// hide all images
function hide_all()
{
    // look through each of the images
	for (a = 0; a <= 3; a++)
	{
	    // set the display to none
		document.getElementById('image_' + Images[a]).style.display = 'none';
	}
}

// show the event image
function show_event(iEvent)
{
    // if we are looking for event 4, set to zero
	if (iEvent == 4)
	{
		iEvent = 0;
	}
	
	// if we are looking at event zero, set precedent to three
	if (iEvent == 0)
	{
		iPrecedent = 3;
	}
	// else set precedent to the number before
	else
	{
		iPrecedent = iEvent - 1;
	}
	
	// hide all events
	hide_all();
	
	// set the image to be shown
	document.getElementById('image_' + Images[iEvent]).style.display = '';
	
	// change opacity
	opacity('main_image_' + Images[iPrecedent], 100, 0, 2000);
	
	// set the preceding image to be hidden
	document.getElementById('main_image_' + Images[iPrecedent]).style.display = 'none';
	
	// set the current image to be shown
	document.getElementById('main_image_' + Images[iEvent]).style.display = '';
	
	// change opacity
	opacity('main_image_' + Images[iEvent], 0, 100, 2000);
	
	// increment event
	iEvent++;
	
	// repeat after 7 seconds.
	setTimeout('show_event(' + iEvent + ')', 7000);
}

function opacity(id, opacStart, opacEnd, millisec)
{
	//speed for each frame
    var speed = Math.round(millisec / 100);
    var timer = 0;
    
    //determine the direction for the blending, if start and end are the same nothing happens
    if(opacStart > opacEnd)
    {
		for(i = opacStart; i >= opacEnd; i--)
		{
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
    }
    else if(opacStart < opacEnd)
    {
        for (i = opacStart; i <= opacEnd; i++)
        {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
    }
}

//change the opacity for different browsers
function changeOpac(opacity, id)
{
    var object = document.getElementById(id).style;
    object.opacity = (opacity / 100);
    object.MozOpacity = (opacity / 100);
    object.KhtmlOpacity = (opacity / 100);
    object.filter = "alpha(opacity=" + opacity + ")";
} 

function check_sondage(form)
{
	bChecked = false;
	
	for (a = 0; a < iReponses; a++)
	{
		if (form.reponse[a].checked)
		{
			bChecked = true;
		}
	}
	
	if (!bChecked)
	{
		alert('Veuillez choisir une reponse');
		return false;
	}
}

Global = {
    FixPng: function( img )
    {
        if(document.all)
        {
            img.parentNode.style.width = img.offsetWidth;
            img.parentNode.style.height = img.offsetHeight;
            img.parentNode.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled=true, sizingMethod=scale src='" + img.src + "')"
        }
        else
        {
            img.style.visibility = "visible"
        }
    }
}