Make it more clear how a Ui Id was derived

[lucasmerlin]

With this, we can see the full tree of how auto ids are derived:

[github-actions]

Preview available at https://egui-pr-preview.github.io/pr/7988-lucasbetter-ui-id-bookkeeping
Note that it might take a couple seconds for the update to show up after the preview_build workflow has completed.

View snapshot changes at kitdiff

[emilk]

I'm not a big fan of that UI. It has A LOT of repetition (Id(…), Source: , Parent: ). It also uses a tree view for something that is really a linked list.

I also think showing all the Ids of all the ancestors is a bit overkill, though I can see how hovering them to find them in the UI would be useful.

So I suggest something like this:

Id(C4BF):
← 6
← 0
← "child"
← 0
← "child"
← 0
← "child"
← "ID Test" (root)

where each row is hoverable, and shows the Id of that widget and where it is in the Ui (its Rect)

…actually, turning it upside down would look even better:

"ID Test" (root)
➝ "child"
➝ 0
➝ "child"
➝ 0
➝ "child"
➝ 0
➝ 6
= Id(C4BF)

[emilk]

get sounds like it doesn't change anything, which it does

Suggested change

	pub fn get_auto_id(&mut self) -> Id {
	pub fn allocate_auto_id(&mut self) -> Id {

[emilk]

Nice!

[lucasmerlin]

I'm not a big fan of that UI. It has A LOT of repetition (Id(…), Source: , Parent: ). It also uses a tree view for something that is really a linked list.

But it is indeed a tree. When you create an Id like this: Id::new(Id::new("a")).with(Id::new("b")) the id has two parents (a and b).
I think the ideal way to disaplay these would be a graph view, but unfortunately egui doesn't have one yet.

I guess we could show the source with the debug format instead, since source usually is pretty flat. But if you e.g. pass a widget id as a source via with(response.id), the source tree would be huge.