I have an handler shared between several TreeViews.
In the handler I have access to a TreeItem instance, is there a (simple) way to determine the TreeView it belongs to?
Currently I'm relying on external variables to record the "currently active" TreeView, but that makes the code messy and, probably also rather brittle. Is there an alternative?
I think it is currently not possible, at least on JavaFX 2.2. Looking at TreeView source code (available here), the TreeView.setRoot(TreeItem<T> root) method just sets the TreeView's root property, without setting some reference back to the TreeView on the root item. In this case, from the root element, there is no reference to the TreeView which it was inserted in.
Thus, even if it is possible to reach the root item from a deeper one using TreeItem.getParent(), it is not possible to reach the TreeView that has the item.
Related
I'm building a GWT application with a Tree.
Every tree items represent an object which has a boolean attribute that we can set through a checkbox displayed in the tree item itself.
I have a selection handler to do some stuff on my tree which gets called on click on every tree items.
What I want to do, is to prevent selection event to firing up when I'm clicking on the checkboxes ...
However, checkboxes don't have a SelectionHandler, so I tried to put a ClickEventHandler with event.stopPropagation(), but SelectionHandler is still getting called ...
EDIT: actually SelectionHandler is getting fired before ClickEventHandler anyway ...
Thanks in advance
You might consider following this method provided in the GWT documentation here. That should do the bit what you are interested in.
Try using the separate click handler for the checkbox and use the event.StopProgation() there after inorder to prevent the event bubbling.
For stop propagation from child's event to parent in GWT you need to use
event.stopPropagation();
I'm using some KendoUI web widgets such as DropDownList, which create 'div' elements that are being added to the bottom of the Body. is there a way to configure those to be added as children of one specific div, instead of being direct children of 'body'?
Some widgets have an appendTo configuration option, e.g. kendoWindow, but most don't. kendo.ui.Popup (which is used by widgets like kendoDropDownList and kendoComboBox) appears to be using that configuration option, so it might be relatively easy to make some changes to achieve what you're after.
In response to your follow-up question: there is no document for kendo.ui.Popup because it's not intended to be used independently - it's just a reusable component for the framework itself.
If you're concerned about having to clean up the DOM elements created by a widget, you can achieve that by using the widget's destroy method.
I want to implement a screen to display a tree of comments in WP7. Each comment can have children comments and so on. Each child comment will be visually distinct from its parent via indenting
ie:
"comment text"
"Some child comment text"
"Some child comment text"
"some child comment text"
"comment text"
"Some child comment text"
What would be the best way to go about implementing this? I'd like to keep the implementation as simple as possible so initially I was thinking I could use a single ListBox and programmatically set the Padding/Margin of each comment/ListItem, depending on its depth in the tree. But I can't seem to get it working. Any examples, suggestions, recommendations, etc?
Edit: Doing some additional reading, it seems like a DataTrigger would have been perfect for this sort of thing http://www.codeproject.com/Articles/113152/Applying-Data-Templates-Dynamically-by-Type-in-WP7 ...But WP7 doesn't support triggers.
One other idea I had was to make the Margin/Padding a Property of the Comment class, and then databind to that...this should work, but I'm contaminating my Comment class with display information. Any ideas on how I could databind the Margin/Padding value but somehow not mix model & view codes?
You'll have to roll your own, either from scratch, or by assembling something out of existing controls. ListBox looks like a good bet for this purpose.
Take a peek at this MSDN thread (web archive - thread now moved/deleted), it has several suggestions about simulating a TreeView using a ListBox, and a claim (which I have not verified) that you can use System.Windows.Controls.TreeView in WP7 (with the caveat that you also need System.Windows.Controls.Toolkit).
The marked answer, written by Shaun Taulbee:
Tree view behaviour in a listbox could be mimiced with a bit of smarts in the collection handling. Features your classes would need to support that come to mind are
a collection whose elements supports retrieving child collections
similarly to be able to detect if an element has child collections
in the data template for the listbox show one element of the stackpanel for expansion state based on presence of children and whether or not expanded
in the data template for the listbox show one element of the stackpanel for indent which reflects the depth of the child - to accomplish this best you should have a collection that represents a flat version of your tree data to bind to - then when you insert items you can make the indent based on the indent of the parent item that was just clicked
when a node is clicked in the listbox you insert the children from that node into the flat collection that the listbox is bound to
when the node is clicked again the children are deleted from the flat collection
You could encapsulate all of this into some neat classes to provide a fairly simple reusable api I would imagine if you wanted.
This thread has a fair amount of noise, but down at the bottom there's a comment from Mark Chamberlain:
"TreeView is not a natural fit for the phone, you can emulate Treeview
in other ways, for example, with ListBox item templates, Pivot or with
other List patterns. It will depend on how many levels of the tree
you will have.
"For example, you can template your ListItem to contain a label and
another Listbox with same item template. Doing this you can emulate
as many drill in levels as you need to handle, but only one branch at
a time."
"You may be able to re-template the TreeView (source is also available
in the Silverlight Toolkit), but it isn’t a supported scenario, and
you would need to do a decent amount of work to get it looking good on
the phone from a design & re-templating standpoint."
The following should be good starting points, both altering the ItemTemplate for a ListBox control :-
http://3water.wordpress.com/2010/07/25/listbox-on-wp7/
http://weblogs.asp.net/psheriff/archive/2010/10/27/windows-phone-list-box-with-images.aspx
For WP8 you can use this one TreeView_WP8
I have been looking for a while for a solution to monitor DOM node insertion/removal, without success. For example events like DOMnodeInserted are not cross-browser and are being deprecated.
I recently watched tutorials about libraries that implement MVC or MVVM patterns, like Backbone or Knockout. As such libraries monitor DOM elements, I was wondering if they could be used to monitor DOM node insertion/removal.
For example:
if I have a select element on the page, I'd like to trigger an action when a new option gets added.
if I have a table element on the page, I'd like to trigger an action when a row is added or removed.
This isn't what Knockout does, and I don't think you'll find success there.
You could do something like binding your select elements to a KO observableArray, then monitor that array for changes. But that doesn't stop someone from manually inserting a select element into the DOM.
Bottom line: for KO, you're barking up the wrong tree.
When a click event occurs, I want to determine which of my widgets was clicked. Note that, for performance reasons, I specifically don't want to add click handlers to each of my widgets.
It's easy enough to obtain the element that was clicked (it'll be the event target of the native event), but then how do I find the corresponding widget?
There is no standard functionality for it, afaik. But you can do it in a similar way as is done in GWT's com.google.gwt.user.client.ui.Tree class.
Basically it work there by first collecting the chain of Elements from the Element of your root Widget to the element of the Widget that clicked (see private method collectElementChain in Tree class). With this chain of Elements the Widget is found by traversing from the Root widget down to the Widget clicked (see private method findItemByChain in the Tree class).
This works for Tree because the Widget and Element index of the children of each Widget/Element match, and because it only allows a specific widget set as TreeItem's.
Actually you can get the widget associated with the main element of a widget using either gwtquery or the DOM.getEventListener(element) method which returns the widget associated with an element.
You can check out my response in another thread for some working code: GWT - How to retrive real clicked widget?