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backend: Allow overriding the Cogl drivers chain

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We have an hardcoded list of drivers we have to go through when creating
a Cogl context. Some platforms may expose those drivers, but not be the
preferred ones.

In order to allow users and system integrators to override the list of
drivers, we should crib the same approach used by GDK, and have an
environment variable with a list of drivers to try.

The new environment variable is called `CLUTTER_DRIVER` and accepts a
comma-separated list of driver names, which will be tested in sequence
until one succeeds. There's also an additional '*' token which is used
to ask Clutter to fall back to the internally defined preferred list of
drivers.

https://bugzilla.gnome.org/show_bug.cgi?id=742678
This commit is contained in:
Emmanuele Bassi 2015-12-09 12:45:12 +00:00
parent b47e1616eb
commit 2c524fbf73
2 changed files with 73 additions and 23 deletions
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69
clutter/clutter-backend.c
View File

@ -362,38 +362,72 @@ error:
return FALSE;
}
static const struct {
const char *driver_name;
const char *driver_desc;
CoglDriver driver_id;
} all_known_drivers[] = {
{ "gl3", "OpenGL 3.2 core profile", COGL_DRIVER_GL3 },
{ "gl", "OpenGL legacy profile", COGL_DRIVER_GL },
{ "gles2", "OpenGL ES 2.0", COGL_DRIVER_GLES2 },
{ "any", "Default Cogl driver", COGL_DRIVER_ANY },
};
static char *allowed_drivers;
static gboolean
clutter_backend_real_create_context (ClutterBackend *backend,
GError **error)
{
static const struct {
const char *driver_name;
CoglDriver driver_id;
} known_drivers[] = {
{ "GL3", COGL_DRIVER_GL3 },
{ "GL (Legacy)", COGL_DRIVER_GL },
{ "GLES 2.0", COGL_DRIVER_GLES2 },
{ "ANY", COGL_DRIVER_ANY },
};
GError *internal_error = NULL;
const char *drivers_list;
char **known_drivers;
gboolean allow_any;
int i;
for (i = 0; i < G_N_ELEMENTS (known_drivers); i++)
{
CLUTTER_NOTE (BACKEND, "Checking for the %s driver", known_drivers[i].driver_name);
if (allowed_drivers == NULL)
allowed_drivers = "*";
if (clutter_backend_do_real_create_context (backend, known_drivers[i].driver_id, &internal_error))
allow_any = strstr (allowed_drivers, "*") != NULL;
drivers_list = g_getenv ("CLUTTER_DRIVER");
if (drivers_list == NULL)
drivers_list = allowed_drivers;
known_drivers = g_strsplit (drivers_list, ",", 0);
for (i = 0; backend->cogl_context == NULL && known_drivers[i] != NULL; i++)
{
const char *driver_name = known_drivers[i];
gboolean is_any = g_str_equal (driver_name, "*");
int j;
for (j = 0; j < G_N_ELEMENTS (all_known_drivers); j++)
{
if (!allow_any && !is_any && !strstr (driver_name, all_known_drivers[j].driver_name))
continue;
if ((allow_any && is_any) ||
(is_any && strstr (allowed_drivers, all_known_drivers[j].driver_name)) ||
g_str_equal (all_known_drivers[j].driver_name, driver_name))
{
CLUTTER_NOTE (BACKEND, "Checking for the %s driver", all_known_drivers[j].driver_desc);
if (clutter_backend_do_real_create_context (backend, all_known_drivers[j].driver_id, &internal_error))
break;
if (internal_error)
{
CLUTTER_NOTE (BACKEND, "Unable to use the %s driver: %s",
known_drivers[i].driver_name,
all_known_drivers[j].driver_desc,
internal_error->message);
g_clear_error (&internal_error);
}
}
}
}
g_strfreev (known_drivers);
if (backend->cogl_context == NULL)
{
@ -402,13 +436,12 @@ clutter_backend_real_create_context (ClutterBackend *backend,
else
g_set_error_literal (error, CLUTTER_INIT_ERROR,
CLUTTER_INIT_ERROR_BACKEND,
_("Unable to initialize the Clutter backend"));
_("Unable to initialize the Clutter backend: no available drivers found."));
return FALSE;
}
backend->cogl_source = cogl_glib_source_new (backend->cogl_context,
G_PRIORITY_DEFAULT);
backend->cogl_source = cogl_glib_source_new (backend->cogl_context, G_PRIORITY_DEFAULT);
g_source_attach (backend->cogl_source, NULL);
return TRUE;

17
doc/reference/running-clutter.xml
View File

@ -64,6 +64,23 @@
windowing system backends.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CLUTTER_DRIVER</term>
<listitem>
<para>Changes the GL driver used when initializing Clutter.
The allowed values for this environment variable are:</para>
<itemizedlist>
<listitem><simpara>gl3, for the GL driver using a 3.2+ core profile</simpara></listitem>
<listitem><simpara>gl, for the GL driver using a legacy profile</simpara></listitem>
<listitem><simpara>gles2, for the GLES 2.0 driver</simpara></listitem>
<listitem><simpara>any, for the default chosen by Cogl</simpara></listitem>
</itemizedlist>
<para>The special '*' value can be used to ask Clutter to use the
default list of drivers, e.g. 'CLUTTER_DRIVER=gles2,*' will ask Clutter
to try the GLES 2.0 driver first, and then fall back to the default list
of Cogl drivers.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CLUTTER_SCALE</term>
<listitem>