[SailfishDevel] LED Flash functionality on a real Jolla

[christopher . lamb]

Hi All

As many will know from previous threads, I am well on the way to  
porting an app for paraglider pilots.

A subsidiary yet still important feature {1} that I added to the  
Harmattan version is an emergency flash, using the phone's LED.

Now that I have got the app's main functionality ported and up and  
running on a real Jolla device, I am now trying to get this feature  
working too.

Unfortunately everything I try fails. But as there is a working  
flashlight app in the Harbour, it must be possible by hook or crock.

So far i have tried 3 solutions:


Solution 1)  A C++ plugin exposing QtMultimedia QCamera to QML

This is the solution that works in the Harmattan version of the app,  
and was therefore the first solution I tried to port to the Sailfish  
version.

When I start the flash I  get the following error:

QCameraPrivate::_q_error:171 - Camera error: "The camera service is missing"


Solution 2) QtMultimedia 5.0 Torch QML element

As QtMultimedia offers a Torch Element this seemed an easier and  
cleaner approach.

import QtMultimedia 5.0

Page {
    id: page

    Torch {
        id: torch
        power: 75       // 75% of full power
        enabled: false   // off
        onEnabledChanged: console.log("onEnabledChanged: " + enabled)
    }

However this gives the following errors on app start up.

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'scene-mode' from interface 'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'noise-reduction' from interface  
'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'image-preview-supported-caps' from  
interface 'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'image-capture-supported-caps' from  
interface 'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'flicker-mode' from interface  
'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'exposure' from interface 'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'ev-compensation' from interface  
'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'colour-tone-mode' from interface  
'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'capabilities' from interface  
'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'autofocus' from interface 'GstPhotography'

(QMLTorch:2300): GLib-GObject-CRITICAL **: Object class GstDroidCamSrc  
doesn't implement property 'aperture' from interface 'GstPhotography'
QObject::connect: No such signal CameraBinExposure::valueChanged(int)


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

Thanks

Chris

{1} at about this time last year I discovered that a GPS position is  
enough to get a helicopter close to you, but on a dark and snowy night  
you need a bright light to get it exactly over you.

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