WinForms, how to implement conditional format for DataGridViews (part 2)

In the previous post I showed you how to implement conditional format functionality for datagridviews using C#, working on conditions that we already know at compile time, which means that those conditions will be written by programmers, not end users.

In this post I’ll show you how to deal with user defined conditional formats, which is a more useful thing to do if what you want to provide this kind of functionality. With this new feature the users are going to be able to write conditions in an Excel fashion (formula like, if you will)

To implement this feature I’ve upgraded the project that we been using for this series to .NET Framework 4.5 in order to use the latest version of the Roslyn compiler. The Roslyn compiler is the backbone of this feature. If you are interested in Roslyn, I made a series on How to build a DSL on top of Roslyn that covers some basic stuff of this great piece of software.

As in the Roslyn DSL series I'll rely on source to source translation to go from the expressions written by users to C# code and then execute that code using the Roslyn APIs.

I’m going to use the same condition that I used in the previous post, but this time instead of using a function written in C# I’ll use a formula written in plain text (the same thing that the end user will do) and use a utility method to compile that formula into a C# function.

If you run the sample app, you will see that the end result is the same that we get with the previous post.

This feature is not ready for prime time yet, on large data sets the performance is not good (sucks, really), there’s no error checking or guidance for syntax errors, we are not persisting the conditional formats and so on and so fort… but I think it’s a good starting point if you have to implement this kind of functionality.

In the meantime I’ll continue working on this feature, sanding off rough edges and posting updates on this blog.

You can get the code from here

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How to create MS Word documents from Office templates using C#

The OpenXML SDK allows you to do pretty much anything you want with office files such as Excel, Word, etc… While many people like this library, I found it complex, unintuitive and poorly documented, not to mention the awful xml format that uses under the hood to represent the documents, styles, etc. So I decided not to use it and build my own solution. If you, like me, don’t like that library, you will find in this post an alternative approach to build word documents from templates using c#.
A neat trick to work with Office is to use the macro recorder to understand how things work. The macro recorder allows you to start a macro, do something by hand, stop it, and then take a look at the generated VBA code. Once you do this, you are pretty much set.
This is how it looks the template I’am going to use.

Note: save the file as a Word template (.dotx)
This is the code to create Word documents from C#:

By running the code, you should get a document that looks like this.

Note that the font, forma…

Printing html using the embedded web browser control

In this post I’ll try to answer some questions about the web browser control and provide some workarounds for known issues involved in the printing process.
I'm assuming that you have some experience with the web browser control and basic knowledge of COM and hosting APIs. So I’m not going to cover those topics.
At the bottom of this page I’ve added the links to download a small library I wrote that takes care of printing HTML and a demo app so you can try it out without having to write any code by yourself.
Using the code The HtmlPrinter class will allow you to print html from an URL or just passing the html as string, you can also specify the title and the number of copies you want to print. The code may look something like this: Now that we know how to use the API let get answer some questions.
Why my app crashes when I try to print multiple copies of a page? Well, apparently when you send a lot of print commands to the web browser control, there is a lot of COM crap in between that l…

WinForms, paging the DataGridView the right way

I know this may sound like old history, but in the enterprise world there is still a lot of WinForms development. Just a couple of days ago, I had to implement a custom DataGridView capable to work over a butt load of data (100K+ records) and keep responses times acceptables.
I thought paging will be a good way to go, and as WinForms is pretty old nowadays, I supposed it will be easy to find a couple examples on the web.
While in fact I found examples, all of them were incompletes and/or they wouldn't perform well in real world apps... So I decided to roll my own component and post it online. Hopefully, someone else will find it useful ;).

The bread and butter of this solution relies on LINQ and deferred execution. As LINQ takes care of all complicated work, it was quite easy to implement.
This component also supports conditional format, sorting and some search capabilities, but in this post I will concentrate on paging only (I'll cover the rest of the features in future posts)…

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