如何在 WPF C# 4.0 中構建放大鏡？

Question

我有一個很大的圖像，需要用戶 cursor 下的內容的縮放部分。

我的圖像在網格內，並以這種方式在 XAML 中定義：

<Grid x:Name="RootImgGrid" Background="#FF333333" >
    <Viewbox x:Name="imgViewBox"  Margin="1,1,1,1" Stretch="Fill" >
        <Canvas x:Name="imgCanvas"  ClipToBounds="True" Width="{Binding ElementName=RootImgGrid, Path=ActualWidth}" Height="{Binding ElementName=RootImgGrid, Path=ActualHeight}">
            <Image x:Name="imgObj" MouseWheel="img_MouseWheel" Cursor="Hand" MouseMove="Img_MouseMove" MouseDown="Img_MouseDown" MouseUp="Img_MouseUp"  >
                <Image.RenderTransform>
                    <TransformGroup x:Name="imgTransformGroup">
                        <ScaleTransform x:Name="imgScaleTransform"></ScaleTransform>
                        <TranslateTransform x:Name="imgTranslateTransform"></TranslateTransform>
                    </TransformGroup>
                </Image.RenderTransform>
                <Image.LayoutTransform>
                    <RotateTransform x:Name="imgRotateTransform"></RotateTransform>
                </Image.LayoutTransform>
            </Image>
        </Canvas>
    </Viewbox>
</Grid>

我有一個放大的區域，應該在我的 cursor 下顯示 2 倍的圖像。

<Viewbox x:Name="imgViewBoxMagnifier" Width="400" Height="90">
    <Canvas  x:Name="imgCanvasMagnifier" Width="400" Height="90">
        <Canvas.Clip>
            <RectangleGeometry Rect="0,0,400,90" />
        </Canvas.Clip>
        <Image  x:Name="imgMagnifier" Margin="2" Width="400" Height="90">
            <Image.RenderTransform>
                <TransformGroup x:Name="imgMagnifierTransformGroup">
                    <ScaleTransform x:Name="imgMagnifierScaleTransform"></ScaleTransform>
                    <TranslateTransform x:Name="imgMagnifierTranslateTransform"></TranslateTransform>
                </TransformGroup>
            </Image.RenderTransform>
            <Image.LayoutTransform>
                <RotateTransform x:Name="imgMagnifierRotateTransform"></RotateTransform>
            </Image.LayoutTransform>
        </Image>
    </Canvas>
</Viewbox>

現在，在 my.CS 代碼中，我有 function 應該顯示放大的圖像：

public void Magnifier(Canvas imgCanvas, Image imgObject, Image imgMagnifier, MouseEventArgs e)
    {
        Int32 width = 400;
        Int32 height = 90;

        if (imgMagnifier.Source != imgObject.Source)
        {
            imgMagnifier.Source = imgObject.Source;
        }

        Size size = imgObject.RenderSize;
        RotateTransform rt = (RotateTransform)imgObject.LayoutTransform;
        TranslateTransform tt = (TranslateTransform)((TransformGroup)imgObject.RenderTransform).Children[1];
        ScaleTransform st = (ScaleTransform)((System.Windows.Media.TransformGroup)(imgObject.RenderTransform)).Children[0];
        Double x = e.GetPosition(imgCanvas).X - tt.X;
        Double y = e.GetPosition(imgCanvas).Y - tt.Y;
        Point pos = e.MouseDevice.GetPosition(imgCanvas);

        TransformGroup transformGroup = new TransformGroup();
        ScaleTransform scale = new ScaleTransform();

        scale.CenterX = x;
        scale.CenterY = y;
        scale.ScaleX = st.ScaleX * 10;
        scale.ScaleY = st.ScaleY * 10;
        transformGroup.Children.Add(scale);

        TranslateTransform translate = new TranslateTransform();
        translate.X = ??????????????????;
        translate.Y = ??????????????????;
        transformGroup.Children.Add(translate);

        imgMagnifier.RenderTransform = transformGroup;

    }

我怎樣才能找到那些“？？？？？？？？？”的正確值

translate.X = -x * 10 / (size.Width / 400);
translate.Y = -y * 10 / (size.Height / 90);

它顯示正確的圖像，放大，但它不顯示我的 cursor 下的圖像區域。

提前致謝。

Answer 1

由於我沒有找到任何打包的解決方案，我從頭開始開發了一個功能齊全的 Microsoft VS 2010 Project Magnifier Zoom C# 4.0 WPF。

它包括放大、縮小、旋轉、適合寬度和放大區域。

隨意下載，讓它變得更好。

WPF 放大鏡 C# 4.0

希望你喜歡。 覺得有用就投票吧。

public void Magnifier(Canvas imgCanvas, Image imgObject, Canvas imgCanvasMagnifier, Image imgMagnifier, MouseEventArgs e)
    {
        Double width = imgCanvasMagnifier.Width;
        Double height = imgCanvasMagnifier.Height;
        Int32 zoom = 3;

        String txtDebug = String.Empty;
        String txtZoom = String.Empty;

        if (imgMagnifier.Source != imgObject.Source)
        {
            imgMagnifier.Source = imgObject.Source;
        }

        Size size = imgObject.RenderSize;
        RotateTransform rt = (RotateTransform)imgObject.LayoutTransform;
        TranslateTransform tt = (TranslateTransform)((TransformGroup)imgObject.RenderTransform).Children[1];
        ScaleTransform st = (ScaleTransform)((System.Windows.Media.TransformGroup)(imgObject.RenderTransform)).Children[0];
        Double x = e.GetPosition(imgCanvas).X - tt.X;
        Double y = e.GetPosition(imgCanvas).Y - tt.Y;
        Point pos = e.MouseDevice.GetPosition(imgCanvas);
        var wnd = Canvas.GetTop(imgObject);

        TransformGroup transformGroup = new TransformGroup();
        ScaleTransform scale = new ScaleTransform();

        scale.ScaleX = st.ScaleX * zoom;
        scale.ScaleY = st.ScaleY * zoom;

        RotateTransform rotate = new RotateTransform();
        rotate.Angle = rt.Angle;

        TranslateTransform translate = new TranslateTransform();

        Double centerX = st.CenterX * (st.ScaleX - 1);
        Double centerY = st.CenterY * (st.ScaleY - 1);

        if (rt.Angle == 0)
        {
            translate.X = -(x + centerX) / st.ScaleX;
            translate.Y = -(y + centerY) / st.ScaleY;
            scale.CenterX = (x + centerX) / st.ScaleX;
            scale.CenterY = (y + centerY) / st.ScaleY;
        }
        if (rt.Angle == 90)
        {
            translate.X = -(x + centerX) / st.ScaleX;
            translate.Y = -(y + centerY) / st.ScaleY;
            translate.X += imgObject.ActualHeight * st.ScaleX * zoom;
            scale.CenterX = (x + centerX) / st.ScaleX;
            scale.CenterY = (y + centerY) / st.ScaleY;
        }

        if (rt.Angle == 180)
        {
            translate.X = -(x + centerX) / st.ScaleX;
            translate.Y = -(y + centerY) / st.ScaleY;
            translate.X += imgObject.ActualWidth * st.ScaleX * zoom;
            translate.Y += imgObject.ActualHeight * st.ScaleY * zoom;
            scale.CenterX = (x + centerX) / st.ScaleX;
            scale.CenterY = (y + centerY) / st.ScaleY;
        }

        if (rt.Angle == 270)
        {
            translate.X = -(x + centerX) / st.ScaleX;
            translate.Y = -(y + centerY) / st.ScaleY;
            translate.Y += imgObject.ActualWidth * st.ScaleX * zoom;
            scale.CenterX = (x + centerX) / st.ScaleX;
            scale.CenterY = (y + centerY) / st.ScaleY;
        }

        translate.X += width / 2;
        translate.Y += height / 2;

        transformGroup.Children.Add(rotate);
        transformGroup.Children.Add(scale);
        transformGroup.Children.Add(translate);


        imgMagnifier.RenderTransform = transformGroup;

    }

Answer 2

僅供參考：我從未對 WPF 做過任何事情，我借此機會學習。 這是我的解決方案：

首先，我禁用了兩個圖像的拉伸： Stretch="None" 並刪除了圖像上的高度和寬度定義。

然后，后面的代碼是：

    double xFactor = 2, yFactor = 2;

    Size size = imgObject.RenderSize;
    Size magSize = new Size(width: imgMagnifier.RenderSize.Width * xFactor,
                            height: imgMagnifier.RenderSize.Height * yFactor);

    Point pos = e.MouseDevice.GetPosition(imgCanvas);

    var transformGroup = new TransformGroup();
    var scale = new ScaleTransform();
    scale.CenterX = 0;
    scale.CenterY = 0;
    scale.ScaleX = xFactor;
    scale.ScaleY = yFactor;
    transformGroup.Children.Add(scale);

    var translate = new TranslateTransform();
    translate.X = -pos.X * xFactor + imgCanvasMagnifier.Width / 2;
    translate.Y = -pos.Y * yFactor + imgCanvasMagnifier.Height / 2;
    transformGroup.Children.Add(translate);

    imgMagnifier.RenderTransform = transformGroup;