User Tips: A Horizontal Percentage Gauge Class
By Michael Balloni
This handy VBScript class comes from Michael Balloni, who has authored a number of
other articles on 4Guys (view
Michael's 4Guys articles). This tip contains a VBScript class Michael sent in that
creates a horizontal percentage bar gauge. (For information on what, exactly, classes are
and how to use/create them in VBScript, be sure to read: Using
Classes within VBScript!) For example, if you ran a testing site that quizzed
users on some topic, you may wish to show the user their test scores graphically, like so:
You score an 87% on the test. Congratulations!
Michael uses this class on the site he works on, Streamload.com,
to display various percentage information to his users.
With this class, creating such horizontal percentage gauges is a breeze - just instantiate
the class, set a few properties, and call a method to generate the gauge. In fact, the
above example uses the following simple, straightforward code (for brevity the actual class is
not included in this sample code):
<%
Dim sl_gauge
Set sl_gauge = new Slgauge
sl_gauge.BgColor = "#FFFFFF"
sl_gauge.FgColor = "#990000"
sl_gauge.Width = 78
sl_gauge.Height = 5
sl_gauge.MinVal = 0
sl_gauge.MaxVal = 100
sl_gauge.CurVal = iTestScore '87% in our example
%>
<!-- Display the gauge -->
<table cellpadding=0 cellspacing=2>
<tr>
<td>0</td>
<td><% = sl_gauge.RenderHtml %></td>
<td>100%</td>
</tr>
</table>
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That's it! Note that to use this you will have to have a small (43 bytes), transparent GIF
file on your Web server that is used to help properly space out the HTML table that is used
to display the gauge. This image, 1_pix_trans.gif, can be downloaded
here (right click on the link and choose save-as; since
the GIF is transparent, if you click on the link you will be shown the GIF, but you will not
see it (due to its transparency)).
Below you will find the complete source code to the class. Feel free to cut and paste the
code into your application (or you can download
the code in text format). There is also a
live demo to try out.
Happy Programming!
<%
' Handy class for displaying a horizontal percentage gauge.
%>
<%
class Slgauge
' Colors.
public BgColor
public FgColor
' Dimensions.
public Width
public Height
' Values.
public MinVal
public MaxVal
public CurVal
' Render this into HTML as a table.
function RenderHtml
' Normalize the properties.
if MinVal > MaxVal then
Dim temp_val
temp_val = MinVal
MinVal = MaxVal
MaxVal = temp_val
end if
if CurVal < MinVal then
CurVal = MinVal
elseif CurVal > MaxVal then
CurVal = MaxVal
end if
' Figure out the percentage that the CurVal is
' within MinVal and MaxVal.
Dim percentage_val
percentage_val = (CurVal - MinVal) / (MaxVal - MinVal)
' Compute the first and second widths.
Dim fg_width
fg_width = Round(Width * percentage_val)
Dim bg_width
bg_width = Width - fg_width
RenderHtml = "<table cellspacing=0 cellpadding=0 width=" & _
Width & " height=" & Height & ">" _
& "<tr>"
if fg_width > 0 then
RenderHtml = RenderHtml _
& "<td width=" & fg_width & " height=" & _
Height & " bgcolor=" & FgColor & _
"><img src=/demos/Images/" & _
"1_pix_trans.gif></td>"
end if
if bg_width > 0 then
RenderHtml = RenderHtml _
& "<td width=" & bg_width & " height=" & _
Height & " bgcolor=" & BgColor & _
"><img src=/demos/Images/" & _
"1_pix_trans.gif></td>"
end if
RenderHtml = RenderHtml _
& "</tr>" _
& "</table>"
end function
end class
%>
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