Customizing HTML5 enterprise apps with Visual WebGui themes

This is the 5th post in our series highlighting new features of Visual WebGui v7. Here we discuss pre-built Visual WebGui themes that come standard with v7 - we will discuss the themes feature generally and show an example of how to customize your app with a theme.
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Designing an HTML5 enterprise app is not the same as building a website

As enterprise app developers know, there are many differences in designing an HTML5 user interface to an enterprise app versus designing a basic website.  While both require a sense of design, managing the look and feel of the many different controls, user input patterns, and screens of an app is different from managing the flat surface of a basic website.  While a high end B2C app may warrant bringing in the skills of UI design specialist and the time to customize the look and feel of all of the controls and other application surfaces, many enterprise app developers building B2B and B2E apps are under budget and time pressure to rapidly adapt their existing apps to web and mobile.  The themes feature within Visual WebGui7 provide an approach to rapidly designing or re-skinning the look and feel of your app with pre-built themes including Android, iOS, Windows, and more.  As an example of how themes work, check out the calendar control in the Visual WebGui CompanionKit. Click "Themes" in the upper right to choose alternate themes and see how it changes the basic look of the calendar control.

Using Visual WebGui themes to design a user interface for HTML5 apps

Visual WebGui themes affect the resulting user interface in 2 broad ways:
  1. Themes  are responsible for how the client application is rendered on a browser.  For example, the theme defines that a TextBox is rendered on the browser as some levels of <div> tags with an <input> tag for the input.
  2. Themes affect how the the core application code drives client side behavior.  For example, the theme also defines that the TextBox input area should be rendered in certain color and font size.
These two purposes are closely related but their separate purposes but are important to understand when thinking through the user interface.

Working with Visual WebGui Themes

A Visual WebGui theme is defined by a set of controls that when applied, are responsible for all appearance and control behavior related properties. The controls in the themes designer are stacked in a TreeView format on the left side of the themes designer screen. When you click on the control level, a properties pane will appear on the right-hand side. Here you are able to customize the properties view of the app’s controls such as its BackColor, its BorderColor, BorderWidth, Font etc. To work on a specific section of a theme, you must work on that section’s family control such as “ButtonBase”, “ComboBox”, “CheckBox”, etc.

Creating a new Visual WebGui Theme

Before we provide an example of customizing an existing theme, we will explain the simple detail of how you create a new theme based on another specific theme. You do this by creating a theme in Visual Studio (Add / New Item / Visual WebGui / Theme…) then you edit the source file for the theme and change the inheritance, so your new theme inherits from a specific theme. It may also deserve a mention that, as with all themes used in a VWG application, you need to register your theme in web.config (through the Registration tab in VS integrations).

Customizing a HTML5 mobile theme

To simplify the explanation of customizing your very own HTML5 mobile theme, we will work on an existing android theme that looks like this:

We would like to change the default ForeColor for this entire mobile theme to the color fuchsia, the ListView border color to red and edit a specific arrow control’s color.
Let’s first customize the ForeColor of this Andriod mobile theme. Select the control level from the TreeView on the Left pane and edit the ForeColor on the properties grid on the right pane as shown below:
The resulting change will appear as follows in the given mobile web application:
As you can see, the ForeColor has changed across the entire app to the color fuchsia. Next, we would like to customize the bottom arrow image in this Android theme. The arrow is part of the ListView family so we would need to select the ListView family control on the left pane. The images associated with this family appear in the middle resources pane. In this example, we will customize the top “ArrowArrowLTR” arrow image. As we can see that it has been inherited to this theme (the small arrow on the bottom left is the sign that it is inherited), we need to save the image to our current theme before we could edit it and therefore we will right click on the image and select “override”.
Now that the image has been copied to our current theme (and is no longer inherited) we can go ahead and edit the image. Simply double click on the image and it will open in your graphic design software. Go ahead and edit it as you wish, change its color or texture if you like. Don’t forget to save it to the theme when you’re done!
Next, we would like to customize the BackColor of the theme from its current default color to red. We do not wish to apply the change to the entire app rather, only to the ListView level, we will choose the ListView family control in the TreeView pane and customize the “BackColor” under the properties pane as shown below:
Once we’re finished, we will be able to view our app with the changes to the theme that we made.

We have our new ForeColor text, ListView BackColor and arrow color and we’re all set!

Considerations when changing pre-built themes

While it is relatively easy and safe to change the simple attributes of a control in a theme(in the property grid, and even override an image), it is important to be aware of the consequences regarding later upgrades once you start overriding any of the xslt, html, js and css resources:
  1. If you override such a resource (say an xslt or js), this resource will keep on being overridden and will contain the data/code it had at the time it was overridden.
  2. If you decide to upgrade your Visual WebGui version in a later stage, this overridden resource will keep on containing the data at the time of the original overriding of that resource. This means that updates/fixes/enhancements Gizmox is making to that particular resource will not be included in your theme, unless you delete the overridden resource, re-override it and re-apply your customizations to that resource.
This fact is highly important as it is overlooked by most users customizing a theme, which causes many frustrations regarding themes during upgrades of Visual WebGui to a newer version. It must be understood that it takes time to do Visual WebGui upgrades, especially where there are heavy theme customizations on the client resources. Further to this, it is most important to understand that customized themes (as are custom control skins) are very dependent on the namespace current when the theme was created. For instance, if you create a theme in a Library project with namespace MyTestLibrary and you edit your customizations to that theme in the same Library project, you will not be able to simply copy that custom theme to your MyRealApplication Visual WebGui application. Rather, you will need to either make sure the custom theme has the same namespace as it originally had, or you need to re-create the theme within the new namespace and re-do the customizations. In the example given, we discussed customizing the “simple property values”. Keep in mind that this does not involve overriding any resource files and the given example is a simple customization example that should be able to survive a VWG upgrade without modifications. Further, keep in mind that this article describes the attributes you set for the actual Html representation of the control and not exactly how the control is constructed.  
Go ahead and start customizing your mobile web app’s look and feel!

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