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C#WPF连续无延迟地调用OnRender

render controls xaml wpf c#

Ben · 技术社区 · 7 年前

我正在为我的WPF应用程序创建自定义控件。这是我的代码:

主窗口。xaml。反恐精英:

public sealed class MainTimer : FrameworkElement
{
    public DispatcherTimer Timer = new DispatcherTimer();

    public MainTimer()
    {
        Timer.Tick += delegate 
        {
            UpdateLayout();

            // No luck
            // Dispatcher.Invoke(delegate { },DispatcherPriority.Render);

            // InvalidateVisual();
        };
        Timer.Interval = new TimeSpan(10);
        Timer.Start();
    }

    protected override void OnRender(DrawingContext drawingContext)
    {
        string mode = "12";

        Console.WriteLine("RENDERING");


        if (Application.Current.MainWindow != null)
        {
            if (mode == "24")
            {
                //drawingContext.DrawRectangle(new SolidColorBrush(Color.FromArgb(50,150,255,255)), null, BoundsRelativeTo(this, Application.Current.MainWindow));
                drawingContext.DrawText(new FormattedText(DateTime.Now.ToLongTimeString(), System.Globalization.CultureInfo.CurrentCulture, FlowDirection.LeftToRight, new Typeface("Microsoft PhagsPa"), 50, new SolidColorBrush(Color.FromArgb(50, 235, 255, 255))), new Point(0, -15));
            }
            else
            {
                string st = "";

                if (DateTime.Now.Hour > 12)
                {
                    st = ((DateTime.Now.Hour - 12).ToString("00") + " : " + DateTime.Now.Minute.ToString("00") + " : " + DateTime.Now.Second.ToString("00")) + " pm" ;
                }
                else
                {
                    st = ((DateTime.Now.Hour).ToString("00") + " : " + DateTime.Now.Minute.ToString("00") + " : " + DateTime.Now.Second.ToString("00")) + " am";
                }


                drawingContext.DrawText(new FormattedText(st, System.Globalization.CultureInfo.CurrentCulture, FlowDirection.LeftToRight, new Typeface("Microsoft PhagsPa"), 40, new SolidColorBrush(Color.FromArgb(50, 200, 255, 255))), new Point(0, -12));
            }
        }
        //Dispatcher.Invoke(new Action(() => { }), DispatcherPriority.ContextIdle, null);

    }

    public static Rect BoundsRelativeTo(FrameworkElement element,Visual relativeTo)
    {
        return
          element.TransformToVisual(relativeTo)
                 .TransformBounds(LayoutInformation.GetLayoutSlot(element));
    }

}

主窗口。xaml:

<Window x:Class="WpfApp1.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:WpfApp1"
    mc:Ignorable="d"
    ShowInTaskbar="False"
    AllowsTransparency="True" WindowStyle="None"  
    WindowStartupLocation="Manual"
    Left="1168"
    Top="120"
    ResizeMode="NoResize"
    WindowState="Normal"
    Title="MainWindow" Height="75.132" Width="283.621" FontFamily="Microsoft PhagsPa">
<Window.Background>
    <SolidColorBrush Opacity="0" Color="LightCyan"/>
</Window.Background>

<local:MainTimer Loaded="Grid_Loaded"/>

问题是消息“RENDERING”应该每秒出现在控制台中,但它只出现一次! 我希望我的控件每秒都重新渲染。
我试过使用 InvalidateVisual() ,但该程序占用了我将近70%-80%的CPU资源。
如何在不使用大量系统资源的情况下重新呈现控件?
WinForm中是否有类似于“Refresh()”的方法?

提前感谢:)

1 回复 | 直到 7 年前

nvoigt 7 年前

您的设置使其非常模糊,但如果您知道要查找什么,您可以看到时间:

以下代码工作正常:

using System;

namespace WpfApp1
{
    using System.Windows;
    using System.Windows.Media;
    using System.Windows.Threading;

    public sealed class MainTimer : FrameworkElement
    {
        private DispatcherTimer Timer = new DispatcherTimer();

        public MainTimer()
        {
            // what you are looking for is InvalidateVisual
            this.Timer.Tick += (sender, args) => this.InvalidateVisual();

            // changed your timespan to a more appropriate value
            this.Timer.Interval = TimeSpan.FromSeconds(1);
            this.Timer.Start();
        }

        protected override void OnRender(DrawingContext drawingContext)
        {
            string mode = "12";

            System.Diagnostics.Trace.WriteLine("Rendering");

            if (Application.Current.MainWindow != null)
            {
                if (mode == "24")
                {
                    drawingContext.DrawText(new FormattedText(DateTime.Now.ToLongTimeString(), System.Globalization.CultureInfo.CurrentCulture, FlowDirection.LeftToRight, new Typeface("Microsoft PhagsPa"), 50, new SolidColorBrush(Color.FromArgb(50, 235, 255, 255))), new Point(0, -15));
                }
                else
                {
                    string st = "";

                    if (DateTime.Now.Hour > 12)
                    {
                        st = ((DateTime.Now.Hour - 12).ToString("00") + " : " + DateTime.Now.Minute.ToString("00") + " : " + DateTime.Now.Second.ToString("00")) + " pm";
                    }
                    else
                    {
                        st = ((DateTime.Now.Hour).ToString("00") + " : " + DateTime.Now.Minute.ToString("00") + " : " + DateTime.Now.Second.ToString("00")) + " am";
                    }


                    drawingContext.DrawText(new FormattedText(st, System.Globalization.CultureInfo.CurrentCulture, FlowDirection.LeftToRight, new Typeface("Microsoft PhagsPa"), 40, new SolidColorBrush(Color.FromArgb(50, 200, 255, 255))), new Point(0, -12));
                }
            }
        }
    }
}

使用XAML:

<Window x:Class="WpfApp1.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:WpfApp1"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <local:MainTimer/>
    </Grid>
</Window>

它每秒都在渲染。

我仍然认为这这不是自定义渲染的目的,您可以在XAML中通过计时器更改viewmodel来执行此操作价值 . 然而,如果情况变得更复杂,您可能会对 this other thread 以及详细说明如何使用绘图组提高性能的答案。