Allow Dialogs to have a MainWindow independent config

[mayman99]

Signed-off-by: Mohamad mohamad@openrobotics.org
🎉 New feature

This PR allows Dialogs to read and write to the config file.
The motivation for this PR is, all the current reading/writing of the Config is implemented in MainWindow, and the Application has not been initialized yet then there is not MainWindow object.

a dialog config looks like <dialog name=\"dialog_name\" attribute_1=\"true\"/>"

Workflow:

1. Set dialog name SetName
2. set the dialog default config using SetDefaultConfig
3. Read an attribute of the dialog config using ReadAttribute
4. if the dialog config doesn't exist in the existing config file
   5. append the dialog default config to the config file
   6. read from the written config
5. if the dialog config exists in the existing config file, read it and return the value as string
6. update an attribute value in the dialog config using WriteAttributre

The changes here are used in this PR.

Summary

Test it

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #418 (94e5bbc) into ign-gui3 (bc53940) will increase coverage by 0.29%.
The diff coverage is 76.71%.

@@             Coverage Diff              @@
##           ign-gui3     #418      +/-   ##
============================================
+ Coverage     66.12%   66.42%   +0.29%     
============================================
  Files            29       29              
  Lines          3218     3291      +73     
============================================
+ Hits           2128     2186      +58     
- Misses         1090     1105      +15     

Impacted Files	Coverage Δ
include/ignition/gui/MainWindow.hh	100.00% <ø> (ø)
src/Dialog.cc	77.17% <76.71%> (+8.75%)	⬆️

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[mayman99]

I had to comment the test here , until someone could give me some feedback, as I couldn't figure out why it was failing

[chapulina]

The motivation for this PR is, all the current reading/writing of the Config is implemented in MainWindow, and the Application has not been initialized yet then there is not MainWindow object.

I'm not sure I understand this part. The application has to be initialized before the dialog. Can't we use leave the config path handling to the Application? It would be nice if we didn't need another config file and could reuse the same one. The <dialog> elements could be siblings of the <window> element.

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Have you seen the WindowConfig struct? That's used to hold an in-memory representation of an XML config file, load from a file and write to it. It would be interesting to follow the same pattern for consistency of the API, creating a new DialogConfig struct.

[mayman99]

Updated the PR per VC, except of using templates with ReadAttributeValue, as it results in a seg-fault when using in gazebo, which needs further debugging to figure out why.

[mayman99]

@chapulina green 👍
I didn't have time to convert the Read/Update functions to use template functions (I did but it results in a seg fault when used in gz-sim, my maintenance time was not enough to find the problem)