The CSS editor in Visual Studio has unprecedented support for both W3C standards and vendor specific properties, pseudos and @-directives. See the full list here. However, not all vendor specific prefixes are supported, just the major ones: -moz-, -ms-, -o- and -webkit-. In case you have to target really old versions of Safari, it would be nice to have -khtml- as well. Visual Studio 2012 makes it very easy to add support for new properties or to augment existing ones with additional values.

An easy VS extension

Visual Studio extensions or VSIX packages as they are called, have a reputation of being notoriously difficult to write and the documentation is lacking. For adding your own custom schema to the CSS editor, this is most definitely not the case. In fact, it couldn’t be easier.

Step 1: Download and install the Visual Studio 2012 SDK

The SDK is needed for Visual Studio to know how to open extensibility project types.

Step 2: Download the CustomCssSchema project  and open it in VS2012

This project contains the custom -khtml- schema and the ability to compile into an extensibility package – a VSIX. The project is very small as shown below.

The only 2 files we care about for this scenario are the /Schemas/css-vendor-khtml.xml and KhtmlSchemaProvider.cs files. The rest of the files are used by the VSIX to display the right icons and descriptions in the Visual Studio Extension Manager as well as on the VS Gallery website. They are pretty self-explanatory once you open them and look at what they do.

The CSS schema

The css-vendor-khtml.xml schema file is not a complete KHTML schema. It is merely an examples to get you started. Check it out here. It makes it possible to create brand new properties, pseudos and @-directives. You can even inherit from properties already supported by VS and you can add additional property values to existing properties. It’s all explained in the XML file.

The schema provider class

The KhtmlSchemaProvider class is responsible for registering your XML schema file with the CSS editor. It is really simple as you can see below:

That’s all the class does.

Get started

After downloading the SDK and the CustomCssSchema project, just hit F5 in Visual Studio. That launches an instance of Visual Studio. This extensibility instance is called the Experimental instance. Now open a .css file in the Experimental instance and check to see if the -khtml- properties are present in Intellisense. If they are, you are ready to start customizing the css-vendor-khtml.xml file.

The different ways to extend the schema is all explained inside the css-vendor-khtml.xml file itself, so I won’t go in to details here.

You can add multiple XML schema files. As many as you like, actually. Just make sure to create corresponding SchemaProvider classes as well.

Publishing the extension

You are now done with your custom CSS schema extension and want to put it on the VS Gallery for everyone to download. First, you need to locate the .vsix file that is produced every time you build the CustomCssSchema project. It’s in the bin folder.

Now go to the VS Gallery website and sign in using your Live ID credentials. After signing in, this button becomes visible:

Click it. It takes you to the first step of the little upload wizard.

Choose “Tool” and click Next to show the next step where you are going to upload the .vsix file.

Step 3 is basically about adding some tags and descriptions.

That’s it. Your VSIX is now available for everybody to download!!

Extra benefits

When building custom schemas, you get some added benefits you might didn’t consider.

1. Snippets are automatically created to include your custom properties.

All the vendor specific snippets in VS2012 are auto-generated based on the schema files. That means that if you include -khtml-border-radius in your custom schema, that property will now be included in the regular border-radius snippet.

2. Works in LESS and SCSS too

Any editor that is built on top of the VS2012 CSS editor will get the same Intellisense for your custom schema. One such editor is the LESS editor included in Web Essentials 2012.

Happy coding!

Today is a big day for all ASP.NET web developers. Both Visual Studio 2012, Windows 8 and Windows Server 8 is being released to MSDN subscribers.

It is also the day that the first version of Web Essentials for Visual Studio 2012 is being released, or simply Web Essentials 2012. Download it here

As we developed the brand new CSS editor in VS2012, we did it with extensibility in mind. The first Web Essentials for VS2010 already demonstrated what could be done with the old CSS editor, but we wanted to make sure we wouldn’t run into any shortcomings in the extensibility model for VS2012. So the development of Web Essentials 2012 started back in January and it helped shape the extensibility of both the HTML and CSS editors.

Here are some of the most interesting new features.

Browser compatibility checks

Did you remember to use all the vendor specific CSS properties? How would you know if you didn’t? Don’t worry, Web Essentials uses VS2012’s CSS schemas to find out for you. Those schema files are up-to-date with all the vendor specific properties.

You can do quick checks on any property, pseudo class/element or @-directive to get a overview of what browsers are supporting the particular thing your mouse is hovering over. In this case the border-radius property:

In case there are any issues with your CSS file’s browser compatibility, the Messages list will be used to display them.

I’ve build a website that shows you exactly what’s supported by the VS2012 CSS editor. Web Essentials for VS2010 also had this feature, but it has been approved immensely in the new version and is a lot more accurate and up-to-date.

Clicking one of the browser compatibility errors takes you directly to the place in your CSS file where the error occurred. You can now use a Smart Tag to add the missing vendor specific properties.

In a big CSS file, going through the errors one-by-one can be a little time consuming, so it would be nice if you could perform some of these actions for the entire file in just a single click.

See the numbers 1-4 in the context menu? They are numbered like that for a reason. To clean up your stylesheet, start clicking the first menu item. Then move to number 2, then 3 and lastly 4. This ensures that things are done in the right order.

I’ve tested this on really big CSS files up to 15,000 lines with hundreds of browser compatibility errors and it only took a few seconds to run the auto-fix.

LESS, CoffeeScript and Sass

Good news for any LESS or CoffeeScript fans and semi-good news for Sass fans. The LESS editor is the most evolved of the three and you get all the goodness that Web Essentials 2012 brings to CSS directly in your LESS files. CoffeeScript and Sass (only .sass files, not .scss yet!) are supported in terms of colorization, formatting and outlining/code-folding.

The LESS editor does a lot more than just colorize nicely as shown above. It gives you full Intellisense for variables and Mixin’s as well.

Also variables gets a first-class treatment in Intellisense. Hovering a variable will also show you its value.

For both LESS and CoffeeScript, a preview window is shown on the right side of the editor where the compiled CSS or JavaScript respectively, are displayed.

Every time the LESS or CoffeeScript document is saved, the preview window is updated to reflect the changes. Sass doesn’t have this ability in this first release of Web Essentials, but it’s coming. So is support for the new Sass syntax, often referred to as SCSS.

Paste JSON as classes

When you have to work with JSON and especially JSON REST API’s, it can be time consuming and cumbersome to create all your C# classes after what an API is returning. With Web Essentials 2012, that is now very easy.

Let’s say you copied this example JSON from the documentation of some JSON API out on the web.

You could construct the C# class manually based on this JSON string. But you could also just right-click in the C# editor.

Clicking Paste JSON As Classes will parse the copied JSON string from the clipboard and convert it into C# classes.

It uses JSON.NET behind the scenes, just like ASP.NET Web API does, so by using them together you will know that the serialization and deserialization is working as expected.

Improved color workflow

The color squares introduced in Web Essentials for VS2010 has been vastly improved. They now cover all types of colors, including all the new CSS 3 specific color formats.

The color converter has also been updated accordingly.

Let’s say you want to slightly darken or lighten a color in your stylesheet. That is now very easy using SHIFT+CTRL+ARROW UP/DOWN when the cursor is located on a hex color value. I don’t have a image demoing this, so you will have to imagine that the color changes its brightness. The color stays the same, but the brightness is adjusted.

The same shortcut key combination can be used to change any number values as well as move properties or whole rules up and down in the document.

Intellisense everywhere

A lot of work has been put into making Intellisense appear everywhere you might need it. Even as a URL auto-completer.

Animation names are also populated from the keyframes or any vendor specific keyframes implementation as well.

CSS 3 font embedding is of course also supported.

Even the more important ones are covered.

HTML elements, class names and ID’s? Yep, got that too.

   

And a whole lot more.

Download Web Essentials 2012

So that was a brief overview of just a few of the features that I like the most, but there is so much more. Head over to the VS Gallery and check out a list of all the other features available.

Download Web Essentials 2012