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.
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 noticed that after using the .HeightRequest property on a View in Xamarin.Forms that a method I have assigned to the SizeChanged event is no longer called.
The content within the View that had called .HeightRequest is a Label that contains text which can be zoomed in. When zooming in, the text now exceeds the "bounds" of the View's height, and the height is no longer adjusting as it once was.
public ExpandableEntryView(...)
{
InitializeComponent();
// my beautiful code
SizeChanged += ExpandableEntryView_SizeChanged;
UpdateUI();
}
private void ExpandableEntryView_SizeChanged(object sender, EventArgs e)
{
// this is never called once .HeightRequest is assigned a value
}
private void SomeFunction() {
sectionsStackLayout.HeightRequest = 0; // this causes SizeChanged to no longer work
}
I essentially need this View to minimize its height to 0, and then return to its original height when I tell it to. I am also using IsVisible, but the Height property is required for an animation I am trying to do.
Thank you in advance.
Nevermind, I was able to figure it out. The reason why the SizeChanged event is no longer called is because the view is no longer responsible for keeping track of its size after assigning a value to HeightRequest. So, if you would like for your View to return to being able to determine its own size once again, (i.e. if a child element in that View happens to change size/scale) you need to assign the HeightRequest to -1. This will then reenable the SizeChanged event.
Hope this helps somebody!
I have implemented a clickable Frame in Xamarin.Forms 2.3.4 with a custom FrameRenderer that set Clickable (and LongPressable FWIW) to true, subscribed the respective events and set the FrameRenderers foreground
TypedValue typedValue = new TypedValue();
this.Context.Theme.ResolveAttribute(Android.Resource.Attribute.SelectableItemBackground, typedValue, true);
this.Foreground = this.Resources.GetDrawable(typedValue.ResourceId, this.Context.Theme);
to achieve Material motion (ripple touch).
After updating to XF 2.5 (most likely as of 2.3.5, since fast renderers have been introduced with that release) my touch events have ceased to work. My custom renderer is assigned correctly, so are the Clickable and LongPressable properties, but nothing happens. Partially I have been able to work around the issue - at least for the moment - by subscribing to FrameRenderer.Touch and call OnClick from that event handler. This renders the app usable, but unfortunately lacks the visual feedback in form of the ripple touch effect.
Is there any way I can restore the original behavior? Is there any way to implement a clickable frame with ripple touch in XF 2.5?
With the help of this answer I have figured out a solution. Here's a draft of it:
First of all I store a local reference to my RippleDrawable (see documentation)
private void SetMaterialMotion()
{
TypedValue typedValue = new TypedValue();
this.Context.Theme.ResolveAttribute(Android.Resource.Attribute.SelectableItemBackground, typedValue, true);
this.Foreground = this.Resources.GetDrawable(typedValue.ResourceId, this.Context.Theme);
this._layerDrawable = this.Foreground as RippleDrawable;
}
then I have to subscribe to the Touch event
private void SubscribeClickEvent()
{
if (this.ClickableFrame.IsClickable)
{
this.Touch += ClickableFrameRenderer_Touch;
}
}
In my ClickableFrameRenderer_Touch I set the Pressed property and the hotspot of the RippleDrawable
private void ClickableFrameRenderer_Touch(object sender, TouchEventArgs e)
{
if(e.Event.Action == Android.Views.MotionEventActions.Down)
{
this.Pressed = true;
}
if(e.Event.Action == Android.Views.MotionEventActions.Up)
{
this._layerDrawable.SetHotspot(e.Event.GetX(), e.Event.GetY());
this.Pressed = false;
}
}
This will show the ripple touch motion (more or less) as expected. Of course this does not handle long presses, yet, but I'm on a way.
Anyway, this is not a solution I like very much. I still think that there has to be a supported way on making FastRenderers.FrameRenderer clickable. If anyone knows it: Please share your knowledge.
I have made a hierarchy in which there is a main page, using add element i have attached a component mxml of type group. There is a single button on main page when clicked it should add children of type group in that group type mxml component along with two buttons. Now using one of buttons i am attaching another component mxml type group. the problem is even they overlap i can still excess the children groups of first group component mxml. how can i stop this mouse events to happen.
I think those kind of events usually bubble up to parent components.
You can try using the following code in your mouse click event listener to stop further propagation:
private function onMouseClicked(event: MouseEvent): void {
event.stopPropagation();
... do whatever you wanted when smth was clicked ...
}
By setting enabled, mouseChildren, mouseEnabled to false, you will disable the entire component and it's children. example below
private var myPreviousGroupComponent:Group = null;
function addNewGroup():void
{
if(myPreviousGroupComponent != null)
{
myPreviousGroupComponent.enabled = false;
myPreviousGroupComponent.mouseChildren = false;
myPreviousGroupComponent.mouseEnabled = false;
}
var newGroup:Group = new Group();
addElement(newGroup);
myPreviousGroupComponent = newGroup;
}
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>