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Core Wayland window system code and protocol
493ab79bd2
When an application and a toolkit share the same Wayland connection,
it will receive events with each others objects. For example if the
toolkit manages a set of surfaces, and the application another set, if
both the toolkit and application listen to pointer focus events,
they'll receive focus events for each others surfaces.
In order for the toolkit and application layers to identify whether a
surface is managed by itself or not, it cannot only rely on retrieving
the proxy user data, without going through all it's own proxy objects
finding whether it's one of them.
By adding the ability to "tag" a proxy object, the toolkit and
application can use the tag to identify what the user data pointer
points to something known.
To create a tag, the recommended way is to define a statically allocated
constant char array containing some descriptive string. The tag will be
the pointer to the non-const pointer to the beginning of the array.
For example, to identify whether a focus event is for a surface managed
by the code in question:
static const char *my_tag = "my tag";
static void
pointer_enter(void *data,
struct wl_pointer *wl_pointer,
uint32_t serial,
struct wl_surface *surface,
wl_fixed_t surface_x,
wl_fixed_t surface_y)
{
struct window *window;
const char * const *tag;
tag = wl_proxy_get_tag((struct wl_proxy *) surface);
if (tag != &my_tag)
return;
window = wl_surface_get_user_data(surface);
...
}
...
static void
init_window_surface(struct window *window)
{
struct wl_surface *surface;
surface = wl_compositor_create_surface(compositor);
wl_surface_set_user_data(surface, window);
wl_proxy_set_tag((struct wl_proxy *) surface,
&my_tag);
}
Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
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| cursor | ||
| doc | ||
| egl | ||
| m4 | ||
| protocol | ||
| src | ||
| tests | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| autogen.sh | ||
| configure.ac | ||
| CONTRIBUTING.md | ||
| COPYING | ||
| Makefile.am | ||
| publish-doc | ||
| README | ||
| releasing.txt | ||
| TODO | ||
| wayland-scanner.m4 | ||
| wayland-scanner.mk | ||
What is Wayland?
Wayland is a project to define a protocol for a compositor to talk to
its clients as well as a library implementation of the protocol. The
compositor can be a standalone display server running on Linux kernel
modesetting and evdev input devices, an X application, or a wayland
client itself. The clients can be traditional applications, X servers
(rootless or fullscreen) or other display servers.
The wayland protocol is essentially only about input handling and
buffer management. The compositor receives input events and forwards
them to the relevant client. The clients creates buffers and renders
into them and notifies the compositor when it needs to redraw. The
protocol also handles drag and drop, selections, window management and
other interactions that must go through the compositor. However, the
protocol does not handle rendering, which is one of the features that
makes wayland so simple. All clients are expected to handle rendering
themselves, typically through cairo or OpenGL.
The weston compositor is a reference implementation of a wayland
compositor and the weston repository also includes a few example
clients.
Building the wayland libraries is fairly simple, aside from libffi,
they don't have many dependencies:
$ git clone https://gitlab.freedesktop.org/wayland/wayland
$ cd wayland
$ ./autogen.sh --prefix=PREFIX
$ make
$ make install
where PREFIX is where you want to install the libraries. See
https://wayland.freedesktop.org for more complete build instructions
for wayland, weston, xwayland and various toolkits.