I'm working on a dynamic C# WPF application (on Windows 10) that uses a fullscreen Grid. Controls are added to the grid dynamically at runtime (which are managed in a Dictionary<>) and I recently added code to move the controls along the grid with the mouse (also at runtime) using a TranslateTransform (which I am now doubting the viability of).
Is there a way I can prevent the controls from overlapping or "sharing space" on the grid when moving them? In other words, adding some sort of collision detection. Would I use an if statement to check the control margin ranges or something? My move events are shown below:
MainWindow.xaml.cs:
public partial class MainWindow : Window
{
// Orientation variables:
public bool _isInDrag = false;
public Dictionary<object, TranslateTransform> PointDict = new Dictionary<object, TranslateTransform();
public Point _anchorPoint;
public Point _currentPoint;
public MainWindow()
{
InitializeComponent();
}
public static void Control_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
if (_isInDrag)
{
var element = sender as FrameworkElement;
element.ReleaseMouseCapture();
_isInDrag = false;
e.Handled = true;
}
}
public static void Control_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var element = sender as FrameworkElement;
_anchorPoint = e.GetPosition(null);
element.CaptureMouse();
_isInDrag = true;
e.Handled = true;
}
public static void Control_MouseMove(object sender, MouseEventArgs e)
{
if (_isInDrag)
{
_currentPoint = e.GetPosition(null);
TranslateTransform tt = new TranslateTransform();
bool isMoved = false;
if (PointDict.ContainsKey(sender))
{
tt = PointDict[sender];
isMoved = true;
}
tt.X += _currentPoint.X - _anchorPoint.X;
tt.Y += (_currentPoint.Y - _anchorPoint.Y);
(sender as UIElement).RenderTransform = tt;
_anchorPoint = _currentPoint;
if (isMoved)
{
PointDict.Remove(sender);
}
PointDict.Add(sender, tt);
}
}
}
MainWindow.xaml (example):
<Window x:Name="MW" x:Class="MyProgram.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:MyProgram"
mc:Ignorable="d"
Title="MyProgram" d:DesignHeight="1080" d:DesignWidth="1920" ResizeMode="NoResize" WindowState="Maximized" WindowStyle="None">
<Grid x:Name="MyGrid" />
<Image x:Name="Image1" Source="pic.png" Margin="880,862,0,0" Height="164" Width="162" HorizontalAlignment="Left" VerticalAlignment="Top" MouseLeftButtonDown="Control_MouseLeftButtonDown" MouseLeftButtonUp="Control_MouseLeftButtonUp" MouseMove="Control_MouseMove" />
<TextBox x:Name="Textbox1" Margin="440,560,0,0" HorizontalAlignment="Left" VerticalAlignment="Top" MouseLeftButtonDown="Control_MouseLeftButtonDown" MouseLeftButtonUp="Control_MouseLeftButtonUp" MouseMove="Control_MouseMove" />
</Window>
Edit: It seems that moving a control with a TranslateTransform does not change the margin for that control. Not sure why.
Edit 2: Not getting much traction. If anyone needs clarification on anything, please ask.
Edit 3: Pretty sure I can't use TranslateTransform because it does not change the margin of a given control. Is there an alternative?
Edit 4: Added some 'boilerplate' code for those who want to copy & paste. Let me know if you have any questions about it.
TL;DR: Demo from the bottom of this answer
When you want to modify your UI without adding event handlers to every single control, the way to go is with Adorners. Adorners are (as the name implies) controls that adorn another control to add additional visuals or as in your case functionality. Adorners reside in an AdornerLayer which you can either add yourself or use the one that every WPF Window already has. The AdornerLayer is on top of all your other controls.
You never mentioned what should happen when the user lets go of the mouse button when controls overlap so I just reset the control to its original position if that happens.
At this point I'd usually explain what to keep in mind when moving controls but since your original example even contains the CaptureMouse people usually forget, I think you'll understand the code without further explanation :)
A couple of things you might want to add / improve:
A snap to grid feature (pixel precise movement can be a bit overwhelming for the average user)
Take RenderTransform, LayoutTransform and non-rectangular shapes (if needed) into account when calculating the overlap
Move the editing functionality (enable, disable, etc.) into a separate control and add a dedicated AdornerLayer
Disable interactive controls (Buttons, TextBoxes, ComboBoxes, etc.) in edit-mode
Cancel movement when the user presses Esc
Restrict movement to the bounds of the parent container done
Move the active Adorner to the top of the AdornerLayer
Let the user move multiple controls at once (typically by selecting them with Ctrl)
Previously unanswered question:
Are you saying controls are no longer assigned a margin when using TranslateTransform?
Not at all - You could use a combination of Grid.Row, Grid.Column, Margin, RenderTransform and LayoutTransform but then it would be a nightmare to determine where the control is actually displayed. If you stick with one (In this case for example Margin or LayoutTransform) it is much easier to work with and keep track of. If you ever find yourself in a situation where you need more than one at the same time, you would have to find the actual position by determining the corners of the control by transforming (0, 0) and (ActualWidth, ActualHeight) with TransformToAncestor. Trust me, you don't want to go there - keep it simple, stick with one of them.
The below code is not the "holy grail of how to move things" but it should give you an idea of how to do it and what else you could do with it (resize, rotate, remove controls, etc.). The layouting is based purely on the Left and Top margin of the controls. It shouldn't be to hard to swap out all Margins for LayoutTransforms if you prefer that, as long as you keep it consistent.
Move Adorner
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;
public class MoveAdorner : Adorner
{
// The parent of the adorned Control, in your case a Grid
private readonly Panel _parent;
// Same as "AdornedControl" but as a FrameworkElement
private readonly FrameworkElement _child;
// The visual overlay rectangle we can click and drag
private readonly Rectangle _rect;
// Our own collection of child elements, in this example only _rect
private readonly UIElementCollection _visualChildren;
private bool _down;
private Point _downPos;
private Thickness _downMargin;
private List<Rect> _otherRects;
protected override int VisualChildrenCount => _visualChildren.Count;
protected override Visual GetVisualChild(int index)
{
return _visualChildren[index];
}
public MoveAdorner(FrameworkElement adornedElement) : base(adornedElement)
{
_child = adornedElement;
_parent = adornedElement.Parent as Panel;
_visualChildren = new UIElementCollection(this,this);
_rect = new Rectangle
{
HorizontalAlignment = HorizontalAlignment.Stretch,
VerticalAlignment = VerticalAlignment.Stretch,
StrokeThickness = 1,
};
SetColor(Colors.LightGray);
_rect.MouseLeftButtonDown += RectOnMouseLeftButtonDown;
_rect.MouseLeftButtonUp += RectOnMouseLeftButtonUp;
_rect.MouseMove += RectOnMouseMove;
_visualChildren.Add(_rect);
}
private void SetColor(Color color)
{
_rect.Fill = new SolidColorBrush(color) {Opacity = 0.3};
_rect.Stroke = new SolidColorBrush(color) {Opacity = 0.5};
}
private void RectOnMouseMove(object sender, MouseEventArgs args)
{
if (!_down) return;
Point pos = args.GetPosition(_parent);
UpdateMargin(pos);
}
private void UpdateMargin(Point pos)
{
double deltaX = pos.X - _downPos.X;
double deltaY = pos.Y - _downPos.Y;
Thickness newThickness = new Thickness(_downMargin.Left + deltaX, _downMargin.Top + deltaY, 0, 0);
//Restrict to parent's bounds
double leftMax = _parent.ActualWidth - _child.ActualWidth;
double topMax = _parent.ActualHeight - _child.ActualHeight;
newThickness.Left = Math.Max(0, Math.Min(newThickness.Left, leftMax));
newThickness.Top = Math.Max(0, Math.Min(newThickness.Top, topMax));
_child.Margin = newThickness;
bool overlaps = CheckForOverlap();
SetColor(overlaps ? Colors.Red : Colors.Green);
}
// Check the current position for overlaps with all other controls
private bool CheckForOverlap()
{
if (_otherRects == null || _otherRects.Count == 0)
return false;
Rect thisRect = GetRect(_child);
foreach(Rect otherRect in _otherRects)
if (thisRect.IntersectsWith(otherRect))
return true;
return false;
}
private Rect GetRect(FrameworkElement element)
{
return new Rect(new Point(element.Margin.Left, element.Margin.Top), new Size(element.ActualWidth, element.ActualHeight));
}
private void RectOnMouseLeftButtonUp(object sender, MouseButtonEventArgs args)
{
if (!_down) return;
Point pos = args.GetPosition(_parent);
UpdateMargin(pos);
if (CheckForOverlap())
ResetMargin();
_down = false;
_rect.ReleaseMouseCapture();
SetColor(Colors.LightGray);
}
private void ResetMargin()
{
_child.Margin = _downMargin;
}
private void RectOnMouseLeftButtonDown(object sender, MouseButtonEventArgs args)
{
_down = true;
_rect.CaptureMouse();
_downPos = args.GetPosition(_parent);
_downMargin = _child.Margin;
// The current position of all other elements doesn't have to be updated
// while we move this one so we only determine it once
_otherRects = new List<Rect>();
foreach (FrameworkElement child in _parent.Children)
{
if (ReferenceEquals(child, _child))
continue;
_otherRects.Add(GetRect(child));
}
}
// Whenever the adorned control is resized or moved
// Update the size of the overlay rectangle
// (Not 100% necessary as long as you only move it)
protected override Size MeasureOverride(Size constraint)
{
_rect.Measure(constraint);
return base.MeasureOverride(constraint);
}
protected override Size ArrangeOverride(Size finalSize)
{
_rect.Arrange(new Rect(new Point(0,0), finalSize));
return base.ArrangeOverride(finalSize);
}
}
Usage
private void DisableEditing(Grid theGrid)
{
// Remove all Adorners of all Controls
foreach (FrameworkElement child in theGrid.Children)
{
var layer = AdornerLayer.GetAdornerLayer(child);
var adorners = layer.GetAdorners(child);
if (adorners == null)
continue;
foreach(var adorner in adorners)
layer.Remove(adorner);
}
}
private void EnableEditing(Grid theGrid)
{
foreach (FrameworkElement child in theGrid.Children)
{
// Add a MoveAdorner for every single child
Adorner adorner = new MoveAdorner(child);
// Add the Adorner to the closest (hierarchically speaking) AdornerLayer
AdornerLayer.GetAdornerLayer(child).Add(adorner);
}
}
Demo XAML
<Grid>
<Button Content="Enable Editing" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Width="100" Click="BtnEnable_Click"/>
<Button Content="Disable Editing" HorizontalAlignment="Left" Margin="115,10,0,0" VerticalAlignment="Top" Width="100" Click="BtnDisable_Click"/>
<Grid Name="grid" Background="AliceBlue" Margin="10,37,10,10">
<Button Content="Button" HorizontalAlignment="Left" Margin="83,44,0,0" VerticalAlignment="Top" Width="75"/>
<Ellipse Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="100" Margin="207,100,0,0" Stroke="Black" VerticalAlignment="Top" Width="100"/>
<Rectangle Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="100" Margin="33,134,0,0" Stroke="Black" VerticalAlignment="Top" Width="100"/>
</Grid>
</Grid>
Expected Result
When editing is disabled controls cannot be moved, interactive controls can be clicked / interacted with without obstruction. When editing mode is enabled, each control is overlayed with an adorner that can be moved. If the target position overlaps with another control, the adorner will turn red and the margin will be reset to the initial position if the user lets go of the mouse button.
There is no other way then to check if there control exists on place where you are moving.
Since you are moving UI elements a lot it is better to use canvas instead of grid where you can layout elements with Top and Left parameters.
Here is modified code of yours that do that
public partial class MainWindow : Window
{
public bool _isInDrag = false;
public Dictionary<object, TranslateTransform> PointDict = new Dictionary<object, TranslateTransform>();
public Point _anchorPoint;
public Point _currentPoint;
public MainWindow()
{
InitializeComponent();
}
public void Control_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
if (_isInDrag)
{
var element = sender as FrameworkElement;
element.ReleaseMouseCapture();
Panel.SetZIndex(element, 0);
_isInDrag = false;
e.Handled = true;
}
}
public void Control_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var element = sender as FrameworkElement;
_anchorPoint = e.GetPosition(null);
element.CaptureMouse();
Panel.SetZIndex(element, 10);
_isInDrag = true;
e.Handled = true;
}
public void Control_MouseMove(object sender, MouseEventArgs e)
{
if (_isInDrag)
{
_currentPoint = e.GetPosition(null);
FrameworkElement fw = sender as FrameworkElement;
if (fw != null)
{
FrameworkElement fwParent = fw.Parent as FrameworkElement;
if (fwParent != null)
{
Point p = new Point(_currentPoint.X - _anchorPoint.X + Canvas.GetLeft((sender as UIElement)), _currentPoint.Y - _anchorPoint.Y + Canvas.GetTop((sender as UIElement)));
List<HitTestResult> lst = new List<HitTestResult>()
{
VisualTreeHelper.HitTest(fwParent , p),
VisualTreeHelper.HitTest(fwParent, new Point(p.X + fw.Width, p.Y)),
VisualTreeHelper.HitTest(fwParent, new Point(p.X, p.Y + fw.Height)),
VisualTreeHelper.HitTest(fwParent, new Point(p.X + fw.Width, p.Y +fw.Height)),
};
bool success = true;
foreach (var item in lst)
{
if (item != null)
{
if (item.VisualHit != sender && item.VisualHit != fwParent && fw.IsAncestorOf(item.VisualHit) == false)
{
success = false;
break;
}
}
}
if (success)
{
Canvas.SetTop((sender as UIElement), p.Y);
Canvas.SetLeft((sender as UIElement), p.X);
_anchorPoint = _currentPoint;
}
}
}
}
}
}
Xaml
<Window x:Class="ControlsOverlapWpf.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:ControlsOverlapWpf"
mc:Ignorable="d"
Title="MyProgram" d:DesignHeight="500" d:DesignWidth="500" ResizeMode="NoResize" WindowState="Normal" WindowStyle="None">
<Canvas Background="Pink">
<Button Canvas.Top=" 200" Canvas.Left="200" Height="150" Width="150" Background="Aqua" HorizontalAlignment="Left" VerticalAlignment="Top" PreviewMouseLeftButtonDown="Control_MouseLeftButtonDown" PreviewMouseLeftButtonUp="Control_MouseLeftButtonUp" PreviewMouseMove="Control_MouseMove" />
<Button Canvas.Top=" 200" Canvas.Left="200" Height="150" Width="150" Background="Aqua" HorizontalAlignment="Left" VerticalAlignment="Top" PreviewMouseLeftButtonDown="Control_MouseLeftButtonDown" PreviewMouseLeftButtonUp="Control_MouseLeftButtonUp" PreviewMouseMove="Control_MouseMove" />
<Button Canvas.Top=" 200" Canvas.Left="200" Height="150" Width="150" Background="Aqua" HorizontalAlignment="Left" VerticalAlignment="Top" PreviewMouseLeftButtonDown="Control_MouseLeftButtonDown" PreviewMouseLeftButtonUp="Control_MouseLeftButtonUp" PreviewMouseMove="Control_MouseMove" />
<Button Canvas.Top=" 200" Canvas.Left="200" Height="150" Width="150" Background="Aqua" HorizontalAlignment="Left" VerticalAlignment="Top" PreviewMouseLeftButtonDown="Control_MouseLeftButtonDown" PreviewMouseLeftButtonUp="Control_MouseLeftButtonUp" PreviewMouseMove="Control_MouseMove" />
<Button Canvas.Top=" 200" Canvas.Left="200" Height="150" Width="150" Background="Aqua" HorizontalAlignment="Left" VerticalAlignment="Top" PreviewMouseLeftButtonDown="Control_MouseLeftButtonDown" PreviewMouseLeftButtonUp="Control_MouseLeftButtonUp" PreviewMouseMove="Control_MouseMove" />
<Button Canvas.Top=" 200" Canvas.Left="200" Height="150" Width="150" Background="Aqua" HorizontalAlignment="Left" VerticalAlignment="Top" PreviewMouseLeftButtonDown="Control_MouseLeftButtonDown" PreviewMouseLeftButtonUp="Control_MouseLeftButtonUp" PreviewMouseMove="Control_MouseMove" />
</Canvas>
</Window>
How to clear the contents of a canvas in wpf? Tried canvas.clear() doesn't work.
Also how can i add zoom control in a wpf application? Zoom with a scroller to move the image.
Any help is greatly appreciated
You want to do MyCanvas.Children.Clear();
Tested with the following code:
<Grid>
<Canvas Name="MyCanvas"/>
<Button Click="Button_Click" HorizontalAlignment="Right" VerticalAlignment="Bottom" Width="200" Content="Clear"/>
</Grid>
and
public MainWindow()
{
InitializeComponent();
MyCanvas.Children.Add(new TextBlock() { Text = "Foo" });
}
private void Button_Click(object sender, RoutedEventArgs e)
{
MyCanvas.Children.Clear();
}
how can move (change position) label from position to another using wpf **
animation
** in specify event such click using c# code not trigger ??
using System.windows.media.animation;
XAML
<Window x:Class="WpfApplication2.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">
<Canvas>
<Button Content="Button" HorizontalAlignment="Left" VerticalAlignment="Top" Width="75" Click="Button_Click" Canvas.Left="201" Canvas.Top="116" x:Name="Button"/>
</Canvas>
</Window>
Code
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
var storyboard = new Storyboard();
var pointAnimation = new DoubleAnimation()
{
From = Canvas.GetLeft(Button),
To = Canvas.GetLeft(Button) + 200,
Duration = new Duration(TimeSpan.FromSeconds(10))
};
Storyboard.SetTarget(pointAnimation, Button);
Storyboard.SetTargetProperty(pointAnimation, new PropertyPath(Canvas.LeftProperty));
storyboard.Children.Add(pointAnimation);
storyboard.Begin();
}
I'm working on wpf application , the application draws the countours on an existing image and i want to add a button which give me the hand to zoom the image to see the countours
i added a button and a fonction on .cs but it doesn't work
here's the code cs
namespace AnimationTest
{
public partial class MainWindow: Window
{
public MainWindow()
{
InitializeComponent();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
DoubleAnimation da = new DoubleAnimation();
da.From = 0;
da.To = 1000;
da.Duration = new Duration(TimeSpan.FromSeconds(1));
image1.BeginAnimation(ScaleTransform.CenterXProperty, da);
}
}
}
and XAML Code
<Window x:Class="AnimationTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="720" Width="1280">
<Grid>
<Image Height="681" HorizontalAlignment="Left" Name="image1" Stretch="None" VerticalAlignment="Top" Width="1258" Source="/AnimationTest;component/Images/world.jpg" />
<Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="1171,12,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
</Grid>
what's the problem ? and how can i fixe it ?
thanks
This has no sens image1.BeginAnimation(ScaleTransform.CenterXProperty, da); You start an animation on an image of a property that don't belong to Image control. You should create a scale transform, set it on the image and then start the animation on scale transform object, not the image.
I am searching all the time for solution and cant get correct one.
I have grid that have width 960 and have ScrollViewer in it. Now i would like to know value (horizontal offset) of my scroll while scrolling. All solutions that i am finding is for wpf/silverlight and it wont works for me.
Edit
Ok, here is the example code, xaml:
<ScrollViewer Name="Scroll" LayoutUpdated="ScrollViewer_LayoutUpdated" IsEnabled="True" Width="480" ScrollViewer.HorizontalScrollBarVisibility="Auto">
<Grid x:Name="ContentPanel" Background="Red" Margin="12,0,12,0" Width="960">
<Rectangle Name="GreenRectangle" Fill="Green" Width="240" Height="240"></Rectangle>
</Grid>
</ScrollViewer>
c#
private void ScrollViewer_LayoutUpdated(object sender, EventArgs e)
{
GreenRectangle.Width = Scroll.HorizontalOffset;
GreenRectangle.Height = Scroll.HorizontalOffset;
}
But the problem is that it is not changing size all the time. Maybe my English is not well and you cant uderstand me. Here is movie example, i am sliding left right and the size is always the same. When i stop sliding it is changing size.
https://www.dropbox.com/s/eh28oavxpsy19bw/20130122_1601_56.avi
It is possible by using the scrollviewers dependency properties, it has a HorizontalOffset and a VerticalOffset. The trick is to bind event to the scrollviewer, but it can bee done in the load event handler. If you put a wide grid in your scrollviewer you can get the offset!
In your xaml file (MainPage sample here):
<ScrollViewer Loaded="ScrollViewer_Loaded_1">
<Grid x:Name="ContentPanel" Grid.Row="1" Width="1000" Margin="12,0,12,0">
<StackPanel>
...
In your code behind file (MainPage.cs here):
public static readonly DependencyProperty ScrollViewVerticalOffsetProperty =
DependencyProperty.Register(
"ScrollViewVerticalOffset",
typeof(double),
typeof(MainPage),
new PropertyMetadata(new PropertyChangedCallback(OnScrollViewVerticalOffsetChanged))
);
public static readonly DependencyProperty ScrollViewHorizontalOffsetProperty =
DependencyProperty.Register(
"ScrollViewHorizontalOffset",
typeof(double),
typeof(MainPage),
new PropertyMetadata(new PropertyChangedCallback(OnScollViewHorizontalOffsetChanged))
);
private ScrollViewer _listScrollViewer;
private void ScrollViewer_Loaded_1(object sender, RoutedEventArgs e)
{
_listScrollViewer = sender as ScrollViewer;
Binding binding1 = new Binding();
binding1.Source = _listScrollViewer;
binding1.Path = new PropertyPath("VerticalOffset");
binding1.Mode = BindingMode.OneWay;
this.SetBinding(ScrollViewVerticalOffsetProperty, binding1);
Binding binding2 = new Binding();
binding2.Source = _listScrollViewer;
binding2.Path = new PropertyPath("HorizontalOffset");
binding2.Mode = BindingMode.OneWay;
this.SetBinding(ScrollViewHorizontalOffsetProperty, binding2);
}
public double ScrollViewVerticalOffset
{
get { return (double)this.GetValue(ScrollViewVerticalOffsetProperty); }
set { this.SetValue(ScrollViewVerticalOffsetProperty, value); }
}
public double ScrollViewHorizontalOffset
{
get { return (double)this.GetValue(ScrollViewHorizontalOffsetProperty); }
set { this.SetValue(ScrollViewHorizontalOffsetProperty, value); }
}
private static void OnScrollViewVerticalOffsetChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
MainPage page = obj as MainPage;
ScrollViewer viewer = page._listScrollViewer;
// ... do something here
}
private static void OnScollViewHorizontalOffsetChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
MainPage page = obj as MainPage;
ScrollViewer viewer = page._listScrollViewer;
// ... do something here
}
here's the XAML code I used
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0" LayoutUpdated='ContentPanel_LayoutUpdated'>
<ScrollViewer x:Name='scroller' VerticalAlignment='Stretch' VerticalScrollBarVisibility='Visible' >
<StackPanel
x:Name='listItems'></StackPanel>
</ScrollViewer>
</Grid>
and here's the C# code behind
private void ContentPanel_LayoutUpdated(object sender, EventArgs e)
{
var offset = scroller.VerticalOffset;
}
whenever the scroller is scrolled then the layout of the Grid (Container grid) changes so layout updated event is fired ... please try debugging by placing break point inside the event and look for the offset value ..
Add the property ManipulationMode="Control" to your ScrollViewer. This is needed because otherwise the UI thread will not be notified with enough ScrollViewer scroll values to get a fluid animation – the normal mode is a performance optimization from Windows Phone that you need to bypass!