utils.js

老外的在线考试

/*
 * CyberTester - J2EE Web application for creating, delivering and managing tests/exams/surveys. 
 * Copyright (C) 2003 CyberDemia Research and Services Pty Ltd
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (see the file COPYING); if not, write to the
 * Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * See the COPYING file located in the top-level-directory of
 * the archive of this program for complete text of license.
 */

/*
Provides cross-browser interface for basic functions. 
Browser differences are handled here.
*/

var bIE = (document.all) ? true : false;
var bOPERA = (navigator.userAgent.toLowerCase().indexOf('opera')!=-1);

/*
Gets the width of the document in the specified window object.
*/
function getDocWidth(theWin) {
    if (bIE) {
        return theWin.document.body.clientWidth;
    }
    return theWin.innerWidth;
}

/*
Gets the height of the document in the specified window object.
*/
function getDocHeight(theWin) {
    if (bIE) {
        return theWin.document.body.clientHeight;
    }
    return theWin.innerHeight;
}

/*
Gets X scroll position of specified window
*/
function getScrollX(theWin) {
    if (bIE) {
        return theWin.document.body.scrollLeft;
    }
    return theWin.scrollX;
}

/*
Gets Y scroll position of specified window
*/
function getScrollY(theWin) {
    if (bIE) {
        return theWin.document.body.scrollTop;
    }
    return theWin.scrollY;
}

/*
Sets the left, top, width and height style properties of the element
with specified ID in the specified window.
The properties must be specified as integers (pixels).
To leave out a particular property, just pass in "" (or any non-integer String).
For example: To set left & top properties and leave out width & height :
    setElemByIdBounds( window.self, "button1", 200, 50, "", "");
*/
function setElemByIdBounds( theWin, id, posLeft, posTop, width, height ) {
    setElemBounds( theWin.document.getElementById( id ), posLeft, posTop, width, height );
}

/*
Sets the left, top, width and height style properties of the
specified element object.
The properties must be specified as integers (pixels).
To leave out a particular property, just pass in "" (or any non-integer String).
For example: To set left & top properties and leave out width & height :
    setElemBounds( button1Ref, 200, 50, "", "");
*/
function setElemBounds( elem, posLeft, posTop, width, height ) {
    if (elem) {
        if (elem.style) {
            if (bIE || bOPERA) {
                if (!isNaN(parseInt(posTop))) {
                    elem.style.pixelTop = posTop;
                }
                if (!isNaN(parseInt(posLeft))) {
                    elem.style.pixelLeft = posLeft;
                }
                if (!isNaN(parseInt(width))) {
                    elem.style.pixelWidth = width;
                }
                if (!isNaN(parseInt(height))) {
                    elem.style.pixelHeight = height;
                }
            } else {
                if (!isNaN(parseInt(posTop))) {
                    elem.style.top = posTop+'px';
                }
                if (!isNaN(parseInt(posLeft))) {
                    elem.style.left = posLeft+'px';
                }
                if (!isNaN(parseInt(width))) {
                    elem.style.width = width+'px';
                }
                if (!isNaN(parseInt(height))) {
                    elem.style.height = height+'px';
                }
            }

        }
    }
}
 
/*
Gets the top coordinate (pixels) of the element
with specified ID in the specified window.
*/
function getElemByIdTop( theWin, id ) {
    return getElemTop( theWin.document.getElementById( id ) );
}

/*
Gets the top coordinate (pixels) of the specified element object.
*/
function getElemTop( elem ) {
    if (elem) {
        if (elem.style) {
            if (bIE || bOPERA) {
                return elem.style.pixelTop;
            } else {
                var topInt = parseInt(elem.style.top);
                if (isNaN(topInt)) {
                    topInt = 0;
                }
                return topInt;
            }
        }
    }
    return 0;
}

/*
Gets the left coordinate (pixels) of the element
with specified ID in the specified window.
*/
function getElemByIdLeft( theWin, id ) {
    return getElemLeft( theWin.document.getElementById( id ) );
}

/*
Gets the left coordinate (pixels) of the specified element object.
*/
function getElemLeft( elem ) {
    if (elem) {
        if (elem.style) {
            if (bIE|| bOPERA) {
                return elem.style.pixelLeft;
            } else {
                var leftInt = parseInt(elem.style.left);
                if (isNaN(leftInt)) {
                    leftInt = 0;
                }
                return leftInt;
            }
        }
    }
    return 0;
}

/*
Gets the width (pixels) of the element
with specified ID in the specified window.
*/
function getElemByIdWidth( theWin, id ) {
    return getElemWidth( theWin.document.getElementById( id ) );
}

/*
Gets the width (pixels) of the specified element object.
*/
function getElemWidth( elem ) {
    if (elem) {
        if (elem.style) {
            if (bIE|| bOPERA) {
                return elem.style.pixelWidth;
            } else {
                var wInt = parseInt(elem.style.width);
                if (isNaN(wInt)) {
                    wInt = 0;
                }
                return wInt;
            }
        }
    }
    return 0;
}

/*
Gets the height (pixels) of the element
with specified ID in the specified window.
*/
function getElemByIdHeight( theWin, id ) {
    return getElemHeight( theWin.document.getElementById( id ) );
}

/*
Gets the height (pixels) of the specified element object.
*/
function getElemHeight( elem ) {
    if (elem) {
        if (elem.style) {
            if (bIE|| bOPERA) {
                return elem.style.pixelHeight;
            } else {
                var hInt = parseInt(elem.style.height);
                if (isNaN(hInt)) {
                    hInt = 0;
                }
                return hInt;
            }
        }
    }
    return 0;
}

/*
Returns true if val is a number and
    min <= val <= max
Otherwise returns false.
*/
function isIntegerInRange( val, min, max ) {
    if (isNaN(val)) {
        return false;
    }

    if (val < min) {
        return false;
    }
    
    if (val > max) {
        return false;
    }
    
    return true;
}

/*
 Gets the target element of an event. The target is always the
 element that the event originally happens on.
*/
function getEventTarget( evt ) {
    var eTgt = null;
    if ( evt.target ) {
        eTgt = evt.target;
    } else if ( evt.srcElement ) {
        eTgt = evt.srcElement;
    }
    return eTgt;
}

/*
  Gets the x screen position of a window.
*/
function getWindowScreenXPos( win ) {
    if (!isNaN(win.screenX)) {
        return win.screenX;
    }
    return win.screenLeft;
}

/*
  Gets the y screen position of a window.
*/
function getWindowScreenYPos( win ) {
    if (!isNaN(win.screenY)) {
        return win.screenY;
    }
    return win.screenTop;
}

/*
  Gets X offset of an element from the document's left edge.
*/
function getXOffsetFromDocument( elem ) {
    if ( elem==document) {
        return 0;
    }
    var offset = elem.offsetLeft;
    var parent = elem.offsetParent;
    while ((parent!=null) && (parent!=document))
    {
        offset = offset + parent.offsetLeft;
        parent = parent.offsetParent;
    }
    return offset;
}

/*
  Gets Y offset of an element from the document's top edge.
*/
function getYOffsetFromDocument( elem ) {
    if ( elem==document) {
        return 0;
    }
    var offset = elem.offsetTop;
    var parent = elem.offsetParent;
    while ((parent!=null) && (parent!=document))
    {
        offset = offset + parent.offsetTop;
        parent = parent.offsetParent;
    }
    return offset;
}

/*
  Checks if specified element contains coordinates xpos,ypos
  relative to the top-left corner of the document.
*/
function isElemContainsPoint( elem, xpos, ypos ) {
    var elemX = getXOffsetFromDocument(elem);
    var elemY = getYOffsetFromDocument(elem);
    if ( (xpos<elemX) || (xpos>(elemX+elem.offsetWidth))) {
        return false;
    }
    if ( (ypos<elemY) || (ypos>(elemY+elem.offsetHeight))) {
        return false;
    }
    return true;
}

/*
Truncates a string if it is longer than specified maxlen.
*/
function truncateString(str, maxlen) {
    if (str.length>maxlen) {
        if (maxlen>3) {
            return str.substr(0, maxlen-3)+"...";
        } else {
            return "...";
        }
    }
    return str;
}