As the document said, TreeView in GTK4 has been deprecated since 4.10. The recommended replacement for it is ColumnView. However, I can't find clear documentation or example about how to build a treeView-like widget in GTK4 by ColumnView.
I found maybe TreeExpander related to it but I still don't know how to deal with it.
A very brief outline of what I did:
Familiarize yourself with how the new dynamic list widgets (Gtk.GridView and Gtk.ColumnView) work for a flat model (GLib.ListStore). There is example code in the Demo app.
Create a Gtk.TreeListModelCreateModelFunc function that takes a model item as a parameter and, if that item has children (e.g. is a folder in a filesystem model), creates and returns a Gtk.ListStore to hold the children. If the child items are already available then they can also be appended to the child model here. This means the child items are preloaded whether or not the row is expanded. For startup performance reasons, you might want to arrange to load them when the row is actually expanded which is more difficult - in this case you have to add a dummy child to the model else the expander will not be displayed.
Create a Gtk.SignalListItemFactory.
In the setup handler, create a display widget as usual then instead of using your display widget as child of the Gtk.ListItem, you create a Gtk.TreeExpander, and make that the child the Gtk.ListItem and make the display widget a child of the expander.
In the bind handler, get the display widget and model item from the supplied object. A complication here is that the object may be a Gtk.TreeListRow whose item might be another Gtk.TreeListRow so getting to the model item is harder. Bind the widget to the model item as usual. Then get the Gtk.TreeListRow from the Gtk.ListItem position and set the expander's list-row property to it.
If you delayed loading the child items then you would need to detect when the row is first expanded. You can connect to the notify signal for the Gtk.TreeListRow.expanded property to do this.
Use a Gtk.TreeListModel with a GLib.ListStore as its root_store as the model of a Gtk.ColumnView (after wrapping in Gtk.SelectionModel as usual). You must set the passthrough property to false else no expanders appear. If you are loading child items on demand then autoexpand should also be false.
If you are using a Gtk.ColumnView with multiple columns, you only need add the expander to the first column. Otherwise the factory signal handlers or similar to the flat model except the bind handler needs to be adapted for Gtk.TreeListRow parameter.
Simplifications and performance improvements may well be possible or later versions of Gtk4 may introduce some conveniences to make it less fiddly.
I am working on a file browser implementation using the above strategy, currently at https://github.com/elementary/files/tree/gtk4-treelistmodel but this may be merged into other branches (or abandoned!). Note that this branch is under development and contains unresolved bugs but the display of items works.
Related
I would like to append a Binding node to another Binding node without re-rendering the parent node.
Is there a specific way how Binding.scala would handle this?
Bindings can be nested and composed, so in general it's not something you need to think about. A Binding[T] represents an object that is dynamically bound and will be recomputed when any upstream Binding's value changes.
Your question is a bit ambiguous so you may want to clarify or add a code example, but there is nothing extra you need to do to accomplish your goal. Look at the examples and also this section of the README:
https://github.com/ThoughtWorksInc/Binding.scala/blob/11.0.x/README.md#precise-data-binding
Also, I made a quick example of what I'm talking about here:
https://scalafiddle.io/sf/XZgtwHM/1
If you open up your browser console, you'll see that the method that renders out the parent node is only called the first time, but if you click the button more child elements will be appended without the parent node being affected. Inspect the HTML and pay attention to the id of the parent div, it is set up to increment the ID each time it gets rendered, and the id remains as "parent_1" the whole time.
I'm just picking up om.next and have run into a situation where I've got some form inputs realized as components which hold on to local state, e.g. validation state, actual input value, etc--this state is updated and accessed via om.next/update-state! and om.next/get-state. The trouble with this seems to be when I wrap the inputs in a form in a parent component I'm unsure how to get the state held by the input components. Is it better to pass along the parent component as a property of the input component? What about situations where there is no parent component?
It seems to me that there are 2 options for the use case you want to achieve:
pass the parent component as an argument as you said
have an entry in the global app-state that represents the current form being edited, which you can update via transact! irregardless of the component corresponding to the input. This way every component that represents an input knows where in the app-state to update itself (which key in the current form) — probably captured succintly in one mutation function.
1) is probably the easiest to implement given the code you have currently, but I always like to go for 2) because it doesn't deviate from the "single source of truth" opinion that Om Next recommends (and tries to enforce). Form data is in fact business data, which might not be desirable to have scattered in components. Testability is just one advantage that I immediately see from such approach.
I have a list of widgets which needs to be sorted. I want to create a container for these list of widgets to re-sort them each time new widget is added. How can I do it?
I can see the following ways:
a straightforward way is place them into arraylist and sort via Comparator, but after a new element is added we have to remove all list from container and add them again, in a new order.
use some sorting container. i have found only CellTable for this. But actually I dont need its rich functionality - I have only one column, dont need to sort on user events, only when new element added or removed, - so is there something else I can utilize in my use case?
GWT 2.4
PS
Actually, I am looking for something, that can be expressed like "widget container backed by widget collection", i.e. I change collection - container changes its contents, how can I implement this, or where can I find it?
PPS
The widgets can be different, thats why I dont think I can use CellTable easily.
There is no straightforward way of re-sorting the elements in the DOM after you add a new widget.
When the widgets are attached you cannot just move them (change their position in the document structure) without detaching and re-attaching.
Well, with absolute positioning you can just change the left-top coordinates to move the items, if it is what you need.
I had a similar problem to solve when I had to sort TreeItem elements (no built-in sort method available). As a workaround, I read all the children into the list and remove them from the parent widget at the same time, then sort these items using Comparator and add them back to parent from the sorted list. Everything is in a single sort() method, which encapsulates all required functionality and kind of simplifies understanding of this code.
"widget container backed by widget collection"
I would like to learn about one like that that also can do sorting and re-attaching on the fly. But it still will be backed by the same detaching-attaching I assume. I would recommend you to write one yourself, that will fit your particular needs. Either you need a Tree or a FlowPanel or anything else - you can extend that and add sort() logic according to context. And override add() method accordingly. So, your first option looks like a possible solution to me.
Suppose I have a <String,String> map defined in my i18n .properties files, e.g.:
userGroupMap = 0, 1, 2, 3
0=Factory
1=Administrators
2=Superusers
3=Operators
The dev guide explains that introducing a corresponding Map<String,String> userGroupMap() method in MyConstants implements Constants interface will result in calls such as MyConstants.userGroupMap().get("1") returning the localized "Administrators". So far so good.
What about UiBinder? How do I use one of the mapped values in a UiBinder template? Is there a syntax I'm missing, e.g. <ui:msg key="userGroupMap:1">Administrators</ui:msg> (doesn't actually work)?
One way you could do this would be a non-xml solution, but you could use a #UiFactory to help with the creation of the specific fields or labels that you need I18N'd. But to me, this particular problems seems like it begs the solution below, since you seem to be looking to decouple your widgets from your screen or panel layouts.
I struggled with this, and for my implementation, I ended up making core widgets with UiBinder backing for their internals(for instance a label and a text field with a help button), and then passing in a 'fieldKey' that was used as a prepender for all the I18N keys in the various maps.
For instance, for the PartNumber field, I had a key in the following maps: labelTexts(), helpTexts(), tooltipTexts(), defaultFieldValues(). Then in the constructor for that widget, I would pass in the string key 'partNumber', and that would be used to build up all the keys needed, so I would call labelTexts().get('partNumberLabelText'), helpTexts().get('partNumberHelpText'), etc.
I didn't want to do this directly in UiBinder, since I wanted the widget key to map back to it's display information, so I could create a widget with as little input information as possible, in many cases just the key and then the widget (provided it was configured in the I18N setup correctly) would just populate everything from the maps based on that.
From a design standpoint, for me it didn't make sense to have separate UiBinders for the screen sets, they were composited from objects that defined the screen layout and relation of all the widgets (meaning that you could define screen content at runtime).
I have issues with GWT CellTree and at this point, I'm wondering if it's really ready for prime time. Maybe I'm not getting the default use-cases??
Most questions that have seen over the Web so far are related to CRUD operations with a CellTree but using a simple ListDataProvider such as GWT - Add and remove nodes in celltree.
In my case, I'm populating the nodes of a CellTree using an AsyncDataProvider.
The nodes are fetched on-demand using a RequestFactory service.
Given a selection, I would like to add child nodes, remove/update the current selection. The GWT TreeViewModel interface is way too basic in my opinion.
From my current understanding, the way to go would be to use a map of DataProviders, keep a reference of the underlying list returned by the remote call and likely a reference to the parent NodeInfo object.
For example to delete the current selection I'd probably do the following:
TreeViewModel model = cellTree.getTreeViewModel();
TreeViewModel.NodeInfo nodeInfo = model.getNodeInfo(selectionFromChangeListener);
CustomNodeInfo parent = ((CustomNodeInfo) nodeInfo).getParent();
parent.getUnderLyingNodeListFromDataProvider().remove(selectionFromChangeListener);
// maybe force refresh using dataProvider???
parent.getDataProvider().refreshDisplayAsInRepopulateData()
Any better suggestion? It looks like it's going to be a challenging task, unless I'm mistaken... It seems a bit overkill though. In Swing it would be very easy to achieve or even in most other Web Frameworks providing Tree widgets.
Would using the default Tree widget and replacing myself the icons with the "loading" image be a more straightforward thing? It looks like the basic Tree allows way more manipulations of nodes as TreeItems.
The CellTree widget seems to be based on the original code of FastTree.
The FastTree already have more or less what I need, without some kind of setUserObject method as in a Swing DefaultMutableTreeNode
For spinning icons, someone already investigated it in the past.
I guess that for now, I'll switch from CellTree to a customized version of FastTree and FastTreeItem.
Out of the box ability to have methods such as getParentItem, remove(current node or specific child node)?? Thank you very much sir...