In my xaml setup I have a Label, which should wrap its text. It is contained within a border, and I want the Label width to be the width of the border. I've tried to do this with the following binding on the label:
WidthRequest="{Binding Source={RelativeSource Mode=FindAncestor, AncestorType={x:Type Border}}, Path=Width}"
This has not worked though, and i suspect it hasn't because the Width that gets returned is NaN (I've written out the width of the border during runtime and it was NaN). But this is confusing to me, as I have a binding on the Border to the width of the Flexlayout which is working. Is there anything I'm missing and is there any better way to do this?
xaml:
<ScrollView Grid.Row="1">
<FlexLayout BindableLayout.ItemsSource="{Binding DisplayedUserActions}" JustifyContent="Start" Wrap="Wrap" Direction="Row">
<BindableLayout.ItemTemplate>
<DataTemplate>
<Border FlexLayout.AlignSelf="Stretch" FlexLayout.Basis="{Binding Source={RelativeSource FindAncestor, AncestorType{x:Type ScrollView}}, Path=Width, Converter={StaticResource WidthToFlexlayoutBasisConverter}}">
<Grid RowDefinitions="*,*">
-- more content --
<Label Grid.Row="1" Text="{Binding Title}" LineBreakMode="WordWrap" HorizontalTextAlignment="Center" VerticalOptions="Center" HorizontalOptions="Center" TextColor="Black" Margin="5" WidthRequest="{Binding Source={RelativeSource Mode=FindAncestor, AncestorType={x:Type Border}}, Path=Width}"/>
</Grid>
</Border>
</DataTemplate>
</BindableLayout.ItemTemplate>
</FlexLayout>
</ScrollView>
You can use data binding to achieve the same width for Label and Border. Bind the Border and Label's WidthRequest properties to the TestWidth property in the same binding context. like this:
Xaml:
<StackLayout>
<StackLayout.BindingContext>
<local:MyViewModel/>
</StackLayout.BindingContext>
<Border BackgroundColor="Pink" WidthRequest="{Binding Testwidth}">
<Label x:Name="lable" Text="test1111111111111111" WidthRequest="{Binding Testwidth}"/>
</Border>
</StackLayout>
ViewModel:
public class MyViewModel : INotifyPropertyChanged
{
public double testwidth;
public event PropertyChangedEventHandler PropertyChanged;
public double Testwidth
{
get { return testwidth; }
set
{
if (testwidth != value)
{
testwidth = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Testwidth"));
}
}
}
public MyViewModel() { testwidth= 100; }
}
Related
I have a flexlayout inside of a frame, a grid and a stacklayout:
<CollectionView x:Name="collectionView"
Margin="20"
SelectionMode="Single"
SelectionChanged="OnSelectionChanged">
<CollectionView.ItemsLayout>
<LinearItemsLayout Orientation="Vertical"
ItemSpacing="10" />
</CollectionView.ItemsLayout>
<!-- Define the appearance of each item in the list -->
<CollectionView.ItemTemplate>
<DataTemplate>
<StackLayout Margin="0,10,0,0" Spacing="0">
<StackLayout Orientation="Horizontal" Margin="0">
<Label FontSize="Medium" FontAttributes="Bold" Text="{Binding Name, Mode=OneWay}" />
<Label Text="{Binding Bottle.ID, Mode=OneWay}" FontSize="Medium"
FontAttributes="Italic" VerticalTextAlignment="Center"
Margin="20,0,0,0"/>
</StackLayout>
<Frame CornerRadius="10" BorderColor="Black" IsVisible="{Binding IsConnected, Converter={StaticResource InverseBooleanConverter}, Mode=OneWay}" Padding="10">
<Label Text="not connected" FontSize="Small"/>
</Frame>
<Frame CornerRadius="10" BorderColor="Black" IsVisible="{Binding IsConnected, Mode=OneWay}" Padding="10">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="40" />
</Grid.ColumnDefinitions>
<StackLayout Grid.Column="0">
<FlexLayout BindableLayout.ItemsSource="{Binding Bottle.Components, Mode=OneWay}"
Direction="Row" JustifyContent="Start" Wrap="Wrap"
AlignItems="Center" AlignContent="Start"
>
<BindableLayout.ItemTemplate>
<DataTemplate>
<Label FontSize="Small" Text="{Binding DisplayString}" VerticalOptions="CenterAndExpand" Margin="0,0,10,0" Padding="0"/>
</DataTemplate>
</BindableLayout.ItemTemplate>
</FlexLayout>
<StackLayout Orientation="Horizontal" IsVisible="{Binding IsConnected, Mode=OneWay}" VerticalOptions="FillAndExpand">
<Label FontSize="Small" Text="in " IsVisible="{Binding Bottle.IsCarrier, Converter={StaticResource InverseBooleanConverter}, Mode=OneWay}"/>
<Label FontSize="Small" Text="{Binding Bottle.CarrierGas, Mode=OneWay}"/>
<Label FontSize="Small" Text=" 100%" IsVisible="{Binding Bottle.IsCarrier, Mode=OneWay}" />
</StackLayout>
</StackLayout>
<Label FontSize="Small" Text="(ISO)" FontAttributes="Italic" Grid.Column="1" IsVisible="False">
<Label.Triggers>
<MultiTrigger TargetType="Label">
<MultiTrigger.Conditions>
<BindingCondition Binding="{Binding Bottle.IsISOCertified, Mode=OneWay}" Value="True" />
<BindingCondition Binding="{Binding IsConnected, Mode=OneWay}" Value="True" />
</MultiTrigger.Conditions>
<Setter Property="IsVisible" Value="True" />
</MultiTrigger>
</Label.Triggers>
</Label>
</Grid>
</Frame>
</StackLayout>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
At a specific input data, the flexlayout is not displayed correctly (see first element in the list):
If I remove the frame, the texts are displayed correctly:
If I keep the frame and increase the margin or the padding of the flexlayout elements by one, the text is displayed correctly in 2 lines.
<DataTemplate>
<Label FontSize="Small" Text="{Binding DisplayString}" VerticalOptions="CenterAndExpand" Margin="0,0,11,0"/>
</DataTemplate>
Also if I increase the fontsize to medium, it is displayed correctly. Plus, if I do not restart the application but let visual studio automatically update the form, after decreasing the font size, the display is correct. However, if I restart the Android Emulator, the problem is there again.
With font size medium:
<DataTemplate>
<Label FontSize="Medium" Text="{Binding DisplayString}" VerticalOptions="CenterAndExpand" Margin="0,0,10,0"/>
</DataTemplate>
After resetting it to small, but not restarting the app:
I guess, increasing the Margin/Padding or increasing the font size or removing the frame would not work correctly on the long run, because there's always going to be some data/screen size combination which breaks the layout.
It seems to me, that the layout only fails in some corner cases. However, when the element widths (+margins) are over some limit, the flexlayout recognizes that the elements have to be displayed in 2 lines, and after that the layout is ok.
Is this a bug of xamarin/android, or is there a problem in my code? Could anyone suggest a workaround, solution, that works reliably?
Some extra information, not sure what is necessary:
Target Android Version: Android 9.0 (API Level 28 - Pie)
emulator: Pixel 2 Pie 9.0 - API28 1080x1920 420dpi
Edit: I also tested with 1020x1920, 1000x1920, 800x1920, 1200x1920 display size, all of them showed the same problem. So either the setting in Android Device Manager was not taken over (hw.lcd.width), or the problem is independent of the display size.
Edit2: changing the display size in Settings/Display affects the layout, and fixes it, if I set it to lower or larger. But I guess it is only changing the FontSize parameter of the labels.
While testing #ToolmakerSteve's solution, I found out, that the children bound.Width-s are higher if I remove the last item in the list (NO 2100ppm). Then I called measure for each children, and I saw, that the widths match those bound.Width-s when the last item was missing. So I ended up with this code:
//https://stackoverflow.com/a/70526712/9963147
class FlexLayoutImproveMeasure : FlexLayout
{
protected override void LayoutChildren(double x, double y, double width, double height)
{
base.LayoutChildren(x, y, width, height);
foreach (var child in Children)
{
Rectangle cb = child.Bounds;
Size s = child.Measure(double.PositiveInfinity, cb.Height).Request;
double newW = s.Width;
var childBounds2 = new Rectangle(cb.X, cb.Y, newW, cb.Height);
child.Layout(childBounds2);
}
}
}
I discovered that FlexLayout sometimes doesn't give each label quite enough room; the labels get truncated.
Here is a subclass of FlexLayout, that adds a small amount of width to each Label.
FlexLayoutImproveMeasure.cs:
using Xamarin.Forms;
namespace XFSOAnswers
{
class FlexLayoutImproveMeasure : FlexLayout
{
protected override void LayoutChildren(double x, double y, double width, double height)
{
base.LayoutChildren(x, y, width, height);
//var childBoundss = new List<Rectangle>();
foreach (var child in Children)
{
Rectangle cb = child.Bounds;
// Make each child slightly wider: labels were being truncated.
// Less than 2 didn't always work. Increase as needed, up to right margin.
const int extraW = 2;
double newX = cb.X;
// TBD whether part of the problem is label that isn't pixel-aligned.
// (So far, seems more reliable to increase extraW instead.)
//MAYBE double newX = Math.Floor(cb.X);
double newW = cb.Width + extraW;
// TBD whether it helps to ensure width extends to next pixel.
// (So far, seems more reliable to increase extraW instead.)
//MAYBE double newW = Math.Ceiling(cb.Width) + extraW;
//double ceilingRight = Math.Ceiling(cb.X + cb.Width);
//MAYBE double newW = ceilingRight - Math.Floor(cb.X) + extraW;
var childBounds2 = new Rectangle(newX, cb.Y, newW, cb.Height);
child.Layout(childBounds2);
//childBoundss.Add(child.Bounds);
//childBoundss.Add(cb);
}
}
}
}
Use this in place of FlexLayout. This is done by adding to a page an xmlns: declaration to access a namespace in your project. Here the namespace is XFSOAnswers. Change xmlns:local line to refer to whatever namespace you put the above class in.
XAML of a page:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:XFSOAnswers"
x:Class="XFSOAnswers.FlexLayoutInItemTemplatePage">
<ContentPage.Content>
<StackLayout>
<!-- labels truncated at width in range 188-194 -->
<CollectionView ItemsSource="{Binding Items}"
WidthRequest="190" HorizontalOptions="Center"
Margin="20" >
<CollectionView.ItemsLayout>
<LinearItemsLayout Orientation="Vertical" ItemSpacing="10" />
</CollectionView.ItemsLayout>
<CollectionView.ItemTemplate>
<DataTemplate>
<Frame CornerRadius="10" BorderColor="Black"
BackgroundColor="LightBlue" Padding="10">
<local:FlexLayoutImproveMeasure
Wrap="Wrap"
BindableLayout.ItemsSource="{Binding Items2}"
BackgroundColor="LightGray" >
<BindableLayout.ItemTemplate>
<DataTemplate>
<Label FontSize="Small" Text="{Binding .}"
VerticalOptions="Start" HorizontalOptions="Start" Margin="0,0,10,0" Padding="0"/>
</DataTemplate>
</BindableLayout.ItemTemplate>
</local:FlexLayoutImproveMeasure>
</Frame>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
</StackLayout>
</ContentPage.Content>
</ContentPage>
page's code behind has the bindings:
using System.Collections.Generic;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace XFSOAnswers
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class FlexLayoutInItemTemplatePage : ContentPage
{
public FlexLayoutInItemTemplatePage()
{
InitializeComponent();
BindingContext = this;
}
public List<ListModel> Items { get; } = new List<ListModel> {
new ListModel(),
new ListModel(),
};
}
public class ListModel
{
public List<string> Items2 { get; } = new List<string> {
"aaa", "bbbbbbbbb", "cc", "dddd", "e",
};
}
}
Items2 strings chosen such that at WidthRequest=190, "dddd" barely fit on first line. Tests were done with and without the final "e", to see what FlexLayout did in both cases.
Original FlexLayout, truncating labels:
Using FlexLayoutImproveMeasure with extraW = 2:
I have two CollectionViews in my ContentPage inside a StackLayout, one above the other. Each binds to a separate ItemsSource. Above each one I have a Label. At this point each one take up 50% of the screen and scrolls separately.
I would like everything to scroll as though it were one long list.
So I surrounded everything with a ScrollView. But then, depending on where you put your finger, the scroll may scroll the entire page (which is what I want) or just the current CollectionView.
It seems like there is no way to cancel the scroll capability of the CollectionView. Is that true? and if not, How should I set up my ContentPage ?
In the below example both CollectionViews have the same model and binding but in reality they will be different.
Here is the xaml:
<RefreshView
x:DataType="local:AllRestaurantsViewModel"
Command="{Binding LoadItemsCommand}"
IsRefreshing="{Binding IsBusy, Mode=TwoWay}">
<ScrollView>
<StackLayout>
<Label
FontSize="Large"
HorizontalOptions="Center"
Text="Suggested Restaurants" />
<CollectionView
x:Name="ItemsListView"
ItemsSource="{Binding SuggestedRestsComments}"
SelectionMode="None">
<CollectionView.ItemTemplate>
<DataTemplate>
<StackLayout Padding="10" x:DataType="model:SuggestedRestsComment">
<Label
FontSize="16"
LineBreakMode="NoWrap"
Style="{DynamicResource ListItemTextStyle}"
Text="{Binding restaurantName}" />
<Label
FontSize="13"
LineBreakMode="NoWrap"
Style="{DynamicResource ListItemDetailTextStyle}"
Text="{Binding CityName}" />
<StackLayout.GestureRecognizers>
<TapGestureRecognizer
Command="{Binding Source={RelativeSource AncestorType={x:Type local:ItemsViewModel}}, Path=ItemTapped}"
CommandParameter="{Binding .}"
NumberOfTapsRequired="1" />
</StackLayout.GestureRecognizers>
</StackLayout>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
<Label
FontSize="Large"
HorizontalOptions="Center"
Text="Existing Restaurants" />
<CollectionView
x:Name="ItemsListView2"
ItemsSource="{Binding SuggestedRestsComments}"
SelectionMode="None">
<CollectionView.ItemTemplate>
<DataTemplate>
<StackLayout Padding="10" x:DataType="model:SuggestedRestsComment">
<Label
FontSize="16"
LineBreakMode="NoWrap"
Style="{DynamicResource ListItemTextStyle}"
Text="{Binding restaurantName}" />
<Label
FontSize="13"
LineBreakMode="NoWrap"
Style="{DynamicResource ListItemDetailTextStyle}"
Text="{Binding CityName}" />
<StackLayout.GestureRecognizers>
<TapGestureRecognizer
Command="{Binding Source={RelativeSource AncestorType={x:Type local:ItemsViewModel}}, Path=ItemTapped}"
CommandParameter="{Binding .}"
NumberOfTapsRequired="1" />
</StackLayout.GestureRecognizers>
</StackLayout>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
</StackLayout>
</ScrollView>
</RefreshView>
You could have a try with Custom CollectionViewRenderer to achieve that in each platform.
For example, send a mesage in Forms:
void OnButtonClicked(object sender, EventArgs e)
{
MessagingCenter.Send<object>(this, "StopScrollinng");
}
Then in iOS CustomCollectionViewRenderer class stop scrolling:
public class CustomCollectionViewRenderer: CollectionViewRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<GroupableItemsView> e)
{
base.OnElementChanged(e);
MessagingCenter.Subscribe<object>(this, "StopScrollinng", (sender) =>
{
// Do something whenever the "StopScrollinng" message is received
if (Control != null)
{
NSArray s = Control.ValueForKey(new NSString("_subviewCache")) as NSMutableArray;
UICollectionView c = s.GetItem<UICollectionView>(0);
c.SetContentOffset(c.ContentOffset, true);
}
});
}
}
And in Android CustomCollectionViewRenderer class stop scrolling:
public class CustomCollectionViewRenderer: CollectionViewRenderer
{
public CustomCollectionViewRenderer(Context context) : base(context)
{
}
protected override void OnElementChanged(ElementChangedEventArgs<ItemsView> elementChangedEvent)
{
base.OnElementChanged(elementChangedEvent);
MessagingCenter.Subscribe<object>(this, "StopScrollinng", (sender) =>
{
// Do something whenever the "StopScrollinng" message is received
this.DispatchTouchEvent(MotionEvent.Obtain(SystemClock.UptimeMillis(), SystemClock.UptimeMillis(), MotionEventActions.Cancel, 0, 0, 0));
});
}
}
How about this?
In your scrollview set InputTransparent="True" this allows the input to go through to the layer underneath.
<ScrollView InputTransparent="True">
Then leave some white space (background) on the right side of the collection views.
Now when someone swipes in the white space, the entire page scrolls. And when someone swipes inside the collection view, the collection view scrolls.
taken from https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/collectionview/populate-data
the idea is to not use two separate collectionviews and merge them into one by choosing a datatemplate at runtime
xmlns:controls="clr-namespace:<your namespace>.Controls"
<ContentPage.Resources>
<DataTemplate x:Key="DataTemplate1">
...
</DataTemplate>
<DataTemplate x:Key="DataTemplate2">
...
</DataTemplate>
<controls:DataTemplateSelector1 x:Key="DataTemplateSelector1"
Template1="{StaticResource DataTemplate1}"
Template2="{StaticResource DataTemplate2}" />
</ContentPage.Resources>
namespace <your namespace>.Controls
{
public class DataTemplateSelector1: DataTemplateSelector
{
public DataTemplate Template1 { get; set; }
public DataTemplate Template2 { get; set; }
protected override DataTemplate OnSelectTemplate(object item, BindableObject container)
{
//here you return which template you want to use based on the properties of "item" . e.g you can do item is SomeClass ? Template1 : Template2
}
}
}
<ScrollView>
<CollectionView x:Name="collection" ItemTemplate="{StaticResource DataTemplateSelector1}"></CollectionView>
</ScrollView>
I'm trying to make a better solution architecture, for that I've separated many parts of code in differents files. Because my application use a lot of DataTemplates, I push them in different ResourceDictionary.xaml files.
Problem :
I have a view Agenda.xaml, with the viewModel AgendaViewModel. This view have a ListView which call's datatemplate in external ResourceDictionary file. But if I want put a Binding Command in the dataTemplate, the command is never executed because (I guess) the resource Dictionary where is my DataTemplate not reference ViewModel.
What can I do ?
I've already tried some weird Binding code like
<TapGestureRecognizer Command="{Binding BindingContext.OpenActiviteCommand, Source={x:Reference agendaPage}}" CommandParameter="{Binding .}"/>
Where "agendaPage" is the x:Name of Agenda.xaml.
All I found on Google was about WPF and Binding property not available on Xamarin Forms (RelativeSource, ElementName etc...)
I know I can put dataTemplate in my Agenda.xaml view, but I really want keep it in an external file. I want avoid view files with 1500 lines....
This is my Agenda.xaml view
<?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="Corim.Portable.CorimTouch.ViewForms.Agenda.AgendaViewDetail"
xmlns:converters="clr-namespace:Corim.Portable.CorimTouch.Converters"
Title="Agenda"
x:Name="agendaPage">
<ContentPage.Content>
<Grid HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" BackgroundColor="{StaticResource LightGrayCorim}">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<!-- Liste itv,pointage,activite -->
<ListView
x:Name="listAgenda"
Grid.Row="1"
SeparatorVisibility="None"
HasUnevenRows="True"
SelectionMode="None"
CachingStrategy="RecycleElement"
ItemsSource="{Binding AgendaList}"
ItemTemplate="{StaticResource agendaTemplateSelector}"
BackgroundColor="{StaticResource LightGrayCorim}">
</ListView>
</Grid>
</ContentPage.Content>
</ContentPage>
And this is one part of Datatemplate in AgendaTemplates.xaml
<DataTemplate x:Key="agenda-adresse-intervention">
<ViewCell>
<Frame Margin="10,5,10,0" HasShadow="False" Padding="0" CornerRadius="10" IsClippedToBounds="True">
<controls:CustomTappedStackLayout
BackgroundColor="White"
TappedBackgroundColor="{StaticResource RollOver}"
HorizontalOptions="FillAndExpand"
Orientation="Horizontal"
Padding="10">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding Path=BindingContext.OpenParcCommand, Source={x:Reference agendaPage}}" CommandParameter="{Binding .}" NumberOfTapsRequired="1"/>
</StackLayout.GestureRecognizers>
<Image
Source="localisation_adresse"
WidthRequest="30"
HeightRequest="30"
Aspect="AspectFit"
HorizontalOptions="Start"
Margin="10"
VerticalOptions="StartAndExpand"/>
<StackLayout
HorizontalOptions="FillAndExpand"
Orientation="Vertical">
<Label
Text="{Binding Client}"
IsVisible="{Binding Client, Converter={StaticResource StringEmptyBooleanConverter}}"
FontFamily="{StaticResource SemiBoldFont}"
FontSize="{StaticResource MediumTextSize}"
TextColor="Black"/>
<Label
Text="{Binding Title}"
IsVisible="{Binding Title, Converter={StaticResource StringEmptyBooleanConverter}}"
FontFamily="{StaticResource RegularFont}"
FontSize="{StaticResource DefaultTextSize}"
TextColor="Gray"/>
</StackLayout>
</controls:CustomTappedStackLayout>
</Frame>
</ViewCell>
</DataTemplate>
But if I want put a Binding Command in the dataTemplate, the command
is never executed because (I guess) the resource Dictionary where is
my DataTemplate not reference ViewModel.
You guess wrong: it's totally fine to do what you are doing and should work transparently. The binding is resolved at runtime your data template does not know anything about the object that will be bound.
1st: drop the BindingContext.OpenActiviteCommand nonsense :) Just bind to OpenActiviteCommand, the only question is:
2nd: Where is your OpenActiviteCommand ?
The data context of your AgendaTemplates is the item in your AgendaList.
If the type of the AgendaList is an ObservableCollection<AgendaViewModel>, and your AgendaViewModel has a OpenParcCommand then it should be fine:
public class AgendaViewModel
{
public AgendaViewModel(ICommand openParcCommand)
{
OpenParcCommand = openParcCommand;
}
public ICommand OpenParcCommand { get; }
}
and in your AgendaPageViewModel:
public class AgendaPageViewModel
{
public ObservableCollection<AgendaViewModel> AgendaList { get; }
}
Thanks to #Roubachof
The soluce was replace my ListView of InterventionModel by ListView of AgendaDataViewModel.
AgendaViewModel is a new class which contains all the commands I need, and an InterventionModel.
this is AgendaDataViewModel :
public class AgendaDataViewModel : HybridContentViewModel
{
private InterventionModel _model;
public InterventionModel Model
{
get => _model;
set { _model = value; }
}
public ICommand OpenActiviteCommand { get; private set; }
public AgendaDataViewModel()
{
this.OpenActiviteCommand = new Command<InterventionModel>(this.OpenActivite);
}
/// <summary>
/// Ouvre le formulaire d'édition de l'activité
/// </summary>
/// <param name="model"></param>
private void OpenActivite(InterventionModel model)
{
//TODO amener sur le formulaire d'activité
}
}
my AgendaTemplate.xaml
<!--Template pour l'affichage du parc-->
<DataTemplate x:Key="agenda-adresse-intervention">
<ViewCell>
<Frame Margin="10,5,10,0" HasShadow="False" Padding="0" CornerRadius="10" IsClippedToBounds="True">
<controls:CustomTappedStackLayout
BackgroundColor="White"
TappedBackgroundColor="{StaticResource RollOver}"
HorizontalOptions="FillAndExpand"
Orientation="Horizontal"
Padding="10">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding OpenParcCommand}" CommandParameter="{Binding Model}" NumberOfTapsRequired="1"/>
</StackLayout.GestureRecognizers>
<Image
Source="localisation_adresse"
WidthRequest="30"
HeightRequest="30"
Aspect="AspectFit"
HorizontalOptions="Start"
Margin="10"
VerticalOptions="StartAndExpand"/>
<StackLayout
HorizontalOptions="FillAndExpand"
Orientation="Vertical">
<Label
Text="{Binding Model.Client}"
IsVisible="{Binding Model.Client, Converter={StaticResource StringEmptyBooleanConverter}}"
FontFamily="{StaticResource SemiBoldFont}"
FontSize="{StaticResource MediumTextSize}"
TextColor="Black"/>
<Label
Text="{Binding Model.Title}"
IsVisible="{Binding Model.Title, Converter={StaticResource StringEmptyBooleanConverter}}"
FontFamily="{StaticResource RegularFont}"
FontSize="{StaticResource DefaultTextSize}"
TextColor="Gray"/>
</StackLayout>
</controls:CustomTappedStackLayout>
</Frame>
</ViewCell>
</DataTemplate>
As you can see, the values binding is made by this line :
{Binding Model.Client}
where Client is the name of Binded property. And to Bind a Command, you don't need Model, and just bind like this :
Command={Binding CommandName}
Hope it helps someone in the future !
I'm trying to use XAML binding to affect the gridview datatemplate element size from a slider on my screen.
I have a gridview made of thumbnails images where the elements are defined as following:
<GridView.ItemTemplate >
<DataTemplate >
<StackPanel Orientation="Vertical"
HorizontalAlignment="Center"
VerticalAlignment="Center"
KeyDown="IsitenterThumb"
BorderBrush="LightSeaGreen"
BorderThickness="1"
PointerWheelChanged="ctlThumbnails_PointerWheelChanged">
<Image Source="{Binding thumb}"
x:Name="thumbimg"
Visibility="Visible"
Height="{Binding ItemSize}" Width="{Binding ItemSize, ElementName=page}" Stretch="Uniform"
Tapped="ThumbnailSelected"
DoubleTapped="CloseThumbnails"
/>
<TextBlock Text="{Binding name}" Margin="5,5"
Foreground="White"
Width="{Binding ItemSize}"
/>
</StackPanel>
</DataTemplate>
And I have the following variable defined as follow:
public double ItemSize
{
get => _itemSize;
set
{
if (_itemSize != value)
{
_itemSize = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(ItemSize)));
}
}
}
private double _itemSize;
public event PropertyChangedEventHandler PropertyChanged;
I would have thought that changing the value of ItemSize would have affected the gridview datatemplate. This is taken litterally from the PhotoLab sample.
Instead I get a single huge "thumbimg" per page... Any help would be greatly appreciated!
Ok... I got it finally. I'm not quite sure what I was doing wrong above, but the code below works.
I have put the DataTemplate as part of a Page.Resource, I'm not sure if this is what was causing the binding issue. However the Xaml code looks like this:
<Page.Resources>
<DataTemplate x:Key="ThumbnailsTemplate">
<StackPanel Orientation="Vertical"
HorizontalAlignment="Center"
VerticalAlignment="Center"
KeyDown="IsitenterThumb"
BorderBrush="LightSeaGreen"
BorderThickness="1"
<Image Source="{Binding thumb}"
x:Name="thumbimg"
Visibility="Visible"
Height="{Binding ItemSize, ElementName=page}" Width="{Binding ItemSize, ElementName=page}"
Stretch="Uniform"
Tapped="ThumbnailSelected"
DoubleTapped="CloseThumbnails"
/>
<TextBlock Text="{Binding name}" Margin="5,5"
Foreground="White" Width="{Binding ItemSize}"
/>
</StackPanel>
</DataTemplate>
</Page.Resources>
<GridView x:Name = "ctlThumbnails" Grid.Column="0"
BorderBrush="White" BorderThickness="2"
Grid.RowSpan="4" Grid.Row="0" Grid.ColumnSpan="3" Height ="auto" Width="auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
Margin="30,30,30,30" KeyDown="IsitenterThumb"
DoubleTapped="CloseThumbnails"
ItemTemplate="{StaticResource ThumbnailsTemplate}">
</GridView>
And here is the C# code to affect the bound variable ItemSize
public event PropertyChangedEventHandler PropertyChanged;
public double ItemSize
{
get => _itemSize;
set
{
if (_itemSize != value)
{
_itemSize = value;
topcmdbarcontent.Text = "Thumb Size:" + _itemSize.ToString();
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(ItemSize)));
}
}
}
private double _itemSize;
From this, when you change the value of ItemSize, through a ValueChanged event, for example, it does change the grid element size dynamically.
I have a button with the image and textblock.
Buttons are created dynamically based on the values from the database.
Now for a particular value text is present and no image is there I want to show that text in the center of the button (horizontally and vertically), but it is not working.
Please find the xaml below:
<ItemsControl ItemsSource="{Binding CategoriesList}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Width="100" Margin="5" HorizontalContentAlignment="Center" VerticalContentAlignment="Center">
<Button.Template>
<ControlTemplate>
<Border CornerRadius="10" Background="Maroon">
<StackPanel Orientation="Vertical">
<Image Source="{Binding CategoryImagePath}" Height="50"></Image>
<TextBlock Text="{Binding CategoryName}" Height="20" HorizontalAlignment="Center" VerticalAlignment="Center"></TextBlock>
</StackPanel>
</Border>
</ControlTemplate>
</Button.Template>
</Button>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
If no image is available I want to show only the text on the button but it should be centered.
If there is Image then I make the Image and text both displayed but when the Image is not available the text is getting displayed but it is not in the center It moves to the top portion of the button.
You can use a DataTemplateSelector to select different templates depending on whether you have an image. Such a selector might look like this:
public sealed class ButtonTemplateSelector : DataTemplateSelector
{
/// <summary>
/// Gets or sets the <see cref="DataTemplate"/> to use when we have an image.
/// The value is set in XAML.
/// </summary>
public DataTemplate ImageTemplate { get; set; }
/// <summary>
/// Gets or sets the <see cref="DataTemplate"/> to use when we don't have an image.
/// The value is set in XAML.
/// </summary>
public DataTemplate NoImageTemplate { get; set; }
public override DataTemplate SelectTemplate(object item, DependencyObject container)
{
Category category = item as Category;
if (category != null)
{
return category.CategoryImagePath == null ? NoImageTemplate : ImageTemplate;
}
return base.SelectTemplate(item, container);
}
}
I'm assuming a model object something like this:
public class Category
{
public string CategoryImagePath { get; set; }
public string CategoryName { get; set; }
}
Create and initialize a ButtonTemplateSelector resource in your XAML, then reference it from your ItemsControl:
<Window
x:Class="WPF.MainWindow"
x:Name="self"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:wpf="clr-namespace:WPF"
mc:Ignorable="d"
Title="MainWindow"
Height="350"
Width="525">
<Grid>
<Grid.Resources>
<wpf:ButtonTemplateSelector x:Key="ButtonTemplateSelector">
<wpf:ButtonTemplateSelector.ImageTemplate>
<DataTemplate DataType="wpf:Category">
<Button
Width="100"
Margin="5"
HorizontalContentAlignment="Center"
VerticalContentAlignment="Center">
<Button.Template>
<ControlTemplate>
<Border CornerRadius="10" Background="Maroon">
<StackPanel Orientation="Vertical">
<Image
Source="{Binding CategoryImagePath}"
Height="50" />
<TextBlock
Foreground="White"
Text="{Binding CategoryName}"
Height="20"
HorizontalAlignment="Center"
VerticalAlignment="Center" />
</StackPanel>
</Border>
</ControlTemplate>
</Button.Template>
</Button>
</DataTemplate>
</wpf:ButtonTemplateSelector.ImageTemplate>
<wpf:ButtonTemplateSelector.NoImageTemplate>
<DataTemplate DataType="wpf:Category">
<Button
Width="100"
Margin="5"
HorizontalContentAlignment="Center"
VerticalContentAlignment="Center">
<Button.Template>
<ControlTemplate>
<Border
CornerRadius="10"
Background="Maroon"
Height="70">
<TextBlock
Foreground="White"
Text="{Binding CategoryName}"
Height="20"
HorizontalAlignment="Center"
VerticalAlignment="Center" />
</Border>
</ControlTemplate>
</Button.Template>
</Button>
</DataTemplate>
</wpf:ButtonTemplateSelector.NoImageTemplate>
</wpf:ButtonTemplateSelector>
</Grid.Resources>
<ItemsControl
DataContext="{Binding ElementName=self}"
ItemsSource="{Binding CategoriesList}"
ItemTemplateSelector="{StaticResource ButtonTemplateSelector}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</Grid>
</Window>
For completeness, the code-behind for the window:
public partial class MainWindow
{
public MainWindow()
{
InitializeComponent();
}
public IEnumerable<Category> CategoriesList { get; } = new List<Category>
{
new Category { CategoryName = "First", CategoryImagePath = "/Assets/Square.bmp" },
new Category { CategoryName = "Second", CategoryImagePath = null },
};
}
This shows up as follows, which I think is what you're asking: