[SailfishDevel] LED Flash functionality on a real Jolla

Artem Marchenko artem.marchenko at gmail.com
Thu Jan 23 10:44:02 UTC 2014

Cool to see that ported, Chris! Are you into porting a tracker such as

I am flying a paraglider myself, so would be interested to help.

As for LED. I did a flashlight that is currently in the app store. Here is
the state of art:

1. Qt Multimedia's torch mode is promised to come, but does not work yet

2. GStreamer way should work and that's what flashlight uses

3. GStreamer library, however, is not allowed to link to in harbour rules,
so you will have to provide your own copy of GStreamer

4. Resource policy is needed, but for now I go around it by just stopping
LED whenever app is not maximized. That's not exactly correct, but will do
for now

5. Note also that you can start LED in a shell by running gst-launch and..
that is actually a workaround flashlight is using while I am figuring out
the resource policy and how to provide gstreamer lib with the app.

I hope it helps.

Best regards,

On Thu, Jan 23, 2014 at 10:16 AM, <christopher.lamb at thurweb.ch> wrote:

> Hi Mohammed
> thanks. I will try that later (am at work at the moment). I will also need
> to look into the resource policy engine, as that is new to me.
> Harbour entry is becoming less and less of a concern for me. My app does
> too many things that are not considered kosher under the current Harbour
> rules (sending SMS direct, use of QtContacts, LED access, other Qt
> Libraries etc.)
> As an aside, on Harmattan while I got the the Gstreamer route working in
> developer mode, I never got it working when launching the app direct from
> the device (and thus chose the QCamera approach). This was probably down to
> AEGIS, but that should not be a concern on the Jolla.
> Chris
> Zitat von "Mohammed Hassan" <mohammed.hassan at jollamobile.com>:
>  On Wed, Jan 22, 2014 at 08:29:19PM +0100, christopher.lamb at thurweb.chwrote:
>> [...]
>>> Solution 3)
>>> Via a Gstreamer QML Plugin.
>>> I dug out some old code that worked on Harmattan, basically the code
>>> from this link to create a qml plugin
>>> http://developer.nokia.com/Community/Wiki/How_to_turn_
>>> your_camera_flash_into_a_torch_on_Harmattan_using_GStreamer
>>> On Sailfish this compiles, but gives the following error when I
>>> start the torch.
>>> (GSTTorch:708): GStreamer-CRITICAL **: gst_element_set_state:
>>> assertion `GST_IS_ELEMENT (element)' failed
>> This is not the recommended way but it's the only way to get flash light
>> to work but I have to
>> warn you that it wil prevent your app from entering harbour. You will
>> also have to make use
>> of resource policy engine to arbitrate access to camera. Failing to do so
>> will lead to breaking
>> jolla camera app.
>> Simply replace subdevsrc with droidcamsrc and use droideglsink as the
>> sink and
>> it should work fine.
>> Cheers,
>> _______________________________________________
>> SailfishOS.org Devel mailing list
> _______________________________________________
> SailfishOS.org Devel mailing list

Artem Marchenko
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