使用 Timer 在 C# 中更新 UI

我正在努力使我的应用程序从串行端口读取数据并更新 UI 上的仪表更加高效，我想就处理 UI 更改的代码寻求一些建议。我设置了一个计时器来检查发送到 COM 端口的数据，另一个计时器则使用从 COM 端口接收到的变量更新 UI。基本上发生的事情是我正在旋转仪表。这是我处理图形的代码......

void timer_Tick(object sender, EventArgs e) //Timer regulates how often the gauge is     updated on the UI
{
    if (pictureBox1.Image != null)
        pictureBox1.Image.Dispose(); // dispose old image (you might consider reusing it rather than making a new one each frame)

    Point test = new Point((int)_xCor, (int)_yCor);
    Image img = new Bitmap(400, 400); // The box tht contains the image <--- Play around with this more
    pictureBox1.Image = img; // Setting the img Image to the pictureBox class?


    Graphics g = Graphics.FromImage(pictureBox1.Image); // G represents a drawing surface
    Matrix mm1 = new Matrix();
    //
    mm1.RotateAt((float)(90 + (((12.5 * state) - 20.95) * 6)), new Point((int)_xrotate, (int)_yrotate), MatrixOrder.Append);
    GraphicsPath gp = new GraphicsPath();
    g.Transform = mm1; // transform the graphics object so the image is rotated
    g.DrawImage(imgpic, test); // if the image needs to be behind the path, draw it beforehand
    mm1.Dispose();// prevent possible memory leaks
    gp.Dispose();// prevent possible memory leaks
    g.Dispose(); // prevent possible memory leaks
    pictureBox1.Refresh();
}

我想知道是否有一种更有效的方法可以在屏幕上旋转图像。我觉得必须有，但我无法弄清楚。

这是我第二次为winforms问题提供WPF解决方案。

只需将我的代码复制并粘贴到文件 -> 新项目 -> WPF 应用程序中，然后亲自查看结果。

另请看一下这段代码到底有多简单（我使用的是随机值，因此您可以删除它并根据您的需要进行调整）。

我用的图（<Path/>XAML 中的部分）对于仪表来说是不够的。我刚刚已经绘制了该路径，但我懒得创建新路径。您应该创建一个新绘图（我建议使用 Expression Blend）。但您可以看到正在应用的旋转及其运行速度。

using System;
using System.Threading;
using System.Windows;
using System.ComponentModel;

namespace WpfApplication4
{
    public partial class Window2
    {
        public Window2()
        {
            InitializeComponent();
            DataContext = new ViewModel();
        }
    }

    public class ViewModel: INotifyPropertyChanged
    {
        private double _value;
        public double Value
        {
            get { return _value; }
            set
            {
                _value = value;
                NotifyPropertyChange("Value");
            }
        }

        private int _speed = 100;
        public int Speed
        {
            get { return _speed; }
            set
            {
                _speed = value;
                NotifyPropertyChange("Speed");
                Timer.Change(0, value);
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        public void NotifyPropertyChange(string propertyName)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

        private System.Threading.Timer Timer;

        public ViewModel()
        {
            Rnd = new Random();
            Timer = new Timer(x => Timer_Tick(), null, 0, Speed);
        }

        private void Timer_Tick()
        {
            Application.Current.Dispatcher.BeginInvoke((Action) (NewValue));
        }

        private Random Rnd;
        private void NewValue()
        {
            Value = Value + (Rnd.Next(20) - 10);
        }
    }
}

XAML:

<Window x:Class="WpfApplication4.Window2"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window2" WindowState="Maximized">
    <DockPanel>
        <StackPanel DockPanel.Dock="Top">
            <TextBlock Text="Delay (MS):" Margin="2"/>
            <Slider Width="200" Minimum="100" SmallChange="1" LargeChange="10" Maximum="1500" Value="{Binding Speed}" Margin="2"/>
            <TextBlock Text="Current Value:" Margin="2"/>
            <TextBox Text="{Binding Value}" Margin="2"/>
        </StackPanel>

        <Path Data="M0.95991516,0.5 L73.257382,1.866724 90.763535,1.866724 90.763535,90.822725 66.430534,90.822725 66.430534,26.075016 0.5,24.828653 z" Fill="#FF506077" RenderTransformOrigin="0.861209625003783,0.507482926584064" Stretch="Fill" Stroke="Black">
            <Path.LayoutTransform>
                <TransformGroup>
                    <ScaleTransform ScaleY="1" ScaleX="-1"/>
                    <SkewTransform AngleY="0" AngleX="0"/>
                    <RotateTransform Angle="{Binding Value}" x:Name="Rotation"/>
                    <TranslateTransform/>
                </TransformGroup>
            </Path.LayoutTransform>
        </Path>
    </DockPanel>
</Window>