微软.net精简框架常见问题及回答(中文版)(30)
Dim form1 As New Form1()
Me.Text = ""
form1.Text = AppName
form1.ShowDialog()
Me.Text = AppName
7.35. How do I access a Control from its instance name?
You can use Reflection to look up a control instance by its name. Here is some sample code:
//C#
private void Form1_Load(object sender, System.EventArgs e)
{
ComboBox c = (ComboBox)this.ControlFromName("combobox1");
c.Items.Add("1");
this.GetControls();
}
private Control ControlFromName(string name)
{
object o = this.GetType().GetField(name,
System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance |
System.Reflection.BindingFlags.IgnoreCase).GetValue(this);
return((Control)o);
}
private void GetControls()
{
System.Reflection.FieldInfo[] fis = this.GetType().GetFields
(
System.Reflection.BindingFlags.NonPublic |
System.Reflection.BindingFlags.Instance |
System.Reflection.BindingFlags.IgnoreCase
);
foreach(System.Reflection.FieldInfo fi in fis)
{
if (fi.GetValue(this) is Control)
MessageBox.Show(fi.Name);
}
}
'VB
Private Function ControlFromName(ByVal name As String) As Control
Dim o As ObjectDim o As Object
o = Me.GetType().GetField(name, Reflection.BindingFlags.NonPublic Or _
Reflection.BindingFlags.Instance Or _
Reflection.BindingFlags.IgnoreCase).GetValue(Me)
Return (CType(o, Control))
End Function
Private Sub Form1_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
Dim c As ComboBox
c = CType(ControlFromName("_combobox1"), ComboBox)
c.Items.Add("1")
Me.GetControls()e.GetControls()
End Sub
Private Sub GetControls()
Dim fis As System.Reflection.FieldInfo()
fis = Me.GetType().GetFields(Reflection.BindingFlags.NonPublic Or _
Reflection.BindingFlags.Instance Or _
Reflection.BindingFlags.IgnoreCase)
For Each fi As Reflection.FieldInfo In fis
If TypeOf (fi.GetValue(Me)) Is Control Then
MessageBox.Show(fi.Name)
End Ifnd If
Next
End Sub
7.36. How do I detect the hardware directional pad buttons?
The hardware directional pad buttons can be detected through the standard key events by comparing the KeyCode from the KeyEventArgs parameter. //C#
protected override void OnKeyDown(KeyEventArgs e)
{
switch (e.KeyCode)
{
case Keys.Up:
MessageBox.Show("Up Key Pressed");
break;
case Keys.Down:
MessageBox.Show("Down Key Pressed");
break;
case Keys.Left:
MessageBox.Show("Left Key Pressed");
break;
case Keys.Right:
MessageBox.Show("Right Key Pressed");
break;
}
base.OnKeyDown (e);
}