我尝试编写一个将自己绘制在控件上的类(.NET )。但是这个“东西”不能正确地重绘自己(不会使其父母无效)。在.NET中绘制矩形
这里的用法:
Public Class Form1
Dim myCadre As New Cadre
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
For i As Integer = 0 To 100
myCadre.Location = New Point(myCadre.Location.X + 1, myCadre.Location.Y + 1)
System.Threading.Thread.Sleep(500)
Next i
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
myCadre.Location = New Point(10, 10)
myCadre.Size = New Size(60, 90)
myCadre.Parent = Me
End Sub
End Class
下面是代码:
Public Class Cadre
Private _Rectangle As Rectangle
Private _Parent As Control
Public Event ParentChanged As EventHandler
Private _Location As Point
Public ReadOnly Property DisplayRectangle() As Rectangle
Get
Return _Rectangle
End Get
End Property
Public Property Location() As Point
Get
Return _Rectangle.Location
End Get
Set(ByVal value As Point)
_Rectangle.Location = value
DrawInternal()
End Set
End Property
Public Property Size() As Size
Get
Return _Rectangle.Size
End Get
Set(ByVal value As Size)
_Rectangle.Size = value
DrawInternal()
End Set
End Property
Public Property Parent() As Control
Get
Return _Parent
End Get
Set(ByVal value As Control)
If _Parent IsNot value Then
_Parent = value
OnParentChanged(Me, EventArgs.Empty)
End If
End Set
End Property
Overridable Sub OnParentChanged(ByVal sender As Object, ByVal e As EventArgs)
DrawInternal()
RaiseEvent ParentChanged(sender, e)
End Sub
Private Sub DrawInternal()
If _Parent Is Nothing Then Return
Dim g As Graphics = _Parent.CreateGraphics()
g.DrawRectangle(Pens.Black, Me._Rectangle)
End Sub
End Class
- 我做错了吗?
- 更好的是:使用
private Graphic g
和 设置它,只有当父母换一次, 或创建g
每DrawInternal
? - 是否有可能有
Click
事件?
干部V2(后温贝托建议):
Public Class Cadre
Private _FormerRectangle As Rectangle
Private _Rectangle As Rectangle
Private WithEvents _Parent As Control
Public Event ParentChanged As EventHandler
Private _Location As Point
Public Sub New()
_FormerRectangle = New Rectangle
_Rectangle = _FormerRectangle
End Sub
Private Sub DrawInternal(ByVal sender As Object, ByVal e As PaintEventArgs) Handles _Parent.Paint
If _FormerRectangle <> _Rectangle Then
_Parent.Invalidate(_FormerRectangle, False) ' !!! does not work '
End If
e.Graphics.DrawRectangle(Pens.Black, Me._Rectangle)
_FormerRectangle = Me._Rectangle
End Sub
Public ReadOnly Property DisplayRectangle() As Rectangle
Get
Return _Rectangle
End Get
End Property
Public Property Location() As Point
Get
Return _Rectangle.Location
End Get
Set(ByVal value As Point)
_Rectangle.Location = value
End Set
End Property
Public Property Size() As Size
Get
Return _Rectangle.Size
End Get
Set(ByVal value As Size)
_Rectangle.Size = value
End Set
End Property
Public Property Parent() As Control
Get
Return _Parent
End Get
Set(ByVal value As Control)
If _Parent IsNot value Then
_Parent = value
OnParentChanged(Me, EventArgs.Empty)
End If
End Set
End Property
Overridable Sub OnParentChanged(ByVal sender As Object, ByVal e As EventArgs)
RaiseEvent ParentChanged(sender, e)
End Sub
End Class
EDIT3
位置示例:
Public Property Location() As Point
Get
Return _Rectangle.Location
End Get
Set(ByVal value As Point)
If _Parent IsNot Nothing Then
_Parent.Invalidate(_Rectangle, False) ' 1st Call with former '
End If
_Rectangle.Location = value
If _Parent IsNot Nothing Then
_Parent.Invalidate(_Rectangle, False) ' 2nd Call with new '
_Parent.Update()
End If
End Set
End Property
不工作...
我认为你在错误的时间无效。让系统为你调用Paint(),并通过Parent.Invalidate()和Parent.Update()来控制系统。此场景运行后,添加功能并测试性能。 – Humberto 2010-06-14 14:12:27
@Humberto:那么,我应该在哪里调用Invalidate + Update? – serhio 2010-06-14 14:15:03
在干部状态发生变化时调用它们 - “位置”和“大小”属性。 – Humberto 2010-06-14 14:19:19