在MultiScaleImage上保持相对位置

Question

在看到this instructions后，我实现了以下Silverlight应用程序，以下是我的代码：

public partial class MainPage : UserControl
{
    private Point lastMousePos = new Point();
    private double zoom = 1;
    private Point lastMouseLogicaPos = new Point();
    private Point lastMouseViewPort = new Point();
    private bool duringDrag = false;
    private bool duringOpen = false;
    private List<Dot> dots = new List<Dot>();
    private bool addDot = false;

    public MainPage()
    {
        InitializeComponent();

        this.MouseMove += delegate(object sender, MouseEventArgs e)
        { this.lastMousePos = e.GetPosition(this.ZoomImage); };

        ZoomImage.MouseWheel += new MouseWheelEventHandler(ZoomImage_MouseWheel);
        this.ZoomImage.UseSprings = false;
    }

    private void ZoomImage_MouseWheel(object sender, MouseWheelEventArgs e)
    {
        double newzoom = zoom;

        if (e.Delta > 0)
        { newzoom /= 1.3; }
        else
        { newzoom *= 1.3; }

        Point logicalPoint = this.ZoomImage.ElementToLogicalPoint(this.lastMousePos);
        this.ZoomImage.ZoomAboutLogicalPoint(zoom / newzoom, logicalPoint.X, logicalPoint.Y);

        zoom = newzoom;
        e.Handled = true;
    }

    private void ZoomImage_MouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        lastMouseLogicaPos = e.GetPosition(LayoutRoot);
        lastMouseViewPort = this.ZoomImage.ViewportOrigin;

        foreach (var dot in this.dots)
        { dot.LastMouseLogicPos = e.GetPosition(LayoutRoot); }

        if (!this.addDot)
        { duringDrag = true; }
    }

    private void ZoomImage_MouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        if (this.addDot)
        {
            Dot dot = new Dot(this.lastMouseLogicaPos.X, this.lastMouseLogicaPos.Y) 
                                { Name = "Dot" + (this.dots.Count + 1).ToString() };

            this.dots.Add(dot);
            this.DotCanvas.Children.Add(dot);
        }
        else
        { duringDrag = false; }
    }

    private void ZoomImage_MouseMove(object sender, System.Windows.Input.MouseEventArgs e)
    {
        if (duringDrag)
        {
            double zoomFactor = 1 / this.ZoomImage.ViewportWidth;
            Point newPoint = lastMouseViewPort;
            Point thisMouseLogicalPos = e.GetPosition(LayoutRoot);
            newPoint.X += (lastMouseLogicaPos.X - thisMouseLogicalPos.X) / (this.ZoomImage.ActualWidth * zoomFactor);
            newPoint.Y += (lastMouseLogicaPos.Y - thisMouseLogicalPos.Y) / (this.ZoomImage.ActualWidth * zoomFactor);
            this.ZoomImage.ViewportOrigin = newPoint;

            foreach (var dot in this.dots)
            {
                Point dotLogicPoint = this.ZoomImage.ElementToLogicalPoint(new Point(dot.X, dot.Y));
                thisMouseLogicalPos = e.GetPosition(LayoutRoot);

                dotLogicPoint.X -= (dot.LastMouseLogicPos.X - thisMouseLogicalPos.X) / ((1 / 1.8) * this.ZoomImage.ViewportWidth);
                dotLogicPoint.Y -= (dot.LastMouseLogicPos.Y - thisMouseLogicalPos.Y) / (this.ZoomImage.ActualWidth * this.ZoomImage.ViewportWidth);

                dot.X = (this.ZoomImage.LogicalToElementPoint(locLogicPoint).X);
                dot.Y = (this.ZoomImage.LogicalToElementPoint(locLogicPoint).Y);
            }
        }
    }

    private void ZoomImage_ImageOpenSucceeded(object sender, System.Windows.RoutedEventArgs e)
    { duringOpen = true; }

    private void ZoomImage_MotionFinished(object sender, System.Windows.RoutedEventArgs e)
    {
        if (duringOpen)
        { duringOpen = false; }
    }

    private void Button_Click(object sender, System.Windows.RoutedEventArgs e)
    {
        this.addDot = !this.addDot;

        if (this.addDot)
        { this.btnAddDot.Content = "Click on Image"; }
        else
        { this.btnAddDot.Content = "Add Dot"; }
    }
}

这样，我就可以在MultiScaleImage上缩放和平移，并将我的自定义Dot对象添加到DotCanvas画布中。下面是XAML：

<UserControl x:Class="DeepZoomSample.MainPage"
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"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400" Width="800" Height="600">

<Grid x:Name="LayoutRoot" Background="Black" Margin="0,0,-98,-86">

    <MultiScaleImage x:Name="ZoomImage" Source="GeneratedImages/dzc_output.xml" 
                     Margin="8,8,0,0" MouseLeftButtonDown="ZoomImage_MouseLeftButtonDown" 
                     MouseLeftButtonUp="ZoomImage_MouseLeftButtonUp" MouseMove="ZoomImage_MouseMove" ImageOpenSucceeded="ZoomImage_ImageOpenSucceeded" 
                     MotionFinished="ZoomImage_MotionFinished" Height="584" VerticalAlignment="Top" HorizontalAlignment="Left" Width="784"/>

    <Canvas x:Name="DotCanvas" HorizontalAlignment="Left" Height="584" Margin="8" VerticalAlignment="Top" Width="784" MouseLeftButtonUp="LocationCanvas_MouseLeftButtonUp"/>
    <Button x:Name="btnAddDot" Content="Add Location" HorizontalAlignment="Right" Height="44" Margin="0,0,24,24" VerticalAlignment="Bottom" Width="112" Click="Button_Click"/>

</Grid>

​

现在，问题是，当我平移和缩放时，由于点被放置在MultiScateImage (ZoomImage对象)上的画布中，点将停留在画布上它们各自的位置。此代码在图像平移和缩放时尝试将点保持在适当的位置，但未进行一些尝试。

这是应用程序的图片，周围的蓝点是我的自定义Dot对象：

​

​

主要的问题是，当用户缩放和平移时，如何将点保持在图像上的相对位置。

Answer 1

这很棘手，但绝对可以做到，我最近为一个类似的应用程序做了同样的事情。我不会说谎，我花了几个小时才让它工作，所以准备一些令人头疼的事情吧。

基本上涉及到两件事：

1.将点定位在正确的位置

数学在这里是你的朋友。您必须创建一些方法，将基于multiScaleImage的坐标转置为画布(即视口)坐标。

首先，您必须深入了解ViewPortOrigin和ViewPortWidth (this是一个很好的开始)。他们有几个警告(例如。我似乎记得viewPortHeight必须乘以图像比率才能得到实际值-or类似的值)。

给你指出解决方案:你必须减去viewPortOrigin，然后乘/除viewPortWidth。如果你有耐心(和幸运;-)，今晚我会看看我的项目并发布一些代码，但如果你真的理解这些参数是很好的，-otherwise它将是棘手的调试和故障排除。

在浏览multiscaleImage时，我在周围放置了一些文本块，并始终显示viewportWidth/Origin/等，这对我理解所发生的事情有很大帮助。

编辑:你很幸运，我记得这个-so这里有一些代码应该会有帮助。再一次，我建议你不要在不了解的情况下复制和粘贴，因为你不会走得那么远。

private Point CanvasToDeepZoom(MultiScaleImage msi, Point absoluteInsideCanvas)
{
    // the only non-logical (to me) step: viewportOrigin.Y must be multiplied by the aspectRatio
    var ViewportHeight = msi.ViewportWidth * msi.AspectRatio * msi.ActualHeight / msi.ActualWidth;

    var relativeToCanvas = new Point(
        absoluteInsideCanvas.X / msi.ActualWidth,
        absoluteInsideCanvas.Y / msi.ActualHeight);

    return new Point(
        msi.ViewportOrigin.X + msi.ViewportWidth * relativeToCanvas.X,
        msi.ViewportOrigin.Y * msi.AspectRatio + ViewportHeight * relativeToCanvas.Y);
}


private Point DeepZoomToCanvas(MultiScaleImage msi, Point relativeInsideDeepZoom)
{
    var ViewportHeight = msi.ViewportWidth * msi.AspectRatio * msi.ActualHeight / msi.ActualWidth;

    var relativeToCanvas = new Point(
        (relativeInsideDeepZoom.X - msi.ViewportOrigin.X) / msi.ViewportWidth,
        (relativeInsideDeepZoom.Y - msi.ViewportOrigin.Y * msi.AspectRatio) / ViewportHeight);

    return new Point(
        relativeToCanvas.X * msi.ActualWidth,
        relativeToCanvas.Y * msi.ActualHeight);
 }

2.在缩放和平移动画过程中保持点的同步。

基本的想法是循环一个0秒长的动画，在缩放/平移的整个持续时间内不断更新点的位置(如果我没记错的话是1.5秒)。该技术在here中得到了很好的解释。在该博客中，您还可以找到针对您的特定问题的其他有用资源。

Answer 2

如果你看到Deep Zoom Composer，它还允许你设置超链接区域，并有模板来生成源码项目。因此，这些点可以是图像本身(使用图像集合，这样您甚至可以通过编程方式打开/关闭子图像SubMultiScaleImage，如果我记得很清楚的话是通过编程实现的)，并在它们上有超链接，让MultiScaleImage处理集合，并在单击超链接时通知您(参见生成的代码)。