Wayland D bindings

D bindings to wayland.

There are several components:

• Scanner: XML protocol parser and code generator. It generates high level objects.

  • support for client and server side code generation.
  • support foreign protocols (such as xdg-shell. See the simple-egl example)

• Client: client protocol and libwayland-client native API wrapped into higher level objects.

• EGL: allow use of wayland-egl (see this example).

• Server: server side protocol and bindings to libwayland-server to allow the creation of a compositor.

Scanner usage

$ dub run wayland:scanner -- -h
wayland:scanner-v0.1.0
  A Wayland protocol scanner and D code generator.

Options:
-c   --code generated code: client|server [client]
-i  --input input file [stdin]
-o --output output file [stdout]
-m --module D module name (required)
-h   --help This help information.

Client usage

Add the wayland:client dependency in your dub.json:

"dependencies": {
    "wayland:client": "~>0.1.0"
}

The main wayland protocol is automatically generated by the scanner as a pre-build step of wayland:client. To use other protocols, the scanner must be used and XML protocol definition provided by the application. See the simple-egl example that uses the xdg-shell protocol.

Requests

Requests are made by calling methods on the WlProxy objects generated by the protocol. For example:

WlSurface surf = makeSurf();
WlBuffer buf = makeBuf();
surf.attach(buf, 0, 0);

As described in the protocol, some requests are void, others return a new object.

Events

Events are listened to by registering a delegate in the WlProxy objects. See WlRegistry.onGlobal in the example hereunder.

Example of client code

import wayland.client;
import std.exception;
import std.stdio;

void main()
{
    auto display = enforce(WlDisplay.connect());
	scope(exit) display.disconnect();

    auto reg = enforce(display.getRegistry());
	scope(exit) reg.destroy();

    reg.onGlobal = (WlRegistry /+reg+/, uint /+name+/, string iface, uint /+ver+/) {
        writeln("registering ", iface);
    };
    display.roundtrip();
}

Server usage

In the current implementation of the bindings, handling client requests is done by subclassing the WlGlobal and WlResource subclasses generated by the protocol. All protocol-generated classes that have requests are abstract. In the requests creating new resources, the application must therefore return a subclass object that implement the protocol requests.

Events are sent to clients by calling the send[EventName] methods of resource objects.

A part of the main protocol is implemented natively by libwayland-server. This is the case of wl_shm and wl_shm_pool. A consequence of this is that wl_buffer objects are not created under the application control. To create a WlBuffer subclass object that implement the requests, it is required to listen to native resource creation:

class Compositor : WlCompositor
{
    ...
	void newClientConnection(WlClient cl)
	{
		cl.addNativeResourceCreatedListener((wl_resource* natRes) {
			import core.stdc.string : strcmp;
			if (strcmp(wl_resource_get_class(natRes), "wl_buffer") == 0) {
				new Buffer(natRes);
			}
		});
	}
}

class Buffer : WlBuffer
{
    ...
}

See the compositor example that implement a quick and dirty compositor. It is not a good design of compositor, it only illustrates the bindings mechanics.

Playground

You can run the examples if you are under a wayland compositor:

dub run wayland:list_registry

For some of the examples, this only works if you cd first to the project root directory:

git clone https://github.com/rtbo/wayland-d.git
cd wayland-d
dub run wayland:hello