Grab-to-pan in Silverlight app - silverlight

I have a Canvas inside a ScrollViewer. I want to have the user to be able to grab the canvas and move it around, with the thumbs on the scrollbars updating appropriately.
My initial implementation calculates the offset on each mouse move, and updates the scrollbars:
// Calculate the new drag distance
Point newOffsetPos = e.GetPosition(MapCanvas);
System.Diagnostics.Debug.WriteLine(" newOffsetPos : " + newOffsetPos.X + " " + newOffsetPos.Y);
double deltaX = newOffsetPos.X - _offsetPosition.X ;
double deltaY = newOffsetPos.Y - _offsetPosition.Y ;
System.Diagnostics.Debug.WriteLine(" delta X / Y : " + deltaX + " " + deltaY);
System.Diagnostics.Debug.WriteLine(" sv offsets X / Y : " + _scrollViewer.HorizontalOffset + " " + _scrollViewer.VerticalOffset);
_scrollViewer.ScrollToHorizontalOffset(_scrollViewer.HorizontalOffset - deltaX);
_scrollViewer.ScrollToVerticalOffset(_scrollViewer.VerticalOffset - deltaY);
_offsetPosition = newOffsetPos;
While this works, it is not very smooth.
Is there a better way to do this? If Transforms are used, will the scrollbars update automagically when the Canvas is moved?
Thanks for any tips...

Actually this sort of problem is really a matter of using the right pattern to track the mouse. I've seen this issue in variety of cases not just in Silverlight.
The best pattern is to trap the original locations of both mouse and subject, then recalculate the new offset from the fixed original values. That way the mouse stays planted solid at a single point on the image being panned. Here is my simple Repro:-
Start with a fresh Silverlight Application in visual studio. Modify MainPage.Xaml thus:-
<UserControl x:Class="SilverlightApplication1.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid x:Name="LayoutRoot" Background="White">
<ScrollViewer x:Name="Scroller" HorizontalScrollBarVisibility="Auto">
<Image x:Name="Map" Source="test.jpg" Width="1600" Height="1200" />
</ScrollViewer>
</Grid>
</UserControl>
Add the following code to the MainPage.xaml.cs file:-
public MainPage()
{
InitializeComponent();
Map.MouseLeftButtonDown += new MouseButtonEventHandler(Map_MouseLeftButtonDown);
}
void Map_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
Point mapOrigin = new Point(Scroller.HorizontalOffset, Scroller.VerticalOffset);
Point mouseOrigin = e.GetPosition(Application.Current.RootVisual);
MouseEventHandler moveHandler = null;
MouseButtonEventHandler upHandler = null;
moveHandler = (s, args) =>
{
Point mouseNew = args.GetPosition(Application.Current.RootVisual);
Scroller.ScrollToHorizontalOffset(mapOrigin.X - (mouseNew.X - mouseOrigin.X));
Scroller.ScrollToVerticalOffset(mapOrigin.Y - (mouseNew.Y - mouseOrigin.Y));
};
upHandler = (s, args) =>
{
Scroller.MouseMove -= moveHandler;
Scroller.MouseLeftButtonUp -= upHandler;
};
Scroller.MouseMove += moveHandler;
Scroller.MouseLeftButtonUp += upHandler;
}
}
Give it a reasonably large test.jpg (doesn't need to be 1600x1200 Image will scale it).
You'll note that when dragging the mouse remains exactly over a fixed point in the image until you hit a boundary. Move the mouse as fast as you like it always tracks, this is because it doesn't depend on deltas being accurate and up-to-date. The only variable is the current mouse position, the other values remain fixed as they were at mouse down.

You could try this (or at least take a peek at how it's implemented).

Related

Binding of relative position of a control

I have a draggable user control within another user control indicating the distance of a vessel from another vessel. The placement of the object is bound to X, Y values in the back end. If the user loads a "mission", the location of this draggable object should snap to the position based on the X and Y values. Additionally, if the user drags the boat but then cancels, the position of the boat should snap back to its original position before it was dragged.
I find that if I bind to the Margin field, the margin is set correctly on the control but the draggable object stays in the same place, as if it is at 0,0,0,0 with the updated values (I can force it to move by editing the xaml and proving that any margin changes act as if the new values are 0,0,0,0:
public Thickness DaughtershipMargin
{
get { return _daughtershipMargin; }
set
{
_daughtershipMargin = value;
OnPropertyChanged();
}
}
I have also experimented with using a Canvas instead with similar results.
When initially dragging, the position is based on the relative position of the control based on a parent control - so it needs I need to do something similar
private void MouseDragElementBehavior_Dragging(object sender, MouseEventArgs e)
{
double x = System.Math.Round((e.GetPosition(colabdragObjectGrid).X - 280), 3);
double y = System.Math.Round((-1 * (e.GetPosition(colabdragObjectGrid).Y - 280)), 3);
if (x >= _minFollowDistance && x <= _maxFollowDistance && y >= _minFollowDistance && y <= _maxFollowDistance)
{
_parent.ProcessDragEvent(x.ToString(), y.ToString());
}
}
<Grid x:Name="colabdragObjectGrid" Margin="0,-10,0,0" Height="575" Width="575">
<local:colabdrag x:Name="colabdragObject" Height="100" Width="100" RenderTransformOrigin="0.5,0.5" Margin="{Binding DaughtershipMargin}">
<i:Interaction.Behaviors>
<ei:MouseDragElementBehavior ConstrainToParentBounds="True" Dragging="MouseDragElementBehavior_Dragging"/>
</i:Interaction.Behaviors>
</local:colabdrag>
</Grid>
Edit:
I got this to work by creating a point relative to the draggable area and another point for the desired position based on that point, then using TranslateTranform to get the object where it needs to be
var pointA = (colabdragObject.TransformToAncestor(colabDragObjectGrid).Transform(new Point(X,Y))
var pointB = colabdragObjectGrid.TranslatePoint(pointA, colabDragObject);
colabdragObject.RenderTransform = new TranslateTransform(pointB.X, -1 * pointB.Y);

Zoom and pan WPF canvas

I have a question regarding WPF.
I have a Canvas that serves as a visual editor! I have a few 'nodes' positioned in the Canvas using 'X' and 'Y' properties (Canvas.Left and Canvas.Top). Now, I need this Canvas to let the user Zoom (in & out) and Pan around, as he want's to.
I implemented kind of a hack to emulate that behavior. This is the Code that let's the user 'pan' around in the Canvas:
///In file MainWindow.xaml.cs
private void ZoomPanCanvas_MouseMove(object sender, MouseEventArgs e) {
if (IsMouseDown) {
///Change the Cursor to Scroll
if (mNetworkUI.Cursor != Cursors.ScrollAll)
mNetworkUI.Cursor = Cursors.ScrollAll;
var currPosition = e.GetPosition(mNetworkUI);
var diff = currPosition - MouseLastPosition;
var p = new Point(diff.X, diff.Y);
mNetworkUI.ViewModel.Network.SetTransformOffset(p);
MouseLastPosition = currPosition;
}
}
///In file NetworkViewModel.cs
public void SetTransformOffset(Point newOffset) {
for (int i = 0; i < Nodes.Count; i++) {
Nodes[i].X += newOffset.X;
Nodes[i].Y += newOffset.Y;
}
}
Where the 'Nodes' are my editor-nodes displayed in the Canvas. The Zooming (with respect to the mouse position works as follows:
///File MainWindow.xaml.cs
private void ZoomPanCanvas_MouseWheel(object sender, MouseWheelEventArgs e) {
///Determine the Scaling Factor and Scale the Rule-Editor
var factor = (e.Delta > 0) ? (1.1) : (1 / 1.1);
currrentScale = factor * currrentScale;
ScaleNetwork();
///Translate the Nodes to the desired Positions
var pos = e.GetPosition(mNetworkUI);
var transform = new ScaleTransform(factor, factor, pos.X, pos.Y);
var offSet = new Point(transform.Value.OffsetX, transform.Value.OffsetY);
mNetworkUI.ViewModel.Network.SetTransformOffset(offSet);
}
///Also in MainWindow.xaml.cs
private void ScaleNetwork() {
mNetworkUI.RenderTransform = new ScaleTransform(currrentScale, currrentScale);
mNetworkUI.Width = ZoomPanCanvas.ActualWidth / currrentScale;
mNetworkUI.Height = ZoomPanCanvas.ActualHeight / currrentScale;
}
So, in the 'panning' I calculate the difference to the last mouse position and use that vector to manipulate the nodes, not the Canvas itself.
When I zoom, I determine the new zoom, set a new RenderTransform, resize the Canvas to again fill the provided space and again re-position the nodes in the Canvas.
It works very well for now. I can 'pan & zoom' around how I want, but I realized, that with many nodes present in my 'network' (connected nodes), things get quite slow.
One reason is, that on every movement of a node some events are raised resulting in a noticable delay when panning.
How is such a thing (without fixed Canvas-size and Scrollbars) possible in a performant manner? Is there a control out there that I can use? Is this possible with the Extended WPF toolkit's ZoomBox control?
Thank you!
I've written a Viewport control for this exact functionality.
I've also packaged this up on nuget
PM > Install-Package Han.Wpf.ViewportControl
It extends a ContentControl which can contain any FrameworkElement and provides constrained zoom and pan functionality. Just make sure to add Generic.xaml to your app.xaml
<Application.Resources>
<ResourceDictionary Source="pack://application:,,,/Han.Wpf.ViewportControl;component/Themes/Generic.xaml" />
</Application.Resources>
Usage:
<Grid width="1200" height="1200">
<Button />
</Grid>
The source code for the control and theme is on my gist and can be found on my github along with a demo application that loads an image into the viewport control.

WPF Display Mouse Coordinates on canvas using a tooltip

Can someone point me in the right track for displaying the XY mouse position on a Canvas using a tooltip?
I would like to drag the mouse and the tooltip update the position as the user moves the mouse. I tried doing this programmatically using the mouse enter to update the tooltip but was failing to get anything to show up. Thanks
If anyone is interested in the solution...
private void Canvas_MouseMove(object sender, MouseEventArgs e)
{
tt.Placement = System.Windows.Controls.Primitives.PlacementMode.Relative;
tt.HorizontalOffset = e.GetPosition((IInputElement)sender).X + 10;
tt.VerticalOffset = e.GetPosition((IInputElement)sender).Y + 10;
tt.Content = "X-Coordinate: " + e.GetPosition((IInputElement)sender).X + "\n" + "Y-Coordinate: " + e.GetPosition((IInputElement)sender).Y;
}

Creating a Circular GUI

So one of my latest side projects is developing a application detection and populating assistant. Programmatically I am absolutely fine populating the backend code for what I want accomplished. But I've run into a road block on the GUI. I need a GUI that is a Quarter circle that extends from the task bar to the bottom right of a standard windows operating system. When the user doubleclicks on the application, the circle rotates into view. I can do this with a typical windows form that has a transparent background and a fancy background image. But the square properties of the form will still apply when the user has the application open. And I do not want to block the user from higher priority apps when the circle is open.
I'm not really stuck on any one specific programming language. Although, I would prefer that it not contain much 3d rendering as it is supposed to be a computing assistant and should not maintain heavy RAM/CPU consumption whilst the user is browsing around.
Secondarily, I would like the notches of the outer rings to be mobile and extend beyond the gui a mere centimeter or so.
I would not be here if I hadn't had scoured the internet for direction on this capability. But what I've found is application GUI's of this nature tend to be most used in mobile environments.
So my questions are: How can I accomplish this? What programming language can I write this in? Is this a capability currently available? Will I have to sacrifice user control for design?
I wrote out some code doing something close to what you described.
I’m not sure to understand how you do want the circle to appear, so I just let a part of it always visible.
And I didn’t get the part about the mobile outer ring.
Creating and placing the window
The XAML is very simple, it just needs a grid to host the circle’s pieces, and some attributes to remove window decorations and taskbar icon:
<Window x:Class="circle.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Circle"
Width="250"
Height="250"
AllowsTransparency="True"
Background="Transparent"
MouseDown="WindowClicked"
ShowInTaskbar="False"
WindowStyle="None">
<Grid Name="Container"/>
</Window>
To place the window in the bottom right corner, you can use SystemParameters.WorkArea in the constructor:
public MainWindow()
{
InitializeComponent();
var desktopDim = SystemParameters.WorkArea;
Left = desktopDim.Right - Width;
Top = desktopDim.Bottom - Height;
}
Creating the shape
I build the circle as a bunch of circle pieces that I generate from code behind:
private Path CreateCirclePart()
{
var circle = new CombinedGeometry
{
GeometryCombineMode = GeometryCombineMode.Exclude,
Geometry1 = new EllipseGeometry { Center = _center, RadiusX = _r2, RadiusY = _r2 },
Geometry2 = new EllipseGeometry { Center = _center, RadiusX = _r1, RadiusY = _r1 }
};
var sideLength = _r2 / Math.Cos((Math.PI/180) * (ItemAngle / 2.0));
var x = _center.X - Math.Abs(sideLength * Math.Cos(ItemAngle * Math.PI / 180));
var y = _center.Y - Math.Abs(sideLength * Math.Sin(ItemAngle * Math.PI / 180));
var triangle = new PathGeometry(
new PathFigureCollection(new List<PathFigure>{
new PathFigure(
_center,
new List<PathSegment>
{
new LineSegment(new Point(_center.X - Math.Abs(sideLength),_center.Y), true),
new LineSegment(new Point(x,y), true)
},
true)
}));
var path = new Path
{
Fill = new SolidColorBrush(Colors.Cyan),
Stroke = new SolidColorBrush(Colors.Black),
StrokeThickness = 1,
RenderTransformOrigin = new Point(1, 1),
RenderTransform = new RotateTransform(0),
Data = new CombinedGeometry
{
GeometryCombineMode = GeometryCombineMode.Intersect,
Geometry1 = circle,
Geometry2 = triangle
}
};
return path;
}
First step is to build two concentric circles and to combine them in a CombinedGeometry with CombineMode set to exclude. Then I create a triangle just tall enough to contain the section of the ring that I want, and I keep the intersection of these shapes.
Seeing it with the second CombineMode set to xor may clarify:
Building the circle
The code above uses some instance fields that make it generic: you can change the number of pieces in the circle or their radius; it will always fill the corner.
I then populate a list with the required number of shape, and add them to the grid:
private const double MenuWidth = 80;
private const int ItemCount = 6;
private const double AnimationDelayInSeconds = 0.3;
private readonly Point _center;
private readonly double _r1, _r2;
private const double ItemSpacingAngle = 2;
private const double ItemAngle = (90.0 - (ItemCount - 1) * ItemSpacingAngle) / ItemCount;
private readonly List<Path> _parts = new List<Path>();
private bool _isOpen;
public MainWindow()
{
InitializeComponent();
// window in the lower right desktop corner
var desktopDim = SystemParameters.WorkArea;
Left = desktopDim.Right - Width;
Top = desktopDim.Bottom - Height;
_center = new Point(Width, Height);
_r2 = Width;
_r1 = _r2 - MenuWidth;
Loaded += (s, e) => CreateMenu();
}
private void CreateMenu()
{
for (var i = 0; i < ItemCount; ++i)
{
var part = CreateCirclePart();
_parts.Add(part);
Container.Children.Add(part);
}
}
ItemSpacingAngle define the blank between two consecutive pieces.
Animating the circle
The final step is to unfold the circle. Using a rotateAnimation over the path rendertransform make it easy.
Remember this part of the CreateCirclePart function:
RenderTransformOrigin = new Point(1, 1),
RenderTransform = new RotateTransform(0),
The RenderTransform tells that the animation we want to perform is a rotation, and RenderTransformOrigin set the rotation origin to the lower right corner of the shape (unit is percent).
We can now animate it on click event:
private void WindowClicked(object sender, MouseButtonEventArgs e)
{
for (var i = 0; i < ItemCount; ++i)
{
if (!_isOpen)
UnfoldPart(_parts[i], i);
else
FoldPart(_parts[i], i);
}
_isOpen = !_isOpen;
}
private void UnfoldPart(Path part, int pos)
{
var newAngle = pos * (ItemAngle + ItemSpacingAngle);
var rotateAnimation = new DoubleAnimation(newAngle, TimeSpan.FromSeconds(AnimationDelayInSeconds));
var tranform = (RotateTransform)part.RenderTransform;
tranform.BeginAnimation(RotateTransform.AngleProperty, rotateAnimation);
}
private void FoldPart(Path part, int pos)
{
var rotateAnimation = new DoubleAnimation(0, TimeSpan.FromSeconds(AnimationDelayInSeconds));
var tranform = (RotateTransform)part.RenderTransform;
tranform.BeginAnimation(RotateTransform.AngleProperty, rotateAnimation);
}
Not actually answering this, but I liked your question enough that I wanted to get a minimal proof of concept together for fun and I really enjoyed doing it so i thought I'd share my xaml with you:
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:ed="http://schemas.microsoft.com/expression/2010/drawing" x:Class="WpfApplication1.Window2"
Title="Window2" Height="150" Width="150" Topmost="True" MouseLeftButtonDown="Window2_OnMouseLeftButtonDown"
AllowsTransparency="True"
OpacityMask="White"
WindowStyle="None"
Background="Transparent" >
<Grid>
<ed:Arc ArcThickness="40"
ArcThicknessUnit="Pixel" EndAngle="0" Fill="Blue" HorizontalAlignment="Left"
Height="232" Margin="33,34,-115,-116" Stretch="None"
StartAngle="270" VerticalAlignment="Top" Width="232" RenderTransformOrigin="0.421,0.471"/>
<Button HorizontalAlignment="Left" VerticalAlignment="Top" Width="41" Margin="51.515,71.385,0,0" Click="Button_Click" RenderTransformOrigin="0.5,0.5">
<Button.Template>
<ControlTemplate>
<Path Data="M50.466307,88.795148 L61.75233,73.463763 89.647286,102.42368 81.981422,113.07109 z"
Fill="DarkBlue" HorizontalAlignment="Left" Height="39.606"
Stretch="Fill" VerticalAlignment="Top" Width="39.181"/>
</ControlTemplate>
</Button.Template>
</Button>
</Grid>
</Window>
And it looks like this:

Wrong Mouse position with different DPI settings in WPF

I am using the below code to get the current mouse position in a WPF application.
System.Drawing.Point _point = System.Windows.Forms.Control.MousePosition;
This works good. But when the user has a 125% display settings in the machine (Windows 7), the mouse position is wrong. Am I doing anything wrong?
See if anything in this Blog or this Blog helps and since you are using Wpf try using Mouse.GetPosition as in this modified MSDN example:
// displayArea is the main window and txtBoxMousePosition is
// a TextBox used to display the position of the mouse pointer.
private void Window_MouseMove(object sender, MouseEventArgs e)
{
Point position = Mouse.GetPosition(this);
txtBoxMousePosition.Text = "X: " + position.X + "\n" + "Y: " + position.Y;
}

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