背水一战 Windows 10 (67) - 控件(控件基类): DependencyObject - CoreDispatcher, 依赖属性的设置与获取, 依赖属性的变化回调
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作者:webabcd
介绍
背水一战 Windows 10 之 控件(控件基类 - DependencyObject)
- CoreDispatcher
- 依赖属性的设置与获取
- 依赖属性的变化回调
示例
1、演示 CoreDispatcher 的应用
Controls/BaseControl/DependencyObjectDemo/CoreDispatcherDemo.xaml
<Page x:Class="Windows10.Controls.BaseControl.DependencyObjectDemo.CoreDispatcherDemo" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:Windows10.Controls.BaseControl.DependencyObjectDemo" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Transparent"> <StackPanel Margin="10 0 10 10"> <TextBlock Name="lblMsg1" Margin="5" /> <TextBlock Name="lblMsg2" Margin="5" /> <TextBlock Name="lblMsg3" Margin="5" /> </StackPanel> </Grid> </Page>
Controls/BaseControl/DependencyObjectDemo/CoreDispatcherDemo.xaml.cs
/* * DependencyObject - 依赖对象(可以在 DependencyObject 上定义 DependencyProperty) * Dispatcher - 获取 CoreDispatcher 对象 * * * CoreDispatcher - 核心调度器 * CurrentPriority - 获取或设置当前任务的优先级(CoreDispatcherPriority 枚举) * HasThreadAccess - 获取一个值,用于说明当前线程是否可更新此 CoreDispatcher 线程上的 UI * RunAsync(), RunIdleAsync(), TryRunAsync(), TryRunIdleAsync() - 在此 CoreDispatcher 线程上使用指定的优先级执行指定的方法(一般用于更新 CoreDispatcher 线程上的 UI) * ShouldYield() - 用于获知当前任务队列中是否存在更高优先级的任务,或指定的优先级及其以上的任务 * AcceleratorKeyActivated - 有按键操作时触发的事件(针对 UIElement 的键盘事件监听请参见:/Controls/BaseControl/UIElementDemo/KeyDemo.xaml) * * CoreDispatcherPriority - 任务优先级枚举(High, Normal, Low, Idle) * * 在 UWP 中优先级从高到低的排序如下 * 1、本地代码中的 SendMessage * 2、CoreDispatcherPriority.High * 3、CoreDispatcherPriority.Normal * 4、所有设备输入消息 * 5、CoreDispatcherPriority.Low * 6、CoreDispatcherPriority.Idle(一般用于后台任务) * * * 本例用于演示 DependencyObject 的 Dispatcher(CoreDispatcher 类型) 的应用 */ using System; using System.Threading; using Windows.UI.Core; using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; namespace Windows10.Controls.BaseControl.DependencyObjectDemo { public sealed partial class CoreDispatcherDemo : Page { public CoreDispatcherDemo() { this.InitializeComponent(); this.Loaded += CoreDispatcherDemo_Loaded; // 监听按键事件 Window.Current.CoreWindow.Dispatcher.AcceleratorKeyActivated += Dispatcher_AcceleratorKeyActivated; } private void CoreDispatcherDemo_Loaded(object sender, RoutedEventArgs e) { Timer timer = new Timer((p) => { // 当前线程是否可修改 CoreDispatcher 上的 UI if (base.Dispatcher.HasThreadAccess) { lblMsg1.Text = "相同线程 " + DateTime.Now.ToString("mm:ss"); } else { // 非 UI 线程通过 CoreDispatcher 更新 UI var ignored = base.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => { lblMsg1.Text = "不同线程 " + DateTime.Now.ToString("mm:ss"); }); } }, null, TimeSpan.Zero, TimeSpan.FromSeconds(1)); DispatcherTimer dTimer = new DispatcherTimer(); dTimer.Interval = TimeSpan.FromSeconds(1); dTimer.Tick += (x, y) => { // 当前线程是否可修改 Dispatcher 上的 UI if (base.Dispatcher.HasThreadAccess) { lblMsg2.Text = "相同线程 " + DateTime.Now.ToString("mm:ss"); } else { // 非 UI 线程通过 CoreDispatcher 更新 UI var ignored = base.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => { lblMsg2.Text = "不同线程 " + DateTime.Now.ToString("mm:ss"); }); } }; dTimer.Start(); } private void Dispatcher_AcceleratorKeyActivated(CoreDispatcher sender, AcceleratorKeyEventArgs args) { /* * AcceleratorKeyEventArgs - 按键事件参数 * EventType - 事件类型(比如 KeyDown, KeyUp 之类的,详细参见 CoreAcceleratorKeyEventType 枚举) * VirtualKey - 按键枚举(比如 A, B, C, D, LeftControl 之类的,详细参见 VirtualKey 枚举) * KeyStatus - 按键的状态(一个 CorePhysicalKeyStatus 类型的对象,有好多字段,详细参见文档) */ lblMsg3.Text += $"EventType:{args.EventType}, VirtualKey:{args.VirtualKey}, IsExtendedKey:{args.KeyStatus.IsExtendedKey}, IsKeyReleased:{args.KeyStatus.IsKeyReleased}, IsMenuKeyDown:{args.KeyStatus.IsMenuKeyDown}, RepeatCount:{args.KeyStatus.RepeatCount}, ScanCode:{args.KeyStatus.ScanCode}, WasKeyDown:{args.KeyStatus.WasKeyDown}"; lblMsg3.Text += Environment.NewLine; // 屏蔽系统对按键的处理 args.Handled = true; } } }
2、演示依赖属性的设置与获取
Controls/BaseControl/DependencyObjectDemo/DependencyPropertyDemo.xaml
<Page x:Class="Windows10.Controls.BaseControl.DependencyObjectDemo.DependencyPropertyDemo" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:Windows10.Controls.BaseControl.DependencyObjectDemo" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Transparent"> <StackPanel Margin="10 0 10 10"> <Rectangle Name="rect1" Height="50" Fill="Red" HorizontalAlignment="Left" Margin="5" /> <Rectangle Name="rect2" Height="50" Fill="Red" HorizontalAlignment="Left" Margin="5" /> <Rectangle Name="rect3" Height="50" Fill="Red" HorizontalAlignment="Left" Margin="5" /> <Rectangle Name="rect4" Width="400" Height="50" Fill="Red" Margin="5" /> <Button Name="button" Content="点我" Click="button_Click" Margin="5" /> <TextBlock Name="lblMsg" Margin="5" /> </StackPanel> </Grid> </Page>
Controls/BaseControl/DependencyObjectDemo/DependencyPropertyDemo.xaml.cs
/* * DependencyObject - 依赖对象(可以在 DependencyObject 上定义 DependencyProperty) * SetValue(DependencyProperty dp, object value) - 设置依赖属性的值 * ClearValue(DependencyProperty dp) - 清除依赖属性的值 * GetValue(DependencyProperty dp) - 获取依赖属性的当前值 * GetAnimationBaseValue(DependencyProperty dp) - 获取依赖属性的基值 * ReadLocalValue(DependencyProperty dp) - 获取依赖属性的本地值 * * * 本例用于演示 DependencyObject 的依赖属性的设置与获取 */ using System; using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; using Windows.UI.Xaml.Media.Animation; using Windows.UI.Xaml.Shapes; namespace Windows10.Controls.BaseControl.DependencyObjectDemo { public sealed partial class DependencyPropertyDemo : Page { public DependencyPropertyDemo() { this.InitializeComponent(); this.Loaded += DependencyPropertyDemo_Loaded; } private void DependencyPropertyDemo_Loaded(object sender, RoutedEventArgs e) { // 直接设置依赖属性(rect1.Width = 400; 其实调用的就是这个) rect1.SetValue(FrameworkElement.WidthProperty, 400); // 直接设置依赖属性 rect2.SetValue(FrameworkElement.WidthProperty, 200); // 通过动画的方式修改依赖属性的值 SetRectWidth(rect2); // 通过 Style 的方式设置依赖属性 Style style = new Style(); style.TargetType = typeof(Rectangle); Setter setter = new Setter(); setter.Property = Rectangle.WidthProperty; setter.Value = 200; style.Setters.Add(setter); rect3.Style = style; // 通过动画的方式修改依赖属性的值 SetRectWidth(rect3); // 清除依赖属性的值 rect4.ClearValue(FrameworkElement.WidthProperty); } private void button_Click(object sender, RoutedEventArgs e) { DependencyProperty dp = FrameworkElement.WidthProperty; // 通过 SetValue 设置依赖属性后,再通过 GetValue, GetAnimationBaseValue, ReadLocalValue 取出的值和设置的值都是一样的 lblMsg.Text = $"rect1 GetValue:{rect1.GetValue(dp)}, GetAnimationBaseValue:{rect1.GetAnimationBaseValue(dp)}, ReadLocalValue:{rect1.ReadLocalValue(dp)}"; lblMsg.Text += Environment.NewLine; // 通过 SetValue 设置依赖属性后,再通过动画的方式修改其值 // GetValue - 获取当前值 // GetAnimationBaseValue - 获取基值,也就是动画之前的值 // ReadLocalValue - 获取本地值,即通过 SetValue 或者资源或者绑定设置的值 lblMsg.Text += $"rect2 GetValue:{rect2.GetValue(dp)}, GetAnimationBaseValue:{rect2.GetAnimationBaseValue(dp)}, ReadLocalValue:{rect2.ReadLocalValue(dp)}"; lblMsg.Text += Environment.NewLine; // 通过 Style 设置依赖属性后,再通过动画的方式修改其值 // GetValue - 获取当前值 // GetAnimationBaseValue - 获取基值,也就是动画之前的值 // ReadLocalValue - 获取本地值,即通过 SetValue 或者资源或者绑定设置的值(如果是通过其他方式,比如 Style 方式设置的值,则无本地值) lblMsg.Text += $"rect3 GetValue:{rect3.GetValue(dp)}, GetAnimationBaseValue:{rect3.GetAnimationBaseValue(dp)}, ReadLocalValue:{rect3.ReadLocalValue(dp)}"; lblMsg.Text += Environment.NewLine; // 通过 ClearValue 清除了依赖属性的值,则再通过 GetValue, GetAnimationBaseValue, ReadLocalValue 均无法获取到值 lblMsg.Text += $"rect4 GetValue:{rect4.GetValue(dp)}, GetAnimationBaseValue:{rect4.GetAnimationBaseValue(dp)}, ReadLocalValue:{rect4.ReadLocalValue(dp)}, ActualWidth:{rect4.ActualWidth}"; } private void SetRectWidth(Rectangle rect) { DoubleAnimation da = new DoubleAnimation(); da.EnableDependentAnimation = true; da.BeginTime = TimeSpan.Zero; da.To = 400; da.Duration = TimeSpan.FromSeconds(5); Storyboard.SetTarget(da, rect); Storyboard.SetTargetProperty(da, nameof(rect.Width)); Storyboard sb = new Storyboard(); sb.Children.Add(da); sb.Begin(); } } }
3、演示如何监听依赖属性的变化
Controls/BaseControl/DependencyObjectDemo/RegisterPropertyChangedCallbackDemo.xaml
<Page x:Class="Windows10.Controls.BaseControl.DependencyObjectDemo.RegisterPropertyChangedCallbackDemo" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:Windows10.Controls.BaseControl.DependencyObjectDemo" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Transparent"> <Grid.Resources> <BeginStoryboard x:Name="sb"> <Storyboard> <DoubleAnimation EnableDependentAnimation="True" Storyboard.TargetName="rect1" Storyboard.TargetProperty="Width" From="0" To="200" Duration="0:0:3"> </DoubleAnimation> </Storyboard> </BeginStoryboard> </Grid.Resources> <StackPanel Margin="10 0 10 10"> <Rectangle Name="rect1" Height="50" Fill="Red" HorizontalAlignment="Left" Margin="5" /> <TextBlock Name="lblMsg" Margin="5" /> </StackPanel> </Grid> </Page>
Controls/BaseControl/DependencyObjectDemo/RegisterPropertyChangedCallbackDemo.xaml.cs
/* * DependencyObject - 依赖对象(可以在 DependencyObject 上定义 DependencyProperty) * RegisterPropertyChangedCallback() - 为指定的依赖属性注册一个变化回调 * UnregisterPropertyChangedCallback() - 取消 RegisterPropertyChangedCallback() 的注册 * * * 本例用于演示如何监听 DependencyObject 的依赖属性的变化 */ using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; using Windows.UI.Xaml.Navigation; using Windows.UI.Xaml.Shapes; namespace Windows10.Controls.BaseControl.DependencyObjectDemo { public sealed partial class RegisterPropertyChangedCallbackDemo : Page { private long _token = -1; public RegisterPropertyChangedCallbackDemo() { this.InitializeComponent(); } protected override void OnNavigatedTo(NavigationEventArgs e) { // 为 WidthProperty 注册一个变化回调(返回值是一个 token 用于取消注册用) _token = rect1.RegisterPropertyChangedCallback(Rectangle.WidthProperty, WidthChanged); base.OnNavigatedTo(e); } protected override void OnNavigatedFrom(NavigationEventArgs e) { // 为 WidthProperty 取消指定的变化回调(通过 token 来指定取消的是哪个变化回调) rect1.UnregisterPropertyChangedCallback(Rectangle.WidthProperty, _token); base.OnNavigatedFrom(e); } private void WidthChanged(DependencyObject sender, DependencyProperty prop) { double width = (double)sender.GetValue(prop); lblMsg.Text = $"width: {width}"; } } }
OK
[源码下载]
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