/* ***********************************************************
Example 4-3 (DHTMLapi.js)
"Dynamic HTML:The Definitive Reference"
2nd Edition
by Danny Goodman
Published by O'Reilly & Associates  ISBN 1-56592-494-0
http://www.oreilly.com
Copyright 2002 Danny Goodman.  All Rights Reserved.
************************************************************ */
// DHTMLapi.js custom API for cross-platform
// object positioning by Danny Goodman (http://www.dannyg.com).
// Release 2.0. Supports NN4, IE, and W3C DOMs.

// Global variables
var isCSS, isW3C, isIE4, isNN4;
// Global "corrector" for IE/Mac et al., but doesn't hurt others
// (this is for centerIt function only)
var fudgeFactor = {top:-1, left:-1};
// initialize upon load to let all browsers establish content objects
function initDHTMLAPI() {
    if (document.images) {
        isCSS = (document.body && document.body.style) ? true : false;
        isW3C = (isCSS && document.getElementById) ? true : false;
        isIE4 = (isCSS && document.all) ? true : false;
        isNN4 = (document.layers) ? true : false;
        isIE6CSS = (document.compatMode && document.compatMode.indexOf("CSS1") >= 0) ? true : false;
    }
}

// Seek nested NN4 layer from string name
function seekLayer(doc, name) {
    var theObj;
    for (var i = 0; i < doc.layers.length; i++) {
        if (doc.layers[i].name == name) {
            theObj = doc.layers[i];
            break;
        }
        // dive into nested layers if necessary
        if (doc.layers[i].document.layers.length > 0) {
            theObj = seekLayer(document.layers[i].document, name);
        }
    }
    return theObj;
}

// Convert object name string or object reference
// into a valid element object reference
function getRawObject(obj) {
    var theObj;
    if (typeof obj == "string") {
        if (isW3C) {
            theObj = document.getElementById(obj);
        } else if (isIE4) {
            theObj = document.all(obj);
        } else if (isNN4) {
            theObj = seekLayer(document, obj);
        }
    } else {
        // pass through object reference
        theObj = obj;
    }
    return theObj;
}

// Convert object name string or object reference
// into a valid style (or NN4 layer) reference
function getObject(obj) {
    var theObj = getRawObject(obj);
    if (theObj && isCSS) {
        theObj = theObj.style;
    }
    return theObj;
}

// Position an object at a specific pixel coordinate
function shiftTo(obj, x, y) {
    var theObj = getObject(obj);
    if (theObj) {
        if (isCSS) {
            // equalize incorrect numeric value type
            var units = (typeof theObj.left == "string") ? "px" : 0 
            theObj.left = x + units;
            theObj.top = y + units;
        } else if (isNN4) {
            theObj.moveTo(x,y)
        }
    }
}

// Move an object by x and/or y pixels
function shiftBy(obj, deltaX, deltaY) {
    var theObj = getObject(obj);
    if (theObj) {
        if (isCSS) {
            // equalize incorrect numeric value type
            var units = (typeof theObj.left == "string") ? "px" : 0 
            theObj.left = getObjectLeft(obj) + deltaX + units;
            theObj.top = getObjectTop(obj) + deltaY + units;
        } else if (isNN4) {
            theObj.moveBy(deltaX, deltaY);
        }
    }
}

// Set the z-order of an object
function setZIndex(obj, zOrder) {
    var theObj = getObject(obj);
    if (theObj) {
        theObj.zIndex = zOrder;
    }
}

// Set the background color of an object
function setBGColor(obj, color) {
    var theObj = getObject(obj);
    if (theObj) {
        if (isNN4) {
            theObj.bgColor = color;
        } else if (isCSS) {
            theObj.backgroundColor = color;
        }
    }
}

// Set the visibility of an object to visible
function show(obj) {
    var theObj = getObject(obj);
    if (theObj) {
        theObj.visibility = "visible";
    }
}

// Set the visibility of an object to hidden
function hide(obj) {
    var theObj = getObject(obj);
    if (theObj) {
        theObj.visibility = "hidden";
    }
}

// Retrieve the x coordinate of a positionable object
function getObjectLeft(obj)  {
    var elem = getRawObject(obj);
    var result = 0;
    if (document.defaultView) {
        var style = document.defaultView;
        var cssDecl = style.getComputedStyle(elem, "");
        result = cssDecl.getPropertyValue("left");
    } else if (elem.currentStyle) {
        result = elem.currentStyle.left;
    } else if (elem.style) {
        result = elem.style.left;
    } else if (isNN4) {
        result = elem.left;
    }
    return parseInt(result);
}

// Retrieve the y coordinate of a positionable object
function getObjectTop(obj)  {
    var elem = getRawObject(obj);
    var result = 0;
    if (document.defaultView) {
        var style = document.defaultView;
        var cssDecl = style.getComputedStyle(elem, "");
        result = cssDecl.getPropertyValue("top");
    } else if (elem.currentStyle) {
        result = elem.currentStyle.top;
    } else if (elem.style) {
        result = elem.style.top;
    } else if (isNN4) {
        result = elem.top;
    }
    return parseInt(result);
}

// Retrieve the rendered width of an element
function getObjectWidth(obj)  {
    var elem = getRawObject(obj);
    var result = 0;
    if (elem.offsetWidth) {
        result = elem.offsetWidth;
    } else if (elem.clip && elem.clip.width) {
        result = elem.clip.width;
    } else if (elem.style && elem.style.pixelWidth) {
        result = elem.style.pixelWidth;
    }
    return parseInt(result);
}

// Retrieve the rendered height of an element
function getObjectHeight(obj)  {
    var elem = getRawObject(obj);
    var result = 0;
    if (elem.offsetHeight) {
        result = elem.offsetHeight;
    } else if (elem.clip && elem.clip.height) {
        result = elem.clip.height;
    } else if (elem.style && elem.style.pixelHeight) {
        result = elem.style.pixelHeight;
    }
    return parseInt(result);
}


// Return the available content width space in browser window
function getInsideWindowWidth() {
    if (window.innerWidth) {
        return window.innerWidth;
    } else if (isIE6CSS) {
        // measure the html element's clientWidth
        return document.body.parentElement.clientWidth
    } else if (document.body && document.body.clientWidth) {
        return document.body.clientWidth;
    }
    return 0;
}
// Return the available content height space in browser window
function getInsideWindowHeight() {
    if (window.innerHeight) {
        return window.innerHeight;
    } else if (isIE6CSS) {
        // measure the html element's clientHeight
        return document.body.parentElement.clientHeight
    } else if (document.body && document.body.clientHeight) {
        return document.body.clientHeight;
    }
    return 0;
}

// Center a positionable element whose name is passed as 
// a parameter in the current window/frame, and show it
function centerIt(layerName) {
    // 'obj' is the positionable object
    var obj = getRawObject(layerName);
    // set fudgeFactor values only first time
    if (fudgeFactor.top == -1) {
        if ((typeof obj.offsetTop == "number") && obj.offsetTop > 0) {
            fudgeFactor.top = obj.offsetTop;
            fudgeFactor.left = obj.offsetLeft;
        } else {
            fudgeFactor.top = 0;
            fudgeFactor.left = 0;
        }
        if (obj.offsetWidth && obj.scrollWidth) {
            if (obj.offsetWidth != obj.scrollWidth) {
                obj.style.width = obj.scrollWidth;    
            }
        }
    }
    var x = Math.round((getInsideWindowWidth()/2) - (getObjectWidth(obj)/2));
    var y = Math.round((getInsideWindowHeight()/2) - (getObjectHeight(obj)/2));
    shiftTo(obj, x - fudgeFactor.left, y - fudgeFactor.top);
    show(obj);
}

// Horizontally center a positionable element whose name is passed as 
// a parameter in the current window/frame, and show it
function centerX(layerName, y_position) {
    // 'obj' is the positionable object
    var obj = getRawObject(layerName);
    // set fudgeFactor values only first time
    if (fudgeFactor.top == -1) {
        if ((typeof obj.offsetTop == "number") && obj.offsetTop > 0) {
            fudgeFactor.top = obj.offsetTop;
            fudgeFactor.left = obj.offsetLeft;
        } else {
            fudgeFactor.top = 0;
            fudgeFactor.left = 0;
        }
        if (obj.offsetWidth && obj.scrollWidth) {
            if (obj.offsetWidth != obj.scrollWidth) {
                obj.style.width = obj.scrollWidth;    
            }
        }
    }
    var x = Math.round((getInsideWindowWidth()/2) - (getObjectWidth(obj)/2));
    var y = y_position;
    shiftTo(obj, x - fudgeFactor.left, y - fudgeFactor.top);
    show(obj);
}

// Vertically center a positionable element whose name is passed as 
// a parameter in the current window/frame, and show it
function centerY(layerName) {
    // 'obj' is the positionable object
    var obj = getRawObject(layerName);
    // set fudgeFactor values only first time
    if (fudgeFactor.top == -1) {
        if ((typeof obj.offsetTop == "number") && obj.offsetTop > 0) {
            fudgeFactor.top = obj.offsetTop;
            fudgeFactor.left = obj.offsetLeft;
        } else {
            fudgeFactor.top = 0;
            fudgeFactor.left = 0;
        }
        if (obj.offsetWidth && obj.scrollWidth) {
            if (obj.offsetWidth != obj.scrollWidth) {
                obj.style.width = obj.scrollWidth;    
            }
        }
    }
    var x = Math.round(getObjectLeft(obj));
    var y = Math.round((getInsideWindowHeight()/2) - (getObjectHeight(obj)/2));
    shiftTo(obj, x - fudgeFactor.left, y - fudgeFactor.top);
    show(obj);
}

// Special handling for CSS-P redraw bug in Navigator 4
function handleResize() {
    if (isNN4) {
        // causes extra re-draw, but gotta do it to get banner object color drawn
        location.reload();
    } else {
        centerIt("main");
    }
}

// still testing this one...
function limitAutoWidth(obj, maxWidth) {
	var width;
	width = getObjectWidth(obj);
	if (width >= maxWidth)
		obj.style.width = maxWidth;
	else if (width < maxWidth)
		obj.style.width = "auto";
}