Progress of this project
Some weeks ago I had really need this simple test for ASP (and ASP.Net also), but I found
only some very long codes with css or some script generating bmp images. I have decided to use some simple code
with public object, Chart from Office web components
The component works on most Windows 2000 or 2003 hostings (please see licensing note on the download
page if you have your own hosting)
How it works inside
Some of such object is a Chart object from
Office web components
You can generate a gif picture in a short code using the component:
Set Chs = CreateObject("OWC10.ChartSpace")
Chs.ExportPicture "c:\temp\image.gif", , 120, 55
And there is a quick way to captcha image - simple add a chart,
create a title (HasTitle = True), write some text to the title (Caption = inText), set
font family and size and the image finished.
'Get chart constants
Dim chConstants: Set chConstants = Chs.Constants
'Get a chart object
Dim Chart: Set Chart = Chs.Charts.Add
'Enable title for the chart.
Chart.HasTitle = True
'Set the text and properties.
Chart.Title.Caption = inText
Chart.Title.Font.Name = "Algerian" '"Algerian"
Chart.Title.Font.Size = 20
The last thing to do is to set some background patterns,
font styles, sizes and colors to make harder to read the text by automated program. You can use several
Interior object, the best
of them for this usage is a
There are several preset patterns and colors gallery in the office web components library. You can see some of them bellow:
The chart is created. Now you can export the "chart" (empty chart with title only) by
method of the chartspace object. Then I used ReadBinaryFile
VBS function to retrieve the stored image from a disk and BinaryWrite method to show the image on client.
Performance of the script
There is no problem with performance of the
image generating script. I tested office web components with very high load also,
and my code using OWC can handle up to 200 requests/second on AMD 3000+. (I mean you never reach the limit :-)
What other you can do with OWC?
OWC is a powerful component for charts and server work.
One of very simple task is Gradient generator