Screenshot plugin

[jennuine]

Closes #95

This plugin takes screenshots similar to Gazebo-classic by clicking the camera icon. The plugin uses a screenshot service that saves an image of the current 3D scene from the user camera. The default directory of saved screenshots is ~/.ignition/gui/pictures but users can change the directory by selecting the folder icon.

This can be used along with ign-gazebo's screenshot service in gazebosim/gz-sim#588

EDIT: depends on gazebosim/gz-sim#598

[codecov]

Codecov Report

Merging #170 (c33970b) into ign-gui3 (8fb1564) will decrease coverage by 1.32%.
The diff coverage is 26.41%.

@@             Coverage Diff              @@
##           ign-gui3     #170      +/-   ##
============================================
- Coverage     60.55%   59.23%   -1.33%     
============================================
  Files            21       23       +2     
  Lines          2624     2730     +106     
============================================
+ Hits           1589     1617      +28     
- Misses         1035     1113      +78     

Impacted Files	Coverage Δ
src/plugins/scene3d/Scene3D.cc	12.78% <ø> (ø)
src/plugins/screenshot/Screenshot.cc	25.71% <25.71%> (ø)
src/plugins/screenshot/Screenshot.hh	100.00% <100.00%> (ø)

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[chapulina]

Works for me! Some suggestions below.

Also, do you mind adding some basic tests? Maybe just instantiating the plugin, requesting the service, and checking that a file was created?

[jennuine]

Currently looking into an issue where the colors in the the saved screenshot do not match what is shown in ignition. Here are some examples, the image on the left is ignition and on the right is the saved screenshot:

[chapulina]

Here's a fix for the swapped colors: gazebosim/gz-common#162

[jennuine]

Also, do you mind adding some basic tests? Maybe just instantiating the plugin, requesting the service, and checking that a file was created?

Added a simple test that only instantiates plugin e8c3cd2. The code that loads the Scene3D plugin and requests the service is commented out because currently unable to load Scene3D from another plugin.

[chapulina]

I pushed c33970b directly to this branch so we suppress the 4251 warnings on all plugin files. I have no idea where the ign-rendering warnings are leaking through, but this should handle it. This warning is already suppressed on all src files that are not in plugins.

[chapulina]

Thanks for iterating, works great!