I am writing this because I had difficulties in implementing a specific function during WPF implementation.
For data model
latitude and longitude (location in current window)
MainViewModel is
I am managing it as an observableCollection.
In xaml, the upper and longitude values for each model list were displayed,
The part that implements the button control in the form of an image to move according to the location information that is continuously updated in xaml is blocked, so I am posting this.
In addition, I want to display a line for the azimuth or each component, but I also want to implement this so that the line moves according to the changing value.
Is there a method that is usually used for these changing values or is there a method that is mainly used in practice?
In the case of Winform, I used the method of drawing a line using a Graphics object, but if anyone knows how to display it in real time by moving it in real time in C# WPF and binding the position value, I would appreciate it if you could share it.
In my previous answer I demonstrated a way to position a line based on a property in the viewmodel.
However, this only answers part of your question.
In the example below I will demonstrate how to have an ObservableCollection with positions that will be reflected on screen by showing the positions as text at the screen location corresponding with their values.
To start with, while the ObservableCollection can be used as an Itemsource, we must make sure the Items themselves are suitable to be used as viewmodels:
So, you could declare a Positionclass as follows (using 'CommunityToolkit.Mvvm'):
using CommunityToolkit.Mvvm.ComponentModel;
namespace ViewModels;
public partial class Position : ObservableObject
{
[ObservableProperty]
private double _x;
[ObservableProperty]
private double _y;
public Position(double x = 0.0, double y = 0.0)
{
X = x;
Y = y;
}
}
Now you can declare a MainViewModel containing a ObservableCollection<Position> property that will be used as an itemsource. For demonstration purposes, the values for the positions will be changed continuously based upon a DispatchTimer:
using CommunityToolkit.Mvvm.ComponentModel;
using System;
using System.Collections.ObjectModel;
using System.Windows.Threading;
namespace PresentationLayer.ViewModels;
public class MainViewModel : ObservableObject
{
private DispatcherTimer _timer = new();
private Random _random = new();
// binding properties
public ObservableCollection<Position> TextPositions { get; private set; } = new();
public MainViewModel()
{
TextPositions.Add(new(10, 10));
TextPositions.Add(new(20, 100));
TextPositions.Add(new(50, 300));
_timer.Interval = TimeSpan.FromMilliseconds(100);
_timer.Tick += OntimerTick;
_timer.Start();
}
private void OntimerTick(object? sender, EventArgs e)
{
foreach (var item in TextPositions)
{
item.X = (item.X + _random.Next(30)) % 600;
item.Y = (item.Y + _random.Next(20)) % 350;
}
}
}
Finally, this MainViewModel can be used as datacontext for a WPF-Window displaying the positions in an ItemsControl using a datatemplate to construct the Textvalues to be displayed.
The positioning is handled using an ItemsControl.ItemContainerStyle attribute binding the position of the items.
Note: for this to work, you need to specify the ItemsPanel should be of type Canvas since the binding for the Location uses Canvas.Top and Canvas.Left.
The MainWindow (using a MainViewModelinstance as datacontext):
<Canvas>
<ItemsControl ItemsSource="{Binding TextPositions}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Canvas.Top" Value="{Binding Y}"/>
<Setter Property="Canvas.Left" Value="{Binding X}"/>
</Style>
</ItemsControl.ItemContainerStyle>
<ItemsControl.ItemTemplate >
<DataTemplate>
<Border BorderBrush="Blue" BorderThickness="1" CornerRadius="2" Background="LightSkyBlue">
<WrapPanel>
<TextBlock Text="{Binding X}" />
<TextBlock Text=", "/>
<TextBlock Text="{Binding Y}" />
</WrapPanel>
</Border>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Canvas>
For the positioning of controls or display-elements, you can use binding to a property in your ViewModel.
In the example below I am using a Canvas and bind the Canvas.Top attribute of a line to the LinePos property in the Viewmodel.
An alternative could be to bind the Rendertransform instead...
<Canvas>
<Line X1="0" Y1="10" X2="500" Y2="10" Stroke="Blue" StrokeThickness="3" Canvas.Top="{Binding LinePos}" />
</Canvas>
And the ViewModel:
public class MainViewModel : ObservableObject
{
private int _linePos;
private DispatcherTimer _timer = new();
// binding properties
public int LinePos
{
get => _linePos;
set => SetProperty(ref _linePos, value);
}
public MainViewModel()
{
_timer.Interval = TimeSpan.FromMilliseconds(10);
_timer.Tick += OnTimerTick;
_timer.Start();
}
private void OnTimerTick(object? sender, EventArgs e)
{
LinePos = (LinePos+1) % 500;
}
}
Related
I am new to MVVM and I am currently trying to add the drag/drop feature to my application. The thing is I already developed the interface in the code-behind but I am trying now to re-write the code into MVVM as I am only at the beginning of the project.
Here is the context: the user will be able to add boxes (ToggleButton but it may change) to a grid, a bit like a chessboard. Below is the View Model I am working on:
<Page.Resources>
<Style TargetType="{x:Type local:AirportEditionPage}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Page}">
<!-- The page content-->
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding ToolKitWidth, FallbackValue=50}" />
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="{Binding RightPanelWidth, FallbackValue=400}"/>
</Grid.ColumnDefinitions>
<!-- The airport grid where Steps and Links are displayed -->
<ScrollViewer Grid.ColumnSpan="4" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto">
<Viewbox Height="{Binding AirportGridHeight}" Width="{Binding AirportGridWidth}" RenderOptions.BitmapScalingMode="HighQuality">
<ItemsControl x:Name="ChessBoard" ItemsSource="{Binding Items}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas Width="{Binding CardQuantityRow}" Height="{Binding CardQuantityColumn}" Background="{StaticResource AirportGridBackground}"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid Width="1" Height="1">
<ToggleButton Style="{StaticResource StepCardContentStyle}"/>
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Canvas.Left" Value="{Binding Pos.X}"/>
<Setter Property="Canvas.Top" Value="{Binding Pos.Y}" />
</Style>
</ItemsControl.ItemContainerStyle>
</ItemsControl>
</Viewbox>
</ScrollViewer>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Page.Resources>
Items are basically from a class (child of INotifiedPropertyChanged) with a name, an icon and a position (Point).
Now, I am trying to make the user able to drag and drop the box (ToggleButton) within the grid wherever he/she wants. However, I am totally lost with Commands, AttachedProperties etc. I spent all the whole day on tutorials and tried drag/drop solutions but with my poor knowledge, I don't know how to apply all of this into my code.
On my code-behinded version of the code, it was easy. When the button is left-clicked, I say to a variable of the grid "hey, I am being dragged and dropped". While the user is moving, I changed the Item coordinates and when the user released the left button (left button up), the dragdrop_object variable comes null again.
In the frame of the MVVM, I am totally lost. Could you give me some tracks to help me trough ? I intended to give up with MVVM a lot of time, but I know that it is better to keep up even if every little feature takes litteraly hours for me to implement (it should decrease with time...).
Do not hesitate if you need further details to answer to my question.
I found the solution here : Move items in a canvas using MVVM and here : Combining ItemsControl with draggable items - Element.parent always null
To be precise, here is the code I added :
public class DragBehavior
{
public readonly TranslateTransform Transform = new TranslateTransform();
private static DragBehavior _instance = new DragBehavior();
public static DragBehavior Instance
{
get { return _instance; }
set { _instance = value; }
}
public static bool GetDrag(DependencyObject obj)
{
return (bool)obj.GetValue(IsDragProperty);
}
public static void SetDrag(DependencyObject obj, bool value)
{
obj.SetValue(IsDragProperty, value);
}
public static readonly DependencyProperty IsDragProperty =
DependencyProperty.RegisterAttached("Drag",
typeof(bool), typeof(DragBehavior),
new PropertyMetadata(false, OnDragChanged));
private static void OnDragChanged(object sender, DependencyPropertyChangedEventArgs e)
{
// ignoring error checking
var element = (UIElement)sender;
var isDrag = (bool)(e.NewValue);
Instance = new DragBehavior();
((UIElement)sender).RenderTransform = Instance.Transform;
if (isDrag)
{
element.MouseLeftButtonDown += Instance.ElementOnMouseLeftButtonDown;
element.MouseLeftButtonUp += Instance.ElementOnMouseLeftButtonUp;
element.MouseMove += Instance.ElementOnMouseMove;
}
else
{
element.MouseLeftButtonDown -= Instance.ElementOnMouseLeftButtonDown;
element.MouseLeftButtonUp -= Instance.ElementOnMouseLeftButtonUp;
element.MouseMove -= Instance.ElementOnMouseMove;
}
}
private void ElementOnMouseLeftButtonDown(object sender, MouseButtonEventArgs mouseButtonEventArgs)
{
((UIElement)sender).CaptureMouse();
}
private void ElementOnMouseLeftButtonUp(object sender, MouseButtonEventArgs mouseButtonEventArgs)
{
((UIElement)sender).ReleaseMouseCapture();
}
private void ElementOnMouseMove(object sender, MouseEventArgs mouseEventArgs)
{
FrameworkElement element = sender as FrameworkElement;
Canvas parent = element.FindAncestor<Canvas>();
var mousePos = mouseEventArgs.GetPosition(parent);
if (!((UIElement)sender).IsMouseCaptured) return;
if (mousePos.X < parent.Width && mousePos.Y < parent.Height && mousePos.X >= 0 && mousePos.Y >=0)
((sender as FrameworkElement).DataContext as Step).Pos = new System.Drawing.Point(Convert.ToInt32(Math.Floor(mousePos.X)), Convert.ToInt32((Math.Floor(mousePos.Y))));
}
}
And my DataTemplate is now:
<DataTemplate>
<ContentControl Height="1" Width="1" local:DragBehavior.Drag="True" Style="{StaticResource StepCardContentControl}"/>
</DataTemplate>
I added the FindAncestor static class in a dedicated file like this:
public static class FindAncestorHelper
{
public static T FindAncestor<T>(this DependencyObject obj)
where T : DependencyObject
{
DependencyObject tmp = VisualTreeHelper.GetParent(obj);
while (tmp != null && !(tmp is T))
{
tmp = VisualTreeHelper.GetParent(tmp);
}
return tmp as T;
}
}
(My items are now ContentControls).
As the items' positions within the canvas are directly managed with their Pos variable (Canvas.SetLeft and Canvas.SetTop based on Pos (Pos.X and Pos.Y) with Binding), I just update it according to the MousePosition within the Canvas.
Also, as suggested in a commentary, I will see if there is something better than the ScrollViewer and Viewbox I'm using.
I am trying to convert a System.Windows.Shapes.Shape object into a System.Windows.Media.Geometry object.
With the Geometry object, I am going to render it multiple times with a custom graph control depending on a set of data points. This requires that each instance of the Geometry object has a unique TranslateTransform object.
Now, I am approaching the issue in two different ways, but neither seems to be working correctly. My custom control uses the following code in order to draw the geometry:
//Create an instance of the geometry the shape uses.
Geometry geo = DataPointShape.RenderedGeometry.Clone();
//Apply transformation.
TranslateTransform translation = new TranslateTransform(dataPoint.X, dataPoint.Y);
geo.Transform = translation;
//Create pen and draw geometry.
Pen shapePen = new Pen(DataPointShape.Stroke, DataPointShape.StrokeThickness);
dc.DrawGeometry(DataPointShape.Fill, shapePen, geo);
I have also tried the following alternate code:
//Create an instance of the geometry the shape uses.
Geometry geo = DataPointShape.RenderedGeometry;
//Apply transformation.
TranslateTransform translation = new TranslateTransform(dataPoint.X, dataPoint.Y);
dc.PushTransform(translation);
//Create pen and draw geometry.
Pen shapePen = new Pen(DataPointShape.Stroke, DataPointShape.StrokeThickness);
dc.DrawGeometry(DataPointShape.Fill, shapePen, geo);
dc.Pop(); //Undo translation.
The difference is that the second snippet doesn't clone or modify the Shape.RenderedGeometry property.
Oddly enough, I occasionally can view the geometry used for the data points in the WPF designer. However, the behavior is inconsistent and difficult to figure out how to make the geometry always appear. Also, when I execute my application, the data points never appear with the specified geometry.
EDIT: I have figured out how to generate the appearance of the geometry. But this only works in design-mode. Execute these steps:
Rebuild project.
Go to MainWindow.xaml and click in the custom shape object so that the shape's properties load into Visual Studio's property window. Wait until the property window renders what the shape looks like.
Modify the data points collection or properties to see the geometry rendered properly.
Here is what I want the control to ultimately look like for now:
How can I convert a Shape object to a Geometry object for rendering multiple times?
Your help is tremendously appreciated!
Let me give the full context of my problem, as well as all necessary code to understanding how my control is set up. Hopefully, this might indicate what problems exist in my method of converting the Shape object to a Geometry object.
MainWindow.xaml
<Window x:Class="CustomControls.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:CustomControls">
<Grid>
<local:LineGraph>
<local:LineGraph.DataPointShape>
<Ellipse Width="10" Height="10" Fill="Red" Stroke="Black" StrokeThickness="1" />
</local:LineGraph.DataPointShape>
<local:LineGraph.DataPoints>
<local:DataPoint X="10" Y="10"/>
<local:DataPoint X="20" Y="20"/>
<local:DataPoint X="30" Y="30"/>
<local:DataPoint X="40" Y="40"/>
</local:LineGraph.DataPoints>
</local:LineGraph>
</Grid>
DataPoint.cs
This class just has two DependencyProperties (X & Y) and it gives a notification when any of those properties are changed. This notification is used to trigger a re-render via UIElement.InvalidateVisual().
public class DataPoint : DependencyObject, INotifyPropertyChanged
{
public static readonly DependencyProperty XProperty = DependencyProperty.Register("XProperty", typeof(double), typeof(DataPoint), new FrameworkPropertyMetadata(0.0d, DataPoint_PropertyChanged));
public static readonly DependencyProperty YProperty = DependencyProperty.Register("YProperty", typeof(double), typeof(DataPoint), new FrameworkPropertyMetadata(0.0d, DataPoint_PropertyChanged));
private static void DataPoint_PropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
DataPoint dp = (DataPoint)sender;
dp.RaisePropertyChanged(e.Property.Name);
}
public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChanged(string name)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
public double X
{
get { return (double)GetValue(XProperty); }
set { SetValue(XProperty, (double)value); }
}
public double Y
{
get { return (double)GetValue(YProperty); }
set { SetValue(YProperty, (double)value); }
}
}
LineGraph.cs
This is the control. It contains the collection of data points and provides mechanisms for re-rendering the data points (useful for WPF designer). Of particular importance is the logic posted above which is inside of the UIElement.OnRender() method.
public class LineGraph : FrameworkElement
{
public static readonly DependencyProperty DataPointShapeProperty = DependencyProperty.Register("DataPointShapeProperty", typeof(Shape), typeof(LineGraph), new FrameworkPropertyMetadata(default(Shape), FrameworkPropertyMetadataOptions.AffectsRender, DataPointShapeChanged));
public static readonly DependencyProperty DataPointsProperty = DependencyProperty.Register("DataPointsProperty", typeof(ObservableCollection<DataPoint>), typeof(LineGraph), new FrameworkPropertyMetadata(default(ObservableCollection<DataPoint>), FrameworkPropertyMetadataOptions.AffectsRender, DataPointsChanged));
private static void DataPointShapeChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
LineGraph g = (LineGraph)sender;
g.InvalidateVisual();
}
private static void DataPointsChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{ //Collection referenced set or unset.
LineGraph g = (LineGraph)sender;
INotifyCollectionChanged oldValue = e.OldValue as INotifyCollectionChanged;
INotifyCollectionChanged newValue = e.NewValue as INotifyCollectionChanged;
if (oldValue != null)
oldValue.CollectionChanged -= g.DataPoints_CollectionChanged;
if (newValue != null)
newValue.CollectionChanged += g.DataPoints_CollectionChanged;
//Update the point visuals.
g.InvalidateVisual();
}
private void DataPoints_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{ //Collection changed (added/removed from).
if (e.OldItems != null)
foreach (INotifyPropertyChanged n in e.OldItems)
{
n.PropertyChanged -= DataPoint_PropertyChanged;
}
if (e.NewItems != null)
foreach (INotifyPropertyChanged n in e.NewItems)
{
n.PropertyChanged += DataPoint_PropertyChanged;
}
InvalidateVisual();
}
private void DataPoint_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
//Re-render the LineGraph when a DataPoint has a property that changes.
InvalidateVisual();
}
public Shape DataPointShape
{
get { return (Shape)GetValue(DataPointShapeProperty); }
set { SetValue(DataPointShapeProperty, (Shape)value); }
}
public ObservableCollection<DataPoint> DataPoints
{
get { return (ObservableCollection<DataPoint>)GetValue(DataPointsProperty); }
set { SetValue(DataPointsProperty, (ObservableCollection<DataPoint>)value); }
}
public LineGraph()
{ //Provide instance-specific value for data point collection instead of a shared static instance.
SetCurrentValue(DataPointsProperty, new ObservableCollection<DataPoint>());
}
protected override void OnRender(DrawingContext dc)
{
if (DataPointShape != null)
{
Pen shapePen = new Pen(DataPointShape.Stroke, DataPointShape.StrokeThickness);
foreach (DataPoint dp in DataPoints)
{
Geometry geo = DataPointShape.RenderedGeometry.Clone();
TranslateTransform translation = new TranslateTransform(dp.X, dp.Y);
geo.Transform = translation;
dc.DrawGeometry(DataPointShape.Fill, shapePen, geo);
}
}
}
}
EDIT 2:In response to this answer by Peter Duniho, I would like to provide the alternate method to lying to Visual Studio in creating a custom control. For creating the custom control execute these steps:
Create folder in root of project named Themes
Create resource dictionary in Themes folder named Generic.xaml
Create a style in the resource dictionary for the control.
Apply the style from the control's C# code.
Generic.xamlHere is an example of for the SimpleGraph described by Peter.
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:CustomControls">
<Style TargetType="local:SimpleGraph" BasedOn="{StaticResource {x:Type ItemsControl}}">
<Style.Resources>
<EllipseGeometry x:Key="defaultGraphGeometry" Center="5,5" RadiusX="5" RadiusY="5"/>
</Style.Resources>
<Style.Setters>
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<Canvas IsItemsHost="True"/>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate DataType="{x:Type local:DataPoint}">
<Path Fill="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:SimpleGraph}}, Path=DataPointFill}"
Stroke="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:SimpleGraph}}, Path=DataPointStroke}"
StrokeThickness="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:SimpleGraph}}, Path=DataPointStrokeThickness}"
Data="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:SimpleGraph}}, Path=DataPointGeometry}">
<Path.RenderTransform>
<TranslateTransform X="{Binding X}" Y="{Binding Y}"/>
</Path.RenderTransform>
</Path>
</DataTemplate>
</Setter.Value>
</Setter>
</Style.Setters>
</Style>
</ResourceDictionary>
Lastly, apply the style like so in the SimpleGraph constructor:
public SimpleGraph()
{
DefaultStyleKey = typeof(SimpleGraph);
DataPointGeometry = (Geometry)FindResource("defaultGraphGeometry");
}
I think that you are probably not approaching this in the best way. Based on the code you posted, it seems that you are trying to do manually things that WPF is reasonably good at handling automatically.
The main tricky part (at least for me…I'm hardly a WPF expert) is that you appear to want to use an actual Shape object as the template for your graph's data point graphics, and I'm not entirely sure of the best way to allow for that template to be replaced programmatically or declaratively without exposing the underlying transformation mechanic that controls the positioning on the graph.
So here's an example that ignores that particular aspect (I will comment on alternatives below), but which I believe otherwise serves your precise needs.
First, I create a custom ItemsControl class (in Visual Studio, I do this by lying and telling VS I want to add a UserControl, which gets me a XAML-based item in the project…I immediately replace "UserControl" with "ItemsControl" in both the .xaml and .xaml.cs files):
XAML:
<ItemsControl x:Class="TestSO28332278SimpleGraphControl.SimpleGraph"
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"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:TestSO28332278SimpleGraphControl"
mc:Ignorable="d"
x:Name="root"
d:DesignHeight="300" d:DesignWidth="300">
<ItemsControl.Resources>
<EllipseGeometry x:Key="defaultGraphGeometry" Center="5,5" RadiusX="5" RadiusY="5" />
</ItemsControl.Resources>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas IsItemsHost="True" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate DataType="{x:Type local:DataPoint}">
<Path Data="{Binding ElementName=root, Path=DataPointGeometry}"
Fill="Red" Stroke="Black" StrokeThickness="1">
<Path.RenderTransform>
<TranslateTransform X="{Binding X}" Y="{Binding Y}"/>
</Path.RenderTransform>
</Path>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
C#:
public partial class SimpleGraph : ItemsControl
{
public Geometry DataPointGeometry
{
get { return (Geometry)GetValue(DataPointShapeProperty); }
set { SetValue(DataPointShapeProperty, value); }
}
public static DependencyProperty DataPointShapeProperty = DependencyProperty.Register(
"DataPointGeometry", typeof(Geometry), typeof(SimpleGraph));
public SimpleGraph()
{
InitializeComponent();
DataPointGeometry = (Geometry)FindResource("defaultGraphGeometry");
}
}
The key here is that I have an ItemsControl class with a default ItemTemplate that has a single Path object. That object's geometry is bound to the controls DataPointGeometry property, and its RenderTransform is bound to the data item's X and Y values as offsets for a translation transform.
A simple Canvas is used for the ItemsPanel, as I just need a place to draw things, without any other layout features. Finally, there is a resource defining a default geometry to use, in case the caller doesn't provide one.
And about that caller…
Here is a simple example of how one might use the above:
<Window x:Class="TestSO28332278SimpleGraphControl.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:TestSO28332278SimpleGraphControl"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<PathGeometry x:Key="dataPointGeometry"
Figures="M 0.5000,0.0000
L 0.6176,0.3382
0.9755,0.3455
0.6902,0.5618
0.7939,0.9045
0.5000,0.7000
0.2061,0.9045
0.3098,0.5618
0.0245,0.3455
0.3824,0.3382 Z">
<PathGeometry.Transform>
<ScaleTransform ScaleX="20" ScaleY="20" />
</PathGeometry.Transform>
</PathGeometry>
</Window.Resources>
<Grid>
<Border Margin="3" BorderBrush="Black" BorderThickness="1">
<local:SimpleGraph Width="450" Height="300" DataPointGeometry="{StaticResource dataPointGeometry}">
<local:SimpleGraph.Items>
<local:DataPoint X="10" Y="10" />
<local:DataPoint X="25" Y="25" />
<local:DataPoint X="40" Y="40" />
<local:DataPoint X="55" Y="55" />
</local:SimpleGraph.Items>
</local:SimpleGraph>
</Border>
</Grid>
</Window>
In the above, the only truly interesting thing is that I declare a PathGeometry resource, and then bind that resource to the control's DataPointGeometry property. This allows the program to provide a custom geometry for the graph.
WPF handles the rest through implicit data binding and templating. If the values of any of the DataPoint objects change, or the data collection itself is modified, the graph will be updated automatically.
Here's what it looks like:
I will note that the above example only allows you to specify the geometry. The other shape attributes are hard-coded in the data template. This seems slightly different from what you asked to do. But note that you have a few alternatives here that should address your need without requiring the reintroduction of all the extra manual-binding/updating code in your example:
Simply add other properties, bound to the template Path object in a fashion similar to the DataPointGeometry property. E.g. DataPointFill, DataPointStroke, etc.
Go ahead and allow the user to specify a Shape object, and then use the properties of that object to populate specific properties bound to the properties of the template object. This is mainly a convenience to the caller; if anything, it's a bit of added complication in the graph control itself.
Go whole-hog and allow the user to specify a Shape object, which you then convert to a template by using XamlWriter to create some XAML for the object, add the necessary Transform element to the XAML and wrap it in a DataTemplate declaration (e.g. by loading the XAML as an in-memory DOM to modify the XAML), and then using XamlReader to then load the XAML as a template which you can then assign to the ItemTemplate property.
Option #3 seems the most complicated to me. So complicated in fact that I did not bother to prototype an example using it…I did a little research and it seems to me that it should work, but I admit that I did not verify for myself that it does. But it would certainly be the gold standard in terms of absolute flexibility for the caller.
I have a Control that displays something (let's call it Display). In this control I have a class Camera that stores things like zoom, position and rotation.
I can change the zoom from an external control (let's call it ZoomBar).
Now I had the idea to connect all of them with a TwoWay-Binding like this:
ZoomBar.Value <--> Display.Zoom <--> Camera.Zoom
It should be like: ZoomBar value changes --> update Display.Zoom --> update Camera.Zoom. Display.Zoom does not really do something. It's only for exchange the data between Camera and ZoomBar.
But I get nothing. After a short check in the Camera:
public float Zoom
{
get { MessageBox.Show("Any calls here?"); return (float)GetValue(ZoomProperty); }
set { ... }
}
I get a massive amount of MessageBoxes. I guess there is something like loop in there. Like ZoomBar.Value --> Display.Zoom --> ZoomBar.Value --> ...
My question
Are the two-way bindings causing the problem and if it is the bindings, is there a XAML way to fix this?
XAML ZoomBar
<StatusBarItem Title="Zoom Bar" HorizontalAlignment="Right">
<Slider x:Name="uxInputZoom" Style="{DynamicResource ZoomSliderStyle}" Value="100" Maximum="500" Minimum="20" />
</StatusBarItem>
XAML Display
<Display x:Name="uxDisplay" Zoom="{Binding Value, Converter={StaticResource PercentToFractionConverter}, ElementName=uxInputZoom, Mode=TwoWay}" />
Code Display
public static readonly DependencyProperty ZoomProperty = DependencyProperty.Register("Zoom", typeof(float), typeof(Display), new FrameworkPropertyMetadata(1f));
public float Zoom
{
get { return (float)GetValue(ZoomProperty); }
set { SetValue(ZoomProperty, value); }
}
Camera _camera = new Camera();
//...
public Display()
{
Binding binding = new Binding("Zoom");
binding.Source = _camera;
binding.Mode = BindingMode.TwoWay;
BindingOperations.SetBinding(this, Display.ZoomProperty, binding);
InitializeComponent();
...
}
You certainly can data bind one property value to more than one UI control. Take this simple example which enables movements of the Slider to update the value in the TextBox, while also enabling values entered in the TextBox to update the Slider.Value property:
<StackPanel>
<Slider Value="{Binding Width2}" Minimum="0.0" Maximum="100.0" Margin="0,0,0,20" />
<TextBox Text="{Binding Width2, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
This will not cause any feedback loops as in your code, so I suspect that you have something else doing that.
I've been working on a small 3D preview window in a MVVM style application... The view is created then its data context is set. Therefore it seems that ZoomExtentsWhenLoaded="True" doesn't seem to help do what I need. I need something like, ZoomExtentsWhenDataContextChanges.
Interestingly, I've found that if I use a mouse gesture like the one defined below, I can physically click on the HelixViewport3D and it will perform a ZoomExtents.
HelixViewport3D.ZoomExtentsGesture = new MouseGesture(MouseAction.LeftDoubleClick);
However, if do something like this...
HelixViewport3D.DataContextChanged += (o, e) => ResetCamera();
private void ResetCamera()
{
var dc = HelixViewport3D.DataContext as WellSurveyPlot3DViewModel;
HelixViewport3D.ResetCamera();
HelixViewport3D.Camera = dc.PerspectiveCamera;
HelixViewport3D.ZoomExtents();
}
The viewport does zoom, it just doesn't center itself, like it does when activating ZoomExtents when using the mouse gesture.
I tried ResetCamera, and several other things... What is the standard way of dealing with keeping a viewport around and swapping out the DataContext instead of creating a new one each time?
I fixed this with an attached property. I read through the HelixViewport3D source code and got this idea, after noticing how the camera works. It seems an update to the default camera through a property binding doesn't really do anything after the control is initialized.
public static class HelixViewport3DZoomExtent
{
private static readonly Type OwnerType = typeof(HelixViewport3DZoomExtent);
public static readonly DependencyProperty ZoomExtentsOnUpdateProperty = DependencyProperty.RegisterAttached("ZoomExtentsOnUpdate", typeof(bool), OwnerType, new PropertyMetadata(false, OnDataContextChanged));
public static bool GetZoomExtentsOnUpdate(DependencyObject obj)
{
return (bool)obj.GetValue(ZoomExtentsOnUpdateProperty);
}
public static void SetZoomExtentsOnUpdate(DependencyObject obj, bool value)
{
obj.SetValue(ZoomExtentsOnUpdateProperty, value);
}
private static void OnDataContextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var viewport = d as HelixViewport3D;
if (viewport == null) return;
if (viewport.DataContext == null) return;
viewport.Camera = viewport.DefaultCamera;
viewport.ZoomExtents();
}
}
Here is the Xaml
<Border BorderBrush="Black" BorderThickness="1">
<Grid>
<h:HelixViewport3D Name="HelixViewport3D"
PanGesture="LeftClick"
DataContext="{Binding PreviewPlot, UpdateSourceTrigger=PropertyChanged}"
DefaultCamera="{Binding PerspectiveCamera, UpdateSourceTrigger=PropertyChanged}"
services:HelixViewport3DZoomExtent.ZoomExtentsOnUpdate="{Binding RelativeSource={RelativeSource AncestorType={x:Type views:WellSurveyPlot3DPreview}},
Path=DataContext.PreviewUpdatedReZoom, UpdateSourceTrigger=PropertyChanged}">
<h:SunLight/>
<h:TubeVisual3D Path="{Binding TubePath}" Diameter="75" ThetaDiv="12" IsPathClosed="False" Fill="LightGray"/>
<h:GridLinesVisual3D Width="{Binding GridLength}" Length="{Binding GridLength}" MajorDistance="{Binding MajorGridLines}" Thickness="25"
MinorDistance="{Binding MajorGridLines, UpdateSourceTrigger=PropertyChanged}" LengthDirection="1,0,0" Normal="0,0,1"
Center="{Binding BottomPlaneCenter,UpdateSourceTrigger=PropertyChanged}" Fill="Red" />
<h:GridLinesVisual3D Width="{Binding GridLength}" Length="{Binding GridLength, UpdateSourceTrigger=PropertyChanged}" LengthDirection="0,0,1" Normal="1,0,0" Thickness="25"
MajorDistance="{Binding MajorGridLines}" MinorDistance="{Binding MajorGridLines}"
Center="{Binding BackLeftPlaneCenter, UpdateSourceTrigger=PropertyChanged}" Fill="Blue" />
<h:GridLinesVisual3D Width="{Binding GridLength}" Length="{Binding GridLength, UpdateSourceTrigger=PropertyChanged}" LengthDirection="1,0,0" Normal="0,1,0" Thickness="25"
MajorDistance="{Binding MajorGridLines}" MinorDistance="{Binding MajorGridLines}"
Center="{Binding BackRightPlaneCenter,UpdateSourceTrigger=PropertyChanged}" Fill="Green" />
</h:HelixViewport3D>
<Button Content="Open Well Viewer" HorizontalAlignment="Left" VerticalAlignment="Top" Command="{Binding OpenWindowCmd}"/>
</Grid>
</Border>
In my view model I have to toggle my PreviewUpdateReZoom property.
private void LoadSurveyPoints(List<WellSurveyPointCalculated> surveyPoints)
{
_coordinatesCalculator = _calcGlobalCoordsFactory.Create(surveyPoints);
_wellXyzCoordinates = _coordinatesCalculator.PlotGlobalCoordinates(100).ToList();
PreviewPlot = WellSurveyPlot3DViewModel();
PreviewUpdatedReZoom = false;//Toggle true false to send property changed and get attached property to fire.
PreviewUpdatedReZoom = true;
}
This now works such that every new item drawn into the viewport has the correct camera settings and zooms to extents...
I have the following view in my mvvm model based app which should display all the pushpins I bind to it using binding property "PushPinLocation" from my view model.
<MapNS:Map
Center="{Binding MapCenter, Mode=TwoWay}" Margin="0,0,-5,0"
CartographicMode="{Binding MapMode, Mode=TwoWay}"
LandmarksEnabled="True" PedestrianFeaturesEnabled="True"
ZoomLevel="{Binding MapZoomLevel, Mode=TwoWay}"
Foreground="AliceBlue" Grid.Row="1" Height="713" Width="425"
x:Name="mapPanoramaAddress" >
<!--Adding Location to show map initially until the data arrived-->
<maptk:MapExtensions.Children>
<maptk:MapItemsControl Name="StoresMapItemsControl" >
<maptk:MapItemsControl.ItemTemplate>
<DataTemplate>
<maptk:Pushpin x:Name="PushPins" Background="White"
GeoCoordinate="{Binding PushPinLocation}"
Content="{Binding PushPinDisplayText}"
Visibility="Visible" />
</DataTemplate>
</maptk:MapItemsControl.ItemTemplate>
</maptk:MapItemsControl>
<maptk:UserLocationMarker GeoCoordinate="{Binding PushPinLocation}" x:Name="UserLocationMarker" Visibility="Visible" />
</maptk:MapExtensions.Children>
</MapNS:Map>
In the geolocator positionchanged event which triggers for every few meters I am setting the value for binding property "PushPinLocation" (from my view model) which is common for pushpin and location marker.
//PushPinLocation
private GeoCoordinate _PushPinLocation = new GeoCoordinate(40.712923, -74.013292); //cannot assign null
public GeoCoordinate PushPinLocation
{
get { return _PushPinLocation; }
set
{
if (_PushPinLocation != value)
{
_PushPinLocation = value;
RaisePropertyChanged("PushPinLocation");
}
}
}
in the same viewmodel geolocator_Position changed event I am setting the pushpinlocation:
private void geolocator_PositionChanged(Geolocator sender, PositionChangedEventArgs args)
{
this.PushPinLocation = args.Position.Coordinate.ToGeoCoordinate();
}
But I always see the latest one showing up and old ones are never shown on the map.Is there any way I can retain the old ones as well.
This post is a year old, but unanswered, so here is my answer:
Instead of binding to a single PushPinLocation, use a collection. In your ViewModel, add this:
private List<GeoCoordinate> _pushPinLocations;
public List<GeoCoordinate> PushPinLocations
{
get { return _pushPinLocations; }
set
{
_pushPinLocations = value;
OnPropertyChanged("PushPinLocations");
}
}
and change your event to:
private void geolocator_PositionChanged(Geolocator sender, PositionChangedEventArgs args)
{
this.PushPinLocations.Add(args.Position.Coordinate.ToGeoCoordinate());
}
That will add the new location to the list and as long as its bound to this list of locations, all pins will show.
<maptk:MapItemsControl Name="StoresMapItemsControl" >
<maptk:MapItemsControl.ItemTemplate>
<DataTemplate>
<maptk:Pushpin x:Name="PushPins" Background="White"
GeoCoordinate="{Binding PushPinLocations}"
Content="{Binding PushPinDisplayText}"
Visibility="Visible" />
</DataTemplate>
</maptk:MapItemsControl.ItemTemplate>
</maptk:MapItemsControl>