在vb.net中显示加载屏幕

创建一个用作“加载”对话框的表单。当您准备初始化编码器时,使用 ShowDialog() 方法这会导致它停止用户与显示加载对话框的表单交互。

加载对话框的编码方式应确保在加载时使用 BackgroundWorker

Imports System.ComponentModel

Public Class LoadingForm ' Inherits Form from the designer.vb file

    Private _worker As BackgroundWorker

    Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
        MyBase.OnLoad(e)

        _worker = New BackgroundWorker()
        AddHandler _worker.DoWork, AddressOf WorkerDoWork
        AddHandler _worker.RunWorkerCompleted, AddressOf WorkerCompleted

        _worker.RunWorkerAsync()
    End Sub

    ' This is executed on a worker thread and will not make the dialog unresponsive.  If you want
    ' to interact with the dialog (like changing a progress bar or label), you need to use the
    ' worker's ReportProgress() method (see documentation for details)
    Private Sub WorkerDoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
        ' Initialize encoder here
    End Sub

    ' This is executed on the UI thread after the work is complete.  It's a good place to either
    ' close the dialog or indicate that the initialization is complete.  It's safe to work with
    ' controls from this event.
    Private Sub WorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs)
        Me.DialogResult = Windows.Forms.DialogResult.OK
        Me.Close()
    End Sub

End Class

当您准备好显示对话框时,您可以这样做:

Dim frm As New LoadingForm()
frm.ShowDialog()

有更优雅的实现和更好的实践可以遵循,但这是最简单的。

有很多方法可以做到这一点。最简单的方法可能是显示一个模式对话框,然后启动另一个进程,完成后关闭显示的对话框。不过,您需要处理标准X的显示才能关闭。但是,在标准UI线程中执行这些操作将锁定UI,直到操作完成。

另一种选择可能是有一个“加载”屏幕来填充默认表单,将其置于前端,然后在辅助线程上触发长时间运行的进程,一旦完成,您可以通知UI线程并删除加载屏幕。

这些只是一些想法,这取决于你在做什么。

设置标签后(如对Mitchel的评论中所述)调用 Application.DoEvents()

另一个选项是在BackgroundWorker进程中运行编码器的初始化代码。