Hi Steven,
The solution I can think of is to use a special key (say Control key) along with a mouse click to zoom out. This will need quite a bit of work on your part.
The plot are click event does not provide info about if there was a key press. In order to do this, you will need to manually pass some information from client side to the server side that you had pressed the control key while you clicked. This can be done using a HTML hidden field.
How to pass the control key pressed info from client to server?
1) Add a hidden field (say with id and name attributes set to 'ControlKeyPressed') inside the form that is rendered by default in the .aspx file.
2) At the end of the form, Register the key down and key up events on the document.
3) In the javascript event handlers, when the control key is pressed, set the hidden field's value as 'Y', in all other cases, the hidden field's value will be set to 'N'.
The .aspx code would look something like,
<form id="form1" runat="server">
<!-- IMPORTANT: The hidden field that you would need to pass data to server -->
<input type ="hidden" id="ControlKeyPressed" name="ControlKeyPressed" value="" />
<div>
<ni:WaveformGraph ID="WaveformGraph1" runat="server"
InteractionMode="ZoomX, ZoomY, PlotAreaClick"
onplotareaclick="WaveformGraph1_PlotAreaClick">
<XAxes>
<ni:XAxis>
</ni:XAxis>
</XAxes>
<Plots>
<ni:WaveformPlot XAxis="XAxes[0]" YAxis="YAxes[0]" />
</Plots>
<YAxes>
<ni:YAxis>
</ni:YAxis>
</YAxes>
</ni:WaveformGraph>
</div>
</form>
<!-- Javascript -->
<script type="text/javascript">
function myKeyDownHandler(e) {
if (!e) e = event;
var x = document.getElementById("ControlKeyPressed");
if (e.keyCode == 17) { // check code for contro key.
// If key pressed is control, then set the hidden fields value to 'Y'.
x.value = "Y";
}
else {
x.value = "N";
}
}
function myKeyUpHandler(e) {
if (!e) e = event;
var x = document.getElementById("ControlKeyPressed");
if (e.keyCode == 17) {
// Here the control is is released, so change back the hidden field's value to 'N'.
x.value = "N";
}
}
function init() {
// Attach the events.
if (document.attachEvent) {
document.attachEvent("onkeydown", myKeyDownHandler);
document.attachEvent("onkeypress", myKeyDownHandler);
document.attachEvent("onkeyup", myKeyUpHandler);
}
}
// IMPORTANT: Dont forget to call the init() function once when the document is loaded.
init();
</script>
Now, when there is a PlotAreaClick event fired on the server (here server meaning the C#/VB code), the server maintains the parameters that the client had sent. You can access parameters as follows,
string str = Context.Request.Params["ControlKeyPressed"] as string;
Now, your PlotAreaClick event handler would look something like,
protected void WaveformGraph1_PlotAreaClick(object sender, ClickEventArgs e)
{
if (IsPlotAreaClick())
{
//--------------------------------------------------------------------------------------
// Important Note:
// You will have to maintain a stack to remember the ranges of x/y axes before you set the new ranges.
// Keep the stack in a session variable or an application varaible or make the stack a static variable.
// First, Push the current x/y ranges to the stack.
//--------------------------------------------------------------------------------------
//Then, perform the tasks that you intend to do.
//Set the calculated new range to x/y axes.
WaveformGraph1.XAxes[0].Range = new Range(0, 1); // This is your calculated new range.
WaveformGraph1.YAxes[0].Range = new Range(0, 1); // This is your calculated new range.
}
else
{
//Pop the item from stack and assign the range to x/y axes.
WaveformGraph1.XAxes[0].Range = new Range(0, 10); // here you should use the value popped from stack.
WaveformGraph1.YAxes[0].Range = new Range(0, 10); // here you should use the value popped from stack.
}
}
private bool IsPlotAreaClick()
{
string str = Context.Request.Params["ControlKeyPressed"] as string;
// If the parameter value is 'Y' then that means the action was a zoom back out, not a plot area click.
if (str == "Y")
return false;
else return true;
}
Hope this helps.
Message Edited by vcp on 05-21-2010 09:33 AM
