Calibration Tool: add buttons to start/stop the camera

[matlabbe]

Suggestion from http://official-rtab-map-forum.206.s1.nabble.com/stereo-example-tp10512p10586.html

[nesquik011]

@matlabbe

how the GUI work right now is when we open it , it just start detecting , and it may be laggy or crash so the request will be like

when we open the GUI it will not do anything its on pause , so we could set the data like base line , and size of square
there will be start/stop button and ELP camera check box ( only use if you are using usb stereo camera in case if it lag or ELP brand name also [ Chinese ] )

i posted the updated header and .cpp on the forum , apologize of responding late i forgot i was so excited

thanks in advance

image from my imagination , about the ELP check you can put it back in at the source , this is just an example

[matlabbe]

The UI is generally lagging when the checkerboard is not detected, which could make it difficult to change the checkerboard config before doing calibration. The start/stop button would help to have a responsive UI before starting recording images.

About the ELP mode, do you mean a Step-by-Step recording mode? Like pressing "space-bar" to trigger a sample instead of automatically record new samples?

Overall, to have more control when an image is captured and/or added as sample, we may need to refactor Calibration widget to be the owner of the camera driver to easily pause/start the camera or get a single capture on-demand. Currently, the camera is started in background from the Preferences dialog, then Calibration dialog is just subscribing to published images.