Implement initial IVI-shell support with shell integration.

IVI-shell provides a shell interface for Weston, which maps the GENIVI
API (http://www.genivi.org) for In-Vehicle Infotainment as Wayland-Ivi-Extension
(http://wiki.projects.genivi.org/index.php/Wayland_IVI_Extension_Design).

This patch is included in two protocol. The first is ivi-application protocol
which provided by weston. Next is ivi-controller protocol which provided by
Genivi's wayland-ivi-extension.
In IVI use case, the client create and destroy surface with the unique ID
by using ivi-application protocol. On the other hand, the controller such as
HMI Controller control some properties, which are visibility, position, size,
etc, with created the unique ID by using ivi-controller protocol.
It means the unique ID is necessary to create and control the ivi-surface and
the the ivi-layer. However Qt has no API to set the some surface or layer ID.

In this ivi-shell plugin, the unique ID can be set via the environment
parameter so that we can control the ivi-surface and ivi-layer. The
name of environment parameter is QT_IVI_SURFACE_ID.
QT_IVI_SURFACE_ID will be used as ivi-surface and ivi-layer. If application
needs more than two surfaces, ivi-surface IDs will be incremented.
When QT_IVI_SURFACE_ID isn't set, ivi-surface and ivi-layer ID will be
generated internally.  The ID consists of the process ID and the surface
ID which is incremented in ivi-shell plugin.
The process ID is used as lower 22 bit per 32bit. 23 to 32 bit is used as
the surface IDs in a process.
e.g. When the process ID is 0x765 and create two surfaces,
ivi-layer ID is 0x765 and ivi-surface IDs are 0x765 and 0x00400765.
  +------------+---------------------------+
  |31        23|22                        0|
  +------------+---------------------------+
  |0000 0000 00|00 0000 0000 0000 0000 0000|
  |<- ID     ->|<- process ID            ->|
  +------------+---------------------------+

We can set QT_WAYLAND_SHELL_INTEGRATION of the environment
parameter to "ivi-shell" to use IVI-shell.

Change-Id: Iddcfb3de89dc022530c0285524cf6bbf640147b6
Reviewed-by: Giulio Camuffo <giuliocamuffo@gmail.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/README b/README
index f26089766..dcd47d6eb 100644
--- a/README
+++ b/README
@@ -45,6 +45,29 @@ brcm
 xcomposite-egl
 xcomposite-glx
 
+Shell Integration:
+
+Some platforms, especially non-desktop ones, use a custom Wayland shell
+extension. These are tailored to the specific embedded form factor better than
+the generic wl_shell or xdg_shell extensions that target desktop systems.
+
+Instead of adding multiple protocol implementations into the QPA plugin,
+a plugin architecture is used for selecting the shell integration;
+when creating a shell surface, the protocol to use is taken from
+the QT_WAYLAND_SHELL_INTEGRATION environment variable. If one is not provided or
+not pointing to a valid plugin, wl_shell or xdg_shell will be used as fallbacks.
+
+Example Usage:
+
+Starting the hellowindow example application (one of the examples for qtbase)
+with ivi-shell integration:
+
+    QT_WAYLAND_SHELL_INTEGRATION=ivi-shell ./hellowindow -platform wayland
+
+Available Shell Integrations:
+
+    * ivi-shell
+
 
 We hang out at #qt-labs and #qt-lighthouse on freenode if you have any questions