Windows窗体淡入效果问题VB.Net

Question

我对Windows窗体的淡入效果有问题。这个表单应该读取文件的值并将其存储在一个变量中，然后启动一个计时器，将表单的不透明度增加到读取的值，但这并没有发生。

我尝试了两种方法将值存储在变量中，第一种是：

If My.Computer.FileSystem.FileExists(Application.StartupPath & "Users" & My.Settings.username & "opacity.goodsetting") Then
Try
Using read As New StreamReader(Application.StartupPath & "Users" & My.Settings.username& "opacity.goodsetting")
If read.ReadLine = "50" Then
varOpacity = 0.5
ElseIf read.ReadLine = "60" Then
varOpacity = 0.6
ElseIf read.ReadLine = "70" Then
varOpacity = 0.7
ElseIf read.ReadLine = "80" Then
varOpacity = 0.8
ElseIf read.ReadLine = "90" Then
varOpacity = 0.9
ElseIf read.ReadLine = "100" Then
varOpacity = 1
End If
read.Close()
End Using
Catch ex As Exception
varOpacity = 1
Me.Opacity = 1
End Try
End If
Timer2.Start()

第二种：

Try
varOpacity = My.Computer.FileSystem.ReadAllText(Application.StartupPath & "Users" & My.Settings.username & "opacity.goodsetting")
Me.Opacity = varOpacity / 100
Catch ex As Exception
varOpacity = 1
Me.Opacity = 1
End Try

但这两种方法都不起作用。

我还留下了效果代码：

Me.Opacity = Me.Opacity + 0.1
If Me.Opacity = varOpacity Then
Timer2.Stop()
End If

感谢大家。

Answer 1

下面是一个我认为您想要的示例。。。我试着让它尽量接近你最初的例子。出于测试目的，我将代码放入Form_Load中，并添加了一个Timer。希望您可以根据自己的需要进行测试和更改。

表单需要在设计器中将其Opacity设置为0。代码将从0渐变为存储在文件中的值，否则，默认为1。

代码已导入System.IO

Private varOpacity As Double
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
'Set the path just once.
Dim pathOpacityLimit As String = Path.Combine(Application.StartupPath & "Users" & My.Settings.username, "opacity.goodsetting")
If File.Exists(pathOpacityLimit) Then
Try
Using read As New StreamReader(pathOpacityLimit)
If Double.TryParse(read.ReadLine, varOpacity) Then
'Value parsed - changed to 0.0 > 1.0 so inline with Me.Opacity. Start timer.
varOpacity /= 100
Timer2.Start()
Else
'Incorrect (not parsed) value in file - set default
Me.Opacity = 1
End If
read.Close()
End Using
Catch ex As Exception
'Exception - set default
Me.Opacity = 1
End Try
Else
'File doesn't exist - set default
Me.Opacity = 1
End If
End Sub
Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
Me.Opacity += 0.1
If Me.Opacity < varOpacity Then Exit Sub
Me.Opacity = varOpacity
Timer2.Stop()
End Sub

我希望这足以让你开始。您还可以检查存储的值，看看它是否在要求的0到100范围内。