threads.cls

用VB写“多线程”程序.

VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
END
Attribute VB_Name = "clsThreads"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = True
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Option Explicit
Option Compare Text
Option Base 0

Private Type udtThread
    Handle As Long
    Enabled As Boolean
End Type

Private uThread As udtThread

Private Const CREATE_SUSPENDED As Long = &H4
Private Const THREAD_BASE_PRIORITY_IDLE  As Long = -15
Private Const THREAD_BASE_PRIORITY_LOWRT  As Long = 15
Private Const THREAD_BASE_PRIORITY_MAX As Long = 2
Private Const THREAD_BASE_PRIORITY_MIN As Long = -2
Private Const THREAD_PRIORITY_HIGHEST  As Long = THREAD_BASE_PRIORITY_MAX
Private Const THREAD_PRIORITY_LOWEST  As Long = THREAD_BASE_PRIORITY_MIN
Private Const THREAD_PRIORITY_ABOVE_NORMAL As Long = (THREAD_PRIORITY_HIGHEST - 1)
Private Const THREAD_PRIORITY_BELOW_NORMAL  As Long = (THREAD_PRIORITY_LOWEST + 1)
Private Const THREAD_PRIORITY_IDLE  As Long = THREAD_BASE_PRIORITY_IDLE
Private Const THREAD_PRIORITY_NORMAL As Long = 0
Private Const THREAD_PRIORITY_TIME_CRITICAL As Long = THREAD_BASE_PRIORITY_LOWRT

Private Declare Function CreateThread Lib "Kernel32" (ByVal lpThreadAttributes As Any, ByVal dwStackSize As Long, ByVal lpStartAddress As Long, lpParameter As Any, ByVal dwCreationFlags As Long, lpThreadId As Long) As Long
Private Declare Function ResumeThread Lib "Kernel32" (ByVal hThread As Long) As Long
Private Declare Function SetThreadPriority Lib "Kernel32" (ByVal hThread As Long, ByVal nPriority As Long) As Long
Private Declare Function GetThreadPriority Lib "Kernel32" (ByVal hThread As Long) As Long
Private Declare Function SuspendThread Lib "Kernel32" (ByVal hThread As Long) As Long
Private Declare Function TerminateThread Lib "Kernel32" (ByVal hThread As Long, ByVal dwExitCode As Long) As Long
Public Sub Initialize(ByVal lpfnBasFunc As Long)

Dim lStackSize As Long, lCreationFlags As Long, lpThreadId As Long, lNull As Long
    
On Error Resume Next
lNull = 0
lStackSize = 0
lCreationFlags = CREATE_SUSPENDED
uThread.Handle = CreateThread(lNull, lStackSize, lpfnBasFunc, lNull, lCreationFlags, lpThreadId)
If uThread.Handle = lNull Then MsgBox "Create thread failed!"
    
End Sub
Public Property Get Enabled() As Boolean
    
On Error Resume Next
Enabled = uThread.Enabled

End Property
Public Property Let Enabled(ByVal vNewValue As Boolean)
    
On Error Resume Next
If vNewValue And (Not uThread.Enabled) Then
    ResumeThread uThread.Handle
    uThread.Enabled = True
ElseIf uThread.Enabled Then
    SuspendThread uThread.Handle
    uThread.Enabled = False
End If

End Property
Public Property Get Priority() As Long

On Error Resume Next
Priority = GetThreadPriority(uThread.Handle)

End Property
Public Property Let Priority(ByVal vNewValue As Long)

On Error Resume Next
If vNewValue = -2 Then
    Call SetThreadPriority(uThread.Handle, THREAD_PRIORITY_LOWEST)
ElseIf vNewValue = -1 Then
    Call SetThreadPriority(uThread.Handle, THREAD_PRIORITY_BELOW_NORMAL)
ElseIf vNewValue = 0 Then
    Call SetThreadPriority(uThread.Handle, THREAD_PRIORITY_NORMAL)
ElseIf vNewValue = 1 Then
    Call SetThreadPriority(uThread.Handle, THREAD_PRIORITY_ABOVE_NORMAL)
ElseIf vNewValue = 2 Then
    Call SetThreadPriority(uThread.Handle, THREAD_PRIORITY_HIGHEST)
End If

End Property
Private Sub Class_Terminate()

On Error Resume Next
Call TerminateThread(uThread.Handle, 0)

End Sub