Concept - Setup for UI themeing and extensibility

Abstract

Themeing and Styling need to be improved, especially the stylesheets are quite a mess as of 5.0-alpha2. Project structure needs to be reviewed to properly modularize styling and widgets, so that apps/views can be properly extended. We expect this concept to lead to proper themeing and styling guidelines, as well as reorganizing and cleaning up the stylesheets.

This concept also belongs to the following user story. Unable to locate Jira server for this macro. It may be due to Application Link configuration.

1. Themeing

Problem

• We don't have true themeing so far, only fields in dialogs have decent styles
  
  • If I add a TextField and a Button in my app, they should also have the Magnolia style
• Stylesheets are a real mess
  
  • They're not properly modularized
  • Some rules don't belong to the right stylesheet
  • Widget styles and app styles are also mixed up inside these stylesheets
  • Some style rules are simply duplicated across several stylesheets (forms vs. dialogs)
• All vaadin standard UI components should look visually integrated into magnolia
• Styling could be applied in a more light-weight way

Proposal

• We have a MagnoliaThemeUI demo vaadin application that features UI components from vaadin, for theme development
  
  • either we put it in an external sandbox, with a dependency to magnolia-ui-theme
  • either we start getting theme outside magnolia_ui, because it has no dep here and can be built upstream
    
    • widgets can also make the move in a second step
• Then we try to give proper Magnolia themeing to other standard vaadin widgets, e.g. error messages, loading indicators
  
  • Maybe we can cleanup our widgets a bit

Decision

• We use SASS
• We cannot specify multiple themes in the @Theme annotation
  
  • But we can add @include SASS rules to use themes as mixins
• We start theme again, picking minimal rules from the existing CSS into new SASS stylesheets
  
  • We inherit the base theme
  • We start with standard vaadin fields
• We ultimately serve on the fly compiled scss only for development

2. Project structure and Widgetset

Problem

• It is hard to relate widget java classes - where style names are set - to their actual CSS rules
• All stylesheets even for widgets are in the theme directory, which is not necessarly bad but should be reviewed
  
  • We want these styles to remain dynamically loaded (not processed at GWT compilation time) so that it's easy to develop them
• We need to review the pattern for applying desktop vs. tablet styles as well
• Package structure of the common-widgets project could be clearer
• Naming of widget classes is inconsistent
  
  • Reevaluate usage of "v-" prefix in style names for magnolia widgets, this is not consistent right now
• As Sasha pointed out, there may also be room for Optimizing the WidgetSet
• There is always only one widgetset. It can aggregate as many other widgetsets (e.g. addons) but ultimately results into one compilation unit
  
  • This is a critical issue because we need to recompile the whole widgetset after installing any module that comes with a custom widget (e.g. dam media editor)

Proposal

• We add the magnolia-ui-theme project (location to be specified)
  
  • we start taking vaadin field styles from widgetset to here, using properly modularized SASS files
• We try to draw a meaningful separation for "shell-only" widgets
• Investigate a possibility to compile the widgetset during runtime. e.g during startup.
  
  • Need to investigate if it is possible to place compiled resources into a location that can be served

Decision

• We align on vaadin7 package structure (client/server/shared)
• We align naming of widget classes
  
  • we try to use *Widget / *Connector consistently
  • we drop client-side naming *View / *ViewImpl
  • we leave the v- prefix for standard vaadin component style names, we use m- prefix for magnolia widget styles
  • we don't use any prefix for application views

3. Extensibility

Problem

• An app developers cannot define styles for her own app in its own module
• It is not clearly specified how an app developer would add a custom widget to her app
• There is no guideline either on how an app developer would add her own icons for her app and actions

Proposal

• We cannot use @Theme annotation for third party apps because theme is set on admincentral
• We use CSSInject to dynamically load an @import rule which references a CSS stylesheet
  
  • optionally we try to reference a SASS one

Decision

-

Suggestion box

• The magnolia theme application could ultimately switch between expected screenshot and actual fields, to help on browser support
• Structure (base directory magnolia_ui):
  
  • magnolia-ui-admincentral
    
    • @Theme("admincentral")
      AdminCentralUI
    • themes
      
      • admincentral
        
        • include magnolia
  • magnolia-ui-theme
    
    • themes
      
      • magnolia
        
        • include base
        • include magnolia-widgets-base
  • magnolia-ui-theme-demo
    
    • @Theme("themedemo")
      MagnoliaThemeDemoUI
    • themes
      
      • themedemo
        
        • include magnolia
  • magnolia-ui-widgetset
    
    • themes
      
      • magnolia-widgets-base
        
        
• Use CSSInject add-on to support third-party app styles https://vaadin.com/directory#addon/cssinject
  
  • Inserts styles into <head><style>...</
  • Can load external stylesheets in this manner:  new CSSInject(getUI()).setStyles("@import url('http://theme files/styles.css');");
  • Set this at App level, eventually processing it in BaseApp
    
• Enable SASS for STK themes