {
        return getRequiredWidth(widget.getElement());
    }

    public static int getRequiredHeight(Widget widget) {
        return getRequiredHeight(widget.getElement());
    }

    /**
     * Detects what is currently the overflow style attribute in given element.
     * 
     * @param pe
     *            the element to detect
     * @return true if auto or scroll
     */
    public static boolean mayHaveScrollBars(com.google.gwt.dom.client.Element pe) {
        String overflow = getComputedStyle(pe, "overflow");
        if (overflow != null) {
            if (overflow.equals("auto") || overflow.equals("scroll")) {
                return true;
            } else {
                return false;
            }
        } else {
            return false;
        }
    }

    /**
     * A simple helper method to detect "computed style" (aka style sheets +
     * element styles). Values returned differ a lot depending on browsers.
     * Always be very careful when using this.
     * 
     * @param el
     *            the element from which the style property is detected
     * @param p
     *            the property to detect
     * @return String value of style property
     */
    private static native String getComputedStyle(
            com.google.gwt.dom.client.Element el, String p)
    /*-{
        try {
        
        if (el.currentStyle) {
            // IE
            return el.currentStyle[p];
        } else if (window.getComputedStyle) {
            // Sa, FF, Opera
            var view = el.ownerDocument.defaultView;
            return view.getComputedStyle(el,null).getPropertyValue(p);
        } else {
            // fall back for non IE, Sa, FF, Opera
            return "";
        }
        } catch (e) {
            return "";
        }

     }-*/;

    /**
     * Locates the nested child component of <literal>parent</literal> which
     * contains the element <literal>element</literal>. The child component is
     * also returned if "element" is part of its caption. If
     * <literal>element</literal> is not part of any child component, null is
     * returned.
     * 
     * This method returns the deepest nested VPaintableWidget.
     * 
     * @param client
     *            A reference to ApplicationConnection
     * @param parent
     *            The widget that contains <literal>element</literal>.
     * @param element
     *            An element that is a sub element of the parent
     * @return The VPaintableWidget which the element is a part of. Null if the
     *         element does not belong to a child.
     */
    public static ComponentConnector getConnectorForElement(
            ApplicationConnection client, Widget parent, Element element) {

        Element browseElement = element;
        Element rootElement = parent.getElement();

        while (browseElement != null && browseElement != rootElement) {

            ComponentConnector connector = ConnectorMap.get(client)
                    .getConnector(browseElement);

            if (connector == null) {
                String ownerPid = VCaption.getCaptionOwnerPid(browseElement);
                if (ownerPid != null) {
                    connector = (ComponentConnector) ConnectorMap.get(client)
                            .getConnector(ownerPid);
                }
            }

            if (connector != null) {
                // check that inside the rootElement
                while (browseElement != null && browseElement != rootElement) {
                    browseElement = browseElement.getParentElement();
                }
                if (browseElement != rootElement) {
                    return null;
                } else {
                    return connector;
                }
            }

            browseElement = browseElement.getParentElement();
        }

        // No connector found, element is possibly inside a VOverlay
        // If the overlay has an owner, try to find the owner's connector
        VOverlay overlay = findWidget(element, VOverlay.class);
        if (overlay != null && overlay.getOwner() != null) {

            return getConnectorForElement(client, client.getUIConnector()
                    .getWidget(), overlay.getOwner().getElement());
        } else {
            return null;
        }
    }

    /**
     * Will (attempt) to focus the given DOM Element.
     * 
     * @param el
     *            the element to focus
     */
    public static native void focus(Element el)
    /*-{
        try {
            el.focus();
        } catch (e) {

        }
    }-*/;

    /**
     * Helper method to find the nearest parent paintable instance by traversing
     * the DOM upwards from given element.
     * 
     * @param element
     *            the element to start from
     */
    public static ComponentConnector findPaintable(
            ApplicationConnection client, Element element) {
        Widget widget = Util.findWidget(element, null);
        ConnectorMap vPaintableMap = ConnectorMap.get(client);
        while (widget != null && !vPaintableMap.isConnector(widget)) {
            widget = widget.getParent();
        }
        return vPaintableMap.getConnector(widget);

    }

    /**
     * Helper method to find first instance of given Widget type found by
     * traversing DOM upwards from given element.
     * 
     * @param element
     *            the element where to start seeking of Widget
     * @param class1
     *            the Widget type to seek for
     */
    @SuppressWarnings("unchecked")
    public static <T> T findWidget(Element element,
            Class<? extends Widget> class1) {
        if (element != null) {
            /* First seek for the first EventListener (~Widget) from dom */
            EventListener eventListener = null;
            while (eventListener == null && element != null) {
                eventListener = Event.getEventListener(element);
                if (eventListener == null) {
                    element = element.getParentElement();
                }
            }
            if (eventListener instanceof Widget) {
                /*
                 * Then find the first widget of type class1 from widget
                 * hierarchy
                 */
                Widget w = (Widget) eventListener;
                while (w != null) {
                    if (class1 == null || w.getClass() == class1) {
                        return (T) w;
                    }
                    w = w.getParent();
                }
            }
        }
        return null;
    }

    /**
     * Force webkit to redraw an element
     * 
     * @param element
     *            The element that should be redrawn
     */
    public static void forceWebkitRedraw(Element element) {
        Style style = element.getStyle();
        String s = style.getProperty("webkitTransform");
        if (s == null || s.length() == 0) {
            style.setProperty("webkitTransform", "scale(1)");
        } else {
            style.setProperty("webkitTransform", "");
        }
    }

    /**
     * Performs a hack to trigger a re-layout in the IE8. This is usually
     * necessary in cases where IE8 "forgets" to update child elements when they
     * resize.
     *
     * @param e
     *            The element to perform the hack on
     */
    public static final void forceIE8Redraw(Element e) {
        if (BrowserInfo.get().isIE8()) {
            forceIERedraw(e);
        }
    }

    /**
     * Performs a hack to trigger a re-layout in the IE browser. This is usually
     * necessary in cases where IE "forgets" to update child elements when they
     * resize.
     *
     * @since
     * @param e
     *            The element to perform the hack on
     */
    public static void forceIERedraw(Element e) {
        if (BrowserInfo.get().isIE()) {
            setStyleTemporarily(e, "zoom", "1");
        }
    }

    /**
     * Detaches and re-attaches the element from its parent. The element is
     * reattached at the same position in the DOM as it was before.
     * 
     * Does nothing if the element is not attached to the DOM.
     * 
     * @param element
     *            The element to detach and re-attach
     */
    public static void detachAttach(Element element) {
        if (element == null) {
            return;
        }

        Node nextSibling = element.getNextSibling();
        Node parent = element.getParentNode();
        if (parent == null) {
            return;
        }

        parent.removeChild(element);
        if (nextSibling == null) {
            parent.appendChild(element);
        } else {
            parent.insertBefore(element, nextSibling);
        }

    }

    public static void sinkOnloadForImages(Element element) {
        NodeList<com.google.gwt.dom.client.Element> imgElements = element
                .getElementsByTagName("img");
        for (int i = 0; i < imgElements.getLength(); i++) {
            DOM.sinkEvents(imgElements.getItem(i), Event.ONLOAD);
        }

    }

    /**
     * Returns the index of the childElement within its parent.
     * 
     * @param subElement
     * @return
     */
    public static int getChildElementIndex(Element childElement) {
        int idx = 0;
        Node n = childElement;
        while ((n = n.getPreviousSibling()) != null) {
            idx++;
        }

        return idx;
    }

    private static void printConnectorInvocations(
            ArrayList<MethodInvocation> invocations, String id,
            ApplicationConnection c) {
        ServerConnector connector = ConnectorMap.get(c).getConnector(id);
        if (connector != null) {
            VConsole.log("\t" + id + " (" + connector.getClass() + ") :");
        } else {
            VConsole.log("\t" + id
                    + ": Warning: no corresponding connector for id " + id);
        }
        for (MethodInvocation invocation : invocations) {
            Object[] parameters = invocation.getParameters();
            String formattedParams = null;
            if (ApplicationConstants.UPDATE_VARIABLE_METHOD.equals(invocation
                    .getMethodName()) && parameters.length == 2) {
                // name, value
                Object value = parameters[1];
                // TODO paintables inside lists/maps get rendered as
                // components in the debug console
                String formattedValue = value instanceof ServerConnector ? ((ServerConnector) value)
                        .getConnectorId() : String.valueOf(value);
                formattedParams = parameters[0] + " : " + formattedValue;
            }
            if (null == formattedParams) {
                formattedParams = (null != parameters) ? Arrays
                        .toString(parameters) : null;
            }
            VConsole.log("\t\t" + invocation.getInterfaceName() + "."
                    + invocation.getMethodName() + "(" + formattedParams + ")");
        }
    }

    static void logVariableBurst(ApplicationConnection c,
            Collection<MethodInvocation> loggedBurst) {
        try {
            VConsole.log("Variable burst to be sent to server:");
            String curId = null;
            ArrayList<MethodInvocation> invocations = new ArrayList<MethodInvocation>();
            for (MethodInvocation methodInvocation : loggedBurst) {
                String id = methodInvocation.getConnectorId();

                if (curId == null) {
                    curId = id;
                } else if (!curId.equals(id)) {
                    printConnectorInvocations(invocations, curId, c);
                    invocations.clear();
                    curId = id;
                }
                invocations.add(methodInvocation);
            }
            if (!invocations.isEmpty()) {
                printConnectorInvocations(invocations, curId, c);
            }
        } catch (Exception e) {
            VConsole.error(e);
        }
    }

    /**
     * Temporarily sets the {@code styleProperty} to {@code tempValue} and then
     * resets it to its current value. Used mainly to work around rendering
     * issues in IE (and possibly in other browsers)
     * 
     * @param element
     *            The target element
     * @param styleProperty
     *            The name of the property to set
     * @param tempValue
     *            The temporary value
     */
    public static void setStyleTemporarily(Element element,
            final String styleProperty, String tempValue) {
        final Style style = element.getStyle();
        final String currentValue = style.getProperty(styleProperty);

        style.setProperty(styleProperty, tempValue);
        element.getOffsetWidth();
        style.setProperty(styleProperty, currentValue);

    }

    /**
     * A helper method to return the client position from an event. Returns
     * position from either first changed touch (if touch event) or from the
     * event itself.
     * 
     * @param event
     * @return
     */
    public static int getTouchOrMouseClientX(Event event) {
        if (isTouchEvent(event)) {
            return event.getChangedTouches().get(0).getClientX();
        } else {
            return event.getClientX();
        }
    }

    /**
     * Find the element corresponding to the coordinates in the passed mouse
     * event. Please note that this is not always the same as the target of the
     * event e.g. if event capture is used.
     * 
     * @param event
     *            the mouse event to get coordinates from
     * @return the element at the coordinates of the event
     */
    public static com.google.gwt.user.client.Element getElementUnderMouse(
            NativeEvent event) {
        int pageX = getTouchOrMouseClientX(event);
        int pageY = getTouchOrMouseClientY(event);

        return getElementFromPoint(pageX, pageY);
    }

    /**
     * A helper method to return the client position from an event. Returns
     * position from either first changed touch (if touch event) or from the
     * event itself.
     * 
     * @param event
     * @return
     */
    public static int getTouchOrMouseClientY(Event event) {
        if (isTouchEvent(event)) {
            return event.getChangedTouches().get(0).getClientY();
        } else {
            return event.getClientY();
        }
    }

    /**
     * 
     * @see #getTouchOrMouseClientY(Event)
     * @param currentGwtEvent
     * @return
     */
    public static int getTouchOrMouseClientY(NativeEvent currentGwtEvent) {
        return getTouchOrMouseClientY(Event.as(currentGwtEvent));
    }

    /**
     * @see #getTouchOrMouseClientX(Event)
     * 
     * @param event
     * @return
     */
    public static int getTouchOrMouseClientX(NativeEvent event) {
        return getTouchOrMouseClientX(Event.as(event));
    }

    public static boolean isTouchEvent(Event event) {
        return event.getType().contains("touch");
    }

    public static boolean isTouchEvent(NativeEvent event) {
        return isTouchEvent(Event.as(event));
    }

    public static void simulateClickFromTouchEvent(Event touchevent,
            Widget widget) {
        Touch touch = touchevent.getChangedTouches().get(0);
        final NativeEvent createMouseUpEvent = Document.get()
                .createMouseUpEvent(0, touch.getScreenX(), touch.getScreenY(),
                        touch.getClientX(), touch.getClientY(), false, false,
                        false, false, NativeEvent.BUTTON_LEFT);
        final NativeEvent createMouseDownEvent = Document.get()
                .createMouseDownEvent(0, touch.getScreenX(),
                        touch.getScreenY(), touch.getClientX(),
                        touch.getClientY(), false, false, false, false,
                        NativeEvent.BUTTON_LEFT);
        final NativeEvent createMouseClickEvent = Document.get()
                .createClickEvent(0, touch.getScreenX(), touch.getScreenY(),
                        touch.getClientX(), touch.getClientY(), false, false,
                        false, false);

        /*
         * Get target with element from point as we want the actual element, not
         * the one that sunk the event.
         */
        final Element target = getElementFromPoint(touch.getClientX(),
                touch.getClientY());

        /*
         * Fixes infocusable form fields in Safari of iOS 5.x and some Android
         * browsers.
         */
        Widget targetWidget = findWidget(target, null);
        if (targetWidget instanceof com.google.gwt.user.client.ui.Focusable) {
            final com.google.gwt.user.client.ui.Focusable toBeFocusedWidget = (com.google.gwt.user.client.ui.Focusable) targetWidget;
            toBeFocusedWidget.setFocus(true);
        } else if (targetWidget instanceof Focusable) {
            ((Focusable) targetWidget).focus();
        }

        Scheduler.get().scheduleDeferred(new ScheduledCommand() {
            @Override
            public void execute() {
                try {
                    target.dispatchEvent(createMouseDownEvent);
                    target.dispatchEvent(createMouseUpEvent);
                    target.dispatchEvent(createMouseClickEvent);
                } catch (Exception e) {
                }

            }
        });

    }

    /**
     * Gets the currently focused element.
     * 
     * @return The active element or null if no active element could be found.
     */
    public native static com.google.gwt.user.client.Element getFocusedElement()
    /*-{
       if ($wnd.document.activeElement) {
           return $wnd.document.activeElement;
       }
       
       return null;
     }-*/;

    /**
     * Gets the currently focused element for Internet Explorer.
     * 
     * @return The currently focused element
     * @deprecated Use #getFocusedElement instead
     */
    @Deprecated
    public static com.google.gwt.user.client.Element getIEFocusedElement() {
        return getFocusedElement();
    }

    /**
     * Kind of stronger version of isAttached(). In addition to std isAttached,
     * this method checks that this widget nor any of its parents is hidden. Can
     * be e.g used to check whether component should react to some events or
     * not.
     * 
     * @param widget
     * @return true if attached and displayed
     */
    public static boolean isAttachedAndDisplayed(Widget widget) {
        if (widget.isAttached()) {
            /*
             * Failfast using offset size, then by iterating the widget tree
             */
            boolean notZeroSized = widget.getOffsetHeight() > 0
                    || widget.getOffsetWidth() > 0;
            return notZeroSized || checkVisibilityRecursively(widget);
        } else {
            return false;
        }
    }

    private static boolean checkVisibilityRecursively(Widget widget) {
        if (widget.isVisible()) {
            Widget parent = widget.getParent();
            if (parent == null) {
                return true; // root panel
            } else {
                return checkVisibilityRecursively(parent);
            }
        } else {
            return false;
        }
    }

    /**
     * Scrolls an element into view vertically only. Modified version of
     * Element.scrollIntoView.
     * 
     * @param elem
     *            The element to scroll into view
     */
    public static native void scrollIntoViewVertically(Element elem)
    /*-{
        var top = elem.offsetTop;
        var height = elem.offsetHeight;
    
        if (elem.parentNode != elem.offsetParent) {
          top -= elem.parentNode.offsetTop;
        }
    
        var cur = elem.parentNode;
        while (cur && (cur.nodeType == 1)) {
          if (top < cur.scrollTop) {
            cur.scrollTop = top;
          }
          if (top + height > cur.scrollTop + cur.clientHeight) {
            cur.scrollTop = (top + height) - cur.clientHeight;
          }
    
          var offsetTop = cur.offsetTop;
          if (cur.parentNode != cur.offsetParent) {
            offsetTop -= cur.parentNode.offsetTop;
          }
           
          top += offsetTop - cur.scrollTop;
          cur = cur.parentNode;
        }
     }-*/;

    /**
     * Checks if the given event is either a touch event or caused by the left
     * mouse button
     * 
     * @param event
     * @return true if the event is a touch event or caused by the left mouse
     *         button, false otherwise
     */
    public static boolean isTouchEventOrLeftMouseButton(Event event) {
        boolean touchEvent = Util.isTouchEvent(event);
        return touchEvent || event.getButton() == Event.BUTTON_LEFT;
    }

    /**
     * Performs a shallow comparison of the collections.
     * 
     * @param collection1
     *            The first collection
     * @param collection2
     *            The second collection
     * @return true if the collections contain the same elements in the same
     *         order, false otherwise
     */
    public static boolean collectionsEquals(Collection collection1,
            Collection collection2) {
        if (collection1 == null) {
            return collection2 == null;
        }
        if (collection2 == null) {
            return false;
        }
        Iterator<Object> collection1Iterator = collection1.iterator();
        Iterator<Object> collection2Iterator = collection2.iterator();

        while (collection1Iterator.hasNext()) {
            if (!collection2Iterator.hasNext()) {
                return false;
            }
            Object collection1Object = collection1Iterator.next();
            Object collection2Object = collection2Iterator.next();
            if (collection1Object != collection2Object) {
                return false;
            }
        }
        if (collection2Iterator.hasNext()) {
            return false;
        }

        return true;
    }

    public static String getConnectorString(ServerConnector p) {
        if (p == null) {
            return "null";
        }
        return getSimpleName(p) + " (" + p.getConnectorId() + ")";
    }

    /**
     * Resolve a relative URL to an absolute URL based on the current document's
     * location.
     * 
     * @param url
     *            a string with the relative URL to resolve
     * @return the corresponding absolute URL as a string
     */
    public static String getAbsoluteUrl(String url) {
        if (BrowserInfo.get().isIE8()) {
            // The hard way - must use innerHTML and attach to DOM in IE8
            DivElement divElement = Document.get().createDivElement();
            divElement.getStyle().setDisplay(Display.NONE);

            RootPanel.getBodyElement().appendChild(divElement);
            divElement.setInnerHTML("<a href='" + escapeAttribute(url)
                    + "' ></a>");

            AnchorElement a = divElement.getChild(0).cast();
            String href = a.getHref();

            RootPanel.getBodyElement().removeChild(divElement);
            return href;
        } else {
            AnchorElement a = Document.get().createAnchorElement();
            a.setHref(url);
            return a.getHref();
        }
    }

}