Asp.Net Webforms Charting VB.NET Walkthrough

This page includes Visual Basic instructions for VS2015 / VS2012. Click here for C# Instructions.

ProEssentials WebForm interfaces may be used to serve dynamically generated chart images (png jpg) and binary chart states (data and all settings to initialize a chart) to pass to a client side charting exe connected to the internet.

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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 uncompromising 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. This is mostly for proprietary websites needing advanced graphics and user interaction within the browser. Your implementation may also render as png if Internet Explorer is not the current browser.

You will implement server side behavior in pairs of files. One file, either .HTML 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.

Why two webform pages? The answer is that the first webform renders as viewable ascii html and the second webform renders as non-viewable binary data. 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. See a similar pre-built example within the included ProEssentials9/PE8WebDemo 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

Walk-Through:

The following information demonstrates how to create your first ASP.NET / ProEssentials implementation using the C# language. It discusses using ASP.NET to serve up a dynamically generated PNG image. 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 C# 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.

3) Installing WebForms interfaces into Visual Studio.NET

VS2015 - VS2012 Instructions

• Under the Tools menu, select [Choose Toolbox Items...],
• If not selected, left click the [.NET Framework Components] tab,
• Left click the [Browse...] button and find the file "Gigasoft.ProEssentialsWeb.dll" found in the DotNet48\x64 subdirectory where you installed ProEssentials. By default, this should be located at "C:\ProEssentials9\DotNet48\x64\",
• Select the file "Gigasoft.ProEssentialsWeb.dll" and close the [Open File] dialog,
• The [Choose Toolbox Items] dialog should now show 6 highlighted controls: Pe3doWeb, PegoWeb, PepcoWeb, PepsoWeb, PesgoWeb, and Pedo.
• Close the dialog and the 6 new ProEssentials components will be at the bottom of the toolbox.

4) Add a new paragraph to the Default. aspx page as shown. Click the PegoWeb tool icon in palette and drag the tool to your new paragraph. The adjacent image shows what you see using VS2013.

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 graphs, you'll set the properties PeData.Subsets and PeData.Points which define the quantity of data your graph 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.

5) Double check that the RenderingType property within the Properties window shows the default state of ImageMap. If blank, ImageMap is the default, though adding the setting will clarify the project.

Within the Properties window, change the ImageUrl property to "Default2.aspx".

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".

 

6) Double click the PegoWeb tool within the toolbox and this places an instance of the PegoWeb component within "Default2.aspx".

Within the Properties window, change the RenderingTypeproperty to BinaryImageStream.

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

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

NOTE: It is 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. If there is mistakenly 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.

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

Add the following code to the Page_Load event handler. Type a few lines manually to see examples of embedded XML help and other intellisense features.

Once entered, select this code and copy it to clipboard. Similar code will be used within the first webpage code too.

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

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

Paste the above code into the Page_Loadevent handler for "Default.aspx". Thus both "Default.aspx.vb" and "Default2.aspx.vb" now contain similar Page_Load code.

Add one additional line of code to the "Default.aspx.vb" This line will tell the server to produce ImageMap contents so user can click a bar.

The Page_Load handler within "Default.aspx.vb" should look similar as below...

Your project code should look similar to...

8) Within Visual Studio's main menu, select [Window] and then [Default.aspx]. Left click the PegoWeb control within the form to give it the focus. Then left click the [Event] icon within the [Properties] window. Double click the PeImageMap event which opens the file "Default.aspx.vb" located at the PegoWeb1_PeImageMap event handler.

Add the following code to the PegoWeb1.PeImageMap event handler.

9) Save and run the project. Your project will show an image as follows. Move the mouse over a bar and click to see the DataHotSpot / PeImageMap logic in action.

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.

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 one would actually replace Default.aspx's instance of a ProEssentials asp.net control with a simple generic html image tag.

This completes this walkthrough.

Please read the remaining sections within Chapter 2 and review the demo code and documentation that's installed with the eval/product.

Once installed, the demo program can be accessed via shortcut...

Start / ProEssentials v9 / PeDemo

Note that our main charting demo is replicated in WPF and Winform C#.NET,  VB.NET, VC++ MFC, Delphi, Builder all accessible from where you installed ProEssentials.   These are great for modifying an existing demo to test potential modifications before implementing within your applications.