Panels - nodes that are not movable, holding only one tab at a time

[LiamPClancy]

I'd like to use the doc control for side bars and bottom bars on my app, to allow users to drag and drop the tabs between these sections.
I have a middle Node that i'm creating that I'd prefer if users couldn't drag it or drop other tabs from other nodes into this tab.

i've added a function to DockArea that allow me to set that no tab labels should be shown - this isn't particularly useful in my use case, as it really prevents the ability to see more than one tab in any node - or drag any of them anywhere.

I've made a couple of changes to enable this functionality,

i've added a prop on Node::Leaf hide_label that allow one to set if they what that node to hide the labels - if there are no labels showing it prevents the ability to drag the tab in the node, and i've also used the same setting to prevent dropping other tabs into the node.

to enble this on a node, i've create the additional functions split_left_single... which only accepts a single tab and creates the Node:Leaf with hide_label set to true.

[Adanos020]

I'm not convinced that we need all the split_*_single and leaf_with_single methods. They don't do anything special and have the exact same effect as just passing a Vec with a single tab in it to a split_* method.

Having more than one way to achieve the same effect makes the API more confusing to use and therefore I'd get rid of these functions.

I need to think more about the show_label_bar stuff as something doesn't seem right there, it's probably just the naming.

[Vickerinox]

Looking through the changes so far I think it would be better if the implementation relied on a new kind of node (perhaps something like Node::Panel or Node::Single) or a reimagining of Node::Leaf. egui_dock hasn't ever really displayed anything that isn't a leaf before, so by introducing multiple simultaneous types of nodes we should ideally make it as "right" as possible before opening that can of worms.

Ideally any sort of functionality you wish to have (such as restricting a node to only one tab) should be reinforced by the Node type, otherwise we might set a president for tacking on new fields onto Node::Leaf endlessly for new types of nodes, which wouldn't be sustainable long term and annoying for future developers.

Im also not fond of the idea of being able to disable all nodes from having their tab bars disabled via DockArea, since it sounds like a backalley way of achieving a typical TopBottomPanel/SidePanel ui in vanilla egui. It could also introduce further confusion for developers who aren't familiar with the bigger picture of the api. So I think it's better if it was left to being decided on a node to node basis only.

However it's decided that this implementation should move forward i would highly recommend considdering how future features may come into play, eg. by generalising DockArea to accept displaying multiple kinds of nodes rather than just Node::Leaf or generalising tabs inside Node::Leaf to allow for multiple tab configurations with good customization.

[LiamPClancy]

hey @Adanos020 I can remove the show_label_bar option, don't need it for my use case, just put it in initially to help me follow the code and agree with the comments from @Vickerinox that when turned on it's really just reproducing the native egui functionality.

i'm currently using the leaf_with_single calls to set the additional hide_label prop on the node - which is then used in the show_inside method to prevent showing the label bar on the node.
the split_..._single methods only accept a single Tab rather than an array - to prevent people passing multiple Tabs when creating a node that will not show the title bar and therefore will not allow switching tabs in the node.

happy to explore the other option @Vickerinox of creating a different node type, like Node::Single
would probably then need the four different split methods to generate the nodes, and could add functionality to DockArea for rendering the nodes, to remove changes from the Node::Leaf implementation in the current PR.

let me know if you'd be interested in me moving forward with this other approach?

[Adanos020]

i'm currently using the leaf_with_single calls to set the additional hide_label prop on the node - which is then used in the show_inside method to prevent showing the label bar on the node.
the split_..._single methods only accept a single Tab rather than an array - to prevent people passing multiple Tabs when creating a node that will not show the title bar and therefore will not allow switching tabs in the node.

Once we switch to the Node::Panel approach, we could still do fine without these methods. Instead, I'd opt for creating an enum like this:

enum InsertTabs<Tab> {
    Panel(Tab),
    Leaf(Vec<Tab>),
}

which could be passed to the split_* methods instead of the Vec<Tab>. This way we could keep the number of methods to a minimum while still ensuring that the correct number of tabs is passed every time.

[LiamPClancy]

ok, I'll see what I can do - i'll hopefully get an opportunity to have a look at it over the next couple of weeks.

[Adanos020]

Changing this to a draft as the implementation needs redesigning and probably won't make it to 0.7.