I am doing some manual positioning and need to take into account the safearea on ios.
The problem I have is that when I am in my OnAppearing method, the SafeAreaInserts method returns thickness values of 0. After rotating the device (in the SizeChanged event) this is no longer the case. Since SizeChanged does not get triggered when entering the view, I can't find the event that is raised when the SafeAreaInsets are set.
var safeInsets = On().SafeAreaInsets();
In this topic I found that the event for a changed SafeAreaInsert gets triggered "a fraction later" but I don't seem to have this event available in my shared Xamarin.Forms project.
For the ViewSafeAreaInsetsDidChange method, it gets called from the PageRenderer. You could override the default iOS PageRenderer and hook up to the ViewSafeAreaInsetsDidChange override.
public override void ViewSafeAreaInsetsDidChange()
{
var page = (Element as Page);
if (page != null && Forms.IsiOS11OrNewer)
{
var insets = NativeView.SafeAreaInsets;
if(page.Parent is TabbedPage)
{
insets.Bottom = 0;
}
page.On<PlatformConfiguration.iOS>().SetSafeAreaInsets(new Thickness(insets.Left, insets.Top, insets.Right, insets.Bottom));
}
base.ViewSafeAreaInsetsDidChange();
}
With more details, you could check the link below. https://github.com/xamarin/Xamarin.Forms/blob/4d49e5786a4c9cfc6eea00bbaa5b57bc09679186/Xamarin.Forms.Platform.iOS/Renderers/PageRenderer.cs
Related
I am building a Xamarin Forms mobile app that runs in Android on a Zebra scanner. I flip 2 different StackLayouts to IsVisble true/false to display different stuff in the UI. (StackLayout1 and StackLayout2)
The customer wants the user to be able to use the app entirely from the hardware keyboard on the scanner. So I have used the device Settings so that it never displays the virtual keyboard (I don’t think that matters for the issue I am having.)
I am overriding DispatchKeyEvent in a PageRenderer in the Android project and everything is working great … except.
The problem case:
StackLayout1 is displayed
the user taps an Entry control, putting the focus there
the user taps a button in the UI
the app displays StackLayout2
at this point the DispatchKeyEvent never fires no matter what key I press on the device keyboard
If an Entry box does NOT get the focus (step #2 above) the DispatchKeyEvent always fires in StackLayout2 and the StackLayouts display as expected.
If I programatically put the focus in an Entry box in StackLayout2 at step #3 above the DispatchKeyEvent fires fine.
That is not an OK solution. I have tried to progamatically put the focus on StackLayout2, and that code seems to do what is expected but DispatchKeyEvent does not fire.
Maybe I need to do something in the Android-project PageRenderer so that it is aware of StackLayout2 when it is made IsVisible = true.
Update 2: I found that I did NOT need custom StackLayouts. The solution which I posted below does not include any of this stuff I am describing in Update 1 (sorry, if that's confusing).
Update 1:
I added a ViewRenderer for both StackLayouts, and the code is hitting the OnElementChanged event when StackLayout2's IsVisible property flips to true, just great. Although the problem case is the same: DispatchKeyEvent does not fire once StackLayout2 is displayed, if an EntryBox had the focus in StackLayout1
Here is the OnElementChanged part of the new StackLayout ViewRenders
async void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
switch (e.PropertyName)
{
case "IsVisible":
if (Element.IsVisible)
{
if (sender is StackLayout)
{
this.FocusableViewAvailable(this); // if I comment these 2 lines out I get the same bad result
this.Focusable = true; // if I comment these 2 lines out I get the same bad result
this.FocusableInTouchMode = true;
var dd = this.RequestFocus(); // this is always false
var ee = this.IsFocused; // this is always false
}
}
break;
}
}
Also, as I am pointing out in the comments ^ there, IsFocused is always false.
Ideas?
My hunch, "Maybe I need to do something in the Android project PageRenderer" was correct. In the DispatchKeyEvent I had to make the MainPage have the focus when the keypress was handled.
Here is what the DispatchKeyEvent looks like now (notice the comments):
public override bool DispatchKeyEvent(KeyEvent ke)
{
// MainPage.ReceiveKeyPress(e); is the method that this method returns to
bool KeyPressWasHandled = false;
KeyPressWasHandled = (Element as MainPage).ReceiveKeyPress(ke);
if (KeyPressWasHandled)
{
// this next block seems to be needed so that this class
// continues to receive the keypress event after an Entry box has had the focus
this.Focusable = true;
this.FocusableInTouchMode = true;
this.RequestFocus();
return true; // returning true tells the parent class that the keypress has been handled
} else
{
try
{
return base.DispatchKeyEvent(ke);
}
Now the "problem case" in my initial post is no longer a problem.
NOTE: I found that I did NOT need the custom ViewRenderers that I had made for the StackLayouts.
I have implemented a custom clickable label class in Xamarin.Forms along with a custom renderer, that adds a RippleDrawable as the controls Foreground. I am creating the RippleDrawable with the following code:
public static Drawable CreateRippleDrawable(Context context)
{
var typedValue = new TypedValue();
context.Theme.ResolveAttribute(Resource.Attribute.SelectableItemBackground, typedValue, true);
var rippleDrawable = context.Resources.GetDrawable(typedValue.ResourceId, context.Theme);
return rippleDrawable;
}
In my custom renderer I assign the drawable
this.Control.Foreground = DrawableHelper.CreateRippleDrawable(this.Context);
and update the ripple when the user touches the control
private void LinkLabelRenderer_Touch(object sender, TouchEventArgs e)
{
if (e.Event.Action == MotionEventActions.Down)
{
this.Pressed = true;
}
if (e.Event.Action == MotionEventActions.Cancel)
{
this.Pressed = false;
}
if (e.Event.Action == MotionEventActions.Up)
{
this.Ripple.SetHotspot(e.Event.GetX(), e.Event.GetY());
this.Pressed = false;
// raise the event of the Xamarin.Forms control
}
}
Now, whenever I click the control, the ripple will be shown, which is the expected behavior, but if I touch (tap or long-press) the parents of the control (e.g. the StackLayout, Grid or whatever layout contains the label, including their parent Layout, Page or View) the ripple animation will be triggered. Anyway, the event handler LinkLabelRenderer_Touch in not called in this case, only when the actual control is touched.
I can work around this behavior by adding an empty GestureRecognizer to the respective parent(s), but I really dislike this solution, because this is but a hack. And to make things worse it is a hack I'll always have to remember whenever I use the control.
How can I prevent the RippleDrawable being shown when the parent is touched?
Turned out I got things fundamentally wrong. Subscribing the Touch event is not the way to go. I had to make the control clickable and subscribe the Click event
this.Control.Clickable = true;
this.Click += LinkLabelRenderer_OnClick;
There is no need to handle all that RippleTouch stuff the way I did (via the Touch event) but could let android handle things for me.
I have manually/programmatically set up an up button in my toolbar for a fragment page with the following code in onCreateOptionsMenu in the fragment:
(activity as AppCompatActivity).setSupportActionBar?.setDisplayHomeAsUpEnabled(true)
Tapping the system back button will take the user back to the previous fragment but without an up button (that works) I think some users may get lost.
I am having difficulty trying to work out how to catch and handle the up button to pop the fragment off the back stack.
This SO post shows how to catch the the up button click however it is in Java and doesn't go on to explain how you would navigate up.
I think it needs to look something like the code below but there are errors everywhere:
The case android.R.id.home is showing an 'Incompatible types:Int and MenuItem' error?
onBackPressed() is showing an 'Unresolved reference' error.
Bad code:
override fun onOptionsItemSelected(item: MenuItem?): Boolean {
when (item) {
android.R.id.home -> {
onBackPressed()
return true
}
else -> return super.onOptionsItemSelected(item)
}
}
UPDATE:
A comment to another SO post has a potential solution in Kotlin. It catches the click on the up button and goes back to the previous fragment page but then the up button doesn't go away. So the up button now persists even on the top level fragment destinations in my app (the pages corresponding to each tab in the BottomNavigationView).
I think this might have to do with the fact that there is only one activity in my app and the way that I have set up the up button in the fragment as mentioned above? If so, is there a workaround or other way to set up the up button by referencing the fragment instead of the whole activity?
If it helps, this is the code in the RecyclerView inner ViewHolder class in the adapter.kt file that navigates to the fragment page in question:
class AdapterListItemDetails(val items: List<ItemsList>) : RecyclerView.Adapter<AdapterListItemDeatils.ItemsViewHolder>() {
//overrides for OnCreateViewHolder, getItemCount, onBindViewHolder
inner class ItemsViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
var currentItem: ItemsList? = null
var currentPosition: Int = 0
init {
itemView.setOnClickListener(Navigation.createNavigateOnClickListener(R.id.goto_details, null))
}
fun setData(itemsList: ItemsList, position: Int) {
itemView.tview_Keys.text = itemsList!!.nameText
this.currentItem = itemsList
this.currentPosition = position
}
}
}
You have to override onBackPressed() method in activity and handle the fragment transactions with your manual code. If you could share some snippet of activity and fragment transactions will help me to give some proper solution.
Hi this is what i usually do:
in an activity find the navController from your navHostFragment
val navController = this.findNavController(R.id.myNavHostFragment)
Make sure it's connected to the ActionBar
NavigationUI.setupActionBarWithNavController(this, navController)
Then simply override onSupportNavigateUp, find your navController then navigate up
override fun onSupportNavigateUp(): Boolean{
val navController = this.findNavController(R.id.myNavHostFragment)
return navController.navigateUp()
}
I'm trying to use a flexlib schedule viewer in my application.
I want to have it so that when I click on a scheduled event, it calls a function in my main app (that will allow me to edit the event). But there doesn't seem to be any specific function for anything like this built into the class ie no event dispatched when I click on an event.
I can use the 'click' function to detect that the item has been clicked on.. and have tried something like this:
private function exerciseClickHandler(event:MouseEvent):void{
if (exerciseSeries.selectedItem != null){
//code
}
}
<code:ScheduleViewer id="exerciseSeries" click="exerciseClickHandler(event)" />
This method isn't very reliable because if it only works the first time.. once an item is selected, it stays selected so all following clicks on the item fulfills the condition.
Is there any way to determine whether an event was being clicked on?
Or do I have to extend the component and add some sort of clickEvent when an event is clicked on.
Since exerciseClickHandler is firing up when you click on the component, wouldn't this work?
Instead of
private function exerciseClickHandler(event:MouseEvent):void{
if (exerciseSeries.selectedItem != null){
//code
}
}
write
private function exerciseClickHandler(event:MouseEvent):void{
switch (exerciseSeries.selectedItem)
{
//code
case xy:
break;
}
}
or
private function exerciseClickHandler(event:MouseEvent):void{
//do something with exerciseSeries.selectedItem
}
What I mean is that you wrote that everything stops after the first element is clicked. And according to the code you provided it has to stop, beacuse after the first click exerciseSeries.selectedItem won't be null anymore, since it's selected. So remove the conditional you wrote and use the instance.
I'd suggest you set up a ChangeWatcher to keep an eye on the selectedItem (or selectedItems if you are going to allow multiple selection at some point). Example:
protected exerciseSeriesCreationCompleteHandler(event:FlexEvent):void{
ChangeWatcher.watch(this,['exerciseSeries','selectedItem'], handleChange_SelectedItem);
}
protected function handleChange_SelectedItem(event:PropertyChangeEvent):void{
// Either
dispatchedEvent(//some custom event);
// Or
someDirectMethodCall();
}
An alternative would be to search for an instance of the the event class in the view hierarchy under the mouse coordinates whenever a user clicks.
//Attach this click handler to the component
private function handleClick(event : MouseEvent) : void {
var obj : *EventClass*= null;
var applicationStage : Stage = FlexGlobals.topLevelApplication.stage as Stage;
var mousePoint : Point = new Point(applicationStage.mouseX, applicationStage.mouseY);
var objects : Array = applicationStage.getObjectsUnderPoint(mousePoint);
for (var i : int = objects.length - 1; i >= 0; i--) {
if (objects[i] is *EventClass*) {
obj = objects[i] as *EventClass*;
break;
}
}
if(obj is *EventClass*){
//Dispatch some custom event with obj being the item that was clicked on.
}
}
Where EventClass is the class of the objects that represent events
I have had similar problems and sometimes you can get by with wrapping the object with a Box and putting the click event on the Box. If you have not already tried that, it's a cheap, easy fix (if it works for you).
<mx:Box click="exerciseClickHandler(event)">
<code:ScheduleViewer id="exerciseSeries" />
</mx:Box>
I need to programmatically remove an alert.
This is why:
My application uses BrowserManager to enable deep linking based off of the content in the #hash part of the url. If an alert is currently up, and the user hits the back button, the application will revert back to its previous state. But the Alert will still be up, and in many cases irrelevant at that point.
So is there a way to programmatically remove the Alert? so when the hash fragment changes I can remove it.
Thanks!
It turns out the Alert.show function returns an Alert reference and then just uses PopUpManager to add it to the display list. so if you capture the return reference when you call Alert.show you can tell PopUpManager to remove it. :)
You can do this by keeping the Alert object as member data, and then setting its visible property to false when you're done with it. Next time you need to show an Alert, don't create a new one - grab the one you've already created and set its properties, then set visible to true again.
private var myAlert : Alert;
public void showAlert( message: String, title : String ) : void
{
hideAlert();
myAlert = Alert.show( message, title, Alert.OK | Alert.NONMODAL );
}
public void hideAlert() : void
{
if( myAlert != null && myAlert.visible ) {
myAlert.visible = false;
}
}
I don't think that is possible.
You can create your own alert component subclassing TitleWindow and then use PopupManager to show/hide them.