在进度条 c# 中每 30% 更改一次文本

Question

我想让每 30% 的进度条，文本发生变化。

我想要做的是，当进度条达到 25% 时，文本发生变化并停止一秒钟，然后又回到 50，然后文本再次发生变化，它一直持续到达到 100%。

这是我的代码：

        public WelcomeScreen()
        {
            InitializeComponent();
            _timer.Interval = 2000;
            label1.ForeColor = Color.White;
        }

        private void WelcomeScreen_Load(object sender, EventArgs e)
        {
            var worker = new BackgroundWorker();

            worker.WorkerReportsProgress = true;
            worker.DoWork += worker_DoWork;
            worker.RunWorkerCompleted += worker_RunWorkerCompleted;
            worker.ProgressChanged += worker_ProgressChanged;
            worker.RunWorkerAsync();
        }

        void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            var percentComplete = e.ProgressPercentage;
            var userState = (string)e.UserState;

            progressBar1.Minimum = 0;
            progressBar1.Maximum = 100;
            progressBar1.Value = 100;
            progressBar1.Step = 25;

            if (progressBar1.Step <= 25)
            {
                label1.Text = "Preparing Setup";
            }

            else if (progressBar1.Step <= 50)
            {
                label1.Text = "Preparing Application";
            }

            else if (progressBar1.Step <= 75)
            {
                label1.Text = "Preparing Database";
            }

            else if (progressBar1.Step <= 100)
            {
                label1.Text = "Preparing Contents";
            }

            else
            {
                label1.Text = "Launch Application";
            }
        }

        void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            _timer.Enabled = true;
            _timer.Tick += new EventHandler(Timer_Tick);
        }

        void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            var currentWorker = (BackgroundWorker)sender;

            currentWorker.ReportProgress(0, "Preparing Setup");
            currentWorker.ReportProgress(25, "Preparing Application");
            currentWorker.ReportProgress(50, "Preparing Database");
            currentWorker.ReportProgress(75, "Preparing Contents");
            currentWorker.ReportProgress(100, "Launch Application");
        }

        void Timer_Tick(object sender, EventArgs e)
        {
            _timer.Enabled = false;

            this.Hide();

            _login.ShowDialog();

            this.Close();
        }

当进度条达到 100% 时，我命令应用程序等待 2 秒，然后在文本更改为“启动应用程序”后显示另一个表单。

Answer 1

WelcomeScreen_Load 中的所有代码都会阻塞 UI 线程，直到它完成。这意味着无论您对进度条做什么，它都不会在完成之前显示它的更改（它将“跳转”到最后的设置）。

你会想要查看Background Workers。这些让您可以异步执行代码，并经常报告当前状态（即：完成百分比）。

所以，一个非常简短的例子：

private void WelcomeScreen_Load(object sender, EventArgs e)
{
    var worker = new BackgroundWorker();
    worker.WorkerReportsProgress = true;
    worker.DoWork += worker_DoWork;
    worker.RunWorkerCompleted += worker_RunWorkerCompleted;
    worker.ProgressChanged += worker_ProgressChanged;
    worker.RunWorkerAsync();
}

void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    var percentComplete = e.ProgressPercentage;
    var userState = (string)e.UserState;

    //do something with these values, like moving your progress bar
    progressBar1.Minimum = 0;
    progressBar1.Maximum = 100;
    progressBar1.Value = percentComplete;
}

void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    // do something when the worker completes, like start your timer
}

void worker_DoWork(object sender, DoWorkEventArgs e)
{
    // do the "work" for the background worker

    var currentWorker = (BackgroundWorker)sender;

    currentWorker.ReportProgress(0, "Just Starting");

    // do your first task
    currentWorker.ReportProgress(25, "Finish First Task");

    // ...
}