Saving and referencing images

Question

Okay, I can get the charting component to set a directory where it will place the image.
1) What path should I tell it to write the image to?
2) How do I reference that image with a URL?
I hope that makes it easier for y'all to understand and, hopefully, answer. Thanks! --Shibli

Answer 1

Hi Shibli,
I think you misunderstood.
You should read the <a href="https://www.sdn.sap.comhttp://www.sdn.sap.comhttp://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/dotnet/pdk%20for%20.net/developer's%20Guide%20PDK%202.0%20for%20.NET/How%20to/ThirdPartyChartControl.htm">how-to</a> more carefully.
The how-to relies on the fact that a server can return to a client not just html, but also stream files. In order to do that, it changes the mime type and sends the file as a stream.
So what we do is write a portal component that is called actually TWICE. once for the html, and once AGAIN for the image!
first we set the source of an image control to itself (plus a query param).
like this:
Image1.Source = this.iViewPath + "?Chart=Pie";
This will eventually render like this: <IMG SRC="sameiView?Chart=Pie">
when the browser will receive this, it will call the same component AGAIN, only this time in the page load we will intercept the query and not render the regular html but return the actual image as a stream! (see how-to for the code)
Now you still have the question of how to write this code that will stream the image to the client. This is done by either "saving" the bitmap from the chart control directly to the output stream (like in the how-to), or if the chart control can't provide a real bitmap, and can only save a image somewhere (which is very strange by the way), then we will ask the chart to save the image somewhere first and then we will read it from there again to a bitmap, and then "save" it again, this time to the output stream. In both cases we need to change the mime type to "image" (as in the how-to).
Hope that clears up the confusion,
Ofer