I'm finding it awfully hard to see how to simply cover a rectangular XAML element with repeating copies of a bitmap! I am using WinUI 3 with Windows App SDK. I would like to use the repeating image as a background element in my app.
It would seem to involve the composition API. Some tantalizing clues are given by Deiderik Krohls and by JetChopper ... however (a) there does not seem to be a stable released NuGet package for the required interface and (b) this seems like a very complicated way to do something that should be simple and (c) these solutions would seem to require extra work to integrate with WinUI 3 classes such as ImageSource and BitmapImage.
Any suggestions?
You can use a Direct2D effect, the Tile Effect for that. This effect is hardware accelerated. Microsoft provides a nuget called Win2D that enables that for WinUI: Microsoft.Graphics.Win2D
Once you have created a standard WinUI3 application project, add this nuget, and for this XAML:
<StackPanel
HorizontalAlignment="Center"
VerticalAlignment="Center"
Orientation="Horizontal">
<canvas:CanvasControl
x:Name="myCanvas"
Width="128"
Height="128"
CreateResources="myCanvas_CreateResources"
Draw="myCanvas_Draw" />
</StackPanel>
You can display a repetition of an image with a C# code like this:
public sealed partial class MainWindow : Window
{
public MainWindow()
{
this.InitializeComponent();
}
// handle canvas' CreateResources event for Win2D (Direct2D) resources
private void myCanvas_CreateResources(CanvasControl sender, CanvasCreateResourcesEventArgs args)
=> args.TrackAsyncAction(CreateResources(sender).AsAsyncAction());
// create all needed resources async (here a bitmap)
CanvasBitmap _canvasBitmap;
private async Task CreateResources(CanvasControl sender)
{
// this is my 32x32 image downloaded from https://i.stack.imgur.com/454HU.jpg?s=32&g=1
_canvasBitmap = await CanvasBitmap.LoadAsync(sender, #"c:\downloads\smo.jpg");
}
// handle canvas' Draw event
// check quickstart https://microsoft.github.io/Win2D/WinUI3/html/QuickStart.htm
private void myCanvas_Draw(CanvasControl sender, CanvasDrawEventArgs args)
{
// create an intermediate command list as a feed to the Direct2D effect
using var list = new CanvasCommandList(sender);
using var session = list.CreateDrawingSession();
session.DrawImage(_canvasBitmap);
// create the Direct2D effect (here Tile effect https://learn.microsoft.com/en-us/windows/win32/direct2d/tile)
using var tile = new TileEffect();
tile.Source = list;
// use image size as source rectangle
tile.SourceRectangle = _canvasBitmap.Bounds;
// draw the effect (using bitmap as input)
args.DrawingSession.DrawImage(tile);
}
}
Here is the result with my StackOverflow avatar as the bitmap source:
The image is 32x32 and the canvas is 128x128 so we have 4x4 tiles.
You can use the TilesBrush from the CommunityToolkit.
Install the CommunityToolkit.WinUI.UI.Media NuGet package and try this code:
<Window
x:Class="TileBrushes.MainWindow"
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:toolkit="using:CommunityToolkit.WinUI.UI.Media"
mc:Ignorable="d">
<Grid ColumnDefinitions="*,*">
<Border Grid.Column="0">
<TextBlock Text="No tiles" />
</Border>
<Border Grid.Column="1">
<Border.Background>
<toolkit:TilesBrush TextureUri="ms-appx:///Assets/StoreLogo.png" />
</Border.Background>
<TextBlock Text="Tiles" />
</Border>
</Grid>
</Window>
The answer from #simon-mourier was the key for me in finally getting this done.
I created a TiledContentControl that has a ContentControl in front of the tiled background, and which reloads its bitmap image when the TileUriString property is changed (e.g. due to a binding).
There are also properties TileWidth, TileHeight to control the drawn size of the tile bitmap, as well as AlignRight and AlignBottom to make the bitmap align with the right edge or bottom edge instead of the left or top edge. The alignment parameters are useful to get a seamless continuity between two TiledContentControls that are right next to each other.
I am providing this back to the community with thanks for all of the help I've gotten on various coding challenges in the past. Note: I have done some basic testing but not extensive testing.
The key nuget packages used are Microsoft.Graphics.Win2D 1.0.4 and Microsoft.WindowsAppSDK 1.2. There are some interesting coding challenges that I discuss in a comment in the code. For example the need to prevent memory leakage when subscribing to Win2D C++ events from WinUI3 C# code.
Here is TiledContentControl.xaml:
<UserControl
x:Class="Z.Framework.TiledContentControl"
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:win2d="using:Microsoft.Graphics.Canvas.UI.Xaml"
mc:Ignorable="d"
Padding="0"
>
<Grid
RowDefinitions="*"
ColumnDefinitions="*"
>
<win2d:CanvasControl
x:Name="CanvasControl"
Grid.Row="0"
Grid.Column="0"
>
</win2d:CanvasControl>
<ContentPresenter
Name="ContentPresenter"
Grid.Row="0"
Grid.Column="0"
Background="Transparent"
Foreground="{x:Bind Foreground, Mode=OneWay}"
HorizontalContentAlignment="{x:Bind HorizontalContentAlignment, Mode=OneWay}"
VerticalContentAlignment="{x:Bind VerticalContentAlignment, Mode=OneWay}"
Padding="{x:Bind Padding, Mode=OneWay}"
Content="{x:Bind Content, Mode=OneWay}"
>
</ContentPresenter>
</Grid>
</UserControl>
Here is TiledContentControl.xaml.cs:
using Microsoft.Graphics.Canvas;
using Microsoft.Graphics.Canvas.Brushes;
using Microsoft.Graphics.Canvas.UI;
using Microsoft.Graphics.Canvas.UI.Xaml;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Markup;
using System;
using System.Diagnostics;
using System.Numerics;
using System.Threading.Tasks;
using Windows.Foundation;
namespace Z.Framework
{
/// <summary>
/// A control that has a tiled (repeating) bitmap background behind a content control.
///
/// Setting the TileUriString will change the tiled bitmap. Setting the drawing parameters
/// (TileWidth, TileHeight, AlignRight, AlignBottom) will scale the bitmap or offset it so
/// that it is right or bottom aligned.
/// </summary>
[ContentProperty(Name="Content")]
public sealed partial class TiledContentControl : UserControl
{
#region Discussion
// There are a number of necessary objectives to achieve the Win2D tiling with post-Load updates.
// Goal: to trigger an async load-resources when a resource-related property of the control
// changes. This is accomplished by calling StartLoadingResources when the TileUriString changes.
// Goal: cancel any resource loads that are in progress when the new load is requested.
// This is done in StartNewLoadResourcesTaskAndCleanupOldTaskAsync.
// To do it, one must store the resource-loading task (LoadResourcesTask).
// Goal: to store the resources that have been loaded, and dispose them timely.
// The LoadResourcesTask contains the loaded resources in the Result property.
// They are kept around indefinitely, except if we start a new resource load task
// then any resources in the old load task are disposed. Also, when loading several
// resources, if one of the resource loads fails then we dispose of the others.
// The CanvasResourcesRecord and LoadResourcesAsync provide a generalizable way of
// storing resources in the task result.
// Goal: make sure that any exceptions from resource creation are thrown to Win2D, so that
// Win2D can handle device-lost events (which includes Win2D triggering a new CreateResources).
// It is accomplished by only throwing load-resource exceptions from the Win2d draw handler.
// Goal: prevent Draw from being called before resources are loaded. Resource loads that are
// triggered by Win2D go through the CreateResources event handler, allowing the use of
// CanvasCreateResourcesEventArgs.TrackAsyncAction which will postpone the Draw call -- not
// until the resources are loaded but at least while the load task is started. A Draw
// callback may then occur before the load completes, but then when the load completes
// it will invalidate the CanvasControl and another Draw callback will occur.
// It does not appear to be necessary from a Win2D perspective to prevent Draw calls
// while subsequent (post-CreateResources) resource loads are being done.
// Goal: to prevent memory leaks due to .NET not being able to detect the reference cycle
// between the main control and the CanvasControl. This is accomplished by only subscribing
// to CanvasControl events while the main control is loaded.
// References:
// https://microsoft.github.io/Win2D/WinUI2/html/M_Microsoft_Graphics_Canvas_UI_CanvasCreateResourcesEventArgs_TrackAsyncAction.htm
// https://stackoverflow.com/questions/74527783/repeating-brush-or-tile-of-image-in-winui-3-composition-api
// https://microsoft.github.io/Win2D/WinUI2/html/RefCycles.htm
// https://english.r2d2rigo.es/
// https://microsoft.github.io/Win2D/WinUI3/html/M_Microsoft_Graphics_Canvas_UI_CanvasCreateResourcesEventArgs_TrackAsyncAction.htm
// https://learn.microsoft.com/en-us/windows/win32/direct2d/tile
#endregion
#region ctor
public TiledContentControl()
{
this.InitializeComponent();
this.Loaded += this.TiledContentControl_Loaded; // OK, same lifetime
this.Unloaded += this.TiledContentControl_Unloaded; // OK, same lifetime
}
private void TiledContentControl_Loaded(object sender, RoutedEventArgs e)
{
this.CanvasControl.Draw += this.CanvasControl_Draw; // OK, matched in Unloaded
this.CanvasControl.CreateResources += this.CanvasControl_CreateResources;
}
private void TiledContentControl_Unloaded(object sender, RoutedEventArgs e)
{
this.CanvasControl.Draw -= this.CanvasControl_Draw;
this.CanvasControl.CreateResources -= this.CanvasControl_CreateResources;
}
#endregion
#region CanvasResourcesRecord, LoadResourcesAsync, LoadResourcesTask
private record class CanvasResourcesRecord(
CanvasBitmap TileBitmap,
CanvasImageBrush TileBrush
): IDisposable
{
public void Dispose()
{
this.TileBitmap.Dispose();
this.TileBrush.Dispose();
}
}
static private async Task<CanvasResourcesRecord> LoadResourcesAsync(CanvasControl canvasControl, string tileUriString)
{
object[] resources = new object[2];
try {
Uri tileUri = new Uri(tileUriString);
Task<CanvasBitmap> loadTileBitmap = CanvasBitmap.LoadAsync(canvasControl, tileUri).AsTask();
CanvasBitmap tileBitmap = await loadTileBitmap;
resources[0] = tileBitmap;
CanvasImageBrush tileBrush = new CanvasImageBrush(canvasControl, tileBitmap);
tileBrush.ExtendX = CanvasEdgeBehavior.Wrap;
tileBrush.ExtendY = CanvasEdgeBehavior.Wrap;
resources[1] = tileBrush;
} catch {
// Cleanup from partial/incomplete creation
foreach (object? resource in resources) {
(resource as IDisposable)?.Dispose();
}
throw;
}
canvasControl.Invalidate(); // now that resources are loaded, we trigger an async Draw.
return new CanvasResourcesRecord(
TileBitmap: (CanvasBitmap)resources[0],
TileBrush: (CanvasImageBrush)resources[1]
);
}
private Task<CanvasResourcesRecord>? LoadResourcesTask {
get { return this._loadResourcesTask; }
set { this._loadResourcesTask = value; }
}
private Task<CanvasResourcesRecord>? _loadResourcesTask;
#endregion
#region CanvasControl_CreateResources
private void CanvasControl_CreateResources(CanvasControl sender, CanvasCreateResourcesEventArgs args)
{
Debug.Assert(sender == this.CanvasControl);
args.TrackAsyncAction(this.StartNewLoadResourcesTaskAndCleanupOldTaskAsync().AsAsyncAction());
}
#endregion
#region StartLoadingResources, StartNewLoadResourcesTaskAndCleanupOldTaskAsync
private void StartLoadingResources()
{
if (this.CanvasControl.IsLoaded) {
Task _ = this.StartNewLoadResourcesTaskAndCleanupOldTaskAsync();
}
}
private async Task StartNewLoadResourcesTaskAndCleanupOldTaskAsync()
{
// Start new task, if the necessary input properties are available.
string? tileUriString = this.TileUriString;
Task<CanvasResourcesRecord>? oldTask = this.LoadResourcesTask;
if (tileUriString != null) {
this.LoadResourcesTask = LoadResourcesAsync(this.CanvasControl, tileUriString);
} else {
this.LoadResourcesTask = null;
}
// Cleanup old task.
if (oldTask != null) {
oldTask.AsAsyncAction().Cancel();
try {
await oldTask;
} catch {
// ignore exceptions from the cancelled task
} finally {
if (oldTask.IsCompletedSuccessfully) {
oldTask.Result.Dispose();
}
}
}
}
#endregion
#region CanvasControl_Draw, ActuallyDraw
private void CanvasControl_Draw(CanvasControl sender, CanvasDrawEventArgs args)
{
Debug.Assert(sender == this.CanvasControl);
if (!this.DrawingParameters.AreFullyDefined) { return; }
if (!this.DrawingParameters.AreValid) { throw new InvalidOperationException($"Invalid drawing parameters (typically width or height)."); }
Task<CanvasResourcesRecord>? loadResourcesTask = this.LoadResourcesTask;
if (loadResourcesTask == null) { return; }
if (loadResourcesTask.IsCompletedSuccessfully) {
CanvasResourcesRecord canvasResources = loadResourcesTask.Result;
this.ActuallyDraw( args, canvasResources);
} else if (loadResourcesTask.IsFaulted) {
// Throw exceptions to Win2D, for example DeviceLostException resulting in new CreateResoures event
loadResourcesTask.Exception?.Handle(e => throw e);
} else {
return;
}
}
private void ActuallyDraw( CanvasDrawEventArgs args, CanvasResourcesRecord canvasResources)
{
Debug.Assert(this.DrawingParameters.AreFullyDefined && this.DrawingParameters.AreValid);
Debug.Assert(this.DrawingParameters.AlignRight != null && this.DrawingParameters.AlignBottom != null);
CanvasControl canvasControl = this.CanvasControl;
float scaleX = (float)(this.DrawingParameters.TileWidth / canvasResources.TileBitmap.Bounds.Width);
float scaleY = (float)(this.DrawingParameters.TileHeight / canvasResources.TileBitmap.Bounds.Height);
float translateX = ((bool)this.DrawingParameters.AlignRight) ? (float)((canvasControl.RenderSize.Width % this.DrawingParameters.TileWidth) - this.DrawingParameters.TileWidth) : (float)0;
float translateY = ((bool)this.DrawingParameters.AlignBottom) ? (float)((canvasControl.RenderSize.Height % this.DrawingParameters.TileHeight) - this.DrawingParameters.TileHeight) : (float)0;
Matrix3x2 transform = Matrix3x2.CreateScale( scaleX, scaleY);
transform.Translation = new Vector2(translateX, translateY);
canvasResources.TileBrush.Transform = transform;
Rect rectangle = new Rect(new Point(), canvasControl.RenderSize);
args.DrawingSession.FillRectangle(rectangle, canvasResources.TileBrush);
}
#endregion
#region Content
new public UIElement? Content {
get { return (UIElement?)this.GetValue(ContentProperty); }
set { this.SetValue(ContentProperty, value); }
}
new public static DependencyProperty ContentProperty { get; } = DependencyProperty.Register(nameof(TiledContentControl.Content), typeof(UIElement), typeof(TiledContentControl), new PropertyMetadata(default(UIElement)));
#endregion
#region TileUriString
public string? TileUriString {
get { return (string?)this.GetValue(TileUriStringProperty); }
set { this.SetValue(TileUriStringProperty, value); }
}
public static readonly DependencyProperty TileUriStringProperty = DependencyProperty.Register(nameof(TiledContentControl.TileUriString), typeof(string), typeof(TiledContentControl), new PropertyMetadata(default(string), new PropertyChangedCallback(OnTileUriStringChanged)));
private static void OnTileUriStringChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
{
TiledContentControl #this = (TiledContentControl)sender;
#this.StartLoadingResources();
}
#endregion
#region TileWidth, TileHeight, AlignRight, AlignBottom; OnDrawingParameterChanged, DrawingParametersRecord, DrawingParameters
public double TileWidth {
get { return (double)this.GetValue(TileWidthProperty); }
set { this.SetValue(TileWidthProperty, value); }
}
public static readonly DependencyProperty TileWidthProperty = DependencyProperty.Register(nameof(TileWidth), typeof(double), typeof(TiledContentControl), new PropertyMetadata(double.NaN, new PropertyChangedCallback(OnDrawingParameterChanged)));
public double TileHeight {
get { return (double)this.GetValue(TileHeightProperty); }
set { this.SetValue(TileHeightProperty, value); }
}
public static readonly DependencyProperty TileHeightProperty = DependencyProperty.Register(nameof(TileHeight), typeof(double), typeof(TiledContentControl), new PropertyMetadata(double.NaN, new PropertyChangedCallback(OnDrawingParameterChanged)));
public bool? AlignRight {
get { return (bool?)this.GetValue(AlignRightProperty); }
set { this.SetValue(AlignRightProperty, value); }
}
public static readonly DependencyProperty AlignRightProperty = DependencyProperty.Register(nameof(AlignRight), typeof(bool?), typeof(TiledContentControl), new PropertyMetadata(default(bool?), new PropertyChangedCallback(OnDrawingParameterChanged)));
public bool? AlignBottom {
get { return (bool?)this.GetValue(AlignBottomProperty); }
set { this.SetValue(AlignBottomProperty, value); }
}
public static readonly DependencyProperty AlignBottomProperty = DependencyProperty.Register(nameof(AlignBottom), typeof(bool?), typeof(TiledContentControl), new PropertyMetadata(default(bool?), new PropertyChangedCallback(OnDrawingParameterChanged)));
private static void OnDrawingParameterChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
{
TiledContentControl #this = (TiledContentControl)sender;
#this.DrawingParameters = new DrawingParametersRecord(#this.TileWidth, #this.TileHeight, #this.AlignRight, #this.AlignBottom);
#this.CanvasControl.Invalidate(); // trigger an async redraw using the new parameters.
}
private record struct DrawingParametersRecord(
double TileWidth,
double TileHeight,
bool? AlignRight,
bool? AlignBottom
)
{
public bool AreFullyDefined => !double.IsNaN(this.TileWidth) && !double.IsNaN(this.TileHeight) && this.AlignBottom != null && this.AlignRight != null;
public bool AreValid => this.TileWidth > 0 && this.TileHeight > 0;
}
private DrawingParametersRecord DrawingParameters { get; set; }
#endregion
}
}
I have 2 entries. When I tap anything on entry 1 I would like to get "Yess" on entry 2 and when I type anything on entry 2 I would like to get "Noo"
The problem:
When I tap on entry 1, entry 2 change and get the value "Noo" but entry 1 change too and get the value "yess".
Question :
How can make entry 2 change when tapping on entry 1 without changing entry 1. And the same for entry 2
Here is Xaml code :
<Entry ClassId="1" x:Name="myWord1"TextChanged="OnEntryTextChange"/>
<Entry ClassId="2" x:Name="myWord2" TextChanged="OnEntryTextChange"/>
Code :
private async void OnEntryTextChange(object sender, TextChangedEventArgs e)
{
var EntryTapped = (Xamarin.Forms.Entry)sender;
Device.BeginInvokeOnMainThread(() => {
if (EntryTapped.ClassId == "1")
{
myWord2.Text="Noo";
}
else if (EntryTapped.ClassId == "2")
{
myWord1.Text="yess";
}
});
}
Thanks for your help
You could use the Focused event instead of TextChanged event.
<StackLayout>
<Entry ClassId="1" x:Name="myWord1" Focused="EntryFocused"/>
<Entry ClassId="2" x:Name="myWord2" Focused="EntryFocused"/>
</StackLayout>
private void EntryFocused(object sender, FocusEventArgs e)
{
var EntryTapped = (Xamarin.Forms.Entry)sender;
if (EntryTapped.ClassId == "1")
{
myWord2.Text = "Noo";
}
else if (EntryTapped.ClassId == "2")
{
myWord1.Text = "yess";
}
}
There are several ways of doing this:
Using bindings
In this case you would have 2 private variables and 2 public variables, and the entries binded to each one. Check this link how to implement INotifyPropertyChanged
private string entry1String;
private string entry2String;
public string Entry1String {
get => entry1String;
set
{
entry2String = "Noo";
entry1String = value;
OnPropertyChanged(Entry1String);
OnPropertyChanged(Entry2String);
}
}
public string Entry2String {
get => entry2String;
set
{
entry1String = "Yees";
entry2String = value;
OnPropertyChanged(Entry1String);
OnPropertyChanged(Entry2String);
}
}
Another way could be using a variable as a Semaphore. While the variable is True, the method cannot be fired at the same time by another.
private bool semaphoreFlag=false;
private async void OnEntryTextChange(object sender, TextChangedEventArgs e)
{
if(semaphoreFlag) return;
semaphoreFlag=true;
var EntryTapped = (Xamarin.Forms.Entry)sender;
Device.BeginInvokeOnMainThread(() => {
if (EntryTapped.ClassId == "1")
{
myWord2.Text="Noo";
}
else if (EntryTapped.ClassId == "2")
{
myWord1.Text="yess";
}
});
semaphoreFlag=false;
}
My XAML ComboBox control is stuck in an endless loop when a selection is changed in the UI. The ComboBox sets the value of the bound property. When the property has changed, it raises a property changed event. This in turn causes the databinder to update the property again. This keeps looping until I get a stack overflow exception.
<ComboBox x:Name="OriginCountryCode" Grid.ColumnSpan="2" Grid.Column="2" SelectedValue="{x:Bind Mode=TwoWay, Path=ViewModel.OriginCountryCode}" DisplayMemberPath="Value" SelectedValuePath="Key" ItemsSource="{x:Bind ViewModel.CountryCodes}" />
The control is bound to the following properties.
private static Dictionary<string, string> _countryCodes = null;
public Dictionary<string, string> CountryCodes
{
get
{
if (_countryCodes != null) return _countryCodes;
_countryCodes = new Dictionary<string, string>();
var cultures = CultureInfo.GetCultures(CultureTypes.SpecificCultures);
foreach (var culture in cultures)
{
var region = new RegionInfo(culture.LCID);
_countryCodes[region.TwoLetterISORegionName] = region.DisplayName;
}
return _countryCodes;
}
}
public string OriginCountryCode
{
get => _origin.CountryCode;
set
{
_origin.CountryCode = value; RaisePropertyChanged(nameof(OriginCountryCode));
}
}
This behavior is odd as all my other controls do not exhibit this behavior. The BAML generated connector code for the ComboBox is different. One is is updated when there's a focus change and the other when the SelectedValue changes.
case 15: // Views\QuotesPage.xaml line 77
this.obj15 = (global::Windows.UI.Xaml.Controls.TextBox)target;
(this.obj15).LostFocus += (global::System.Object sender, global::Windows.UI.Xaml.RoutedEventArgs e) =>
{
if (this.initialized)
{
// Update Two Way binding
this.dataRoot.ViewModel.DestinationPostalCode = this.obj15.Text;
}
};
break;
case 16: // Views\QuotesPage.xaml line 78
this.obj16 = (global::Windows.UI.Xaml.Controls.ComboBox)target;
(this.obj16).RegisterPropertyChangedCallback(global::Windows.UI.Xaml.Controls.Primitives.Selector.SelectedValueProperty,
(global::Windows.UI.Xaml.DependencyObject sender, global::Windows.UI.Xaml.DependencyProperty prop) =>
{
if (this.initialized)
{
// Update Two Way binding
this.dataRoot.ViewModel.DestinationCountryCode = (global::System.String)this.obj16.SelectedValue;
}
});
break;
Don't raise PropertyChanged when the property value hasn't changed.
public string OriginCountryCode
{
get => _origin.CountryCode;
set
{
if (_origin.CountryCode != value)
{
_origin.CountryCode = value;
RaisePropertyChanged(nameof(OriginCountryCode));
}
}
}
I have a binding of the following form in XAML,
Title="{Binding SelectedNewsItems[0].Title}"
Note that it refers to a particular element in the SelectedNewsItems which is an ObservableCollection. (I have a collection of nine buttons of various sizes, each styled, and sized differently and so a more standard ListView is not appropriate.)
When I reassign SelectedNewsItems I raise a PropertyChanged event for SelectedNewsItems, however, this does not appear to cause the bindings to update for the individual bound elements and their properties. I have tried the following,
public ObservableCollection<NewsItem> _selectedNewsItems;
public ObservableCollection<NewsItem> SelectedNewsItems
{
get
{
return this._selectedNewsItems;
}
set
{
if (this._selectedNewsItems != value)
{
this._selectedNewsItems = value;
this.NotifyPropertyChanged();
for (int i = 0; i < this._selectedNewsItems.Count; i++)
{
this.NotifyPropertyChanged(String.Format("SelectedNewsItems[{0}].Content", i));
this.NotifyPropertyChanged(String.Format("SelectedNewsItems[{0}].Title", i));
this.NotifyPropertyChanged(String.Format("SelectedNewsItems[{0}].Id", i));
this.NotifyPropertyChanged(String.Format("SelectedNewsItems[{0}].Image", i));
}
}
}
}
Hmm, I cannot exacly say where your code is wrong (as I see only part of it), but maybe you haven't set your DataContex or something else. For the purpose of research I've made simple example, which works quite fine. Take a look at it and maybe it will help you:
In Xaml:
<Button x:Name="first" VerticalAlignment="Top" Content="{Binding SelectedNewsItems[0].Name}" Grid.Row="0"/>
<Button x:Name="second" VerticalAlignment="Center" Content="{Binding SelectedNewsItems[1].Name}" Grid.Row="1"/>
In code behind (I put all the code - yeah quite a lot of, but I cannot guess what is wrong with your code):
public class NewsItem
{
private string name;
public string Name
{
get { return name; }
set { name = value; }
}
}
public partial class MainPage : PhoneApplicationPage, INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void RaiseProperty(string property = null)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(property));
}
private ObservableCollection<NewsItem> _selectedNewsItems = new ObservableCollection<NewsItem>();
public ObservableCollection<NewsItem> SelectedNewsItems
{
get
{
return this._selectedNewsItems;
}
set
{
if (this._selectedNewsItems != value)
{
this._selectedNewsItems = value;
this.RaiseProperty();
for (int i = 0; i < this._selectedNewsItems.Count; i++)
{
this.RaiseProperty(String.Format("SelectedNewsItems[{0}].Name", i));
}
}
}
}
public MainPage()
{
NewsItem firstT = new NewsItem() { Name = "First" };
NewsItem secondT = new NewsItem() { Name = "Second" };
SelectedNewsItems.Add(firstT);
SelectedNewsItems.Add(secondT);
InitializeComponent();
this.DataContext = this;
first.Click += first_Click;
second.Click += second_Click;
}
private void first_Click(object sender, RoutedEventArgs e)
{
NewsItem change = new NewsItem() { Name = "Changed by First" };
SelectedNewsItems[1] = change;
}
private void second_Click(object sender, RoutedEventArgs e)
{
NewsItem change = new NewsItem() { Name = "Changed by Second" };
SelectedNewsItems[0] = change;
}
}
As I click on buttons the bindigs work, so maybe it will help you.
I installed nudget autocomplete toolkit but unfortunately I found it wierd that this control doesn't have enough property to serve as autocomplete. It has ItemsSource but it doesn't show the list of items filtered when you type something. I am also looking for something like textChanged so that I can invoke my service and get the result again and bind the itemsource.
Here's my implementation used in Group Contacts:
XAML:
xmlns:Interactivity="using:Microsoft.Xaml.Interactivity"
xmlns:behaviors="using:MyNamespace.Behaviors"
.
.
<TextBox x:Name="Searchbox" PlaceholderText="contact's name" Width="250"
IsTextPredictionEnabled="False"
IsSpellCheckEnabled="False"
VerticalAlignment="Center">
<Interactivity:Interaction.Behaviors>
<Core:EventTriggerBehavior EventName="KeyUp">
<behaviors:FilterContactAction />
</Core:EventTriggerBehavior>
</Interactivity:Interaction.Behaviors>
</TextBox>
Code:
public class FilterContactAction : DependencyObject, IAction
{
string _previousResult = null;
public object Execute(object sender, object parameter)
{
var textbox = sender as TextBox;
var keyEventArgs = parameter as KeyRoutedEventArgs;
var noChanges = textbox.Text == _previousResult;
var deletionOccurred = keyEventArgs.Key == VirtualKey.Back ||
keyEventArgs.Key == VirtualKey.Delete;
if (noChanges || deletionOccurred)
{
return null;
}
var viewModel = ResourceLocator.Instance[typeof(HomeViewModel)] as HomeViewModel;
viewModel.CanSearch = FindMatch(textbox, viewModel.Contacts);
return null;
}
private bool FindMatch(TextBox textbox, ObservableCollection<Contact> contacts)
{
foreach (var contact in contacts)
{
var suggestionDisplayed = DisplaySuggestion(textbox, contact);
if (suggestionDisplayed)
{
return true;
}
}
return false;
}
private bool DisplaySuggestion(TextBox textbox, Windows.ApplicationModel.Contacts.Contact contact)
{
var characterCount = textbox.Text.Count();
var suggestionDisplayed = false;
var isMatch = contact.DisplayName.ToUpper().StartsWith(textbox.Text.ToUpper());
if (isMatch)
{
textbox.Text = contact.DisplayName;
textbox.SelectionStart = characterCount;
textbox.SelectionLength = textbox.Text.Length - textbox.SelectionStart;
_previousResult = textbox.Text;
suggestionDisplayed = true;
}
return suggestionDisplayed;
}
}
TextBoxExt control from Syncfusion WinRT Studio has enough features to work as an AutoComplete. It has more than 15 suggestion modes including custom filter option. Hope this helps.
http://www.syncfusion.com/products/winrt/controls
Not sure what you used. Can't tell you why it doesn't work either. however last year I wanted AutoCompleteTextBox and ended up writing it myself.
you can find it here.
https://github.com/hermitdave/HermitDaveWinRTControls