[Feat] Add screenshot to clipboard interaction

[yashnator]

Describe your changes

Adds the feature to take a screenshot to the clipboard by using Shift + F12

• Modifies F3DStarter.cxx to handle screenshot to clipboard using clip
• Modifies CMakeLists for importing clip

Issue ticket number and link if any

Resolves #2304

Checklist for finalizing the PR

• I have performed a self-review of my code
• I have added tests for new features and bugfixes
• I have added documentation for new features

AI Disclosure

• I did not use AI to generate any of the content of that pull request

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[mwestphal]

We discussed using a script to test it. Can you tell what exactly the test script should do?

Hum, a bash script could run f3d, trigger the screenshot to clipboard interaction then write the clipboard to a file, then compare that file with a baseline ?

[yashnator]

write the clipboard to a file

I think that would make the implementation platform-dependent and might require additional dependencies (like pngpaste on macOS). I suggest we write a C++ test that reads the clipboard contents using clip after taking the screenshot, opens a baseline PNG using vtk, and compares the data. What do you think?

[mwestphal]

@Meakk

[Meakk]

@yashnator I agree we cannot really rely on a script based test.
We do not have c++ based unit tests in the application though. Also, integrating clip at the library level instead of the application would make sense to me.

Here's my suggestion:

• Add a new f3d::image API: const image& toClipboard() const;
• Add a new f3d::image API: const image& setFromClipboard();
• New APIs throw if F3D_MODULE_CLIP is disabled
• Add a new libf3d unit test that render to an image and call toClipboard(), creates a new image and call setFromClipboard() and compare images.

The new application command take_screenshot_to_clipboard will look like:

      this->Internals->Engine->getWindow().renderToImage().toClipboard();

Is clip::set_image likely to fail? If not just throw, otherwise toClipboard() may have to return a bool.

When this will be done, you will have to add python/C/Java/JS bindings but focus on the C++ implementation for now.

[yashnator]

Sounds good. I will update the PR

[mwestphal]

Need any help moving forward @yashnator ?

[yashnator]

@mwestphal Not yet, I will update the PR tomorrow with some changes