Develop Reference

How to make a control snap to a Grid.Row/Grid.Column in WPF at runtime?

I have a grid with some ColumnDefinitions and RowDefinitions. What I like to do is drag a control at runtime and have it snap to a given GridColumn/GridRow when the control is over that GridColumn/GridRow. I was not able to find any resources on this. Perhaps I am using the wrong key words. Thanks in advance!

You should extend Grid to handle the drop position. Let the Grid add the dropped element to the appropriate cell.
The following simple but working example shows how to enable dragging of any UIElement from a Panel such as StackPanel or Grid to the custom DrockingGrid.
The custom Grid simply overrides the relevant drag&drop overrides. It's a minimal but working example, therefore only OnDragEnter and OnDrop are overridden.
On drop, you basically have to identify the cell the element was dropped in by using the drop position from the DragEventArgs. Then remove the dropped element from its original parent container (where the drag operation has started) and then insert it into the DockingGrid. You then use Grid.Row and Grid.Column to position the element in the appropriate cell:
DockingGrid.cs
public class DockingGrid : Grid
{
private bool AcceptsDrop { get; set; }
private Brush OriginalBackgroundBrush { get; set; }
public DockingGrid()
{
this.AllowDrop = true;
}
protected override void OnDragEnter(DragEventArgs e)
{
base.OnDragEnter(e);
e.Effects = DragDropEffects.None;
this.AcceptsDrop = e.Data.GetDataPresent(typeof(UIElement));
if (this.AcceptsDrop)
{
e.Effects = DragDropEffects.Move;
ShowDropTargetEffects();
}
}
protected override void OnDragLeave(DragEventArgs e)
{
base.OnDragEnter(e);
ClearDropTargetEffects();
}
protected override void OnDrop(DragEventArgs e)
{
base.OnDrop(e);
if (!this.AcceptsDrop)
{
return;
}
ClearDropTargetEffects();
var droppedElement = e.Data.GetData(typeof(UIElement)) as UIElement;
RemoveDroppedElementFromDragSourceContainer(droppedElement);
_ = this.Children.Add(droppedElement);
Point dropPosition = e.GetPosition(this);
SetColumn(droppedElement, dropPosition.X);
SetRow(droppedElement, dropPosition.Y);
}
private void SetRow(UIElement? droppedElement, double verticalOffset)
{
double totalRowHeight = 0;
int targetRowIndex = 0;
foreach (RowDefinition? rowDefinition in this.RowDefinitions)
{
totalRowHeight += rowDefinition.ActualHeight;
if (totalRowHeight >= verticalOffset)
{
Grid.SetRow(droppedElement, targetRowIndex);
break;
}
targetRowIndex++;
}
}
private void SetColumn(UIElement? droppedElement, double horizontalOffset)
{
double totalColumnWidth = 0;
int targetColumntIndex = 0;
foreach (ColumnDefinition? columnDefinition in this.ColumnDefinitions)
{
totalColumnWidth += columnDefinition.ActualWidth;
if (totalColumnWidth >= horizontalOffset)
{
Grid.SetColumn(droppedElement, targetColumntIndex);
break;
}
targetColumntIndex++;
}
}
private void RemoveDroppedElementFromSourceContainer(UIElement droppedElement)
{
DependencyObject parent = droppedElement is FrameworkElement frameworkElement
? frameworkElement.Parent
: VisualTreeHelper.GetParent(droppedElement);
if (parent is null)
{
return;
}
switch (parent)
{
case Panel panel:
panel.Children.Remove(droppedElement);
break;
case ContentControl contentControl:
contentControl.Content = null;
break;
case ContentPresenter contentPresenter:
contentPresenter.Content = null;
droppedElement.UpdateLayout();
break;
case Decorator decorator:
decorator.Child = null;
break;
default:
throw new NotSupportedException($"Parent type {parent.GetType()} not supported");
}
}
private void ShowDropTargetEffects()
{
this.ShowGridLines = true;
this.OriginalBackgroundBrush = this.Background;
this.Background = Brushes.LightBlue;
}
private void ClearDropTargetEffects()
{
this.Background = this.OriginalBackgroundBrush;
this.ShowGridLines = false;
}
}
Usage
Use it like a normal Grid.
Now the user can drag any control into any of the predefined cells.
<local:DockingGrid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100" />
<ColumnDefinition Width="200" />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="100" />
<RowDefinition Height="300" />
<RowDefinition />
</Grid.RowDefinitions>
</local:DockingGrid>
In the parent host of the drag&drop context for example the Window, enable/start the drag behavior:
MainWindow.xaml.cs
partial class MainWindow : Window
{
protected override void OnPreviewMouseMove(MouseEventArgs e)
{
base.OnPreviewMouseMove(e);
if (e.LeftButton == MouseButtonState.Pressed
&& e.Source is UIElement uIElement)
{
_ = DragDrop.DoDragDrop(uIElement, new DataObject(typeof(UIElement), uIElement), DragDropEffects.Move);
}
}
}
See Microsoft Docs: Drag and Drop Overview to learn more about the feature.

The short answer is to put that control inside something which fills that cell. You could just put it in that grid cell by adding it to the grid children and setting grid row and column attached properties but there is a gotcha.
A grid cell is sort of conceptual.
The grid looks at it's content, looks at it's definitions for rows and columns and works out where to put it's content using measure arrange passes.
Which is a wordy way of saying there's nothing there to drag your control into.
You need a drop target to drag drop anything into. As it's name suggests, you need some sort of a receptacle for the thing you are dragging.
Wpf, however has these things called content controls.
A button actually inherits from content control to allow it to have things like a string in it.
There is also a content control itself. Which is just kind of like a receptacle for something or other.
One of these things can be used in a given cell as a sort of a place holder. And then you have something in a cell that you can drop into.
I think if you just throw a contentcontrol in a grid without anything inside it you might have problems hit testing.
Some experimentation in a scratch project is advisable.
But basically you could have something like:
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Rectangle Fill="Red"
Name="DraggAbleThing"
MouseMove="DraggAbleThing_MouseMove"
/>
<ContentControl Grid.Row="1"
Grid.Column="1"
x:Name="BottomRight"
AllowDrop="True"
>
<Rectangle Fill="Yellow"/>
</ContentControl>
</Grid>
There's a fair bit to implement in order to do drag drop but the idea here is you have something in the bottom right cell which you can drop into. You might have to set ishitestable=false on that yellow rectangle.
I'd have to implement all the drag drop methods to try it out.
If I did and drop works ok then when the contentcontrol gets draggablething dropped into it.
Set the content property of the contentcontrol to draggablething and it is now in the bottom right cell.
It will fill that cell because the grid arranges it's contents to fill whichever logical cell it decides they're "in".

I would like to present an example I wrote that is working.
In the Application I wrote I have a Grid with 4 Rows and 4 Columns.
I can place in each Cell a different UserControl that is based on a class I called
BaseDragDropUserControl:
public class BaseDragDropUserControl: UserControl
{
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
if (e.LeftButton == MouseButtonState.Pressed)
{
DataObject data = new DataObject();
data.SetData(DataFormats.StringFormat, nameof(BaseDragDropUserControl));
BaseDragDropUserControl tobemMoved = (BaseDragDropUserControl)e.Source;
int row = (int)tobemMoved.GetValue(Grid.RowProperty);
int col = (int)tobemMoved.GetValue(Grid.ColumnProperty);
data.SetData("Source", tobemMoved);
data.SetData("Row", row);
data.SetData("Col", col);
DragDrop.DoDragDrop(this, data, DragDropEffects.Move);
}
}
protected override void OnGiveFeedback(GiveFeedbackEventArgs e)
{
base.OnGiveFeedback(e);
if (e.Effects.HasFlag(DragDropEffects.Copy))
{
Mouse.SetCursor(Cursors.Cross);
}
else if (e.Effects.HasFlag(DragDropEffects.Move))
{
Mouse.SetCursor(Cursors.Pen);
}
else
{
Mouse.SetCursor(Cursors.No);
}
e.Handled = true;
}
protected override void OnDrop(DragEventArgs e)
{
base.OnDrop(e);
// If the DataObject contains string data, extract it.
if (e.Data.GetDataPresent(DataFormats.StringFormat))
{
string dataString = (string)e.Data.GetData(DataFormats.StringFormat);
if (dataString == nameof(BaseDragDropUserControl))
{
int targetRow = (int)this.GetValue(Grid.RowProperty);
int targetCol = (int)this.GetValue(Grid.ColumnProperty);
int originRow = (int)e.Data.GetData("Row");
int originCol = (int)e.Data.GetData("Col");
BaseDragDropUserControl origin = (BaseDragDropUserControl)e.Data.GetData("Source");
this.SetValue(Grid.RowProperty, originRow);
this.SetValue(Grid.ColumnProperty, originCol);
origin.SetValue(Grid.RowProperty, targetRow);
origin.SetValue(Grid.ColumnProperty, targetCol);
}
}
e.Handled = true;
}
}
The above class is the "Heavy one". It handle both the Drag and the Drop functions.
It ships data object with the origin UserControl and also intercept it when it is dropped. It switch the Grid.Row and Grid.Column values between the origin UserControl and the Target UserControl. In doing this the locations are changed.
I created 2 UsserControls.
RedUserControl and BlueUserControl:
<local:BaseDragDropUserControl x:Class="Problem10.RedUserControl"
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:Problem10"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800" AllowDrop="True">
<Grid>
<Rectangle Fill="Red"/>
</Grid>
</local:BaseDragDropUserControl>
<local:BaseDragDropUserControl x:Class="Problem10.BlueUserControl"
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:Problem10"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800" AllowDrop="True">
<Grid>
<Rectangle Fill="Blue"/>
</Grid>
</local:BaseDragDropUserControl>
The MainWindow is as following:
<Grid >
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<local:RedUserControl Grid.Row="0" Grid.Column="1"/>
<local:BlueUserControl Grid.Row="0" Grid.Column="0"/>
<local:BlueUserControl Grid.Row="0" Grid.Column="2"/>
<local:BlueUserControl Grid.Row="0" Grid.Column="3"/>
<local:RedUserControl Grid.Row="1" Grid.Column="0"/>
<local:BlueUserControl Grid.Row="1" Grid.Column="1"/>
<local:BlueUserControl Grid.Row="1" Grid.Column="2"/>
<local:BlueUserControl Grid.Row="1" Grid.Column="3"/>
<local:RedUserControl Grid.Row="2" Grid.Column="0"/>
<local:BlueUserControl Grid.Row="2" Grid.Column="1"/>
<local:BlueUserControl Grid.Row="2" Grid.Column="2"/>
<local:BlueUserControl Grid.Row="2" Grid.Column="3"/>
<local:RedUserControl Grid.Row="3" Grid.Column="0"/>
<local:BlueUserControl Grid.Row="3" Grid.Column="1"/>
<local:BlueUserControl Grid.Row="3" Grid.Column="2"/>
<local:BlueUserControl Grid.Row="3" Grid.Column="3"/>
</Grid>
</Window>
The Application is ready for you ! Come and play.

Can i add elements programatically to XAML? WPF c# [closed]

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I want to add canvas elements by user input. Something like when a button is clicked, a new <Ellipse/> element is added to the XAML file, inside the Canvas.
<Canvas x:Name="GraphDisplayFrame" Grid.Column="1" Grid.Row="0" Grid.ColumnSpan="3" Grid.RowSpan="4">
<Ellipse
Width="50"
Height="50"
Stroke="Black"
StrokeThickness="2"
Canvas.Left="100"
Canvas.Top="100" />
</Canvas>
I'm new to WPF, i'm not sure if this is the right way to do this.
The other thing i'm trying is System.Windows.Media but manipulating the XAMl file looks easier and nicer, since then the locations of the drawings are anchored to the canvas. I'm not sure if i can achieve something similar with System.Windows.Media.
So my question is in the title, but I'm open to other suggestions.

You probably want to learn about Bindings in WPF. Let's say you want your Ellipses be added by user's input (e.g. on Button click) to your Canvas. I'm not sure about Canvas usage for that purpose (it hasn't auto-alignments for child elements), so I used WrapPanel instead (to allow it align items). And we need 2 Buttons (to Add and Remove Ellipses). And I add a Label to display current amount of Ellipses that we have.
XAML:
<Window x:Class="WpfApp2.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:local="clr-namespace:WpfApp2"
mc:Ignorable="d"
Name ="mainWindow"
Title="Main Window"
Width="800"
MaxWidth="800"
Height="450"
MaxHeight="450">
<Grid x:Name="MainGrid">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="50*"/>
<ColumnDefinition Width="50*"/>
<ColumnDefinition Width="50*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="50*"/>
<RowDefinition Height="50*"/>
<RowDefinition Height="50*"/>
<RowDefinition Height="50*"/>
</Grid.RowDefinitions>
<Label Content="{Binding ElementName=mainWindow, Path=EllipsesCount, UpdateSourceTrigger=PropertyChanged}"
HorizontalContentAlignment="Center"
VerticalContentAlignment="Center"
Grid.Row="0"
Background="DimGray"
Foreground="White"
Margin="15,35" />
<Button x:Name="BtnAddEllipse"
Content="ADD ELLIPSE"
Grid.Row="1"
Margin="10, 25" FontSize="22" FontWeight="Bold"
Background="LightGreen"/>
<Button x:Name="BtnRemoveEllipse"
Content="REMOVE ELLIPSE"
Grid.Row="2"
Margin="10, 25" FontSize="22" FontWeight="Bold"
Background="IndianRed"/>
<WrapPanel Orientation="Horizontal"
Background="Gainsboro"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
Grid.Column="1"
Grid.Row="0"
Grid.ColumnSpan="3"
Grid.RowSpan="4" >
<ItemsControl ItemsSource="{Binding ElementName=mainWindow, Path=Ellipses, UpdateSourceTrigger=PropertyChanged}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</WrapPanel>
</Grid>
</Window>
Here you see that Label.Content property is binded to some EllipsesCount property (you'll see it in code-behind below). Also as WrapPanel is binded to Ellipses property.
Code-behind: (for copypaste purpose)
using System;
using System.Linq;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Media;
using System.Windows.Shapes;
namespace WpfApp2
{
public partial class MainWindow : Window, INotifyPropertyChanged
{
// Text for Label about Ellipses amount in collection
private object _ellipsesCount = "Current ellipses count: 0";
public object EllipsesCount
{
get => _ellipsesCount;
set
{
_ellipsesCount = "Current ellipses count: " + value;
// When we set new value to this property -
// we call OnPropertyChanged notifier, so Label
// would be "informed" about this change and will get new value
OnPropertyChanged(nameof(EllipsesCount));
}
}
// Collection for Ellipses
private ObservableCollection<Ellipse> _ellipses;
public ObservableCollection<Ellipse> Ellipses
{
get => _ellipses;
set
{
_ellipses = value;
OnPropertyChanged(nameof(Ellipses));
}
}
// Hanlder, which would notify our Controls about property changes, so they will "update" itself with new values
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName] string propertyName = "") =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
// Just for random colors
private readonly Random random = new Random();
public MainWindow()
{
InitializeComponent();
// Initialize collection of Ellipses
Ellipses = new ObservableCollection<Ellipse>();
// Handle when collection is changed to update Label
// with a new amount of Ellipses
Ellipses.CollectionChanged += delegate
{
// Update counter of ellipses when new one added or existing removed
EllipsesCount = Ellipses.Count;
};
BtnAddEllipse.Click += delegate
{
// Create an Ellipse with random stroke color
var ellipse = new Ellipse
{
Width = 50,
Height = 50,
Margin = new Thickness(3),
Stroke = new SolidColorBrush(Color.FromRgb((byte)random.Next(255), (byte)random.Next(255), (byte)random.Next(255))),
StrokeThickness = 3
};
// Add to collection of ellipses
Ellipses.Add(ellipse);
};
BtnRemoveEllipse.Click += delegate
{
// Check, that Ellipses collection isn't null and empty,
// so we can remove something from it
if (Ellipses?.Count > 0)
Ellipses.Remove(Ellipses.Last()); // Removing last element
};
}
}
}
So at result you see, actually, "content of collection of Ellipses", without adding Ellipses directly to window. Binding makes WrapPanel to use collection of Ellipses as source of child elements, that should be in that WrapPanel (instead of original my answer, where we add Ellipse to Canvas as Children).
ORIGINAL answer.
Yes, you can. For example (based on your XAML):
XAML (empty window):
<Window x:Class="WPFApp.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:local="clr-namespace:WPFApp"
mc:Ignorable="d">
<!-- No even Grid here -->
</Window>
Code-behind (check comments also):
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
// Setting Window properties (they not exists in XAML)
// XAML: <Window ... Title="Main Window" Height="450" Width="800">...
this.Title = "Main Window";
this.Height = 450;
this.Width = 800;
// Create main Grid and register some its name
// XAML: ...
var mainGrid = new System.Windows.Controls.Grid();
this.RegisterName("MainGrid", mainGrid);
// Add row and column definitions (as Canvas below needs, at least 4 rows and 3 columns)
for (int i = 0; i < 4; i++)
{
mainGrid.RowDefinitions.Add(new System.Windows.Controls.RowDefinition { Height = new GridLength(50, GridUnitType.Star) });
if (i < 3) // Needn't 4th column
mainGrid.ColumnDefinitions.Add(new System.Windows.Controls.ColumnDefinition { Width = new GridLength(50, GridUnitType.Star) });
}
// Create Canvas and register its name too
// XAML: ...
var canvas = new System.Windows.Controls.Canvas
{
// Just to be able see it at Window
Background = System.Windows.Media.Brushes.LightGray
};
this.RegisterName("GraphDisplayFrame", canvas);
canvas.SetValue(System.Windows.Controls.Grid.ColumnProperty, 1);
canvas.SetValue(System.Windows.Controls.Grid.RowProperty, 0);
canvas.SetValue(System.Windows.Controls.Grid.ColumnSpanProperty, 3);
canvas.SetValue(System.Windows.Controls.Grid.RowSpanProperty, 4);
// Create Ellipse (child canvas element)
// XAML: ...
var ellipse = new System.Windows.Shapes.Ellipse
{
Width = 50,
Height = 50,
Stroke = System.Windows.Media.Brushes.Black,
StrokeThickness = 2
};
ellipse.SetValue(System.Windows.Controls.Canvas.LeftProperty, 100D);
ellipse.SetValue(System.Windows.Controls.Canvas.TopProperty, 100D);
// Add child Ellipse to Canvas
canvas.Children.Add(ellipse);
// or you already can find Canvas by its name:
(this.FindName("GraphDisplayFrame") as System.Windows.Controls.Canvas).Children.Add(ellipse);
// Add Canvas to MainGrid. Find Grid by its registered name too
(this.FindName("MainGrid") as System.Windows.Controls.Grid).Children.Add(canvas);
// Set main Grid as window content
this.Content = mainGrid;
}
}
So, as you can see, XAML markuping is quite more compact, that code-behinded one.

Windows Phone 8.1 - XAML C# - VisualTreeHelper doesn't find DataTemplate Controls

I'm trying to build an app that displays in a Pivot informations about several products such as their pictures. Each PivotItem is concerning one product and contains (between other controls) another Pivot where I load the pictures of the product in code behind.
Here's the XAML part :
<Page
x:Class="Inventaire.Fenetres.FicheProduit"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:Inventaire"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Page.Resources>
<ResourceDictionary>
<DataTemplate x:Key="ProductPivotItem">
<Grid x:Name="rootGrid" Loaded="rootGrid_Loaded">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<TextBlock x:Name="productName" Text="{Binding article.name}" FontSize="18"
FontWeight="Bold" HorizontalAlignment="Center" TextWrapping="Wrap"
Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2"/>
<Pivot x:Name="picturesPivot" HorizontalAlignment="Center" Margin="0,5,0,5"
VerticalContentAlignment="Top" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2"/>
<!--
Some other controls
-->
</Grid>
</DataTemplate>
</ResourceDictionary>
</Page.Resources>
<Pivot x:Name="productPivot" ItemsSource="{Binding}"
ItemTemplate="{StaticResource ProductPivotItem}" />
</Page>
For the moment I load images in the rootGrid_Loaded event, using VisualTreeHelper to get picturesPivot with a method i found there.
Here's the C# extracts :
private void rootGrid_Loaded(object sender, RoutedEventArgs e)
{
Grid rootGrid = (Grid)sender;
// FindArticle is a method I wrote to get the product (of class Article) concerned by
// the productPivotItem, according to me irrelevant for my problem
Article art = FindArticle(rootGrid);
Pivot picturesPivot = (Pivot)FindChildControl<Pivot>(rootGrid, "picturesPivot");
loadImage(picturesPivot, art);
}
private async void loadImage(Pivot picturesPivot, Article article)
{
for (int i = 0 ; i < article.images.Count ; i++)
{
// ImageProduit is the class gathering infomations I need to build the picture url
// the images property of the Article class is the collection of ImageProduit for the product
// and I use AppelWebService (pattern singleton) to get the image from web
ImageProduit picture = article.images[i];
BitmapImage bmpImage = await AppelWebService.getInstance().loadImage(picture.ToString());
Image img = new Image();
img.Source = bmpImage;
PivotItem pi = new PivotItem();
pi.Content = img;
picturesPivot.Items.Add(pi);
}
}
private DependencyObject FindChildControl<T>(DependencyObject control, string ctrlName)
{
DependencyObject result = null;
bool done = false;
int i = 0;
int childNumber = VisualTreeHelper.GetChildrenCount(control);
while (i < childNumber && !done)
{
DependencyObject child = VisualTreeHelper.GetChild(control, i);
FrameworkElement fe = child as FrameworkElement;
if (fe == null)
{
done = true;
}
else if (child is T && fe.Name == ctrlName)
{
result = child;
done = true;
}
else
{
DependencyObject nextLevel = FindChildControl<T>(child, ctrlName);
if (nextLevel != null)
{
result = nextLevel;
done = true;
}
}
i++;
}
return result;
}
I modified a bit the FindChildControl method in order to have only one return at the end of the method.
Wrote like this I have no problems loading images.
But, sliding on many products, i discover that after around 70 productPivotItem loaded my emulator crash for OutOfMemoryException.
So I want to try to clear picturesPivot.Items when leaving the corresponding productPivotItem to see if it solve the memory problem.
For this I thought use the PivotItemLoaded and PivotItemUnloaded events on productPivot, load images on load and clear the picturesPivot items collection on unload.
Unfortunately I am not able to get back the picturesPivot in these event methods.
Here's what I tried :
private void productPivot_PivotItemLoaded(Pivot sender, PivotItemEventArgs args)
{
// Next three lines independently
args.Item.UpdateLayout();
sender.UpdateLayout();
UpdateLayout();
Pivot picturesPivot = (Pivot)FindChildControl<Pivot>(args.Item, "picturesPivot");
}
Debuging step by step I saw that args.Item has one child, a Grid without name that has himself one child, a ContentPresenter. This ContentPresenter has no child and I can't get any of my controls defined in the DataTemplate.
How could I find them ? I really need you as I had tearing out on this for too long. I hope I was clear enough, the Pivot Inside Pivot thing can be confusing.

WPF "Hidden" behind a Panel

I am encountering an issue in my project and i don't have much more time to do research.
The goal of this project is to allow attending to tests without being physically present.
You receive a file containing your tests, you attend to them (time limited) and send back the file containing your answers.
I got a TextBox in a StackPanel, itself contained in another StackPanel.
All the controls are created programatically.
The controls are added correctly but the TextBox don't react to mouse input.... (in fact only when the textbox is the ast item and even ther only the little last pixel)
UserControl XAML file :
<UserControl x:Class="DataLibrary.View.Questions.ListQuestionInterface"
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:localization ="clr-namespace:DataLibrary.Resources"
xmlns:convert ="clr-namespace:DataLibrary.View.Converters"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300"
Loaded="ListQuestionInterface_OnLoaded">
<UserControl.Resources>
<localization:LocalizedStrings x:Key="LocalizedStrings"/>
<convert:getVisible x:Key="getVisible"/>
<convert:getText x:Key="getText"/>
</UserControl.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="10*"/>
<RowDefinition Height="40"/>
</Grid.RowDefinitions>
<StackPanel VerticalAlignment="Stretch" Orientation="Horizontal" x:Name="body" Grid.Row="0" FocusManager.IsFocusScope="True"/>
<Label Grid.Row="0" Margin="0,10,0,0" x:Name="explanations"/>
<Button Content="{Binding Path=type, Converter={StaticResource getText}}"
HorizontalAlignment="Right"
Margin="0,0,10,10"
VerticalAlignment="Bottom"
Grid.Row="1"
Width="120"
Height="20"
Click="DisplayAnswerButton_Click"
Visibility="{Binding Path=type, Converter={StaticResource getVisible}}"/>
</Grid>
</UserControl>
Code Behind:
public partial class ListQuestionInterface : UserControl
{
private UIElement _firstElement;
ListQuestion q;
private bool isTest;
public questionType type
{
get
{
return q.Type;
}
set
{
Console.WriteLine("Attempted to write questionType");
}
}
public ListQuestionInterface(ListQuestion question, bool isTest = true)
{
InitializeComponent();
this.explanations.Content = question.Explanation;
this.DataContext = this;
this.q = question;
this.isTest = isTest;
refreshStackPanel();
}
private void refreshStackPanel()
{
bool first = true;
this.body.Children.Clear();
var enumerators = new Hashtable();
foreach (Question subQuestion in this.q.SubQuestions)
{
enumerators.Add(subQuestion, subQuestion.interfaceEnumerator(isTest).GetEnumerator());
((IEnumerator)enumerators[subQuestion]).MoveNext();
}
//If the Alignemnt property has a value we'll want each pair of control to be aligned wit heach other
//if not, we just want them stacked to the left
if (q.Alignment.HasValue)
{
int maxCount = this.q.SubQuestions.Max(x => x.interfaceEnumerator(isTest).Count());
for (int i = 0; i < maxCount; i++)
{
var stack = new StackPanel
{
VerticalAlignment = VerticalAlignment.Stretch,
HorizontalAlignment = HorizontalAlignment.Center
};
foreach (Question subQuestion in this.q.SubQuestions)
{
try
{
var enumerator = (IEnumerator)enumerators[subQuestion];
var control = enumerator.Current as Control;
((Panel)VisualTreeHelper.GetParent(control)).Children.Remove(control);
control.HorizontalAlignment = q.Alignment.Value;
Canvas canvas = null;
if (control.GetType() == typeof(Button) || control.GetType() == typeof(MaskedTextBox))
{
canvas = new Canvas();
if (control.GetType() == typeof(MaskedTextBox))
{
var thick = control.Margin;
thick.Left -= 5;
control.Margin = thick;
}
if (first)
{
this._firstElement = control;
first = false;
}
control.Focusable = true;
canvas.Children.Add(control);
}
if (canvas == null)
{
stack.Children.Add(control);
}
else
{
stack.Children.Add(canvas);
}
enumerator.MoveNext();
}
catch
{
var blank = new Label
{
Content = "BLANK",
Visibility = Visibility.Hidden
};
stack.Children.Add(blank);
Console.WriteLine("No more items to display");
}
}
this.body.Children.Add(stack);
}
}
else
{
var stack = new StackPanel
{
VerticalAlignment = VerticalAlignment.Stretch,
HorizontalAlignment = HorizontalAlignment.Center,
};
foreach (var subQuestion in q.SubQuestions)
{
var subStack = new StackPanel
{
VerticalAlignment = VerticalAlignment.Stretch,
HorizontalAlignment = HorizontalAlignment.Left,
Orientation = Orientation.Horizontal
};
var enumerator = subQuestion.interfaceEnumerator(isTest).GetEnumerator();
while (enumerator.MoveNext())
{
var control = enumerator.Current as Control;
control.HorizontalAlignment = HorizontalAlignment.Left;
if (control.GetType() == typeof(Button) || control.GetType() == typeof(MaskedTextBox))
{
if (first)
{
this._firstElement = control;
first = false;
}
control.Focusable = true;
}
((Panel)VisualTreeHelper.GetParent(control)).Children.Remove(control);
subStack.Children.Add(control);
}
stack.Children.Add(subStack);
}
this.body.Children.Add(stack);
}
}
private void DisplayAnswerButton_Click(object sender, RoutedEventArgs e)
{
foreach (Question question in q.SubQuestions)
{
question.DisplayAnswers();
}
refreshStackPanel();
}
private void ListQuestionInterface_OnLoaded(object sender, RoutedEventArgs e)
{
this._firstElement.Focus();
}
}
}
I don't think the button have somethng to do with the problem so i'll leave the converters code away.
I've checked some things already :
IsHitTestVisible is never set to false
Defining one of the stackpanels as the FocusScope don't change anything
If i place all my controls into canvas and the canvas into the stackpanel i can freely click on my controls but their placement is completely broken.
The Actual Width/height of the control is sufficient to interact with them(60x20)
The problem seems to have appeared just after using the following trick to set a first focused element on other UserControls (which are not in the current VisualTree anymore)
I really do need help since i can't seem to find someone with a similar problem.
And here are two screenshots to illustrate the problem :
The black arrows shows where my i clicked before taking the screenshot (btw if you know of any software that can do a screenshot WITH the mouse i'm taking it :) )

Ok, my fault here -_-'
I was so tired that i didnt't see that my stackpanel was in fact really BEHIND a Label
In my code i only had 2 row definitions, in the first i put the stackpanel AND a Label (who took the entire space).
And because it was declared later, the label was above the stackpanel thus preventing any mouse interaction with it's content.
Here is the corrected XAML :
<UserControl x:Class="DataLibrary.View.Questions.ListQuestionInterface"
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:localization ="clr-namespace:DataLibrary.Resources"
xmlns:convert ="clr-namespace:DataLibrary.View.Converters"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300"
Loaded="ListQuestionInterface_OnLoaded">
<UserControl.Resources>
<localization:LocalizedStrings x:Key="LocalizedStrings"/>
<convert:getVisible x:Key="getVisible"/>
<convert:getText x:Key="getText"/>
</UserControl.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="60*"/>
<RowDefinition Height="20*"/>
<RowDefinition Height="10*"/>
</Grid.RowDefinitions>
<StackPanel VerticalAlignment="Stretch" Orientation="Horizontal" x:Name="body" Grid.Row="0" FocusManager.IsFocusScope="True"/>
<Label Grid.Row="1" Margin="0,10,0,0" x:Name="explanations"/>
<Button Content="{Binding Path=type, Converter={StaticResource getText}}"
HorizontalAlignment="Right"
Margin="0,0,10,10"
VerticalAlignment="Bottom"
Grid.Row="2"
Width="120"
Height="20"
Click="DisplayAnswerButton_Click"
Visibility="{Binding Path=type, Converter={StaticResource getVisible}}"/>
</Grid>
</UserControl>
So in fact, the control was really hidden behind another one -_-'
I now know that this isn't the WPF way of doing things, but i do not know yet how to DataBind to a Template properly
I'm still taking any advices on a good tutorial/starting point for binding to a DataTemplate in XAML, tho only DataBindings i could find were for binding single values to control properties

make process queue graphically in c#

I implemented some cpu scheduling algorithm.and i want to show it in windows form application in c# graphically but i don't know how?
example:
I have these processes:
p1,p2,p3,p4,p5,p6,p7,p8,p9,...
p2 do its process before p1,and p1 before p6 and p6 before p3 and...
I want something like this to show it for me:
http://i.stack.imgur.com/zEWbG.jpg
also each process length change based on its own process time, and show process start time and end time too.
How can I make something like that?
thank u.

I would recommend using WPF. You could achieve this many different ways.
One example is a WPF Grid with multiple columns. You can set the width of the column as a proportion. Eg A width of "3*" would indicate a process that takes half the time as a width of "6*"
<Window x:Class="WpfApplication3.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid Name="MainGrid" Height="80">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"></ColumnDefinition>
<ColumnDefinition Width="2*"></ColumnDefinition>
<ColumnDefinition Width="4*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Rectangle Fill="LightBlue"/>
<Rectangle Grid.Column="1" Fill="LightGreen"/>
<Rectangle Grid.Column="2" Fill="LightPink"/>
<Label HorizontalAlignment="Center" VerticalAlignment="Center">P2</Label>
<Label Grid.Column="1" HorizontalAlignment="Center" VerticalAlignment="Center">P1</Label>
<Label Grid.Column="2" HorizontalAlignment="Center" VerticalAlignment="Center">P6</Label>
</Grid>
</Window>
This XAML code would produce this.
http://img835.imageshack.us/img835/4742/picturelx.png
You could programatically add columns using C# code-behind like this.
private void AddColumn()
{
//Create the columndefinition with a width of "3*"
ColumnDefinition column = new ColumnDefinition();
column.Width = new GridLength(3, GridUnitType.Star);
//Add the column to the grid
MainGrid.ColumnDefinitions.Add(column);
//Create the rectangle
Rectangle rect = new Rectangle();
rect.Fill = new SolidColorBrush(Colors.Beige);
MainGrid.Children.Add(rect);
Grid.SetColumn(rect, 3);
//Create the label
Label label = new Label();
label.VerticalAlignment = System.Windows.VerticalAlignment.Center;
label.HorizontalAlignment = System.Windows.HorizontalAlignment.Center;
label.Content = "P4";
MainGrid.Children.Add(label);
Grid.SetColumn(label, 3);
}