Xamarin Forms Search Bar with Picker - xamarin

I have a xamarin forms app and I would like to use the search bar control that upon focus will pull up a picker. Is there anyway I can extend the search bar to provide this functionality? In other words I don’t want the user to enter text in the search bar box, rather it’s selected from the pick list. Any examples would be appreciated.

You can look at using the XFX Controls for Xamarin Forms.
https://github.com/XamFormsExtended/Xfx.Controls
In the top of your page add a namespace reference to :
xmlns:xfx="clr-namespace:Xfx;assembly=Xfx.Controls"
Then you use the control as follows:
<!-- XfxComboBox-->
<xfx:XfxComboBox
Placeholder="Select make"
SelectedItem="{Binding SelectedVehicleMake}"
Text="{Binding Description}"
ItemsSource="{Binding AssetMakes}"/>
This control allows to bind to a item source and a selected Item

Picker dialog is shown when you call Focus() on the element, so you could just place a hidden Picker and call the method from the Click Handler of the ToolbarItem.
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MyApp.Views.MyPage"
Title="My Page Title"
x:Name="MyPage">
<ContentPage.ToolbarItems>
<ToolbarItem Text="ShowPicker" Clicked="ShowPicker">
</ToolbarItem>
</ContentPage.ToolbarItems>
<ContentPage.Content>
<DatePicker x:Name="MyPicker" IsVisible="false" />
</ContentPage.Content>
</ContentPage>
namespace MyApp.Views
{
public partial class MyPage : ContentPage
{
public ItemsPage()
{
InitializeComponent();
}
void ShowPicker(object sender, EventArgs e)
{
MyPicker.Focus();
}
}
}

Related

XAMARIN Button with Label and image inside / mainpage=navigation page

I am fairly new and inexperienced. I have two questions. First: what would the xaml code in xamarin look like for such a button? The blue one should be the button. The button should contain a text and a picture. So it should also work that when the image or text is clicked, the button is actually clicked.
enter image description here
Second: my app has two sides. The start page is MainPage and the other page is Page1. I can switch to Page1 using a button on MainPage. I looked at a tutorial and in App.xaml.cs "MainPage = new MainPage ();" was made to "MainPage = new NavigationPage (new MainPage ());". Why was that done? Why does the page change via a button click not work differently?
enter image description here
Since it was coded to "MainPage = new NavigationPage (new MainPage ());" , there is a blue bar at the top of my MainPage. How can I remove this bar or make it white?
enter image description here
For the first question:
There is no such control now, but you can do this by using a Frame and adding an Image and Label to it,then you could add a TapGestureRecognizer to the Frame.
like:
<Frame CornerRadius="20" HorizontalOptions="Start" WidthRequest="100" HeightRequest="120" BackgroundColor="Blue" Padding="40">
<StackLayout Orientation="Vertical" >
<Image Source="heart.png"></Image>
<Label Text="hello world" BackgroundColor="Red" ></Label>
</StackLayout>
<Frame.GestureRecognizers>
<TapGestureRecognizer Tapped="TapGestureRecognizer_Tapped">
</TapGestureRecognizer>
</Frame.GestureRecognizers>
</Frame>
handle the click event in code behind:
private void TapGestureRecognizer_Tapped(object sender, EventArgs e)
{
//do something
}
For the second question:
1)To move from one page to another, an application will push a new page onto the navigation stack.The NavigationPage class provides a hierarchical navigation experience where the user is able to navigate through pages, forwards and backwards, as desired. The class implements navigation as a last-in, first-out (LIFO) stack of Page objects.
2)The top blue bar we call it NavigationBar.If you want display it,you could set NavigationPage.SetHasNavigationBar(this, false); in your MainPage.xaml.cs like:
public MainPage()
{
InitializeComponent();
NavigationPage.SetHasNavigationBar(this, false);
}
or set it in the MainPage.xaml like:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
NavigationPage.HasNavigationBar="False"
x:Class="YourNamespace.MainPage">
....
</ContentPage >
You could look at https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/navigation/hierarchical for more details.

How to preview an ItemTemplate in the XAML designer

Say I have a simple ItemTemplate for a ListView
<ListView ItemsSource="{x:Bind ListItems}">
<ListView.ItemTemplate>
<DataTemplate x:DataType="local:TextItem">
<TextBlock Text="{x:Bind Item}"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
MainPage.xaml
When I run the app, I get a ListView populated with TextBlocks - one for each item in ListItems (which is a behind defined variable). However, in the XAML designer, I see nothing.
So, is there a way to preview the ItemTemplate/DataTemplate in the XAML designer, with a set number of placeholder TextBlocks with placeholder text replacing the Text="{x:Bind Item}"? Or just preview a single TextBlock?
This is not a duplicate of
Design View of a DataTemplate in a ResourceDictionary in Visual Studio - because I can't use Blend. Everything I've looked up that says use Blend in a certain way merely gives me the message 'This feature is not available for projects targeting "Windows 10 Fall Creators Update (10.0; Build 16299)"'
Can I preview my DataTemplate(s) in my collection-based controls in the designer? - well, perhaps it is, but I don't understand the accepted answer, which is now several years old. An answer containing an example tailored to my question would be really helpful.
Microsoft actually posted a (semi helpful) tutorial on this in April of this year: link
Requirements
Whatever you want to display, you will need this at the top of your XAML code (should be there by default if you created the page using VS's templates):
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
A simple list of strings
For something simple like a list of strings, something like this will work just fine (taken from the above mentioned MSDN page):
<ListView>
<d:ListView.Items>
<system:String>Item One</system:String>
<system:String>Item Two</system:String>
<system:String>Item Three</system:String>
</d:ListView.Items>
</ListView>
Display something more complex
If you want to use a data source from somewhere else in your code, it gets a little more ugly:
First you need to set your data context (usually done at the page level, but you can also add it just on the element where you want to use it):
d:DataContext="{d:DesignInstance
yournamespace:YourDataSourceClass,
IsDesignTimeCreatable=True}"
And on the ListView add:
d:ItemsSource="{Binding data}"
If you are using an ItemTemplate, you will need to add "d:" variants for everything you want to pull from your data source.
Full example code:
XAML:
<Page
x:Class="exampleApp.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:exampleApp"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DataContext="{d:DesignInstance local:DesignTimeData,
IsDesignTimeCreatable=True}"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid>
<Grid>
<ListView ItemsSource="{x:Bind ListItems}" d:ItemsSource="{Binding DummyData}">
<ListView.ItemTemplate>
<DataTemplate x:DataType="local:TextItem">
<TextBlock Text="{x:Bind Item}" d:Text="{Binding Item}"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
</Grid>
</Page>
C#:
using System.Collections.ObjectModel;
using Windows.UI.Xaml.Controls;
namespace exampleApp {
public sealed partial class MainPage : Page {
public ObservableCollection<TextItem> ListItems;
public MainPage() {
this.InitializeComponent();
//populate you ListItems list
}
}
public class TextItem {
public string Item { get; set; }
}
public class DesignTimeData {
public ObservableCollection<TextItem> DummyData { get; set; } = new ObservableCollection<TextItem> {
new TextItem { Item = "foo" },
new TextItem { Item = "bar" },
new TextItem { Item = "bla" },
new TextItem { Item = "blubb" }
};
}
}
Remarks
It seems you have to use "Binding" rather than "x:Bind" for the design-time bindings. From what I understand, x:Bind works using code generated at compile time, which is not executed by the XAML designer
When you change your Binding declarations or data source code, you will have to recompile to see the changes in the designer. Other design changes will reflect in real time
Binding is more limited than x:Bind in some regards (notably you cannot bind to class methods using Binding, only x:Bind). Keep that in mind when writing your design-time data
Sadly some of the more convenient ways of getting design-time data into your app are WPF and Xamarin only (Blends' data window, data declared in XAML file, and especially auto-generated sample data)
(Everything was tested using Visual Studio 2019 version 16.10.3.)

Custom navigation bar using Xamarin forms with prism broken

I'm using Prism Library for Xamarin.Forms.
And I'm going to create custom navigation bar via Control template. (Reason of creating custom navigation bar - I didn't find solution to make navigation bar transparent for display background image, also I will probably customize my navigation bar and add some controls on it).
<ControlTemplate x:Key="NavigationPageTemplate">
<AbsoluteLayout BackgroundColor="Transparent">
<Image AbsoluteLayout.LayoutBounds="0,0,1,1"
AbsoluteLayout.LayoutFlags="All"
Aspect="AspectFill"
Source="{TemplateBinding BackgroundImageEx}" />
<ContentView Padding="0,50,0,0"
AbsoluteLayout.LayoutBounds="0,0,1,1"
AbsoluteLayout.LayoutFlags="All">
<ContentPresenter />
</ContentView>
<!--Navigation bar started here -->
<ContentView AbsoluteLayout.LayoutBounds="0,0,1,AutoSize"
AbsoluteLayout.LayoutFlags="PositionProportional, WidthProportional"
BackgroundColor="Transparent">
<ContentView.Padding>
<OnPlatform x:TypeArguments="Thickness"
Android="10"
iOS="10, 20, 10, 0" />
</ContentView.Padding>
<controls:ImageButton Command="{TemplateBinding GoBackCommand}"
HeightRequest="30"
HorizontalOptions="StartAndExpand"
Source="ic_back.png"
WidthRequest="30">
</controls:ImageButton>
</ContentView>
</AbsoluteLayout>
</ControlTemplate>
And my problem is to process back button press with Prism Navigation.
I've tried to process click on MyApp.xaml.cs file.
private void Button_OnClicked(object sender, EventArgs e)
{
NavigationService.GoBackAsync();
}
And it seems to have different navigation stack because it shows after press my first page.
I had Navigation this way:
Navigate("FirstPage"); -> Navigate(MasterDetail/NavigationPage/ViewA) -> Navigate("ViewB")
ViewB - uses Control template.
When I click custom back button on ViewB NavigationService back me to FirstPage. It is incorrect for me. I should back to ViewA!
Another question Should first page be saved when we change App.MainPage?
See the discussion of described problem on https://github.com/PrismLibrary/Prism/issues/1262
To navigate back from ViewA to FirstPage you can intercept the back event and go back again if a variable is passed with a specific value from the ViewB page. Code Example:
Sender:
var navigationParams = new NavigationParameters();
navigationParams.Add("yourVariableName", "YourVariableValue");
_navigationService.GoBackAsync(navigationParams);
Receiver:
public void OnNavigatedTo(NavigationParameters parameters)
{
string myVar = null;
if (parameters.ContainsKey("yourVariableName"))
{
myVar = (string)parameters["yourVariableName"];
}
if(myVar=="YourVariableValue"){
NavigationService.GoBackAsync();
}
}
I don't understand your second question.

Wrapping an MPVolumeView inside 2 Stack Layouts (Xamarin.IOS)

I am creating a control based on a generic View that works with a custom renderer based on an iOS MPVolumeView, which is the simple control that allows you to select an alternate output route for audio in your app (i.e. Bluetooth Speaker). The code works just fine if I wrap inside a single stack layout, but not if it's inside two stack layouts. My XAML looks like this... very basic:
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="DABApp.DabTestPage" xmlns:local="clr-namespace:DABApp;assembly=DABApp">
<ContentPage.Content>
<StackLayout VerticalOptions="CenterAndExpand" HorizontalOptions="FillAndExpand" BackgroundColor="Red">
<StackLayout Orientation="Horizontal" HorizontalOptions="CenterAndExpand" VerticalOptions="FillAndExpand">
<local:AudioOutputView />
</StackLayout>
</StackLayout>
</ContentPage.Content>
</ContentPage>
And here's the guts of my custom renderer:
[assembly: ExportRenderer(typeof(AudioOutputView), typeof(iosAudioOutputViewRenderer))]
namespace DABApp.iOS
{
public class iosAudioOutputViewRenderer: ViewRenderer<AudioOutputView, UIView>
{
MPVolumeView view;
protected override void OnElementChanged(ElementChangedEventArgs<AudioOutputView> e)
{
base.OnElementChanged(e);
if (Control == null)
{
view = new MPVolumeView()
{
ShowsRouteButton = true,
ShowsVolumeSlider = false,
};
SetNativeControl(view);
}
}
}
}
With this XAML and code, when I push the page onto the nav stack async, the page won't even show. If I remove one of the StackLayouts, it works fine.
I changed my IOS control in the CustomRenderer to a simple UILabel and this works fine... so it looks like it has something to do with putting the MPVolumeView inside 2 StackLayouts. I need to be able to do this because of the layout requirements of my app, and it doesn't make any sense why 1 StackLayout is fine, but 2 isn't, and only for this native control.
Any ideas?

WPF4: How do you set a value in a UserControl from the Main Window?

This has to be simple, at least it was in good old .Net where it took maybe four lines of code. I'm working in VS2010, C#, WPF4.
I have a user control with a textbox. When I click a button in the main window, I want my user control textbox to reflect some text. Is this possible in WPF4 with less than 500 lines of esoteric code?
The problem is that while I know the textbox is getting the new text as evidenced from breakpoints in the user control code, that text is never being reflected to the main window. The main window still shows the original text. It has to be some kind of binding thing, and I really don't think I should have to create templates and resources and all for this simple situation. It's got to be something simple that I'm forgetting in the forest of WPF4. Below is what I have. After clicking the button, the textbox is still blank; it does not say "hello earthlings."
In the user control code:
public partial class UserControl1 : UserControl
{
public static readonly DependencyProperty TextProperty;
public UserControl1()
{
InitializeComponent();
}
static UserControl1()
{
TextProperty = DependencyProperty.Register("Text", typeof(string), typeof(UserControl1), new UIPropertyMetadata(null));
}
public string Text
{
get { return (string)GetValue(TextProperty); }
set { SetValue(TextProperty, value); }
}
}
User control xaml:
<UserControl x:Class="WTFUserControlLibrary.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006">
<Grid Height="164" Width="220">
<TextBox Name="txtTest" BorderBrush="red" BorderThickness="2" Height="25" Text="{Binding ElementName=UserControl1, Path=Text, Mode=TwoWay}"></TextBox>
</Grid>
(I have no idea what the text binding is supposed to be doing in this case.)
Main window code:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
WTFUserControlLibrary.UserControl1 uc = new WTFUserControlLibrary.UserControl1();
uc.Text = "hello earthlings";
}
}
and the main window xaml:
<Window x:Class="WpfApplication2.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:my="clr-namespace:WTFUserControlLibrary;assembly=WTFUserControlLibrary"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="71,65,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
<my:UserControl1 HorizontalAlignment="Left" Margin="71,94,0,0" Name="userControl11" VerticalAlignment="Top" Height="116" Width="244" />
</Grid>
Thanks Earthlings (and also those who designed this mess!)
In your method button1_Click you are creating a new user control. This is not the usercontrol in the window and is never displayed.
Instead, give your usercontrol a name in the XAML:
x:Name="uc"
Then in the button1_Click method you just remove that first line where you create a new usercontrol.
update
You want the user control XAML to look more like this:
<UserControl x:Class="WTFUserControlLibrary.UserControl1"
x:Name="thisControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006">
<Grid Height="164" Width="220">
<TextBox Name="txtTest" BorderBrush="red"
BorderThickness="2" Height="25"
Text="{Binding ElementName=thisControl, Path=Text, Mode=TwoWay}" />
</Grid>
I added x:Name="thisControl" to the root UserControl element, and then referenced this in the binding.
I'll try to explain the binding:
You have this textbox inside your user control, but you want to be able to bind the text value to something outside the user control. What you've done is set up a dependency property on the user control, and bound that textbox to it, so you are using the binding infrastructure pass values from the top level of the UserControl to constituent controls inside it.
Basically, it looks like this:
data
---> bind UserControl1.Text to data
---> bind TextBox.Text to UserControl1.Text

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