feat: file and status tab support pageup and pagedown

[Fatpandac]

This Pull Request fixes #1951.

It changes the following:

• files tab support

I followed the checklist:

• I added unittests
• I ran make check without errors
• I tested the overall application
• I added an appropriate item to the changelog

[cruessler]

I just tested this PR and ran into the following panic in the status tab (this is not the full stacktrace, but the parts that seemed relevant):

  13: <gitui::components::utils::filetree::FileTreeItems as core::ops::index::Index<usize>>::index
             at src/components/utils/filetree.rs:256:14
  14: gitui::components::utils::statustree::StatusTree::is_visible_index
             at src/components/utils/statustree.rs:328:12
  15: gitui::components::utils::statustree::StatusTree::selection_page_updown
             at src/components/utils/statustree.rs:311:7
  16: gitui::components::utils::statustree::StatusTree::move_selection::{{closure}}
             at src/components/utils/statustree.rs:154:6
  17: core::option::Option<T>::is_some_and
             at /private/tmp/rust-20250318-8204-qqz0f7/rustc-1.85.1-src/library/core/src/option.rs:631:24
  18: gitui::components::utils::statustree::StatusTree::move_selection
             at src/components/utils/statustree.rs:136:3
  19: gitui::components::status_tree::StatusTreeComponent::move_selection
             at src/components/status_tree.rs:132:17
  20: <gitui::components::status_tree::StatusTreeComponent as gitui::components::Component>::event
             at src/components/status_tree.rs:514:9

Before the test, I had prepared the directory by creating 101 empty test files using the following fish script: for i in (seq 0 100); touch "test-feature-$i.txt"; end.

[Fatpandac]

@cruessler Thanks for your comment. I reproduced it and fixed it.

[cruessler]

I’d like to suggest a change that is somewhat larger, but that would, in my opinion at least, make the code more easy to understand. The change would also make the code more re-usable, so it could be re-used for the other movement commands in a follow-up PR.

In particular, you could change selection_page_updown in src/components/utils/statustree.rs as follows:

	fn selection_page_updown(
		&self,
		current_index: usize,
		range: impl Iterator<Item = usize>,
	) -> SelectionChange {
		let page_size = self.window_height.get().unwrap_or(0);

		let new_index = range
			.filter(|index| self.is_visible_index(*index))
			.take(page_size)
			.last()
			.unwrap_or(current_index);

		SelectionChange::new(new_index, false)
	}

If you did that, you would also need to adapt move_selection as follows:

				MoveSelection::PageUp => self.selection_page_updown(
					selection,
					(0..(selection + 1)).rev(),
				),
				MoveSelection::PageDown => self
					.selection_page_updown(
						selection,
						selection..(self.tree.len()),
					),

With these two changes, the code would have fewer conditionals and control flow would be much easier to understand. What do you think?

[Fatpandac]

Your advice is awesome and reliable. I will use it, but I made some changes by adding the code self.available_selections.contains(index) to the condition because, in some cases, the folders could be folded up.

[cruessler]

I’m glad you liked the suggestion! If I’m not mistaken, you could make the same type of change here: https://github.com/Fatpandac/gitui/blob/0f338b8201d185f9afbea24cae9246c5f3080216/filetreelist/src/filetree.rs#L117-L158.

Do you want to rename show_height to window_height, too? Then filetree.rs and status_tree.rs would be more in sync.

[cruessler]

@extrawurst I think this is ready for the final review!

• I’ve tested both the files and the status tree, including by resizing the gitui window. Page up and down behaves similarly to how it behaves in the log tab.
• There are a couple of things that could be done with respect to de-duplicating code in the components that were changed in this PR, but I suggest we do that in a follow-up PR.