[PATCH 03/10] cms-helper/static: Add "identity" builtin cms profile (v2)

[Mario Kleiner]

On 06/26/2015 08:29 PM, Derek Foreman wrote:
> On 21/06/15 02:25 PM, Mario Kleiner wrote:
>> Allows to force loading an identity gamma table if
>> option icc_profile=identity is given in weston.ini for
>> an output.
>>
>> Some special display output devices, e.g., for
>> neuro-science applications, and special display
>> testing hardware need a guaranteed perfect pixel
>> passthrough from framebuffer to output. This is
>> an easy way to set this up for cms-static.
>>
>> v2: Remove confusing/redundant weston_log debug output.
>>
>> Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
>> ---
>>   src/cms-static.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/src/cms-static.c b/src/cms-static.c
>> index 7166f57..e6073df 100644
>> --- a/src/cms-static.c
>> +++ b/src/cms-static.c
>> @@ -56,7 +56,7 @@ cms_output_created(struct cms_static *cms, struct weston_output *o)
>>   	if (weston_config_section_get_string(s, "icc_profile", &profile, NULL) < 0)
>>   		return;
>>   	p = weston_cms_load_profile(profile);
>> -	if (p == NULL) {
>> +	if (p == NULL && strcmp(profile, "identity")) {
>>   		weston_log("cms-static: failed to load %s\n", profile);
>>   	} else {
>>   		weston_log("cms-static: loading %s for %s\n",
>>
>
> Can we use the empty string instead of "identity"?  Or is it intentional
> that someone could override "identity" with a file of that name?
>

I think there isn't much danger of a mixup with the "identity" keyword, 
as 'profile' otherwise needs to be a full "path/filename" to the color 
profile file. Also these files usually end with a suffix like .icc

I'm not opposed to changing it, but i'd find it a bit confusing to have 
a config option with an empty assignment in the config file a la

icc_profile=

It would look like a configuration error in the config file to me?

> Should we just load an identity gamma curve if there's no profile
> specified anyway?  Or is there a situation where someone wants to mess
> up the gamma curve before launching weston?
>

You could have a setup where the user wants to set a profile on some 
output, e.g., "identity", for such outputs with special display 
equipment connected, but leave it to system defaults on others. E.g., i 
usually have weston with drm/kms backend running on one VT for testing, 
but classic XOrg on another VT for development. It's kind of convenient 
that XOrg will color-manage the outputs which don't get overriden by a 
specific profile.

thanks,
-mario