Contributing to FluentAvalonia

Before contributing:

Please open an issue before submitting a PR to ensure the feature or bug fix you want to provide will be accepted and to ensure I don't already have a fix in the works. PRs created without a corresponding issue and approval that do not fit the exception below may be closed without explanation.

NOTE: If the fix you want to supply is a small change (like typo or other single-line issues), then you may skip the issue. If you are unsure, just open the issue.

Code Style

Note FA does not follow all the most recent guidelines from .net. Some yes, but not all. I'm stuck in my ways, sorry in advance.

• Order of C# files:
  • Constructors (instance then static)
  • AvaloniaProperties
  • CLR properties
  • RoutedEvents
  • CLR events
  • Override methods
  • Public/internal methods
  • Private methods
  • Fields, constants, and static members
• If a C# file has more than 3-4 AvaloniaProperties, all AvaloniaProperties, CLR properties, RoutedEvents, and Events should be moved into a separate partial class file with a .prop.cs or .properties.cs extension.
  • Fields can also go in this file (especially if any DirectPropertys)
• Use of var or Type of left-hand side of assignment is up to you. But, do not use var in a traditional for-loop
• Do NOT enable nullable reference types.

Ensure maximum readility and understanding by not hiding details behind the compiler. Operate under the assumption that tooltips and intellisense aren't available:

• Do NOT use new() syntax (e.g., x = new MyClass()). Always include the type on the right-hand side of assignment expressions.
• Do not use primary constructors for non record items. (I don't even like it there, but it is what it is)
• Do not use collection expressions. Please make sure an explicit collection type is on the right-hand side of assignment expressions.
  • Instead use Collection initializers, which are far superior and ensure maximum readibility
• Avoid using the field keyword. Just add the field, it's not that hard.
  • I won't reject new additions with this, but I will reject changes to existing files for this.

For Xaml files:

• When naming controls in a template, do NOT use the PART_ prefix. This is only necessary in the controls inherited from Avalonia where this is used. FluentAvalonia controls should not follow this old WPF convention.
• Identation should be 4 spaces
• When adding properties to a Control, the first property should be on the line with the item, then all remaining properties should be on a separate line aligned to the first property.

<TextBlock Foreground="White"
           Text="My text here"
           Width="50" />

If the properties and values are small (like Width and Height), they may be combined on one line, if desired.

<TextBlock Foreground="White"
           Text="My text here"
           Width="50" Height="50" />

• When adding nested styles inside of ControlThemes:
  • If the nested style is pseudo-class based, there should be no space between the nesting operator ^ and the class name:

<Style Selector="^:pointerover" />

• If the nesting operator is not immediately followed by a pseudoclass, there should be a space following the ^:

<Style Selector="^ /template/ ContentPresenter" />