From: Pekka Paalanen <pekka.paala...@collabora.co.uk> Define what a role is, and what restrictions there are.
A change to existing behaviour is that a role cannot be changed at all once set. However, this is unlikely to cause problems, as there is no reason to re-use wl_surfaces in clients. v2: give more concrete examples of roles, define losing a role, Jasper rewrote the paragraph on how a role is set. Signed-off-by: Pekka Paalanen <pekka.paala...@collabora.co.uk> --- protocol/wayland.xml | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/protocol/wayland.xml b/protocol/wayland.xml index 2d57f69..d3fcaec 100644 --- a/protocol/wayland.xml +++ b/protocol/wayland.xml @@ -973,8 +973,30 @@ local coordinates of the pixel content, in case a buffer_transform or a buffer_scale is used. - Surfaces are also used for some special purposes, e.g. as - cursor images for pointers, drag icons, etc. + A surface without a "role" is fairly useless, a compositor does + not know where, when or how to present it. The role is the + purpose of a wl_surface. Examples of roles are a cursor for a + pointer (as set by wl_pointer.set_cursor), a drag icon + (wl_data_device.start_drag), a sub-surface + (wl_subcompositor.get_subsurface), and a window as defined by a + shell protocol (e.g. wl_shell.get_shell_surface). + + A surface can have only one role at a time. Initially a + wl_surface does not have a role. Once a wl_surface is given a + role, it can never be given a different role again, even if the + wl_surface loses the role in between. + + Surface roles are set by requests in other interfaces such as + wl_pointer.set_cursor. The request should explicitly mention + that this request gives a role to a wl_surface. Often, this + request also creates a new protocol object that represents the + role and adds additional functionality to wl_surface. When a + client wants to destroy a wl_surface, they must destroy this 'role + object' before the wl_surface. + + A wl_surface may lose its role as specified in the interface + that gave it the role or in the interface of the role object. + Losing a role means losing all the role-specific state. </description> <enum name="error"> -- 1.8.5.5 _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/wayland-devel