Tengo algunos caminos dibujados a la pantalla en wpf. Las coordenadas que se utilizan son bastante pequeñas, por lo que se han hecho para llenar la pantalla con un cuadro de vista. Ahora estoy tratando de implementar la funcionalidad de panorámica y zoom. Me gustaría poder hacer zoom en donde sea que esté el mouse en relación con la ui (es decir, el centro de la pantalla con zoom es igual a las coordenadas del mouse). El resultado actual es que el centro de la pantalla cuando se amplía no refleja la posición exacta del mouse en la interfaz de usuario.

Si quieres ver lo que está pasando ...Aquí está mi archivo de solución actual.

O

Heres algún código:

Ver Xaml

<code><Grid Name="MasterGrid" DataContext="{StaticResource mainWindowViewModel}">

    <ScrollViewer HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible" Name="VisualisationScroller">
        <Viewbox Name="VisualisationBox" Stretch="Fill" Loaded="VisualisationBox_Loaded">

            <ItemsControl Name="CustomDrawingElement" ItemsSource="{Binding Trajectories}" Width="{Binding VisualisationWidth}" Height="{Binding VisualisationHeight}">
                <ItemsControl.ItemTemplate>
                    <DataTemplate DataType="data:VisualisedTrajectory">
                        <Path Data = "{Binding PathData}" Stroke="Red" StrokeThickness="0.001" Fill="Transparent" />
                    </DataTemplate>
                </ItemsControl.ItemTemplate>

                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <Canvas
                            Background="DarkGray"
                            IsItemsHost="True">
                        </Canvas>

                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>

                <ItemsControl.RenderTransform>

                    <TransformGroup>
                        <ScaleTransform ScaleX="1" ScaleY="1" />
                        <TranslateTransform />
                    </TransformGroup>

                </ItemsControl.RenderTransform>

            </ItemsControl>

        </Viewbox>
    </ScrollViewer>
</Grid>
</code>

Ver modelo

<code>public class MainWindowViewModel : BaseViewModel
{

    public MainWindowViewModel()
    {
        VisualiseRawTrajectories();

    }

    private ObservableCollection<VisualisedTrajectory> _trajectories = new ObservableCollection<VisualisedTrajectory>();
    public ObservableCollection<VisualisedTrajectory> Trajectories
    {
        get { return _trajectories; } 
    }

    #region VisualisationDimensions

    private double _visualisationWidth = 100;
    public double VisualisationWidth
    {
        get { return _visualisationWidth; }
        private set { _visualisationWidth = value; }
    }

    private double _visualisationHeight = 100;
    public double VisualisationHeight
    {
        get { return _visualisationHeight; }
        private set { _visualisationHeight = value; }
    }

    #endregion

    public void VisualiseRawTrajectories()
    {
        var rand = new Random();

        for (int i = 0; i < 5; i++)
        {
            var currentTrajectorySet = new List<Point>(); //each time through reinitialise
            for (int j = 0; j < 5; j++)
            {
                currentTrajectorySet.Add(new Point(rand.NextDouble() * 0.5, rand.NextDouble() * 0.5)); //add a new point with max 0.5
                if(j == 4)
                {
                    currentTrajectorySet.Add(new Point(0.5, 0.5)); //for good measure :)
                    _trajectories.Add(new VisualisedTrajectory(CreatePathData(currentTrajectorySet)));
                }
            }
        }

        VisualisationHeight = 0.5;
        VisualisationWidth = 0.5; //just for demonstration purposes
        OnPropertyChanged("VisualisationHeight");
        OnPropertyChanged("VisualisationWidth");

    }

    private Geometry CreatePathData(IList<Point> points)
    {
        var geometry = new StreamGeometry {FillRule = FillRule.EvenOdd};
        using (StreamGeometryContext ctx = geometry.Open())
        {
            ctx.BeginFigure(points[0], false, false); //use the first index
            ctx.PolyLineTo(points, true, true);
        }
        return (Geometry)geometry.GetAsFrozen(); 
    }

}
</code>

Ver código detrás

<code>public MainWindow()
    {
        InitializeComponent();
        VisualisationScroller.PreviewMouseWheel += OnPreviewMouseWheel;
    }

    private Point originalDimensions;
    private void VisualisationBox_Loaded(object sender, RoutedEventArgs e)
    {
        Viewbox viewBox = sender as Viewbox;
        viewBox.Width = viewBox.ActualWidth;
        viewBox.Height = viewBox.ActualHeight;
        originalDimensions = new Point(viewBox.ActualWidth, viewBox.ActualHeight);

    }


    #region Zoom

    private int _numberDrawnItems = 0;
    private void OnPreviewMouseWheel(object sender, MouseWheelEventArgs e)
    {
        var zoomScale = new Point(CustomDrawingElement.RenderTransform.Value.M11,
                                  CustomDrawingElement.RenderTransform.Value.M22); //gets the scale x and scale y


        if (CustomDrawingElement != null && _numberDrawnItems != CustomDrawingElement.Items.Count) //if there was something draw to screen
        {
            _numberDrawnItems = CustomDrawingElement.Items.Count;
            CustomDrawingElement.RenderTransformOrigin = new Point(0.5, 0.5); //if not set zoom from center
        }
        if (e.Delta > 0)
        {
            if (CustomDrawingElement != null)
            {

                VisualisationBox.Width = originalDimensions.X * (zoomScale.X + 1);
                VisualisationBox.Height = originalDimensions.Y * (zoomScale.Y + 1);


                var mousePosition = e.GetPosition(MasterGrid);
                CustomDrawingElement.RenderTransformOrigin = new Point(mousePosition.X / MasterGrid.ActualWidth, mousePosition.Y / MasterGrid.ActualHeight);
                CustomDrawingElement.RenderTransform = new MatrixTransform(zoomScale.X + 1, 0, 0, zoomScale.Y + 1, 0, 0);


            }
        }
        if (e.Delta < 0)
        {
            if (zoomScale.X > 1 && zoomScale.Y > 1) //stops you from zooming out too much
            {
                if (CustomDrawingElement != null)
                {

                    VisualisationBox.Width = VisualisationBox.Width - originalDimensions.X;
                    VisualisationBox.Height = VisualisationBox.Height - originalDimensions.Y;

                    CustomDrawingElement.RenderTransform = new MatrixTransform(zoomScale.X - 1, 0, 0, zoomScale.Y - 1, 0, 0);


                }
            }
        }

        e.Handled = true;
    }

    #endregion //Zooming code


}
</code>