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serenity/Documentation/Browser/AddNewIDLFile.md
Andreas Kling 6f433c8656 LibWeb+LibJS: Make the EventTarget hierarchy (incl. DOM) GC-allocated
This is a monster patch that turns all EventTargets into GC-allocated
PlatformObjects. Their C++ wrapper classes are removed, and the LibJS
garbage collector is now responsible for their lifetimes.

There's a fair amount of hacks and band-aids in this patch, and we'll
have a lot of cleanup to do after this.
2022-09-06 00:27:09 +02:00

2.1 KiB

Adding a new IDL file

Serenity's build system does a lot of work of turning the IDL from a Web spec into code, but there are a few things you'll need to do yourself.

For the sake of example, let's say you're wanting to add the HTMLDetailsElement.

  1. Create LibWeb/HTML/HTMLDetailsElement.idl with the contents of the IDL section of the spec. In this case, that would be:
[Exposed=Window]
interface HTMLDetailsElement : HTMLElement {
    [HTMLConstructor] constructor();

    [CEReactions] attribute boolean open;
};
  1. If the IDL refers to other IDL types, you need to import those. For example, CSSRule has an attribute that returns a CSSStyleSheet, so that needs to be imported:
#import <CSS/CSSStyleSheet.idl>

interface CSSRule {
    readonly attribute CSSStyleSheet? parentStyleSheet;
};
  1. If the IDL starts with [Exposed=Window], add the following to LibWeb/Bindings/WindowObjectHelper.h:

    • #include <LibWeb/Bindings/HTMLDetailsElementConstructor.h> and
    • #include <LibWeb/Bindings/HTMLDetailsElementPrototype.h> to the includes list.
    • ADD_WINDOW_OBJECT_INTERFACE(HTMLDetailsElement) \ to the macro at the bottom.
  2. Add a libweb_js_wrapper(HTML/HTMLDetailsElement) call to LibWeb/idl_files.cmake

  3. Forward declare the generated classes in LibWeb/Forward.h:

    • HTMLDetailsElement in its namespace.
    • HTMLDetailsElementWrapper in the Web::Bindings namespace.
  4. The C++ class equivalent of the IDL interface has a few requirements:

    • It must inherit from public RefCounted<HTMLDetailsElement> and public Bindings::Wrappable
    • It must have a public using WrapperType = Bindings::HTMLDetailsElementWrapper;
  5. If your type isn't an Event or Element, you will need to add it to is_wrappable_type() so that it can be accepted as an IDL parameter, attribute or return type.