c# - DispatcherTimer 等待循环

Question

我想每隔几秒加载一张图片。我创建了 DispatcherTimer，我希望在计时器滴答中什么都不做，只是等待间隔。我该怎么做？

if (window.DialogResult == true) {
                st=window.st;
                for(int i=0;i<=st;i++){
                    timer = new DispatcherTimer();
                    timer.Interval = new TimeSpan(0,0,5);
                    timer.Tick += new EventHandler(timer_Tick);
                    timer.Start();
                arr[i]=window.arr[i];
                image1.Source = arr[i];
                }
            }

现在我这里有一个空勾号。

void timer_Tick(object sender, EventArgs e)
        {

        }

Answer 1

一种选择是使用async/await:

async void button_click(object sender, RoutedEventArgs e)
{
    // prepare the array
    // ...

    for (var i = 0; i < 100; i++)
    {
        image1.Source = arr[i];
        await Task.Delay(5000);
    }
}

您可能需要确保在异步循环仍在迭代时不会重新输入 button_click。查看 Lucian Wishick 的 "Async re-entrancy, and the patterns to deal with it".

如果你坚持使用DispatcherTimer:

async void button_click(object sender, RoutedEventArgs e)
{
    // prepare the array
    // ...

    var tcs = new TaskCompletionSource<object>();
    var timer = new DispatcherTimer();
    timer.Interval = new TimeSpan(0,0,5);
    timer.Tick += (_, __) => tcs.SetResult(Type.Missing);
    timer.Start();
    try
    {
        for (var i = 0; i < 100; i++)
        {
            image1.Source = arr[i];
            await tcs.Task;
            tcs = new TaskCompletionSource<object>();
        }
    }
    finally
    {
        timer.Stop();
    }
}