[英]VB.NET Imports without project name
我的表格僅在使用時有效
Imports WindowsApplication1.FrameGrabber
但是當我使用
Imports FrameGrabber
我將在幾個不同的項目中使用FrameGrabber,所以我真的更願意只說“導入FrameGrabber”。
我的“ FrameGrabber / CameraWindow”的定義如下:
Imports System.Collections
Imports System.ComponentModel
Imports System.Drawing
Imports System.Data
Imports System.Windows.Forms
Imports System.Threading
Namespace FrameGrabber
''' <summary>
''' Summary description for CameraWindow.
''' </summary>
Public Class CameraWindow
Inherits System.Windows.Forms.Control
Private m_camera As Camera = Nothing
Private m_autosize As Boolean = False
Private needSizeUpdate As Boolean = False
Private firstFrame As Boolean = True
' AutoSize property
<DefaultValue(False)> _
Public Overrides Property AutoSize() As Boolean
Get
Return m_autosize
End Get
Set(value As Boolean)
m_autosize = value
UpdatePosition()
End Set
End Property
' Camera property
<Browsable(False)> _
Public Property Camera() As Camera
Get
Return m_camera
End Get
Set(value As Camera)
' lock
Monitor.Enter(Me)
' detach event
If m_camera IsNot Nothing Then
RemoveHandler m_camera.NewFrame, AddressOf Me.pCameraWindow_NewFrame
End If
m_camera = value
needSizeUpdate = True
firstFrame = True
' atach event
If m_camera IsNot Nothing Then
AddHandler m_camera.NewFrame, AddressOf Me.pCameraWindow_NewFrame
End If
' unlock
Monitor.[Exit](Me)
End Set
End Property
' Constructor
Public Sub New()
InitializeComponent()
SetStyle(ControlStyles.AllPaintingInWmPaint Or ControlStyles.DoubleBuffer Or ControlStyles.ResizeRedraw Or ControlStyles.UserPaint, True)
End Sub
#Region "Windows Form Designer generated code"
Private Sub InitializeComponent()
Me.SuspendLayout()
Me.ResumeLayout(False)
End Sub
#End Region
' Paint control
Protected Overrides Sub OnPaint(pe As PaintEventArgs)
If (needSizeUpdate) OrElse (firstFrame) Then
UpdatePosition()
needSizeUpdate = False
End If
' lock
Monitor.Enter(Me)
Dim g As Graphics = pe.Graphics
Dim rc As Rectangle = Me.ClientRectangle
If m_camera IsNot Nothing Then
Try
m_camera.Lock()
' draw frame
If m_camera.LastFrame IsNot Nothing Then
g.DrawImage(m_camera.LastFrame, rc.X + 1, rc.Y + 1, rc.Width - 2, rc.Height - 2)
firstFrame = False
Else
' Create font and brush
Dim drawFont As New Font("Arial", 12)
Dim drawBrush As New SolidBrush(Color.White)
g.DrawString("Connecting ...", drawFont, drawBrush, New System.Drawing.PointF(5, 5))
drawBrush.Dispose()
drawFont.Dispose()
End If
Catch generatedExceptionName As Exception
Finally
m_camera.Unlock()
End Try
End If
' unlock
Monitor.[Exit](Me)
MyBase.OnPaint(pe)
End Sub
Public Function getImage() As Image
If Not m_camera Is Nothing Then
If Not m_camera.LastFrame Is Nothing Then
Return m_camera.LastFrame
End If
End If
Return Nothing
End Function
' Update position and size of the control
Public Sub UpdatePosition()
' lock
Monitor.Enter(Me)
If (m_autosize) AndAlso (Me.Parent IsNot Nothing) Then
Dim rc As Rectangle = Me.Parent.ClientRectangle
Dim width As Integer = 320
Dim height As Integer = 240
If m_camera IsNot Nothing Then
m_camera.Lock()
' get frame dimension
If m_camera.LastFrame IsNot Nothing Then
width = m_camera.LastFrame.Width
height = m_camera.LastFrame.Height
End If
m_camera.Unlock()
End If
'
Me.SuspendLayout()
Me.Location = New Point((rc.Width - width - 2) \ 2, (rc.Height - height - 2) \ 2)
Me.Size = New Size(width + 2, height + 2)
Me.ResumeLayout()
End If
' unlock
Monitor.[Exit](Me)
End Sub
' On new frame ready
Private Sub pCameraWindow_NewFrame(sender As Object, e As System.EventArgs)
Invalidate()
End Sub
End Class
End Namespace
感謝您的幫助!
您需要為您的項目更改Root命名空間或對其進行覆蓋。 當您將類包裝在Namespace
塊(例如Namespace FrameGrabber
)中時,給定的名稱空間是相對於項目的根名稱空間的。 換句話說,如果您的根命名空間是WindowsApplication1
,那么當您說Namespace FrameGrabber
,所有包含的類型實際上將在WindowsApplication1.FrameGrabber
命名空間中。
如果要覆蓋一段代碼的根名稱空間,則可以使用Global
關鍵字,以便命名空間聲明不是相對的,如下所示:
Namespace Global.FrameGrabber
' ...
End Namespace
像這樣,在名稱空間聲明中使用Global
關鍵字來覆蓋根名稱空間似乎是VB.NET的新增功能。 據我所知,基於MSDN文章中有關該信息的信息,Visual Studio 2012中已添加了對此信息的支持。您還可以在此MSDN文章中找到有關此信息:
Global關鍵字也可以在命名空間語句中使用。 這使您可以在項目的根名稱空間之外定義名稱空間。 有關更多信息,請參見Visual Basic中命名空間中的“命名空間語句中的全局關鍵字”部分。
另一個選擇是從項目屬性中刪除根名稱空間,然后在項目中的每個代碼文件上聲明完整的名稱空間。 該設置可以在項目設置設計器屏幕中找到: 我的項目 > 應用程序 > 根名稱空間 。
要么這樣做,要么提出更有利於VB.NET怪異性的命名約定。 例如,如果將項目的根名稱空間用作公司名稱,那么MyCompany.FrameGrabber
當然比WindowsApplication1.FrameGrabber
更有意義。
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