'clsThreading:
'Simple class that allows you to implement multithreading in your app
'
'(C) 2001 by Philipp Weidmann
'API Declarations
'Creates a new thread
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
'Terminates a thread
Private Declare Function TerminateThread Lib "kernel32" (ByVal hThread As Long, ByVal dwExitCode As Long) As Long
'Sets the priority of a thread
Private Declare Function SetThreadPriority Lib "kernel32" (ByVal hThread As Long, ByVal nPriority As Long) As Long
'Returns the proirity of a thread
Private Declare Function GetThreadPriority Lib "kernel32" (ByVal hThread As Long) As Long
'Enables a disabled Thread
Private Declare Function ResumeThread Lib "kernel32" (ByVal hThread As Long) As Long
'Disables a thread
Private Declare Function SuspendThread Lib "kernel32" (ByVal hThread As Long) As Long
'Returns the handle of the current thread
Private Declare Function GetCurrentThread Lib "kernel32" () As Long
'Returns the ID of the current thread
Private Declare Function GetCurrentThreadId Lib "kernel32" () As Long
'Consts
Private Const MAXLONG = &H7FFFFFFF
'Thread priority consts
Private Const THREAD_BASE_PRIORITY_IDLE = -15
Private Const THREAD_BASE_PRIORITY_LOWRT = 15
Private Const THREAD_BASE_PRIORITY_MAX = 2
Private Const THREAD_BASE_PRIORITY_MIN = -2
Private Const THREAD_PRIORITY_HIGHEST = THREAD_BASE_PRIORITY_MAX
Private Const THREAD_PRIORITY_LOWEST = THREAD_BASE_PRIORITY_MIN
Private Const THREAD_PRIORITY_ABOVE_NORMAL = (THREAD_PRIORITY_HIGHEST - 1)
Private Const THREAD_PRIORITY_BELOW_NORMAL = (THREAD_PRIORITY_LOWEST + 1)
Private Const THREAD_PRIORITY_ERROR_RETURN = (MAXLONG)
Private Const THREAD_PRIORITY_IDLE = THREAD_BASE_PRIORITY_IDLE
Private Const THREAD_PRIORITY_NORMAL = 0
Private Const THREAD_PRIORITY_TIME_CRITICAL = THREAD_BASE_PRIORITY_LOWRT
'Thread creation flags
Private Const CREATE_ALWAYS = 2
Private Const CREATE_NEW = 1
Private Const CREATE_NEW_CONSOLE = &H10
Private Const CREATE_NEW_PROCESS_GROUP = &H200
Private Const CREATE_NO_WINDOW = &H8000000
Private Const CREATE_PROCESS_DEBUG_EVENT = 3
Private Const CREATE_SUSPENDED = &H4
Private Const CREATE_THREAD_DEBUG_EVENT = 2
'Types and Enums
Public Enum ThreadPriority
tpLowest = THREAD_PRIORITY_LOWEST
tpBelowNormal = THREAD_PRIORITY_BELOW_NORMAL
tpNormal = THREAD_PRIORITY_NORMAL
tpAboveNormal = THREAD_PRIORITY_ABOVE_NORMAL
tpHighest = THREAD_PRIORITY_HIGHEST
End Enum
'Vars
Private mThreadHandle As Long
Private mThreadID As Long
Private mPriority As Long
Private mEnabled As Boolean
Private mCreated As Boolean
Private mID As Long
Public Function CreateNewThread(ByVal iDownloader As Long, ByVal cFunction As Long, Optional ByVal cPriority As Long = tpNormal, Optional ByVal cEnabled As Boolean = True)
'Creates a new Thread
Dim mHandle As Long
Dim CreationFlags As Long
Dim lpThreadID As Long
'Look if the thread has already been created
If mCreated = True Then Exit Function
'Look if the thread should be enabled
If cEnabled = True Then
CreationFlags = 0
Else
'Create a disabled thread, can be enabled later with the
''Enabled' property
CreationFlags = CREATE_SUSPENDED
End If
'The CreateThread Function returns the handle of the created thread;
'if the handle is 0, it failed creating the thread
mHandle = CreateThread(ByVal 0&, ByVal 0&, cFunction, ByVal 0&, CreationFlags, lpThreadID)
If mHandle = 0 Then 'Failed creating the thread
'Insert your own error handling
'Debug.Print "InitializeThread Function in clsThreading failed creating a new thread"
Else
mThreadHandle = mHandle
mThreadID = lpThreadID
mCreated = True
mID = iDownloader
End If
End Function
Public Property Get iDownloader() As Long
iDownloader = mID
End Property
Public Function TerminateCurrentThread()
'Terminates the current thread
'Ignore errors to prevent crashing if no thread has been created
On Error Resume Next
'Terminate the thread to prevent crashing if the app is closed
'and the thread is still running (dangerous!)
Call TerminateThread(mThreadHandle, ByVal 0&)
mCreated = False
End Function
Public Property Get ThreadHandle() As Long
'Returns the Handle of the current Thread
ThreadHandle = mThreadHandle
End Property
Public Property Get ThreadID() As Long
'Returns the ID of the current thread
ThreadID = mThreadID
End Property
Public Property Get Priority() As Long
'Returns a long value because the thread might have other priorities
'than our five in the enum
'Ignore errors to prevent crashing if no thread has been created
On Error Resume Next
Priority = GetThreadPriority(mThreadHandle)
End Property
Public Property Let Priority(ByVal tmpValue As Long)
'Sets the Thread Priority of the actual thread
mPriority = tmpValue
Call SetThreadPriority(mThreadHandle, tmpValue)
End Property
Public Property Get Enabled() As Boolean
'Returns whether the Thread is enabled or not
Enabled = mEnabled
End Property
Public Property Let Enabled(ByVal tmpValue As Boolean)
'Enables/Disables the Thread
'Ignore errors to prevent crashing if no thread has been created
On Error Resume Next
If tmpValue = True Then
'Enable the thread
Call ResumeThread(mThreadHandle)
ElseIf tmpValue = False Then
'Disable the thread
Call SuspendThread(mThreadHandle)
End If
End Property
Private Sub Class_Terminate()
'Terminate the thread to prevent crashing if the app is closed
'and the thread is still running (dangerous!)
Call TerminateCurrentThread
End Sub
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