WPF实现在控件上显示Loading等待动画的方法详解

WPF 如何在控件上显示 Loading 等待动画

• 框架使用.NET40；
• Visual Studio 2022;
• 使用方式需引入命名空间后设置控件的附加属性 wd:Loading.IsShow="true"，即可显示默认等待动画效果如下：

• 如需自定义 Loading 一定要 先设置 wd:Loading.Child 在设置 IsShow="true" 。
• 显示不同 Loading 内容需 wd:Loading.Child ={x:Static wd:NormalLoading.Default} 进行复赋值显示 NormalLoading 效果如下：

Github[2]

Github xaml[3]

Gitee[4]

Gitee xaml[5]

实现代码

也可以自定义 Loading 动画如下：

1、自定义控件 CustomLoading 。

public class CustomLoading : Control
    {
        public static CustomLoading Default = new CustomLoading();
        static CustomLoading()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(CustomLoading),
                new FrameworkPropertyMetadata(typeof(CustomLoading)));
        }
    }

2、编写 CustomLoading.xaml 代码如下。

1）创建装饰 AdornerContainer 代码如下:

using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;

namespace WPFDevelopers.Utilities
{
    public class AdornerContainer : Adorner
    {
        private UIElement _child;
        public AdornerContainer(UIElement adornedElement) : base(adornedElement)
        {
        }
        public UIElement Child
        {
            get => _child;
            set
            {
                if (value == null)
                {
                    RemoveVisualChild(_child);
                    _child = value;
                    return;
                }
                AddVisualChild(value);
                _child = value;
            }
        }
        protected override int VisualChildrenCount
        {
            get
            {
                return _child != null ? 1 : 0;
            }
        }

        protected override Size ArrangeOverride(Size finalSize)
        {
            _child?.Arrange(new Rect(finalSize));
            return finalSize;
        }

        protected override Visual GetVisualChild(int index)
        {
            if (index == 0 && _child != null) return _child;
            return base.GetVisualChild(index);
        }
    }
}

2）创建蒙板控件 MaskControl 代码如下:

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace WPFDevelopers.Controls
{
    public class MaskControl : ContentControl
    {
        private readonly Visual visual;
        public static readonly DependencyProperty CornerRadiusProperty =
          DependencyProperty.Register("CornerRadius", typeof(CornerRadius), typeof(MaskControl), 
              new PropertyMetadata(new CornerRadius(0)));
        public MaskControl(Visual _visual)
        {
            visual = _visual;
        }
        public CornerRadius CornerRadius
        {
            get => (CornerRadius)GetValue(CornerRadiusProperty);
            set => SetValue(CornerRadiusProperty, value);
        }
    }
}

3）创建 Loading 继承 BaseControl 增加附加属性 IsShow 代码如下:

• True 则动态添加装饰器 AdornerContainer 并将 MaskControl 添加到 AdornerContainer.Child 中。
• False 则移除装饰器。

using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Markup;
using System.Windows.Media;
using WPFDevelopers.Helpers;
using WPFDevelopers.Utilities;

namespace WPFDevelopers.Controls
{
    public class Loading : BaseControl
    {
        public static readonly DependencyProperty IsShowProperty =
           DependencyProperty.RegisterAttached("IsShow", typeof(bool), typeof(Loading),
               new PropertyMetadata(false, OnIsLoadingChanged));
        private const short SIZE = 25;
        private const double MINSIZE = 40;
        private static FrameworkElement oldFrameworkElement;
        private static void OnIsLoadingChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (e.NewValue is bool isMask && d is FrameworkElement parent)
            {
                if (isMask)
                {
                    if (!parent.IsLoaded)
                        parent.Loaded += Parent_Loaded;
                    else
                        CreateMask(parent);
                }
                else
                {
                    parent.Loaded -= Parent_Loaded;
                    CreateMask(parent, true);
                }
            }
        }
        private static void Parent_Loaded(object sender, RoutedEventArgs e)
        {
            if (sender is UIElement element)
                CreateMask(element);
        }
        static void CreateMask(UIElement uIElement, bool isRemove = false)
        {
            var layer = AdornerLayer.GetAdornerLayer(uIElement);
            if (layer == null) return;
            if (isRemove && uIElement != null)
            {
                var adorners = layer.GetAdorners(uIElement);
                if (adorners != null)
                {
                    foreach (var item in adorners)
                    {
                        if (item is AdornerContainer container)
                        {
                            var isAddChild = (bool)Loading.GetIsAddChild(uIElement);
                            if (!isAddChild)
                                Loading.SetChild(uIElement, null);
                            container.Child = null;
                            layer.Remove(container);
                        }
                    }
                }
                return;
            }
            var adornerContainer = new AdornerContainer(uIElement);
            var value = Loading.GetChild(uIElement);
            if (value == null)
            {
                var isLoading = GetIsShow(uIElement);
                if (isLoading)
                {
                    var w = (double)uIElement.GetValue(ActualWidthProperty);
                    var h = (double)uIElement.GetValue(ActualHeightProperty);
                    var defaultLoading = new DefaultLoading();
                    if (w < MINSIZE || h < MINSIZE)
                    {
                        defaultLoading.Width = SIZE;
                        defaultLoading.Height = SIZE;
                        defaultLoading.StrokeArray = new DoubleCollection { 10, 100 };
                    }
                    SetChild(uIElement, defaultLoading);
                    value = Loading.GetChild(uIElement);
                }
                if (value != null)
                    adornerContainer.Child = new MaskControl(uIElement) { Content = value, Background = ControlsHelper.Brush };
            }
            else
            {
                var normalLoading = (FrameworkElement)value;
                var frameworkElement = (FrameworkElement)uIElement;
                Loading.SetIsAddChild(uIElement, true);

                if (oldFrameworkElement != null)
                    value = oldFrameworkElement;
                else
                {
                    string xaml = XamlWriter.Save(normalLoading);
                    oldFrameworkElement = (FrameworkElement) XamlReader.Parse(xaml);
                }

                var _size = frameworkElement.ActualHeight < frameworkElement.ActualWidth ? frameworkElement.ActualHeight : frameworkElement.ActualWidth;
                if(_size < MINSIZE)
                {
                    normalLoading.Width = SIZE;
                    normalLoading.Height = SIZE;
                    value = normalLoading;
                }
                
                adornerContainer.Child = new MaskControl(uIElement) { Content = value, Background = ControlsHelper.Brush };

            }
            layer.Add(adornerContainer);

        }
        public static bool GetIsShow(DependencyObject obj)
        {
            return (bool)obj.GetValue(IsShowProperty);
        }

        public static void SetIsShow(DependencyObject obj, bool value)
        {
            obj.SetValue(IsShowProperty, value);
        }
    }
}

4）创建 DefaultLoading.xaml 代码如下:

5）创建 LoadingExample.xaml 实例代码如下:

效果图

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