So I have a searchbar(My searchbar all have a custom renderer) on one page. When a user fills in their search term they get redirect to searchpage where their results get shown.
The problem I have here is that suddenly the searchbar on the new page gets focussed (because I pass the search term from the previous page into this searchbar) and the software keyboard shows.
I want to dismiss keyboard or prevent the keyboard from showing. But when the user clicks inside the searchbar than ofcourse the keyboard can appear.
Note this question has been asked before, the answers I followed were never successfull. Here you can find what I have tried
First try: Unfocus
Just unfocussing my entry, did not work. Tried it both in my constructor and in my OnAppearing code of the page
Second try: Focus other element
Tried focussing my listview, but keyboard stil showed up
Third try: Dependency service
https://forums.xamarin.com/discussion/comment/172077#Comment_172077
Interface:
public interface IKeyboardHelper
{
void HideKeyboard();
}
iOS:
public class iOSKeyboardHelper : IKeyboardHelper
{
public void HideKeyboard()
{
UIApplication.SharedApplication.KeyWindow.EndEditing(true);
}
}
Droid:
public class DroidKeyboardHelper : IKeyboardHelper
{
public void HideKeyboard()
{
var context = Forms.Context;
var inputMethodManager = context.GetSystemService(Context.InputMethodService) as InputMethodManager;
if (inputMethodManager != null && context is Activity)
{
var activity = context as Activity;
var token = activity.CurrentFocus?.WindowToken;
inputMethodManager.HideSoftInputFromWindow(token, HideSoftInputFlags.None);
activity.Window.DecorView.ClearFocus();
}
}
}
Usage in Xamarin Forms:
DependencyService.Get<IKeyboardHelper>().HideKeyboard();
EDIT
My renderer's code for my search page
protected override void OnElementChanged(ElementChangedEventArgs<SearchBar> e)
{
base.OnElementChanged(e);
if (Control != null)
{
var searchView = Control;
searchView.Iconified = true;
searchView.SetIconifiedByDefault(false);
// (Resource.Id.search_mag_icon); is wrong / Xammie bug
int searchIconId = Context.Resources.GetIdentifier("android:id/search_mag_icon", null, null);
var icon = searchView.FindViewById(searchIconId);
(icon as ImageView).SetImageResource(Resource.Drawable.search_zwart);
int cancelIconId = Context.Resources.GetIdentifier("android:id/search_close_btn", null, null);
var eicon = searchView.FindViewById(cancelIconId);
(eicon as ImageView).SetImageResource(Resource.Drawable.close_zwart);
}
}
I got unlock button for game, it works,but I want to user himself can press button, and then button image change. As you can see in code below when score is >= 10, buttons image change immediately. How can I achieve that?
public GameObject lockBtn;
Image lockComp;
public Sprite myLockImage;
public Sprite myLockSecondImage;
/////////////////////////////////////////
lockComp = lockBtn.GetComponent<Image> ();
if (bestScore >= 10) {
lockComp.sprite = myLockImage;
}
else
{
lockComp.sprite = myLockSecondImage;
}
Simply add an event listener to your button so as to change the image.
lockComp.sprite = myLockSecondImage;
if (bestScore >= 10) {
lockBtn.GetComponent<Button>().onClick.addEventListener( OnLockButtonClicked ) ;
}
// ...
private void OnLockButtonClicked()
{
lockComp.sprite = myLockImage ;
}
Be carefull to not add this snippet of code into the Update function. Otherwise, you will add a new event listener every frame
Saving the "unlocked state" of the button into a file so as to not show the unlocked sprite when the user starts the game again could be a good idea.
Put your code in a file and class named ButtonScript and in a method named OnButtonClick()
public class ButtonScript : MonoBehaviour {
public void OnButtonClick(){
lockComp = lockBtn.GetComponent<Image> ();
if (bestScore >= 10) {
lockComp.sprite = myLockImage;
}
else
{
lockComp.sprite = myLockSecondImage;
}
}
}
Then add this script on your Button and in the OnClick event add a reference to the Button and his Method:
I am using Unity 5.2 UI. I am working on a game for iOS. I have a custom keyboard. I want to add the functionality to the del/backspace key so that when i hold the del key for more than 2 secs, it deletes the whole word instead of a single letter, which it deletes on single clicks. How do I achieve that?
Using the UGUI event you'd create a script like the following and attach it to your button:
using UnityEngine;
using UnityEngine.EventSystems;
public class LongPress : MonoBehaviour, IPointerDownHandler, IPointerUpHandler {
private bool isDown;
private float downTime;
public void OnPointerDown(PointerEventData eventData) {
this.isDown = true;
this.downTime = Time.realtimeSinceStartup;
}
public void OnPointerUp(PointerEventData eventData) {
this.isDown = false;
}
void Update() {
if (!this.isDown) return;
if (Time.realtimeSinceStartup - this.downTime > 2f) {
print("Handle Long Tap");
this.isDown = false;
}
}
}
I tried to use the back navigation by overriding OnBackButtonPressed, but somehow it wasn't get called at all. I am using the ContentPage and the latest 1.4.2 release.
Alright, after many hours I figured this one out. There are three parts to it.
#1 Handling the hardware back button on android. This one is easy, override OnBackButtonPressed. Remember, this is for a hardware back button and android only. It will not handle the navigation bar back button. As you can see, I was trying to back through a browser before backing out of the page, but you can put whatever logic you need in.
protected override bool OnBackButtonPressed()
{
if (_browser.CanGoBack)
{
_browser.GoBack();
return true;
}
else
{
//await Navigation.PopAsync(true);
base.OnBackButtonPressed();
return true;
}
}
#2 iOS navigation back button. This one was really tricky, if you look around the web you'll find a couple examples of replacing the back button with a new custom button, but it's almost impossible to get it to look like your other pages. In this case I made a transparent button that sits on top of the normal button.
[assembly: ExportRenderer(typeof(MyAdvantagePage), typeof
(MyAdvantagePageRenderer))]
namespace Advantage.MyAdvantage.MobileApp.iOS.Renderers
{
public class MyAdvantagePageRenderer : Xamarin.Forms.Platform.iOS.PageRenderer
{
public override void ViewWillAppear(bool animated)
{
base.ViewWillAppear(animated);
if (((MyAdvantagePage)Element).EnableBackButtonOverride)
{
SetCustomBackButton();
}
}
private void SetCustomBackButton()
{
UIButton btn = new UIButton();
btn.Frame = new CGRect(0, 0, 50, 40);
btn.BackgroundColor = UIColor.Clear;
btn.TouchDown += (sender, e) =>
{
// Whatever your custom back button click handling
if (((MyAdvantagePage)Element)?.
CustomBackButtonAction != null)
{
((MyAdvantagePage)Element)?.
CustomBackButtonAction.Invoke();
}
};
NavigationController.NavigationBar.AddSubview(btn);
}
}
}
Android, is tricky. In older versions and future versions of Forms once fixed, you can simply override the OnOptionsItemselected like this
public override bool OnOptionsItemSelected(IMenuItem item)
{
// check if the current item id
// is equals to the back button id
if (item.ItemId == 16908332)
{
// retrieve the current xamarin forms page instance
var currentpage = (MyAdvantagePage)
Xamarin.Forms.Application.
Current.MainPage.Navigation.
NavigationStack.LastOrDefault();
// check if the page has subscribed to
// the custom back button event
if (currentpage?.CustomBackButtonAction != null)
{
// invoke the Custom back button action
currentpage?.CustomBackButtonAction.Invoke();
// and disable the default back button action
return false;
}
// if its not subscribed then go ahead
// with the default back button action
return base.OnOptionsItemSelected(item);
}
else
{
// since its not the back button
//click, pass the event to the base
return base.OnOptionsItemSelected(item);
}
}
However, if you are using FormsAppCompatActivity, then you need to add onto your OnCreate in MainActivity this to set your toolbar:
Android.Support.V7.Widget.Toolbar toolbar = this.FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
SetSupportActionBar(toolbar);
But wait! If you have too old a version of .Forms or too new version, a bug will come up where toolbar is null. If this happens, the hacked together way I got it to work to make a deadline is like this. In OnCreate in MainActivity:
MobileApp.Pages.Articles.ArticleDetail.androdAction = () =>
{
Android.Support.V7.Widget.Toolbar toolbar = this.FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
SetSupportActionBar(toolbar);
};
ArticleDetail is a Page, and androidAction is an Action that I run on OnAppearing if the Platform is Android on my page. By this point in your app, toolbar will no longer be null.
Couple more steps, the iOS render we made above uses properties that you need to add to whatever page you are making the renderer for. I was making it for my MyAdvantagePage class that I made, which implements ContentPage . So in my MyAdvantagePage class I added
public Action CustomBackButtonAction { get; set; }
public static readonly BindableProperty EnableBackButtonOverrideProperty =
BindableProperty.Create(
nameof(EnableBackButtonOverride),
typeof(bool),
typeof(MyAdvantagePage),
false);
/// <summary>
/// Gets or Sets Custom Back button overriding state
/// </summary>
public bool EnableBackButtonOverride
{
get
{
return (bool)GetValue(EnableBackButtonOverrideProperty);
}
set
{
SetValue(EnableBackButtonOverrideProperty, value);
}
}
Now that that is all done, on any of my MyAdvantagePage I can add this
:
this.EnableBackButtonOverride = true;
this.CustomBackButtonAction = async () =>
{
if (_browser.CanGoBack)
{
_browser.GoBack();
}
else
{
await Navigation.PopAsync(true);
}
};
That should be everything to get it to work on Android hardware back, and navigation back for both android and iOS.
You are right, in your page class override OnBackButtonPressed and return true if you want to prevent navigation. It works fine for me and I have the same version.
protected override bool OnBackButtonPressed()
{
if (Condition)
return true;
return base.OnBackButtonPressed();
}
Depending on what exactly you are looking for (I would not recommend using this if you simply want to cancel back button navigation), OnDisappearing may be another option:
protected override void OnDisappearing()
{
//back button logic here
}
OnBackButtonPressed() this will be called when a hardware back button is pressed as in android. This will not work on the software back button press as in ios.
Additional to Kyle Answer
Set
Inside YOURPAGE
public static Action SetToolbar;
YOURPAGE OnAppearing
if (Device.RuntimePlatform == Device.Android)
{
SetToolbar.Invoke();
}
MainActivity
YOURPAGE.SetToolbar = () =>
{
Android.Support.V7.Widget.Toolbar toolbar =
this.FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
SetSupportActionBar(toolbar);
};
I use Prism libray and for handle the back button/action I extend INavigatedAware interface of Prism on my page and I implement this methods:
public void OnNavigatedFrom(INavigationParameters parameters)
{
if (parameters.GetNavigationMode() == NavigationMode.Back)
{
//Your code
}
}
public void OnNavigatedTo(INavigationParameters parameters)
{
}
Method OnNavigatedFrom is raised when user press back button from Navigation Bar (Android & iOS) and when user press Hardware back button (only for Android).
For anyone still fighting with this issue - basically you cannot intercept back navigation cross-platform. Having said that there are two approaches that effectively solve the problem:
Hide the NavigationPage back button with NavigationPage.ShowHasBackButton(this, false) and push a modal page that has a custom Back/Cancel/Close button
Intercept the back navigation natively for each platform. This is a good article that does it for iOS and Android: https://theconfuzedsourcecode.wordpress.com/2017/03/12/lets-override-navigation-bar-back-button-click-in-xamarin-forms/
For UWP you are on your own :)
Edit:
Well, not anymore since I did it :) It actually turned out to be pretty easy – there is just one back button and it’s supported by Forms so you just have to override ContentPage’s OnBackButtonPressed:
protected override bool OnBackButtonPressed()
{
if (Device.RuntimePlatform.Equals(Device.UWP))
{
OnClosePageRequested();
return true;
}
else
{
base.OnBackButtonPressed();
return false;
}
}
async void OnClosePageRequested()
{
var tdvm = (TaskDetailsViewModel)BindingContext;
if (tdvm.CanSaveTask())
{
var result = await DisplayAlert("Wait", "You have unsaved changes! Are you sure you want to go back?", "Discard changes", "Cancel");
if (result)
{
tdvm.DiscardChanges();
await Navigation.PopAsync(true);
}
}
else
{
await Navigation.PopAsync(true);
}
}
protected override bool OnBackButtonPressed()
{
base.OnBackButtonPressed();
return true;
}
base.OnBackButtonPressed() returns false on click of hardware back button.
In order to prevent operation of back button or prevent navigation to previous page. the overriding function should be returned as true. On return true, it stays on the current xamarin form page and state of page is also maintained.
The trick is to implement your own navigation page that inherits from NavigationPage. It has the appropriate events Pushed, Popped and PoppedToRoot.
A sample implementation could look like this:
public class PageLifetimeSupportingNavigationPage : NavigationPage
{
public PageLifetimeSupportingNavigationPage(Page content)
: base(content)
{
Init();
}
private void Init()
{
Pushed += (sender, e) => OpenPage(e.Page);
Popped += (sender, e) => ClosePage(e.Page);
PoppedToRoot += (sender, e) =>
{
var args = e as PoppedToRootEventArgs;
if (args == null)
return;
foreach (var page in args.PoppedPages.Reverse())
ClosePage(page);
};
}
private static void OpenPage(Page page)
{
if (page is IPageLifetime navpage)
navpage.OnOpening();
}
private static void ClosePage(Page page)
{
if (page is IPageLifetime navpage)
navpage.OnClosed();
page.BindingContext = null;
}
}
Pages would implement the following interface:
public interface IPageLifetime
{
void OnOpening();
void OnClosed();
}
This interface could be implemented in a base class for all pages and then delegate it's calls to it's view model.
The navigation page and could be created like this:
var navigationPage = new PageLifetimeSupportingNavigationPage(new MainPage());
MainPage would be the root page to show.
Of course you could also just use NavigationPage in the first place and subscribe to it's events without inheriting from it.
Maybe this can be usefull, You need to hide the back button, and then replace with your own button:
public static UIViewController AddBackButton(this UIViewController controller, EventHandler ev){
controller.NavigationItem.HidesBackButton = true;
var btn = new UIBarButtonItem(UIImage.FromFile("myIcon.png"), UIBarButtonItemStyle.Plain, ev);
UIBarButtonItem[] items = new[] { btn };
controller.NavigationItem.LeftBarButtonItems = items;
return controller;
}
public static UIViewController DeleteBack(this UIViewController controller)
{
controller.NavigationItem.LeftBarButtonItems = null;
return controller;
}
Then call them into these methods:
public override void ViewWillAppear(bool animated)
{
base.ViewWillAppear(animated);
this.AddBackButton(DoSomething);
UpdateFrames();
}
public override void ViewWillDisappear(Boolean animated)
{
this.DeleteBackButton();
}
public void DoSomething(object sender, EventArgs e)
{
//Do a barrel roll
}
Another way around is to use Rg.Plugins.Popup Which allows you to implement nice popup. It uses another NavigationStack => Rg.Plugins.Popup.Services.PopupNavigation.Instance.PopupStack. So your page won't be wrap around the NavigationBar.
In your case I would simply
Create a full page popup with opaque background
Override ↩️ OnBackButtonPressed for Android on ⚠️ParentPage⚠️ with something like this:
protected override bool OnBackButtonPressed()
{
return Rg.Plugins.Popup.Services.PopupNavigation.Instance.PopupStack.Any();
}
Since the back-button affect the usual NavigationStack your parent would pop out whenever the user try to use it while your "popup is showing".
Now what? Xaml what ever you want to properly close your popup with all the check you want.
💥 Problem solved for these targets💥
[x] Android
[x] iOS
[-] Windows Phone (Obsolete. Use v1.1.0-pre5 if WP is needed)
[x] UWP (Min Target: 10.0.16299)
When exiting a JavaFX program I'm overriding Application.stop() in order to check for unsaved changes. This works okay, but it would be nice to give the user the option to cancel the operation.
Application.stop() is last-chance-saloon in other words although it does trap the exit, it's a bit late to revoke the exit process.
Better is to set a listener for the close request which can be cancelled by consuming the event.
In the application class:
public void start(Stage stage) throws Exception {
FXMLLoader ldr = new FXMLLoader(getClass()
.getResource("Application.fxml"));
Parent root = (Parent) ldr.load();
appCtrl = (ApplicationController) ldr.getController();
Scene scene = new Scene(root);
stage.setScene(scene);
stage.show();
scene.getWindow().setOnCloseRequest(new EventHandler<WindowEvent>() {
public void handle(WindowEvent ev) {
if (!appCtrl.shutdown()) {
ev.consume();
}
}
});
}
and then in the application controller, referenced as appCtrl above:
/** reference to the top-level pane */
#FXML
private AnchorPane mainAppPane;
public boolean shutdown() {
if (model.isChanged()) {
DialogResult userChoice =
ConfirmDialog.showYesNoCancelDialog("Changes Detected",
"Do you want to save the changes? Cancel revokes the "
+ "exit request.",
mainAppPane.getScene().getWindow());
if (userChoice == DialogResult.YES) {
fileSave(null);
if (model.isChanged()) {
// cancelled out of the save, so return to the app
return false;
}
}
return userChoice == DialogResult.NO;
}
return true;
}
noting: mainAppPane is referenced in the FXML ( using the JavaFX Scene Builder in this case ) to allow access to the scene and window; the dialog is one extended from https://github.com/4ntoine/JavaFxDialog and fileSave is the event handler for File -> Save menu item. For the File -> Exit menu item:
#FXML
private void fileExitAction(ActionEvent ev) {
if (shutdown()) {
Platform.exit();
}
}
Hope this helps someone!