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C# wpf利用附加属性实现界面上定义装饰器

CodeOfCC 人气:0

前言

装饰器是wpf中可以浮在控件上面的一种组件,我们通常可以用来实现一些诸如控件拖动点、提示框、自定义鼠标等界面功能。装饰器的用法其实还是比较复杂的,几乎需要完全再cs中编写所有代码,对于样式要求较高的情况下,完全在cs中些控件的样式是比较困难的。为了改变这种状况,我们可以使用附加属性将装饰器的逻辑封装,提供一个可以在界面上定义的属性。

一、如何实现

1、实现装饰器

由于Adorner是一个抽象类不能直接实现,所有我们需要定义一个子类实现并它。

class NormalAdorner : Adorner
{
    /// <summary>
    /// 构造方法
    /// </summary>
    /// <param name="adornedElement">被添加装饰器的元素</param>
    /// <param name="child">放到装饰器中的元素</param>
    public NormalAdorner(UIElement adornedElement, UIElement child) : base(adornedElement);
    protected override Visual GetVisualChild(int index);
    protected override int VisualChildrenCount;
    protected override Size ArrangeOverride(Size finalSize);
}

2、定义附加属性

通过propa快捷定义一个名称为AdornerContent的附加属性其类型UIElement。

public static UIElementGetAdornerContent(DependencyObject obj)
{
    return (UIElement)obj.GetValue(AdornerContent);
}
public static void SetAdornerContent(DependencyObject obj, Control value)
{
    obj.SetValue(AdornerContent, value);
}
// Using a DependencyProperty as the backing store for MyProperty.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty AdornerContent =
    DependencyProperty.RegisterAttached("AdornerContent", typeof(UIElement), typeof(AdornerHelper), new PropertyMetadata(null));

3、加入装饰层

在附加属性改变事件中,进行装饰层的添加。

public void PropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    var c = d as UIElement;
    //获取装饰层
    var layer = AdornerLayer.GetAdornerLayer(c);
    //添加装饰器
     layer.Add(new NormalAdorner(c, (UIElement)e.NewValue));
}

二、完整代码

AdornerHelper.cs

using System;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;
namespace AC
{
    internal class AdornerHelper
    {
        public static UIElement GetAdornerContent(DependencyObject obj)
        {
            return (UIElement)obj.GetValue(AdornerContent);
        }
        public static void SetAdornerContent(DependencyObject obj, UIElement value)
        {
            obj.SetValue(AdornerContent, value);
        }
        // Using a DependencyProperty as the backing store for MyProperty.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty AdornerContent =
            DependencyProperty.RegisterAttached("AdornerContent", typeof(UIElement), typeof(AdornerHelper), new PropertyMetadata(null, (d, e) =>
            {
                var c = d as FrameworkElement;
                if (c == null)
                    return;
                var adronerContent = e.NewValue as UIElement;
                if (!c.IsLoaded)
                {
                    if (adronerContent != null)
                    {
                        RoutedEventHandler l = null;
                        l = (s, E) =>
                        {
                            var content = GetAdornerContent(c);
                            if (content != null)
                            {
                                var layer = AdornerLayer.GetAdornerLayer(c);
                                if (layer == null)
                                    throw new Exception("获取控件装饰层失败,控件可能没有装饰层!");
                                layer.Add(new NormalAdorner((UIElement)c, (UIElement)e.NewValue));
                            }
                            c.Loaded -= l;
                        };
                        c.Loaded += l;
                    }
                }
                else
                {
                    var layer = AdornerLayer.GetAdornerLayer(d as Visual);
                    if (layer == null)
                        throw new Exception("获取控件装饰层失败,控件可能没有装饰层!");
                    if (e.OldValue != null)
                    {

                        var adorners = layer.GetAdorners(c);
                        foreach (var i in adorners)
                        {
                            if (i is NormalAdorner)
                            {
                                var na = i as NormalAdorner;
                                if (na.Child == e.OldValue)
                                {
                                    layer.Remove(i);
                                    break;
                                }
                            }
                        }
                    }
                    if (adronerContent != null)
                    {
                        layer.Add(new NormalAdorner((UIElement)c, (UIElement)e.NewValue));
                    }
                }
            }));

        class NormalAdorner : Adorner
        {
            UIElement _child;
            /// <summary>
            /// 构造方法
            /// </summary>
            /// <param name="adornedElement">被添加装饰器的元素</param>
            /// <param name="child">放到装饰器中的元素</param>
            public NormalAdorner(UIElement adornedElement, UIElement child) : base(adornedElement)
            {
                _child = child;
                AddVisualChild(child);
            }
            public UIElement Child { get { return _child; } }
            protected override Visual GetVisualChild(int index)
            {
                return _child;
            }
            protected override int VisualChildrenCount
            {
                get
                {
                    return 1;
                }
            }
            protected override Size ArrangeOverride(Size finalSize)
            {
                _child.Arrange(new Rect(new Point(0, 0), finalSize));
                return finalSize;
            }
        }
    }
}

三、使用示例

<Window x:Class="WpfApp2.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:WpfApp2"
        xmlns:ac="clr-namespace:AC"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800"
        >
    <Grid>
        <Border Background="RoyalBlue" Width="320" Height="180" CornerRadius="10">
             <!--添加装饰器-->
            <ac:AdornerHelper.AdornerContent>
                <Grid >
                    <Grid.Resources>
                        <Style TargetType="Thumb">
                            <Setter Property="Template">
                                <Setter.Value>
                                    <ControlTemplate TargetType="Thumb">
                                        <Border BorderBrush="Gray" BorderThickness="2" CornerRadius="8"  Background="White"></Border>
                                    </ControlTemplate>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </Grid.Resources>
                    <!--左-->
                    <Thumb  Margin="-8,0,0,0" Width="16" Height="16" HorizontalAlignment="Left" VerticalAlignment="Center" Cursor="SizeWE"/>
                    <!--上-->
                    <Thumb  Margin="0,-8,0,0" Width="16" Height="16" HorizontalAlignment="Center" VerticalAlignment="Top" Cursor="SizeNS"/>
                    <!--右-->
                    <Thumb  Margin="0,0,-8,0" Width="16" Height="16" HorizontalAlignment="Right" VerticalAlignment="Center" Cursor="SizeWE"/>
                    <!--下-->
                    <Thumb  Margin="0,0,0,-8" Width="16" Height="16" HorizontalAlignment="Center" VerticalAlignment="Bottom" Cursor="SizeNS"/>
                    <!--左上-->
                    <Thumb  Margin="-8,-8,0,0" Width="16" Height="16" HorizontalAlignment="Left" VerticalAlignment="Top" Cursor="SizeNWSE"/>
                    <!--右上-->
                    <Thumb  Margin="0,-8,-8,0" Width="16" Height="16" HorizontalAlignment="Right" VerticalAlignment="Top"  Cursor="SizeNESW"/>
                    <!--右下-->
                    <Thumb  Margin="0,0,-8,-8" Width="16" Height="16" HorizontalAlignment="Right" VerticalAlignment="Bottom"  Cursor="SizeNWSE"/>
                    <!--左下-->
                    <Thumb  Margin="-8,0,0,-8" Width="16" Height="16" HorizontalAlignment="Left" VerticalAlignment="Bottom" Cursor="SizeNESW"/>
                </Grid>
            </ac:AdornerHelper.AdornerContent>
        </Border>
    </Grid>
</Window>

效果预览

总结

以上就是今天要讲的内容,在界面上定义装饰器主要目的是为了方编写复杂样式,使用方式有了较大的变化。想要灵活使用则需要对wpf有一定的深入了解。但从另外一个角度来说在界面上定义装饰器和使用Grid布局调整层叠达到相同效果,可能本质上区别不太大,至少在控件树上两者是一模一样的。总的来说个人觉得这是一种比较有意思的装饰器使用方法。

到此这篇关于C# wpf利用附加属性实现界面上定义装饰器的文章就介绍到这了,更多相关C# wpf界面定义装饰器内容请搜索以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之

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