I am using xamarin forms SearchBar control. I want to remove clear button x icon without using custom renderer.
<controls:ExSearchBar
x:Name="entrySearch"
BackgroundColor="White"
CornerRadius="6"
BorderWidth="1"
HeightRequest="45"
Text="{Binding SearchText}"
HorizontalOptions="FillAndExpand"
Placeholder="search">
</controls:ExSearchBar>
This is ExSearchBar control in shared project
public class ExSearchBar : SearchBar
{
public static readonly BindableProperty ElevationProperty = BindableProperty.Create(nameof(Elevation), typeof(float), typeof(ExFrame), default(float));
public float Elevation
{
get { return (float)GetValue(ElevationProperty); }
set { SetValue(ElevationProperty, value); }
}
}
How can I do that?
The situation you are describing is the exact reason why Xamarin Forms ships with the ability to create custom renderers. The forms team define the UI elements in abstract (seperate from their native implementation) and when there is a specific feature that is not defined in their API, you must go down to the platform level to change it.
You can also use an Effect to achieve the same result, I have provided a custom renderer for iOS & Android to show you how you would go about achieving the UI you desire:
iOS:
public class SearchBarButtonRenderer : SearchBarRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<SearchBar> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
Control.SearchTextField.ClearButtonMode = UITextFieldViewMode.Never;
}
}
}
Really simple, just remove the clear button from the underlying UITextField
Android
public class SearchBarButtonRenderer : SearchBarRenderer
{
private readonly Context _context;
public SearchBarButtonRenderer(Context context)
: base(context)
{
_context = context;
}
protected override void OnElementChanged(ElementChangedEventArgs<SearchBar> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
// Get Search Close Button Drawable
var closeButtonId = Resources.GetIdentifier("android:id/search_close_btn", null, null);
var searchEditText = Control.FindViewById<ImageView>(closeButtonId);
// Get Close Button Drawable To Replace Existing Drawable
var closeDrawable = GetCloseButtonDrawable() as VectorDrawable;
if (closeDrawable is null) return;
// Apply Transparent Color To Drawable (To Make Invisible)
var buttonColor = Xamarin.Forms.Color.Transparent.ToAndroid();
closeDrawable.SetTint(buttonColor);
// Set Drawable On Control
searchEditText.SetImageDrawable(closeDrawable);
}
}
private Drawable GetCloseButtonDrawable()
{
return ContextCompat.GetDrawable(_context, Resource.Drawable.abc_ic_clear_material);
}
}
A little bit of a fiddle, find the close button drawable and replace it with a custom styled drawable
I’m new to Xamarin.Forms and tried using WebView on my Windows 10 x64 v1803 machine with UWP but I can’t see how to get it to work with WebGL.
Sites which use WebGL either display a message that “Your video card does not support WebGL or just don’t display and graphical content at all.
Is this a limitation of UWP or WebView itself?
Is it a WebView configuration issue?
WebGL works in all other browsers on this machine.
UWP WebView control is support WebGL. There is similar issue case in msdn you could refer. Please try to use SeparateProcess mode WebView to replace the default one.
public MainPage()
{
this.InitializeComponent();
var MyWebView = new WebView(WebViewExecutionMode.SeparateProcess);
MyWebView.Source = new Uri("http://cycleblob.com/");
this.RootGrid.Children.Add(MyWebView);
}
I had the same problem, but with the newer Xamarin Forms it took a little more poking around to get this took work right. However, I do like that they moved the native WebView resolver back to the responsibility of the UWP/iOS/Android project (as a native XAML object) instead of using code branching with compiler directives in the Shared project.
Start by creating a HybridWebView class in the shared project to use as your WebForm view object:
public class HybridWebView : Xamarin.Forms.WebView
{
Action<string> action;
public static readonly BindableProperty UriProperty = BindableProperty.Create(
propertyName: "Uri",
returnType: typeof(string),
declaringType: typeof(HybridWebView),
defaultValue: default(string));
public string Uri
{
get { return (string)GetValue(UriProperty); }
set { SetValue(UriProperty, value); }
}
public void RegisterAction(Action<string> callback)
{
action = callback;
}
public void Cleanup()
{
action = null;
}
public void InvokeAction(string data)
{
if (action == null || data == null)
{
return;
}
action.Invoke(data);
}
}
Then in the UWP project, create a custom renderer, which will construct the native WebView and relay the events back to the WebForms object in the Shared project:
Put this at the top of the namespace, to link the HybridWebView with the Custom Renderer:
[assembly: ExportRenderer(typeof(HybridWebView), typeof(WebViewRenderer2))]
Then create the renderer class (for the IOS and android projects, if you leave this class out, it defaults to the standard native controls which seem to work fine for me):
public class WebViewRenderer2 : ViewRenderer<Xamarin.Forms.WebView, Windows.UI.Xaml.Controls.WebView>, IWebViewDelegate
{
Windows.UI.Xaml.Controls.WebView _control;
public void LoadHtml(string html, string baseUrl)
{
}
public void LoadUrl(string url)
{
}
protected override void Dispose(bool disposing)
{
}
protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.WebView> e)
{
if (_control == null) {
_control = new Windows.UI.Xaml.Controls.WebView(WebViewExecutionMode.SeparateProcess);
SetNativeControl(_control);
}
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
var xamWebView = sender as HybridWebView;
switch(e.PropertyName.ToLower())
{
case "source":
var urlSource = xamWebView.Source as Xamarin.Forms.UrlWebViewSource;
_control.Source = new Uri(urlSource.Url);
break;
case "width":
_control.Width = xamWebView.Width;
break;
case "height":
_control.Height = xamWebView.Height;
break;
case "isfocused":
var focused = xamWebView.IsFocused;
if (focused)
_control.Focus(FocusState.Programmatic);
else
_control.Focus(FocusState.Unfocused);
break;
}
}
}
You can also use the Custom Renderer to inject scripts, and you can use it to communicate from the native webview back to the Xamarin App, as seen here: HybridWebView Communication
Is there a way to implement the Android.Views.SoftInput.AdjustResize to a specific page/control (e.g. a grid) rather than inserting it into App.xaml.cs or MainActivity.cs ?Since it is affecting my other pages when the keyboard is being shown.
Thanks!
I have solved my problem. What I did was to implement in on my page.xaml.cs on
protected override void OnAppearing()
{
base.OnAppearing();
App.Current.On<Android>().UseWindowSoftInputModeAdjust(WindowSoftInputModeAdjust.Resize);
}
This would resize your window when the keyboard is being shown when the page appears, and if you want to retain the normal behaviour of your Entry or other elements that will show your keyboard use this code:
protected override void OnDisappearing()
{
base.OnDisappearing();
App.Current.On<Android>().UseWindowSoftInputModeAdjust(WindowSoftInputModeAdjust.Pan);
}
The WindowSoftInputModeAdjust.Pan is the default behaviour of Android when a keyboard is being shown. This way when your page disappears, the settings will go back to default.
As supplement to #jbtamares' solution, I created an extension method which allows to easily revert to the original resize mode once the affected page disappears.
The extension method tracks the original resize modes once UseWindowSoftInputModeAdjust is called on the page. ResetWindowSoftInputModeAdjust reads the original resize mode and sets it accordingly.
This is the code of the extension method:
public static class PageExtensions
{
private static readonly IDictionary<Type, WindowSoftInputModeAdjust> OriginalWindowSoftInputModeAdjusts = new Dictionary<Type, WindowSoftInputModeAdjust>();
public static void UseWindowSoftInputModeAdjust(this Page page, WindowSoftInputModeAdjust windowSoftInputModeAdjust)
{
var platformElementConfiguration = Xamarin.Forms.Application.Current.On<Android>();
var pageType = page.GetType();
if (!OriginalWindowSoftInputModeAdjusts.ContainsKey(pageType))
{
var originalWindowSoftInputModeAdjust = platformElementConfiguration.GetWindowSoftInputModeAdjust();
OriginalWindowSoftInputModeAdjusts.Add(pageType, originalWindowSoftInputModeAdjust);
}
platformElementConfiguration.UseWindowSoftInputModeAdjust(windowSoftInputModeAdjust);
}
public static void ResetWindowSoftInputModeAdjust(this Page page)
{
var pageType = page.GetType();
if (OriginalWindowSoftInputModeAdjusts.TryGetValue(pageType, out var originalWindowSoftInputModeAdjust))
{
OriginalWindowSoftInputModeAdjusts.Remove(pageType);
var platformElementConfiguration = Xamarin.Forms.Application.Current.On<Android>();
platformElementConfiguration.UseWindowSoftInputModeAdjust(originalWindowSoftInputModeAdjust);
}
}
}
And here is how you apply it in the page:
public partial class LoginPage : ContentPage
{
public LoginPage()
{
InitializeComponent();
}
protected override void OnAppearing()
{
base.OnAppearing();
this.UseWindowSoftInputModeAdjust(WindowSoftInputModeAdjust.Resize);
}
protected override void OnDisappearing()
{
base.OnDisappearing();
this.ResetWindowSoftInputModeAdjust();
}
}
Hope this helps. Let me know if you find any problems with the code posted above.
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)
I'm working on porting a Windows Phone 8 application to tablet, and I've bumped into a problem with the WebView API. In Windows Phone 8 and Windows 8.1, the WebBrowser and WebView controls both have a GoBack() method. However, I need my application to be compatible for Windows 8, whose WebView API does not have such a method. Are there any alternatives/workarounds that anyone's used for Windows 8 apps?
In the end I just ended up writing a wrapper for the WebView to manage the navigation stack. Here's the relevant code, for anyone who's interested. Note that I only needed to handle backwards navigation, so I used a Stack. If forwards navigation is also required, it'd probably make sense to replace the Stack with a List and store the index of the current page instead.
public class WebViewWrapper
{
private Stack<Uri> _navigationStack;
private Uri _currentUri;
public WebView WebView { get; private set; }
public bool CanGoBack
{
get { return _navigationStack.Count > 0; }
}
public WebViewWrapper(WebView _webView)
{
_navigationStack = new Stack<Uri>();
WebView = _webView;
WebView.LoadCompleted += (object s, NavigationEventArgs e) => {
if (_currentUri != null)
{
_navigationStack.Push(_currentUri);
}
_currentUri = e.Uri;
};
}
public void GoBack()
{
if (CanGoBack)
{
_currentUri = null;
WebView.Navigate(_navigationStack.Pop());
}
}
}
An example of usage would be as follows:
// Code behind for a view called WebBrowserPage
public sealed partial class WebBrowserPage : Page
{
private WebViewWrapper _webViewWrapper;
public WebBrowserPage()
{
// webView is a WebView in the xaml with x:Name="webView"
_webViewWrapper = new WebViewWrapper(webView);
}
// Other code for navigating to a Uri specified in a ViewModel.
// Event handler for a back button press
private void BackButton_Click(object sender, RoutedEventArgs e)
{
if (_webViewWrapper.CanGoBack)
{
_webViewWrapper.GoBack();
}
else
{
// Code that executes a command in the ViewModel to leave the WebBrowserPage
}
}
}
WinRT XAML Toolkit has a WebBrowser control that does some of that, but I haven't used it in any app, so I can't vouch for its quality.