WPF绘图---Canvas中Polygon屏幕居中显示

问题描述

在一个Canvas中绘制了多个Polygon，由于坐标可能超出界面显示范围，需要将绘制的Polygon居中显示，并且缩放至界面大小，效果如下：

居中显示

xaml代码

<Borderx:Name="border"Background="#fff"ClipToBounds="True"><Canvasx:Name="canvas"Width="{Binding Path=ActualWidth, RelativeSource={RelativeSource AncestorType=Border}}"Height="{Binding Path=ActualHeight, RelativeSource={RelativeSource AncestorType=Border}}"><Canvas.RenderTransform><TransformGroup /></Canvas.RenderTransform></Canvas>
</Border>

实现代码

private void CenterAndScalePolygons()
{if (canvas == null || canvas.Children.Count == 0){return;}// 获取所有 Polygon 的边界框Rect boundingBox = GetBoundingBox(canvas.Children.OfType<Polygon>());// 计算需要进行的缩放和平移操作double scaleX = border.ActualWidth / boundingBox.Width;double scaleY = border.ActualHeight / boundingBox.Height;// 使用较小的缩放比例，保持图形完全在 Canvas 内显示double scale = Math.Min(scaleX, scaleY);double offsetX = border.ActualWidth / 2 - (boundingBox.Left + boundingBox.Right) / 2 * scale;double offsetY = border.ActualHeight / 2 - (boundingBox.Top + boundingBox.Bottom) / 2 * scale;// 遍历 Polygon 进行缩放和平移foreach (var polygon in canvas.Children.OfType<Polygon>()){ScaleTransform scaleTransform = new ScaleTransform(scale, scale);TranslateTransform translateTransform = new TranslateTransform(offsetX, offsetY);TransformGroup transformGroup = new TransformGroup();transformGroup.Children.Add(scaleTransform);transformGroup.Children.Add(translateTransform);polygon.RenderTransform = transformGroup;// 调整 Polygon 边框线宽polygon.StrokeThickness = 1 / scale;}
}private Rect GetBoundingBox(IEnumerable<Polygon> polygons)
{double minX = double.MaxValue;double minY = double.MaxValue;double maxX = double.MinValue;double maxY = double.MinValue;foreach (Polygon polygon in polygons){foreach (Point point in polygon.Points){minX = Math.Min(minX, point.X);minY = Math.Min(minY, point.Y);maxX = Math.Max(maxX, point.X);maxY = Math.Max(maxY, point.Y);}}return new Rect(minX, minY, maxX - minX, maxY - minY);
}