在XAML代码设计器中，添加canvas画布与圆形几何对象，利用VisualBrush笔刷来复制画面内容到指定容器：
<Canvas x:Name="CvsGlass" Width="106" Height="106" HorizontalAlignment="Left" VerticalAlignment="Top" MouseWheel="CvsGlass_MouseWheel" MouseDown="CvsGlass_MouseDown" MouseUp="CvsGlass_MouseUp" MouseMove="CvsGlass_MouseMove" MouseLeave="CvsGlass_MouseLeave">
<Canvas.RenderTransform>
<TransformGroup>
<ScaleTransform/>
</TransformGroup>
</Canvas.RenderTransform>
<Canvas Name="magnifierCanvas">
<Ellipse Width="106" Height="106" >
<Ellipse.Fill>
<LinearGradientBrush EndPoint="0.5,1" MappingMode="RelativeToBoundingBox" StartPoint="0.5,0">
<GradientStop Color="#FFD9D2D2" Offset="1"/>
<GradientStop Color="White"/>
<GradientStop Color="#FFDFDFDF" Offset="0.244"/>
<GradientStop Color="#FF777777" Offset="0.592"/>
</LinearGradientBrush>
</Ellipse.Fill>
</Ellipse>
<Ellipse Width="100" Height="100" Canvas.Left="3" Canvas.Top="3" Fill="Black"/>
<Ellipse Width="100" Height="100" Name="magnifierEllipse" Canvas.Left="3" Canvas.Top="3">
<Ellipse.Fill>
<VisualBrush ViewboxUnits="Absolute" Viewbox="0,0,100,100" ViewportUnits="RelativeToBoundingBox" Viewport="0,0,1,1"/>
</Ellipse.Fill>
</Ellipse>
<TextBlock x:Name="TxtGlassScale" Foreground="Yellow" Visibility="Hidden" FontSize="14" Margin="110,40,0,55" FontFamily="Microsoft YaHei">
<TextBlock.Effect>
<DropShadowEffect/>
</TextBlock.Effect>
</TextBlock>
</Canvas>
</Canvas>
得到一个类似放大镜的界面效果：
其中，TxtGlassScale是显示放大镜倍数的文字控件；
VisualBrush是内容笔刷，看效果：
其中需要注意的是，放大镜应该是和Box平级，属于Cell的子控件，这样在图像平铺模式下则能兼容所有图像范围：
看效果：
参考代码：
#region -----放大镜-----/// <summary>
/// 当前大小与vs设计器中的大小的比例
/// </summary>
public double ActualScaleVal = ; /// <summary>
/// 放大比例
/// </summary>
double glassScale = 2.0; /// <summary>
/// 放大镜视图范围宽度
/// </summary>
double glassWidth = ; /// <summary>
/// 放大镜视图范围高度
/// </summary>
double glassHeight = ; /// <summary>
/// 显示放大镜
/// </summary>
public void UseGlass()
{
if (CvsGlass.IsShow())
{
CvsGlass.Hide();
return;
} if (glassWidth == || glassHeight == )
{
//计算放大镜比例 100是放大镜的viewbox的大小
glassWidth = / glassScale;
glassHeight = / glassScale; }
TxtGlassScale.Foreground = shapeManager.shapeMeasureColor;
TxtGlassScale.FontSize = shapeManager.shapeMeasureFontSize;
SetGlassViewBox(ActualWidth, ActualHeight, new Point(), true);
CvsGlass.Show();
} /// <summary>
/// 关闭放大镜
/// </summary>
public void CloseGlass()
{
CvsGlass.Hide();
} //滚轮控制放比例
private void CvsGlass_MouseWheel(object sender, MouseWheelEventArgs e)
{
if (e.Delta > )
{
glassScale -= 0.05;
}
else
{
glassScale += 0.05;
} glassScale = glassScale < 0.1 ? 0.1 : glassScale;
glassScale = glassScale > ? : glassScale; glassWidth = / glassScale;
glassHeight = / glassScale; Point pos = e.MouseDevice.GetPosition(GridMain);
SetGlassViewBox(pos.X, pos.Y, new Point(), false, false);
TxtGlassScale.Text = ((glassScale * ActualScaleVal * ) * ).ToString("f1") + "%";
TxtGlassScale.Show(); } //是否按下放大镜鼠标
bool isGlassDown = false; //记录按下鼠标的位置
Point glassPoint = new Point(, ); //按下放大镜
private void CvsGlass_MouseDown(object sender, MouseButtonEventArgs e)
{
glassPoint.X = e.GetPosition(CvsGlass).X;
glassPoint.Y = e.GetPosition(CvsGlass).Y;
isGlassDown = true;
} //移动放大镜
private void CvsGlass_MouseMove(object sender, MouseEventArgs e)
{
if (isGlassDown)
{
//相对于 GridLine 获取鼠标的坐标
Point svMainPos = e.MouseDevice.GetPosition(ScrollCell); Point glassPos = e.MouseDevice.GetPosition(CvsGlass); SetGlassViewBox(glassPos.X, glassPos.Y, svMainPos, false); Mouse.Capture(CvsGlass);
}
} /// <summary>
/// 设置放大内容
/// </summary>
/// <param name="vbX">宽度参数</param>
/// <param name="vbY">高度参数</param>
/// <param name="svMainPos">相对于GridLine的坐标</param>
/// <param name="isInit">是否是初始化</param>
/// <param name="reLocation">是否重新定位坐标</param>
private void SetGlassViewBox(double vbX, double vbY, Point svMainPos, bool isInit = false, bool reLocation = true)
{
Rect viewBox = GlassVB.Viewbox;
double xoffset = viewBox.Width / 2.0;
double yoffset = viewBox.Height / 2.0;
if (isInit)
{
viewBox.X = (vbX - xoffset) / ;
viewBox.Y = (vbY - yoffset) / ;
CvsGlass.Margin = new Thickness((vbX - ) / , (vbY - ) / , (vbX - ) / , (vbY - ) / );
}
else
{
if (reLocation)
{
viewBox.X = svMainPos.X - xoffset - (vbX - / );
viewBox.Y = svMainPos.Y - yoffset - (vbY - / ); CvsGlass.Margin = new Thickness(
CvsGlass.Margin.Left + vbX - glassPoint.X,
CvsGlass.Margin.Top + vbY - glassPoint.Y,
CvsGlass.Margin.Right - vbX + glassPoint.X,
CvsGlass.Margin.Bottom - vbY + glassPoint.Y);
}
}
viewBox.Width = glassWidth;
viewBox.Height = glassHeight;
GlassVB.Viewbox = viewBox;
TxtGlassScale.Hide();
} private void CvsGlass_MouseLeave(object sender, MouseEventArgs e)
{
isGlassDown = false;
} private void CvsGlass_MouseUp(object sender, MouseButtonEventArgs e)
{
isGlassDown = false;
Mouse.Capture(null);
} /// <summary>
/// 重新设置放大镜大小和位置
/// </summary>
public void ReSetGlass()
{
if (BoxList.Count == )
{
return;
} //*2是因为放大镜在vs设计器中显小 放大两倍
BoxList[].SetScaleTrans(CvsGlass, ActualScaleVal * , ActualScaleVal * , false);
if (CvsGlass.Margin.Left >= ActualWidth || CvsGlass.Margin.Top >= ActualHeight)
{
CvsGlass.Margin = new Thickness((ActualWidth - ) / , (ActualHeight - ) / , (ActualWidth - ) / , (ActualHeight - ) / );
}
} #endregion