C# wpf 附加属性实现任意控件拖动调整大小-编程知识

摘自这里 https://blog.csdn.net/u013113678/article/details/121719278
调试效果如下

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;namespace Wpf
{public class GridAdorner : Adorner{ //4条边Thumb _leftThumb, _topThumb, _rightThumb, _bottomThumb;//4个角Thumb _leftTopThumb, _rightTopThumb, _rightBottomThumb, _leftbottomThumb;//布局容器，如果不使用布局容器，则需要给上述8个控件布局，实现和Grid布局定位是一样的，会比较繁琐且意义不大。Grid _grid;UIElement _adornedElement;public GridAdorner(UIElement adornedEleemnt) : base(adornedEleemnt){_adornedElement = adornedEleemnt;//初始化thumb_leftThumb = new Thumb();_leftThumb.HorizontalAlignment = HorizontalAlignment.Left;_leftThumb.VerticalAlignment = VerticalAlignment.Center;_leftThumb.Cursor = Cursors.SizeWE;_topThumb = new Thumb();_topThumb.HorizontalAlignment = HorizontalAlignment.Center;_topThumb.VerticalAlignment = VerticalAlignment.Top;_topThumb.Cursor = Cursors.SizeNS;_rightThumb = new Thumb();_rightThumb.HorizontalAlignment = HorizontalAlignment.Right;_rightThumb.VerticalAlignment = VerticalAlignment.Center;_rightThumb.Cursor = Cursors.SizeWE;_bottomThumb = new Thumb();_bottomThumb.HorizontalAlignment = HorizontalAlignment.Center;_bottomThumb.VerticalAlignment = VerticalAlignment.Bottom;_bottomThumb.Cursor = Cursors.SizeNS;_leftTopThumb = new Thumb();_leftTopThumb.HorizontalAlignment = HorizontalAlignment.Left;_leftTopThumb.VerticalAlignment = VerticalAlignment.Top;_leftTopThumb.Cursor = Cursors.SizeNWSE;_rightTopThumb = new Thumb();_rightTopThumb.HorizontalAlignment = HorizontalAlignment.Right;_rightTopThumb.VerticalAlignment = VerticalAlignment.Top;_rightTopThumb.Cursor = Cursors.SizeNESW;_rightBottomThumb = new Thumb();_rightBottomThumb.HorizontalAlignment = HorizontalAlignment.Right;_rightBottomThumb.VerticalAlignment = VerticalAlignment.Bottom;_rightBottomThumb.Cursor = Cursors.SizeNWSE;_leftbottomThumb = new Thumb();_leftbottomThumb.HorizontalAlignment = HorizontalAlignment.Left;_leftbottomThumb.VerticalAlignment = VerticalAlignment.Bottom;_leftbottomThumb.Cursor = Cursors.SizeNESW;_grid = new Grid();_grid.Children.Add(_leftThumb);_grid.Children.Add(_topThumb);_grid.Children.Add(_rightThumb);_grid.Children.Add(_bottomThumb);_grid.Children.Add(_leftTopThumb);_grid.Children.Add(_rightTopThumb);_grid.Children.Add(_rightBottomThumb);_grid.Children.Add(_leftbottomThumb);AddVisualChild(_grid);foreach (Thumb thumb in _grid.Children){thumb.Width = 16;thumb.Height = 16;thumb.Background = Brushes.Red;thumb.Template = new ControlTemplate(typeof(Thumb)){VisualTree = GetFactory(new SolidColorBrush(Colors.Red))};thumb.DragDelta += Thumb_DragDelta;}}protected override Visual GetVisualChild(int index){return _grid;}protected override int VisualChildrenCount{get { return 1; }}protected override Size ArrangeOverride(Size finalSize){Debug.WriteLine(finalSize.Width + ":" + finalSize.Height);//直接给grid布局，grid内部的thumb会自动布局。_grid.Arrange(new Rect(new Point(-_leftThumb.Width / 2, -_leftThumb.Height / 2), new Size(finalSize.Width + _leftThumb.Width, finalSize.Height + _leftThumb.Height)));Debug.WriteLine(finalSize.Width + ":1      " + finalSize.Height);return finalSize;}private FrameworkElementFactory GetFactory(SolidColorBrush back){var fef = new FrameworkElementFactory(typeof(Ellipse));fef.SetValue(Ellipse.FillProperty, back);fef.SetValue(Ellipse.StrokeProperty, new SolidColorBrush((Color)ColorConverter.ConvertFromString("#999999")));fef.SetValue(Ellipse.StrokeThicknessProperty, (double)2);return fef;}private void Thumb_DragDelta(object sender, DragDeltaEventArgs e){var c = _adornedElement as FrameworkElement;var thumb = sender as FrameworkElement;double left, top, right, bottom, width, height;if (thumb.HorizontalAlignment == HorizontalAlignment.Left){right = c.Margin.Right;left = c.Margin.Left + e.HorizontalChange;width = (double.IsNaN(c.Width) ? c.ActualWidth : c.Width) - e.HorizontalChange;}else{left = c.Margin.Left;right = c.Margin.Right - e.HorizontalChange;width = (double.IsNaN(c.Width) ? c.ActualWidth : c.Width) + e.HorizontalChange;}if (thumb.VerticalAlignment == VerticalAlignment.Top){bottom = c.Margin.Bottom;top = c.Margin.Top + e.VerticalChange;height = (double.IsNaN(c.Height) ? c.ActualHeight : c.Height) - e.VerticalChange;}else{top = c.Margin.Top;bottom = c.Margin.Bottom - e.VerticalChange;height = (double.IsNaN(c.Height) ? c.ActualHeight : c.Height) + e.VerticalChange;}if (thumb.HorizontalAlignment != HorizontalAlignment.Center){if (width > 0){c.Margin = new Thickness(left, c.Margin.Top, right, c.Margin.Bottom);c.Width = width;}}if (thumb.VerticalAlignment != VerticalAlignment.Center){if (height > 0){c.Margin = new Thickness(c.Margin.Left, top, c.Margin.Right, bottom);c.Height = height;}}}}
}

用法

<Window>
<Grid><Border x:Name="border" Width="200" Height="200" Background="Gray" /></Grid>
</Window>

public partial class WinResize : Window{public WinResize(){InitializeComponent();this.Loaded += (s, e) => {var layer  =  AdornerLayer.GetAdornerLayer(border);layer.Add(new GridAdorner(border));};}}