Chart Webform-Graphing Asp.Net tutorial in VB.Net with WebForm Api

This page includes instructions for VS2008 / VS2010 / VS2012. See here for VS2005 and earlier.

ProEssentials Chart WebForm is used to serve dynamically generated images (SVG Charts / HTML5 Charts, PNG, JPEG), and ActiveX binary states.

The simplest implementation is using a html IMG tag src="MyDynamicImageBits.asxp" and creating the dedicated MyDynamicImageBits.aspx page to send the image data. For our chart on this WebForm, set RenderingType=BinaryImageStream, and RenderedImageType=SVG or PNG. Your server will produce our default chart. See step 11 below on how this aspx page should look, it's important there's no ascii outside the .net tags.

ProEssentials' web strength is in rendering quality and robustness: Where a chart shape, size, and large annotation property set can automatically produce a quality image packed with details. Our SVG HTML5 chart rendering option is also true vector output and great for HTML5 based reporting where printed output produces razor sharp results via very small file sizes.

ActiveX rendering is an option for those wanting to provide Internet Explorer users with desktop functionality within a webpage. If ActiveX is targeted, we recommend that you also review the standard ASP/ActiveX technical information in Chapter3 and AspReadme. Your webpage's meta tags should target IE8 to force IE's compatibility view mode.

ASP.NET development is very similar to standard ASP development. Generally, you will implement server side behavior in pairs of files much like standard ASP development. One file, either .HTM, .ASP or .ASPX will contain an image tag or ActiveX object tag with source attributes pointing to a secondary .ASPX page which will dynamically generate the respective binary content.

We often get asked why two webform pages are needed. The answer is that the first webform renders as viewable ascii html and the second webform renders as non-viewable binary data streamed directly to the browser. This architecture allows for scalability and efficient processing without the need for passing large amounts of viewstate information back and forth between the client and server. The first form usually contains a ProEssentials object with the RenderingType set to ImageMap or ActiveX. The second form then respectively has a ProEssentials object with the RenderingType set to BinaryImageStream or BinaryActiveXStream. The two forms work in unison to provide the complete ProEssentials implementation. Note the first form can include a ProEssentials object, or if a simple image is needed, can optionally contain an IMG tag pointing the second form with the ProEssentials object's RenderingType set to BinaryImageStream. Similarly, the first form can optionally contain the simple Class ID to our ActiveX and the second form would then contain a ProEssentials object with its RenderingType set to BinaryActiveXStream.

See a similar pre-built example within the included ProEssentials7/PE7WebDemo directory. See example 1-4, with related files within the Walk-Through1, Walk-Through2, Walk-Through3, and Walk-Through4 folders.

The ProEssentials WebForm interfaces have a few key properties and one event which will control server-side specific functionality. These are as follows:

Also, there is one Event and one EventArgs which is used to implement image map support.

It is recommended that the namespace: Gigasoft.ProEssentials.Enums be included at the top of your source code files utilizing ProEssentials. In VB.NET, use the Imports keyword. For example:

Imports Gigasoft.ProEssentials.Enums

Our .NET interfaces currently have limited design time functionality. You will have to write a little code (simple, see below) to develop your graphing solutions. In the end, you'll prefer our .NET (property, method, event) interface. 99% of your code will set simple properties.

Walk-Through:

The following information demonstrates how to create your first ASP.NET / ProEssentials implementation using the Visual Basic language. It discusses using ASP.NET charting interfaces to serve up a dynamically generated PNG image. Other examples are provided within the product/evaluation. Also refer to the "ReadMe.htm", "AspNetReadMe.htm", and "AspReadMe.htm" files installed onto your system with the eval/product (accessible via Start menu).

1) Start Visual Studio.NET and create a new WebSite project targeting an ASP.NET Web Application using VB as our language. Accept the default name of [WebSite1].

2) When the new project opens, you will be presented the design view of "Default.aspx".

If you have already installed the ProEssentials WebForm interfaces, skip to step 4.

Default.aspx [Design]...

Adding ProEssentials to a Form...

4) Double click the [PegoWeb] tool within the toolbox. This places an instance of the PegoWeb component within "Default.aspx". The adjacent image shows what you see. This represents the default state of a ProEssentials Graph. The default state has one subset with four data points. In the course of constructing your own charts, you'll set the properties PeData.Subsets and PeData.Points which define the quantity of data your chart will hold. You'll then pass data via the PeData.Y(subset, point) two dimensional property array. The following section shows example code of passing data. ProEssentials uses the terms Subsets and Points but you can think of these as Rows and Columns. Passing data is as simple as filling each Subset with Points worth of data.

	Adjusting design time settings...
	5) Double check that the RenderingType property within the Properties window shows the default state of ImageMap. 6) Within the Properties window, change the ImageUrl property to "Default2.aspx". 7) Within Visual Studio's main menu, select [WebSite] and then [Add New Item...] and add a new Webform. Accept the default name of "Default2.aspx".

8) Again, double click the PegoWeb tool within the toolbox and this places an instance of the PegoWeb component within "Default2.aspx".

9) Within the Properties window, change the RenderingType property to BinaryImageStream.

10) Within Visual Studio's main menu, select [View] and then [Markup].

11) Remove all HTML content from this page. The resulting Markup or HTML Source content should only be tags...

NOTE: It is very important the entire page looks as above. No ascii characters can be outside < > tags, not even a space character. Any ascii would corrupt the binary data being served to Default.aspx on the client. The client is expecting pure binary data from Default2.aspx which represents an image. If there is mistakenly some ascii, Default.aspx may show a red x instead of an image as the binary data received from server is not recognized as a bitmap.

12) Within Visual Studio's main menu, select [View] and then [Code].

13) Add the following code to the Page_Load event handler. Type it in manually to see examples of embedded XML help and other Intellisense features.

Once entered, select this code and copy it to clipboard.

14) Within Visual Studio's main menu, select [Window] and then "Default.aspx"

15) Within Visual Studio's main menu, select [View] and then [Code]

16) Paste the above code into the Page_Load event handler for "Default.aspx".

17) Add one additional line of code to the "Default.aspx.vb"

So, the Page_Load handler within "Default.aspx.vb" should now contain...

18) At the top of the code window, use the left drop down combo box to select [PegoWeb1]. Then use the right drop down combo box to select [PeImageMap].

19) Add the following code to the _PeImageMap handler...

You should now see...

20) Save and run the project. Your browser will show an image as follows. Move the mouse over bars to see the image map content.

You'll notice that nearly identical code was required for "Default.aspx.vb" and "Default2.aspx.vb" except for the hot spot code which triggers the PeImageMap event. Anytime you develop with image maps, you will need to have similar initialization code for both forms. Also, the control size on both forms must be set to the same size.

This completes this walkthrough. If you do not wish to support image maps, ignore the PeUserInterface.HotSpot and the PeImageMap event handler code. If not using image maps, you will only need code within "Default2.aspx.vb" and could actually replace WebForm1's instance of a ProEssentials WebForm control with a generic html image tag.

For SVG Charting: remove the HotSpot.Data setting from both pages and set RenderedImageType for Default2.aspx from PNG to SVG.

For ActiveX: and working with Internet Explorer, change the RenderingType setting for "Default.aspx" to ActiveX, and the RenderingType setting on "Default2.aspx" to BinaryActiveXStream. Use a meta tag to view as IE8 or set your browser to use Compatibility View. The browser will contain a fully interactive charting control. Right click the control to access the user interface. Read the AspReadme for client-side examples and CAB file issues.