c# - 如何在 WPF C# 4.0 中构建放大镜？

Question

我有一张渲染得很大的图像，需要放大用户光标下的部分。

我的图像位于网格内，并以这种方式在 XAML 中定义:

<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>

我有一个缩放区域，光标下的图像应该会显示放大 2 倍。

<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>

现在，在我的 .CS 代码中，我得到了应该显示缩放图像的函数:

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;

    }

如何找到那些“?????????”的正确值

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

它显示了正确的缩放图像，但没有显示我光标下的图像区域。

提前致谢。

Answer 1

因为我没有找到任何打包的解决方案，所以我从头开始开发了一个功能齐全的 Microsoft VS 2010 Project Magnifier Zoom C# 4.0 WPF。

包括放大、缩小、旋转、适合宽度和放大区域。

请随意下载，并使它变得更好。

WPF Magnifier C# 4.0

希望你喜欢。觉得有用就点个赞吧。

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;

    }