Allow explicit ffmpeg path to be provided when running test suite.

[tom-seddon]

Goal is to simplify use when ffmpeg is somewhere that the test suite can't find it, without having to modify the contents of the test engine working copy.

[ocornut]

Pretty sure this

• would then be accidentally saved to the .ini file
• then then .ini data would keep overriding what the parameter is.

So it might need a different design.

[tom-seddon]

Argh, sorry. My usual tests rebuild everything from scratch with a clean build, including deleting the .ini file and so on, which is how I failed to notice this. (Though, this could actually explain a couple of oddities I noticed in my initial tests, that I put down to user error once it all seemed to be working properly...)

[tom-seddon]

I'll leave this PR open, but if you want to close it please feel free!

I have another idea, so another PR to follow if it works - unless you'd rather this bit were left alone for now.

[ocornut]

You can leave it open, until you or I can spend the time to find a solution. I agree on the general principle that a command-line parameter is desirable but simultaneously I would imagine that capturing would require you to run in GUI mode with a renderer and supposedly that's not something you are doing on CI ?

[tom-seddon]

This was intended for manual use, for me to run from the IDE as a sanity check after upgrading Dear ImGui and/or the test engine.

I've set my project to build a copy of the test suite, which I run standalone, and I was hoping to get it working out of the box on all platforms from a fresh git clone. I'm using CMake, so the configure process can discover ffmpeg's actual path, and add the relevant command line option to the test suite's debugging setup in Visual Studio or Xcode. And I figured the command line option for this might be useful for others.

When building for Linux, I'd run from the command line (but on Linux, ffmpeg is in the expected place for me, so the test suite finds it already).

[tom-seddon]

My alternative PR was quite simple: add /imgui_test_suite/tools/ffmpeg to .gitignore, and now you can symlink imgui_test_suite/tools/ffmpeg to your preferred copy of ffmpeg (it's something like /opt/local/bin/ffmpeg on macOS for me) and the test suite will be certain to pick it up. This does mean modifying the working copy, but the .gitignore entry means it at least won't affect the git status.

(This was intended to be similar to what looks like the way to do it on Windows: copy ffmpeg.exe to imgui_test_suite\tools. And there's *.exe in .gitignore, so git status is unaffected there too.)

But the autodetected ffmpeg path gets saved to the .ini too. So I wasn't sure this would be actually any better.