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WPF拖动改变大小系列
第一节 Grid内控件拖动调整大小
第二节 Canvas内控件拖动调整大小
第三节 窗口拖动调整大小（本章）
第四节 附加属性实现拖动调整大小
第五章 拓展更多调整大小功能
文章目录
- WPF拖动改变大小系列
- 前言
- 一、如何实现？
- 1.继承Adorner
- 2.使用Thumb
- 3.实现拖动逻辑
- 二、完整代码
- 三、使用示例
- 总结
前言
在《C# wpf Grid中实现控件拖动调整大小》中我们实现了Grid中的控件动态调整大小，对于自定义的无边框窗口也可以使用类似的方式实现。虽然能查到的方案有通过Window Api的和通过WindowChrome实现的，一个是对系统有依赖还一个是依赖.net版本，这里提供一种相对轻量的实现方法。
一、如何实现？
1.继承Adorner
通过装饰器的方式添加8个方位拖动区域在窗口上，这样既可以不影响控件布局，又可以自由摆放8个拖动控件。通过重写方法，给装饰添加控件。必要的重写的方法如下面示例所示：
public class WindowResizeAdorner : Adorner
{//获取装饰器的元素个数protected override Visual GetVisualChild(int index);//指定装饰器子元素个数protected override int VisualChildrenCount{get;}//布局，添加的子元素需要手动布局。protected override Size ArrangeOverride(Size finalSize);
}
2.使用Thumb
因为Thumb实现拖动比较容易，有相关事件获取拖动距离。在装饰器中定义8个Thumb，对应8个方位点。
示例代码如下：
//4条边
Thumb _leftThumb, _topThumb, _rightThumb, _bottomThumb;
//4个角
Thumb _lefTopThumb, _rightTopThumb, _rightBottomThumb, _leftbottomThumb;
初始化
public WindowResizeAdorner(UIElement adornedElement) : base(adornedElement){//初始化thumb_leftThumb = new Thumb();_leftThumb.HorizontalAlignment = HorizontalAlignment.Left;_leftThumb.VerticalAlignment = VerticalAlignment.Center;_leftThumb.Cursor = Cursors.SizeWE;//其他略...
}
3.实现拖动逻辑
在Thumb的DragDelta事件可以获取拖动距离，根据八个方位的不同计算并修改控件的大小。
private void Thumb_DragDelta(object sender, DragDeltaEventArgs e)
{
//1.右侧点HorizontalChange加宽
//2.左侧点HorizontalChange减宽，HorizontalChange加左移
//3.下侧点VerticalChange加高
//4.上侧点VerticalChange减高，VerticalChange加上移
}
二、完整代码
代码如下：
public class WindowResizeAdorner : Adorner{//4条边Thumb _leftThumb, _topThumb, _rightThumb, _bottomThumb;//4个角Thumb _lefTopThumb, _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;Window _window;public WindowResizeAdorner(UIElement adornedElement) : base(adornedElement){_adornedElement = adornedElement;_window = Window.GetWindow(_adornedElement);//初始化thumb_leftThumb = new Thumb();_leftThumb.HorizontalAlignment = HorizontalAlignment.Left;_leftThumb.VerticalAlignment = VerticalAlignment.Stretch;_leftThumb.Cursor = Cursors.SizeWE;_topThumb = new Thumb();_topThumb.HorizontalAlignment = HorizontalAlignment.Stretch;_topThumb.VerticalAlignment = VerticalAlignment.Top;_topThumb.Cursor = Cursors.SizeNS;_rightThumb = new Thumb();_rightThumb.HorizontalAlignment = HorizontalAlignment.Right;_rightThumb.VerticalAlignment = VerticalAlignment.Stretch;_rightThumb.Cursor = Cursors.SizeWE;_bottomThumb = new Thumb();_bottomThumb.HorizontalAlignment = HorizontalAlignment.Stretch;_bottomThumb.VerticalAlignment = VerticalAlignment.Bottom;_bottomThumb.Cursor = Cursors.SizeNS;_lefTopThumb = new Thumb();_lefTopThumb.HorizontalAlignment = HorizontalAlignment.Left;_lefTopThumb.VerticalAlignment = VerticalAlignment.Top;_lefTopThumb.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(_lefTopThumb);_grid.Children.Add(_rightTopThumb);_grid.Children.Add(_rightBottomThumb);_grid.Children.Add(_leftbottomThumb);AddVisualChild(_grid);foreach (Thumb thumb in _grid.Children){int thumnSize = 10;if (thumb.HorizontalAlignment == HorizontalAlignment.Stretch){thumb.Width = double.NaN;thumb.Margin = new Thickness(thumnSize, 0, thumnSize, 0);}else{thumb.Width = thumnSize;}if (thumb.VerticalAlignment == VerticalAlignment.Stretch){thumb.Height = double.NaN;thumb.Margin = new Thickness(0, thumnSize, 0, thumnSize);}else{thumb.Height = thumnSize;}thumb.Background = Brushes.Green;thumb.Template = new ControlTemplate(typeof(Thumb)){VisualTree = GetFactory(new SolidColorBrush(Colors.Transparent))};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){//直接给grid布局，grid内部的thumb会自动布局。_grid.Arrange(new Rect(new Point(-(_window.RenderSize.Width - finalSize.Width) / 2, -(_window.RenderSize.Height - finalSize.Height) / 2), _window.RenderSize));return finalSize;}//拖动逻辑private void Thumb_DragDelta(object sender, DragDeltaEventArgs e){var c = _window;var thumb = sender as FrameworkElement;double left, top, width, height;if (thumb.HorizontalAlignment == HorizontalAlignment.Left){left = c.Left + e.HorizontalChange;width = c.Width - e.HorizontalChange;}else{left = c.Left;width = c.Width + e.HorizontalChange;}if (thumb.HorizontalAlignment != HorizontalAlignment.Stretch){if (width > 63){ c.Left = left;c.Width = width; }}if (thumb.VerticalAlignment == VerticalAlignment.Top){top = c.Top + e.VerticalChange;height = c.Height - e.VerticalChange;}else{top = c.Top;height = c.Height + e.VerticalChange;}if (thumb.VerticalAlignment != VerticalAlignment.Stretch){if (height > 63){c.Top = top;c.Height = height;}}}//thumb的样式FrameworkElementFactory GetFactory(Brush back){var fef = new FrameworkElementFactory(typeof(Rectangle));fef.SetValue(Rectangle.FillProperty, back);return fef;}}
三、使用示例
示例代码如下：
<Window x:Class="WpfControlMove.MainWindow"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"xmlns:local="clr-namespace:WpfControlMove"mc:Ignorable="d"Title="MainWindow" Height="360" Width="640" Loaded="Window_Loaded" WindowStyle="None"ResizeMode="NoResize"Background="Transparent" AllowsTransparency="True"><Border Margin="10" Background="White"><Border.Effect><DropShadowEffect Color="#FFAAAAAA" ShadowDepth="0" BlurRadius="10" Opacity="0.4"/></Border.Effect></Border>
</Window>
在窗口或控件的Loaded事件中添加装饰器：
private void Window_Loaded(object sender, RoutedEventArgs e)
{//将装饰器添加到窗口的Content控件上var c = this.Content as UIElement;var layer = AdornerLayer.GetAdornerLayer(c);layer.Add(new WindowResizeAdorner(c));
}
效果预览：
总结
以上就是今天要讲的内容，本文讲述了自定义无边框窗口实现拖动改变大小的方法，其有优点是轻量易于实现和使用，但是也有缺点，往左和往上拖动时会出现一定的界面闪烁，但总得来说，这种实现方法还是可以使用的。
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