/******************************************************************* 
* Author  : Roy Whittle
* Purpose : To create a zooming effect for images
***********************************************************************/
/*** Create some global variables ***/
if (!window.JSFX)
    JSFX = new Object();
JSFX.ImageZoomRunning = false;
/*******************************************************************
*
* Function    : zoomIn
*
* Description : This function is based on the turn_on() function
*		      of animate2.js (animated rollovers from www.roy.whittle.com).
*		      Each zoom object is given a state. 
*			OnMouseOver the state is switched depending on the current state.
*			Current state -> Switch to
*			===========================
*			null		->	OFF.
*			OFF		->	ZOOM_IN + start timer
*			ZOOM_OUT	->	ZOOM_IN
*			ZOOM_IN_OUT	->	ZOOM_IN
*****************************************************************/
JSFX.zoomOn = function (img, zoomStep, maxZoom) {
    if (img) {
        if (!zoomStep) {
            if (img.mode == "EXPAND")
                zoomStep = img.height / 20;
            else
                zoomStep = img.width / 20;
        }

        if (!maxZoom) {
            if (img.mode == "EXPAND")
                maxZoom = img.height / 3;
            else
                maxZoom = img.width / 3;
        }


        if (img.state == null) {
            img.state = "OFF";
            img.index = 0;
            img.orgWidth = img.width;
            img.orgHeight = img.height;
            img.zoomStep = zoomStep;
            img.maxZoom = maxZoom;
        }

        if (img.state == "OFF") {
            img.state = "ZOOM_IN";
            start_zooming();
        }
        else if (img.state == "ZOOM_IN_OUT"
			|| img.state == "ZOOM_OUT") {
            img.state = "ZOOM_IN";
        }
    }
}
JSFX.zoomIn = function (img, zoomStep, maxZoom) {
    img.mode = "ZOOM";
    JSFX.zoomOn(img, zoomStep, maxZoom);
}
JSFX.stretchIn = function (img, zoomStep, maxZoom) {
    img.mode = "STRETCH";
    JSFX.zoomOn(img, zoomStep, maxZoom);
}
JSFX.expandIn = function (img, zoomStep, maxZoom) {
    img.mode = "EXPAND";
    JSFX.zoomOn(img, zoomStep, maxZoom);
}
/*******************************************************************
*
* Function    : zoomOut
*
* Description : This function is based on the turn_off function
*		      of animate2.js (animated rollovers from www.roy.whittle.com).
*		      Each zoom object is given a state. 
*			OnMouseOut the state is switched depending on the current state.
*			Current state -> Switch to
*			===========================
*			ON		->	ZOOM_OUT + start timer
*			ZOOM_IN	->	ZOOM_IN_OUT.
*****************************************************************/
JSFX.zoomOut = function (img) {
    if (img) {
        if (img.state == "ON") {
            img.state = "ZOOM_OUT";
            start_zooming();
        }
        else if (img.state == "ZOOM_IN") {
            img.state = "ZOOM_IN_OUT";
        }
    }
}
/*******************************************************************
*
* Function    : start_zooming
*
* Description : This function is based on the start_animating() function
*	        	of animate2.js (animated rollovers from www.roy.whittle.com).
*			If the timer is not currently running, it is started.
*			Only 1 timer is used for all objects
*****************************************************************/
function start_zooming() {
    if (!JSFX.ImageZoomRunning)
        ImageZoomAnimation();
}

JSFX.setZoom = function (img) {
    if (img.mode == "STRETCH") {
        img.width = img.orgWidth + img.index;
        img.height = img.orgHeight;
    }
    else if (img.mode == "EXPAND") {
        img.width = img.orgWidth;
        img.height = img.orgHeight + img.index;
    }
    else {
        img.width = img.orgWidth + img.index;
        img.height = img.orgHeight + (img.index * (img.orgHeight / img.orgWidth));
    }
}
/*******************************************************************
*
* Function    : ImageZoomAnimation
*
* Description : This function is based on the Animate function
*		    of animate2.js (animated rollovers from www.roy.whittle.com).
*		    Each zoom object has a state. This function
*		    modifies each object and (possibly) changes its state.
*****************************************************************/
function ImageZoomAnimation() {
    JSFX.ImageZoomRunning = false;
    for (i = 0; i < document.images.length; i++) {
        var img = document.images[i];
        if (img.state) {
            if (img.state == "ZOOM_IN") {
                img.index += img.zoomStep;
                if (img.index > img.maxZoom)
                    img.index = img.maxZoom;

                JSFX.setZoom(img);

                if (img.index == img.maxZoom)
                    img.state = "ON";
                else
                    JSFX.ImageZoomRunning = true;
            }
            else if (img.state == "ZOOM_IN_OUT") {
                img.index += img.zoomStep;
                if (img.index > img.maxZoom)
                    img.index = img.maxZoom;

                JSFX.setZoom(img);

                if (img.index == img.maxZoom)
                    img.state = "ZOOM_OUT";
                JSFX.ImageZoomRunning = true;
            }
            else if (img.state == "ZOOM_OUT") {
                img.index -= img.zoomStep;
                if (img.index < 0)
                    img.index = 0;

                JSFX.setZoom(img);

                if (img.index == 0)
                    img.state = "OFF";
                else
                    JSFX.ImageZoomRunning = true;
            }
        }
    }
    /*** Check to see if we need to animate any more frames. ***/
    if (JSFX.ImageZoomRunning)
        setTimeout("ImageZoomAnimation()", 40);
}