NativeScript's RadListView doesn't properly respond to cell layout changes. Calling refresh on the list view is a very heavy-handed approach, as it destroys and recreates all cells.
Here is a Playground demonstrating the issue that I've run into with a side-by-side comparison of using RadListView and a ngFor cell generation: https://play.nativescript.org/?template=play-ng&id=dG1G3n
For long lists, ngFor is awful as it constructs and loads all cells in the list, rather than just those that are currently on the screen. The refresh method is out because it rebinds all data, including those that are feeding into async pipes and may take time to populate (which is also not reflected in the cell UI).
There is a github issue on this topic which is closed: https://github.com/NativeScript/nativescript-angular/issues/872. Does anyone have any advice for resolving this since this github issue is closed?
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I am creating an event screen like Outlook's. The issue I am coming across is that the autocompletebox I am using from Syncfusion doesn't automatically grow in height as more tokens are added.
The current workflow is exactly like outlooks. When the control is clicked on, it brings you to another page where you can select tokens. On return, the selected items populate the autocomplete circled below.
The approach I currently took is to have a listview. Scrolling is disabled for the listview since the page resides in a scrollview and nested scrollviews aren't recommended for xamarin. The height of the listview is dependent on the number of selecteditems.
I am wondering if there's another approach or control that would be more suited for my situation? Or if someone has come across a autocomplete control where the height will grow.
I have an NSCollectionView in an NSScrollView.
The scroll view scrolls horizontally to move along the line of items.
Inside each each collection item is a vertically scrolling NSOutlineView.
I have NSButton objects for opening and closing collection items - as supplementary views in my collection.
I set up NSTrackingAreas on these buttons to support mouse over effects.
This works correctly, until I scroll, at which point the NSTrackingArea areas are clearly left behind (the mouse over effects happen when the mouse is where the button was, not where it is).
I rebuild my tracking areas in updateTrackingAreas in my button class, and this is called, but not often enough.
I have tried using .inVisibleRect when setting up my tracking areas, rather than explicitly rebuilding them, but that doesn't improve the tracking update.
I have tried calling updateTrackingAreas on the NSCollectionView when scroll occurs, but it is never passed down to the child views as I expected it would.
As a side note, I also have NSTextViews in my collection view items with toolTips that are very flakey too. They are often left hanging. Pointing hand cursors over links are often misaligned.
It feels as though the default updateTrackingArea is over-optimised and is not being called as often as it should.
So, I am about to embark on building my own tracking-area-tracker to register and update my views when they are not updated by default...
...but maybe someone can see something obvious that I am missing? Thank you.
The tracking area setup can be subtly broken when nesting scroll views incorrectly. See the answers regarding nesting scroll views here for details:
NSScrollView inside another NSScrollView
I want to write a UI test for my Xamarin.iOS app to make sure that all tableview elements/cells exist on a screen. I could use app.Query(e => e.All()), but this will only retrieve elements that are currently visible on the screen. Is there a way to retrieve all elements (including the ones hidden from the view) in order to assert that the retrieved elements are as expected, without initiating a scroll action?
Any suggestions are greatly appreciated.
There isn't a way to do it directly, but there are methods to scroll list views down to get more items, but the original ones will then be removed from the visual tree.
Table views use cell recycling, so they only creates enough cells to fill the screen. As you scroll cells that are scrolled off the top are 'recycled' and shown on the bottom with new data. This means that the cells of screen actually don't exist - so there is nothing that UI test can access.
I've done it in the past by getting the items and caching some values, scrolling, getting more items, scrolling etc, building up a list of items as I go. Then once there is no more to scroll, checking the values.
Although I know of a solution to this problem, I am interested if someone can explain this solution to me. I also wanted to get this out there because I could not find any mention of this problem online, and it took me several hours over several days to track down. I have an NSTableView behaving strangely regarding redraws and its selection. The problem looks like this:
Table contents fades in, instead of appearing instantly upon it's appearance on screen. When scrolling through the contents, the newly appearing rows also fade in. When you make a selection (single or multiple), and scroll it off screen, then make another selection (that should replace, not add-to first selection), the first selection does not get cleared properly. If you scroll back to it, it is still there, in addition to your new selection. This is a display-update problem, not selection problem - i.e. your new selection is valid, it is just displayed wrong.
I tracked this through the NSArrayController I was binding to, the underlying Array, sorting, all the connections, and settings, etc., but all that has nothing to do with it.
What solved the problem was:
In the View Effects (right-most) Inspector, uncheck "Core Animation Layer" for the Window's main view.
Can anyone explain what is happening here, and perhaps improve upon the solution ?
It looks like Core Animation and NSTableView aren't getting along so well. The "fading" effect is a by-product of the way core animation works. When you have core animation in one view, it is also enabled in all of that view's subviews.
I don't recommend using core animation on the Mac unless absolutely necessary, because some interface elements (NSTextView and NSTableView, for example) aren't compatible with it. iOS has much better support for table views and such using core animation, mainly because it was designed with core animation in mind.
I know that some more simple UI elements are compatible (NSTextField and NSButton, for example).
If you absolutely need core animation in the rest of the window, put all the other views in a subview of the content view, while leaving the table view directly in the content view. You can then enable Core Animation in the other view.
Commenters, feel free to add to the list of what is and isn't compatible.
I am trying to give a ListBox drag and drop ordering functionality and I have hit a wall. I got it to work when I specify the list box items in xaml but it does not work when I bind to a list it no longer works because the items are no longer of a listboxitem type.
I found this code http://blog.dobaginski.com/josh/?p=52 that allows me to get the underlying ListBoxItem but I can't get the mouse move event to fire.
I have went through other tutorials but have not been able to find one that deals with a ListBox. Has anyone done this with a ListBox.
The events I am using are SelectedChange, MouseMove, and LeftMouseButtonUp (I think that name is right). I am not using LeftMouseButtonDown because I couldn't get it to fire.
As far as i know you cannot get at the listbox item container when using data binding. YOu could in Beta 1.
You also cannot set a mouse event handler in the style, you must use a data template, just so you know.
You will likely have to use the mouse move event from a parent element, probably the UserControl or main layout control that hosts the listbox.
State changes and animations need to be in the style though so... you still cant get at the listbox item, just the element inside it in the data template.
Oh and if doing drag and drop HitTest is now protected so that will make the Drop harder.
since today you can download the final 2.0 version of Silverlight with some add ons, check the Scott's web log
I've been trying to do the same thing in WPF,
but have only found many buggy implementations.
One person has guided me towards the blog of Beatriz Costa,
and from what I remember she's one of those rare geniouses,
so I suggest you read that as well... I know I will
Blog of Beatriz Costa