I have an ASP.Net page that contains a <div> with an <img> tag within. The image is large so the <div> is set with a size of 500x500 pixels with overflow set to scroll.
I'm attempting to add image panning using a click and drag on the image. However, every time I begin dragging the image escapes the boundary of the element and consumes the entire page.
Here is example code that illustrates the problem:
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<div id="divInnerDiv" style="overflow:scroll; width:500px; height:500px; cursor:move;">
<img id="imgTheImage" src="Page0001.jpg" border="0" />
</div>
<script type="text/javascript">
document.onmousemove = mouseMove;
document.onmouseup = mouseUp;
var dragObject = null;
var mouseOffset = null;
function mouseCoords(ev){
if(ev.pageX || ev.pageY){
return {x:ev.pageX, y:ev.pageY};
}
return {
x:ev.clientX + document.body.scrollLeft - document.body.clientLeft,
y:ev.clientY + document.body.scrollTop - document.body.clientTop
};
}
function getMouseOffset(target, ev){
ev = ev || window.event;
var docPos = getPosition(target);
var mousePos = mouseCoords(ev);
return {x:mousePos.x - docPos.x, y:mousePos.y - docPos.y};
}
function getPosition(e){
var left = 0;
var top = 0;
while (e.offsetParent){
left += e.offsetLeft;
top += e.offsetTop;
e = e.offsetParent;
}
left += e.offsetLeft;
top += e.offsetTop;
return {x:left, y:top};
}
function mouseMove(ev) {
ev = ev || window.event;
var mousePos = mouseCoords(ev);
if(dragObject){
dragObject.style.position = 'absolute';
dragObject.style.top = mousePos.y - mouseOffset.y;
dragObject.style.left = mousePos.x - mouseOffset.x;
return false;
}
}
function mouseUp(){
dragObject = null;
}
function makeDraggable(item){
if(!item) return;
item.onmousedown = function(ev){
dragObject = this;
mouseOffset = getMouseOffset(this, ev);
return false;
}
}
makeDraggable(document.getElementById("imgTheImage"));
</script>
</div>
</form>
</body>
</html>
Also note that this HTML works fine in a non-ASP.Net page.
Is there something in the ASP.Net Javascript that is causing this issue? Does anyone have a suggestion for panning a JPEG within a <div> block that will work in ASP.Net? I have tried using the jQueryUI library but the result is the same.