I know ScaleTo can create an animation of a view.
but it will change the height and width,Is there anyway to change it's height by an animation?
You can call the method LayoutTo.
For example
in xaml
<StackLayout HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand">
<BoxView x:Name="box" WidthRequest="300" BackgroundColor="Red" HeightRequest="600" />
<Button Clicked="Button_Clicked" Text="Click Me"/>
</StackLayout>
in Code Behind
private async void Button_Clicked(object sender, EventArgs e)
{
await box.LayoutTo(new Rectangle(box.Bounds.X, box.Bounds.Y, box.Bounds.Width, 300), 500, Easing.CubicIn);
}
For more details about different animation you can check https://trailheadtechnology.com/xamarin-forms-fancy-animations/
Related
If I hide an image visibility in CollectionView, multiple image visibility is affecting but image Tapped event fires once.
Simplified CollectionView xaml..
<CollectionView x:Name="favCollectionView"
ItemsSource="{Binding FavoriteCollection}"
RemainingItemsThresholdReachedCommand="{Binding GetNextDatas}"
RemainingItemsThreshold="1"
ItemSizingStrategy="MeasureAllItems"
ItemsLayout="VerticalList"
SelectionMode="Single">
<CollectionView.ItemTemplate>
<DataTemplate>
<Grid VerticalOptions="FillAndExpand">
<Label Grid.Row="0" Text="{Binding TargetText}"/>
<Image Grid.Row="0" Aspect="AspectFill" Source="seeResult.png">
<Image.GestureRecognizers>
<TapGestureRecognizer Tapped="Tapped_TranslatedResult"/>
</Image.GestureRecognizers>
</Image>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
Code behind..
void Tapped_TranslatedResult(System.Object sender, System.EventArgs e)
{
var img = sender as Image;
if (img != null)
{
img.Opacity = 0;
}
}
For example, If I have 50 rows in CollectionView and tapped once top second image item, next ninth image's visibility is changed too and again next ninth one too, so on..
What could be the problem?
I changed the Image to ImageButton and then added Command parameter. The key was the Jason's comment. Binding the Model property to my ImageButton's IsVisibility property and it worked correctly.
I'm trying to call a function in a Xamarin project by using the SelectionChanged property.
Inside this property, I've called a function that I've declared in the cs file.
Here is the XAML code:
<CollectionView x:Name="PCCollection" SelectionMode="Single" SelectionChanged="Cell_Tapped" AutomationId="{Binding Tipologia_Alimento}">
Here is the CS function:
private async void Cell_Tapped(object sender, System.EventArgs e) {
Console.WriteLine("Tapped");
Console.WriteLine((sender as Cell).AutomationId.ToString());
}
When I click on the Collection View cell, it prints the value "Tapped" but it gives me also the Break Mode error: "The application is in break mode".
Could you help me with this error?
Thanks in advance.
Your syntax is not valid. The Collection View control does not have AutomationId property.
Sample
<CollectionView ItemsSource="{Binding Monkeys}"
SelectionChanged="Cell_Tapped"
SelectionMode="Single">
<CollectionView.ItemTemplate>
<DataTemplate>
<Grid Padding="10">
<Label Grid.Column="1"
Text="{Binding Name}"
FontAttributes="Bold" />
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
void Cell_Tapped(object sender, SelectionChangedEventArgs e)
{
if (((CollectionView)sender).SelectedItem == null)
return;
string current = (e.CurrentSelection.FirstOrDefault() as Monkey)?.Name;
}
You can find more here
https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/collectionview/selection
https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/collectionview/populate-data
Edit: apologies for the bad title, apparently something like "Setting bindingmode in code behind" didn't fit the highly nebulous requirements of SO. A title that is clearly more obvious than what the current one is.
Original: I am trying to set the binding of my listview in the code behind of its data selector template. The reason i am doing this, as I suspect (because doing something similar to it in a different template selector fixed it) that once you exit that page android seems to still contain a reference to it and then throws a amarin.forms.platform.android.viewcellrendererA disposed object exception.
my current xaml looks as follows:
<StackLayout Orientation="Vertical"
Padding="0, 20, 0, 0"
HorizontalOptions="FillAndExpand"
VerticalOptions="StartAndExpand">
<Label
x:Name="LabelName"
FontAttributes="Bold"
TextColor="Black"
FontSize="14"
VerticalOptions="Start"
HorizontalOptions="FillAndExpand"/>
<ListView x:Name="MultiselectList"
SeparatorVisibility="None"
RowHeight="30"
Margin="0, 10, 0, 0"
VerticalOptions="FillAndExpand"
HorizontalOptions="StartAndExpand"
SelectedItem="{Binding SelectedItem, Mode=TwoWay}">
<ListView.ItemTemplate>
<DataTemplate>
<customcontrols:NoHighlightCell>
<StackLayout Orientation="Horizontal"
HorizontalOptions="FillAndExpand"
VerticalOptions="StartAndExpand">
<Image
x:Name="image"
Source="{Binding ImageUrl}"
VerticalOptions="StartAndExpand"
HorizontalOptions="Start"
Margin="0, 2, 0, 0"
WidthRequest="15"
HeightRequest="15" />
<Label
x:Name="name"
Text="{Binding Name}"
TextColor="Black"
VerticalOptions="StartAndExpand"
FontSize="14"
HorizontalOptions="Start"/>
</StackLayout>
</customcontrols:NoHighlightCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Label Text="Selection required"
TextColor="Red"
Margin="0, 10, 0, 0"
IsVisible="{Binding ValidationRequired}"
VerticalOptions="StartAndExpand"
HorizontalOptions="FillAndExpand"
FontSize="14"/>
</StackLayout>
Here's my code behind:
private SoapNoteControlsViewModel viewModel;
public SelectListTemplate()
{
InitializeComponent();
}
protected override void OnDisappearing()
{
base.OnDisappearing();
}
protected override void OnAppearing()
{
base.OnAppearing();
LabelName.Text = viewModel.Label;
MultiselectList.ItemsSource = viewModel.CheckboxItems;
MultiselectList.SelectedItem = viewModel.SelectedItem;
//how would i set the BindingMode here? Doing .SetBinding doesn't seem to do it.
}
protected override void OnBindingContextChanged()
{
try
{
base.OnBindingContextChanged();
if(BindingContext == null)
{
return;
}
viewModel = BindingContext as SoapNoteControlsViewModel;
} catch (Exception e)
{
Console.WriteLine(e);
}
}
}
I tried doing .SetBinding, but it keeps saying that BindingMode is a type (given that it is an enum). Looking at some of the examples on MSDN haven't really helped
You would do it like this:
MultiselectList.SetBinding(ListView.ItemsSourceProperty, nameof(viewModels.CheckboxItems), BindingMode.TwoWay);
The first parameter is the property that you want to bind to - e.g. the ItemsSource.
The second parameter is the name of the property to look for - e.g. your viewModel's CheckBoxItems. This collection will be bound/populated in the list.
The last parameter is what you would want to achieve - the BindingMode. You are correct in saying that it is an enum, so here we can set it to BindingMode.TwoWay.
For reference: BindingMode's Remarks page.
I'm totally new to Xamarin, so please be patient!
Somehow Xamarin adds a mysterious Margin to all my Buttons and I don't know how to get rid of it.
Here is my Code:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="RockStamp.CameraSearch_Scan">
<StackLayout Orientation="Vertical" Padding="0" Spacing="0">
<StackLayout Orientation="Horizontal" Padding="0" Spacing="0">
<Button Text="Test" HeightRequest="50" WidthRequest="60" TextColor="#333333" x:Name="btnBack" VerticalOptions="Center" HorizontalOptions="Start" ></Button>
<Label Text="Scan a..." FontSize="20" FontAttributes="Bold" BackgroundColor="{StaticResource BlueBackColor}" TextColor="White" VerticalOptions="Start" HorizontalOptions="FillAndExpand" />
</StackLayout>
<Label Text="Steady now, we try to detect your..." FontSize="16" VerticalOptions="Start" HorizontalOptions="Start" />
<!-- Camera Placeholder -->
<BoxView HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" BackgroundColor="#eeeeee" ></BoxView>
<StackLayout Orientation="Horizontal" Padding="0" Spacing="0">
<Button Text="Cancel" TextColor="#333333" x:Name="btnCancel" VerticalOptions="Center" HorizontalOptions="FillAndExpand" ></Button>
<Button Text="Scan now!" TextColor="#333333" x:Name="btnScan" VerticalOptions="Center" HorizontalOptions="FillAndExpand" ></Button>
</StackLayout>
</StackLayout >
</ContentPage>
Here an image:
You can clearly see the space around the Button. Where does it come from - and more important: How can I remove it?
The problem is that the default button background contains this margin. You have to set the BackgroundColor to a color and set the BorderWidth and BorderRadius to zero manually.
<Button
BackgroundColor="Fuchsia"
BorderRadius="0"
BorderWidth="0"
Text="Test"
HeightRequest="50"
WidthRequest="60"
TextColor="#333333"
x:Name="btnBack"
Margin="0"
VerticalOptions="Start"
HorizontalOptions="Start" />
You may have fixed the problem :
The way I fixed this is to create a renderer on android to override the button on xamarin.
public class FixedMarginRenderer : ButtonRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<Button> e)
{
base.OnElementChanged(e);
if (Control != null)
{
// remove default background image
Control.Background = null;
Control.SetBackgroundColor(Element.BackgroundColor.ToAndroid());
}
}
protected override void OnElementPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName == "BackgroundColor")
{
// You have to set background color here again, because the background color can be changed later.
Control.SetBackgroundColor(Element.BackgroundColor.ToAndroid());
}
}
}
Just to add on to Sven-Michael Stübe's answer.
If none of your buttons require the Margin then create a Style or a custom control in your PCL (eg: MarginLessButton).
Setting BackgroundColor, BorderWidth, and BorderRadius manually does not work anymore. But you can use platform configuration to remove the padding. It is also necessary to remove the shadow otherwise there will be some vertical margin.
Try something like this:
using Xamarin.Forms;
using Xamarin.Forms.PlatformConfiguration;
using Xamarin.Forms.PlatformConfiguration.AndroidSpecific;
namespace MyControls
{
public class ButtonNoMargin : Xamarin.Forms.Button
{
public ButtonNoMargin() : base()
{
this.On<Android>().SetUseDefaultPadding(false);
this.On<Android>().SetUseDefaultShadow(false);
}
}
}
For more information, see https://github.com/xamarin/Xamarin.Forms/pull/1935
I have a Pivot control which I am using as following within the XAML.
I have bound the Pivot Title to a method on my view model as its content will vary depending upon what is being displayed.
<controls:Pivot x:Name="MainPivot" ItemsSource="{Binding PivotItemHeaders}" Title="{Binding ApplicationTitle}" >
<controls:Pivot.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding Description}"/>
</DataTemplate>
</controls:Pivot.HeaderTemplate>
<controls:Pivot.ItemTemplate>
<DataTemplate>
<ListBox x:Name="EventsListbox"
ItemsSource="{Binding allEventItems}"
ItemTemplate="{StaticResource EventDisplay3}"
SelectionChanged="EventsListbox_SelectionChanged"/>
</DataTemplate>
</controls:Pivot.ItemTemplate>
</controls:Pivot>
The collection of items is being refreshed and the binding is working fine for these objects - however the Pivot title is not refreshing with the new value.
It seems stuck at the value when the page/pivot control was first shown.
Any ideas how I can get the pivot control to refresh? - Thanks
I just did a quick test, binding works just fine:
<controls:Pivot Title="MY APPLICATION" ItemsSource="{Binding Items}">
<controls:Pivot.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding LineOne}" />
</DataTemplate>
</controls:Pivot.HeaderTemplate>
<controls:Pivot.ItemTemplate>
<DataTemplate>
<Grid>
<Button Content="Update" Click="Button_Click" />
</Grid>
</DataTemplate>
</controls:Pivot.ItemTemplate>
</controls:Pivot>
And in the C#
private void Button_Click(object sender, RoutedEventArgs e)
{
App.ViewModel.Items.Clear();
App.ViewModel.Items.Add(new ItemViewModel() { LineOne = "foo" });
App.ViewModel.Items.Add(new ItemViewModel() { LineOne = "bar" });
App.ViewModel.Items.Add(new ItemViewModel() { LineOne = "baz" });
}
So clearly you're doing something very wrong. Post your code and we'll take a look.
Update
Title Binding also works
XAML
<controls:Pivot Title="{Binding Title}">
<controls:PivotItem Header="first">
<Grid>
<Button Click="Button_Click" Content="OK!" />
</Grid>
</controls:PivotItem>
</controls:Pivot>
C#:
private void Button_Click(object sender, RoutedEventArgs e)
{
Title = "foobar!";
PropertyChanged(this, new PropertyChangedEventArgs("Title"));
}