关于屏幕保护程序的一个深难问题：

[Dynamic]

为什么我编写的屏幕保护程序在屏幕保护程序选项卡中被选中后不能自动展示其运行时的效果。。。（在那个小显示器上）

[TechnoFantasy]

系统调用屏幕保护会带参数的。具体的参数如下:
Public Sub Main()
If App.PrevInstance = True Then End
'Exit if the SS is already running.
If Left(Command$, 1) = "s" Or Right(Left(Command$, 2), 1) = "s" Then
frmSS.Show vbModal
'If the first or second character is "s" then show frmSS.
ElseIf Left(Command$, 1) = "c" Or Right(Left(Command$, 2), 1) = "c" Then
frmConfig.Show vbModal
'If the first or second character is "c" then show frmConfig.
ElseIf Left(Command$, 1) = "a" Or Right(Left(Command$, 2), 1) = "a" Then
MsgBox "No password protection is available."
'If the first or second character is "a" then show a message box telling the user there's no password protection.
ElseIf Left(Command$, 1) = "p" Or Right(Left(Command$, 2), 1) = "p" Then
End
'If the first or second character is "p" then end the program.
End If
End Sub

如果参数是 "c" 说明是在小窗口中显示。

[Jackyin]

TechnoFantasy，高

[yokel]

来晚了！
不过我用
If Left(Command$, 2) = "/s" Then……来判断的！

[Dynamic]

我的意思是不按"预览"...
只是在左边的组合框里选中"My Screen Saver 1.0"
好像"/c"只出现在按下"设置"之后.
"/s"只出现在按下"预览"之后.

[Dynamic]

我的意思是在选择屏保的列表框中选中我的屏保时，我怎么知道：

／c是在按了“设置“后。。。
／s是在按了“预览“后。。。

[TechnoFantasy]

我又在网上找了一下，上面的参数说明有误，"/p" 并不是系统要结束程序，而是
需要预览，在 /p 后面会跟预览窗口的位置以及大小，你只要在 "/p" 参数下
根据参数设定预览窗口的大小就可以了。下面是一个比较完整的屏幕保护启动的
模块，其中使用了不少API，但是主要的部分还是 读取参数->根据参数执行操作
你可以参考一下:

Attribute VB_Name = "Common"
Option Explicit

'Shows the mouse position
Public CurrentMouseX As Long
Public CurrentMouseY As Long

'Basic RECT structure, used for setting the parameters
'of the Screen Saver window
Public Type RECT
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type

'This will hold the display parameters for the screen
'saver
Public ScrSaverRect As RECT

'Device Mode type, will hold all the values for any
'given device (e.g. Display)
Private Type DEVMODE
dmDeviceName As String * 32
dmSpecVersion As Integer
dmDriverVersion As Integer
dmSize As Integer
dmDriverExtra As Integer
dmFields As Long
dmOrientation As Integer
dmPaperSize As Integer
dmPaperLength As Integer
dmPaperWidth As Integer
dmScale As Integer
dmCopies As Integer
dmDefaultSource As Integer
dmPrintQuality As Integer
dmColor As Integer
dmDuplex As Integer
dmYResolution As Integer
dmTTOption As Integer
dmCollate As Integer
dmFormName As String * 32
dmUnusedPadding As Integer
dmBitsPerPel As Long
dmPelsWidth As Long
dmPelsHeight As Long
dmDisplayFlags As Long
dmDisplayFrequency As Long
End Type

'This type will hold the value of a cursor position,
'it can be used to point to any single point on a
'display
Private Type POINTAPI
x As Long
y As Long
End Type

'Constants go here
Private Const SWP_SHOWWINDOW = &H40
Private Const HWND_TOP = 0
Private Const SWP_NOACTIVATE = &H10
Private Const SWP_NOZORDER = &H4
Private Const SWP_NOMOVE = &H2
Private Const SWP_NOSIZE = &H1

'These are used to set the preview as a child of the
'Control Panel's Display
Private Const GWL_HWNDPARENT = (-8)
Private Const GWL_STYLE = (-16)
Private Const WS_CHILD = &H40000000

'Used when first displaying the Screen Saver, will
'place frmMain as the highest zorder form.
Private Const HWND_TOPMOST = -1
Private Const SPI_SETSCREENSAVEACTIVE = 17
Private Const SPI_SCREENSAVERRUNNING = 97

'This will be used to retrieve the window parameters
'if the user wishes to see a screen saver preview
Private Declare Sub GetClientRect Lib "user32" _
(ByVal hwnd As Long, lpRect As RECT)

'This allows us to enable or disable ALL input to any
'window, this includes all keypresses and mouseclicks
Private Declare Function EnableWindow Lib "user32" _
(ByVal hwnd As Long, ByVal fEnable As Long) As Long

'This will tell us if any given window has mouse and
'keyboard inputs enabled (True or False returned)
Private Declare Function IsWindowEnabled Lib "user32" _
(ByVal hwnd As Long) As Long

'This returns the handle of the first window found that
'matches the class name and window name given
Private Declare Function FindWindow Lib "user32" _
Alias "FindWindowA" (ByVal lpClassName As String, _
ByVal lpWindowName As String) As Long

'This will be used to enable or disable the current
'Windows cursor
Private Declare Function ShowCursor Lib "user32" _
(ByVal bShow As Long) As Long

'This will return the current location of the cursor
Private Declare Sub GetCursorPos Lib "user32" (lpPoint _
As POINTAPI)

'Used to tell the system that a Screen Saver is now
'running on the system
Private Declare Sub SystemParametersInfo Lib _
"user32" Alias "SystemParametersInfoA" (ByVal _
uAction As Long, ByVal uParam As Long, ByRef _
lpvParam As Any, ByVal fuWinIni As Long)

'This function is used to connect to the Windows
'Registry
Private Declare Function RegConnectRegistry Lib _
"advapi32.dll" Alias "RegConnectRegistryA" _
(ByVal lpMachineName As String, ByVal hKey As _
Long, phkResult As Long) As Long

'Returns the handle to the Desktop Window. The desktop
'window covers the entire screen. The desktop window is
'the area on top of which all icons and other windows
'are painted.
Private Declare Function GetDesktopWindow Lib _
"user32" () As Long

'Used in the preview to make frmMain a child of the
'preview display window
Private Declare Sub SetParent Lib "user32" _
(ByVal hWndChild As Long, ByVal hWndNewParent _
As Long)

'Used to get any current style flags for any given
'window
Private Declare Function GetWindowLong Lib "user32" _
Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal _
nIndex As Long) As Long

'Used to set the style flags of the child window (the
'Screen Saver Preview)
Private Declare Sub SetWindowLong Lib "user32" _
Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal _
nIndex As Long, ByVal dwNewLong As Long)

'This is used to set the position of the window (frmMain)
'based on the parameters retrieved by the GetClientRect
'API call (See above)
Private Declare Sub SetWindowPos Lib "user32" _
(ByVal hwnd As Long, ByVal hWndInsertAfter As _
Long, ByVal x As Long, ByVal y As Long, ByVal cx _
As Long, ByVal cy As Long, ByVal wFlags As Long)

'This is used to create a device context for a specific
'device using the specified name (Display)
Private Declare Function CreateDC Lib "gdi32" Alias _
"CreateDCA" (ByVal lpDriverName As String, ByVal _
lpDeviceName As Variant, ByVal lpOutput As _
Variant, lpInitData As DEVMODE) As Long

'Bitblt here to transfer the current Windows Display
'to the image value of frmMain.
'If you are going to use this in your Screen Saver,
'SET IT TO PUBLIC
Private Declare Sub BitBlt Lib "gdi32" (ByVal _
hDestDC As Long, ByVal x As Long, ByVal y As _
Long, ByVal nWidth As Long, ByVal nHeight As _
Long, ByVal hSrcDC As Long, ByVal xSrc As Long, _
ByVal ySrc As Long, ByVal dwRop As Long)

'This procedure is called when the user clicks the
'change password button in the Screen Saver section
'of Control Panel. It handles all the password rules
'and write the encrypted password to the Registry
Private Declare Sub PwdChangePassword Lib "mpr.dll" _
Alias "PwdChangePasswordA" (ByVal lpcRegkeyname _
As String, ByVal hwnd As Long, ByVal uiReserved1 _
As Long, ByVal uiReserved2 As Long)

'This Function is called when the user does something
'which would normally disable a Screen Saver. If the
'user chose the password protection option, this will
'be called. It returns True if the user entered a
'correct password, or False if they exited the dialog
'(ESC Button). Incorrect passwords simply loop through
'and the user is asked to enter it again.
Private Declare Function VerifyScreenSavePwd Lib _
"password.cpl" (ByVal hwnd As Long) As Boolean
Public Sub Main()
Dim CommandLine As String

'First thing we do is check for previous instances
StartUp

'Now, based on the Command Line, do the appropriate
'command
CommandLine = UCase(Trim(Command$))

Select Case Left(CommandLine, 2)
Case "/S"
'This basically tells us to start up the
'screen saver in full screen mode
StartScreenSaver
Case ""
'This will probably happen if you are trying
'to run it through VB or if you execute the
'.SCR file
StartScreenSaver
Case "/P"
'This is the call for the preview
'The additional value is the handle to the
'object windows wishes you to draw to

'If statement used here in case a user with
'some idea of a Screen Saver tries to run
'their own command line argument without a
'handle; just keeps it from crashing
If Len(CommandLine) = 0 Then
StartScreenSaver
Else
StartScreenSaver Int(Mid(CommandLine, 4, Len(CommandLine)))
End If
Case "/A"
'This tells us that the user wishes to set
'a new password for the screen saver.
'Code courtesy of Marco Bellinaso from
'101 Tech Tips Vol. 10 from the VBPJ

'Windows also passes and additional message
'through this string, a number which I assume
'is a handle for the password box to link to

'The first string must be "SCRSAVE" because
'it is used by the function and will fail
'otherwise
PwdChangePassword "SCRSAVE", Int(Mid(CommandLine, 4, Len(CommandLine))), 0, 0
Case "/C"
'This is called if the user chose Settings
'from the Screen Saver Menu in Control
'Panel
'If you have any options for your Screen
'saver, add a call here, e.g.:
frmDialog.Show vbModal
End Select
End Sub


Private Sub StartScreenSaver(Optional ByVal targethWnd As Variant)
'This is where the Screen Saver begins from
'If a handle is passed, we will set the Screen
'Saver's size parameters to that of the preview
'display, otherwise, we will be setting it to
'that of the Desktop Window

'Used to set window styles
Dim WindowStyle As Long
'Temporary variable used in the SPI to disable
'system keys
Dim TempBoolean As Boolean
'Used to get various values pertaining to the
'Windows Task Bar
Dim Taskbar As Long, TaskbarhWnd As Long, TaskBarEnabled As Integer

If IsMissing(targethWnd) Then
'Regular mode
frmMain.Caption = "SCREEN SAVER"

'Get the desktop's size, used to set the
'window's size
GetClientRect GetDesktopWindow, ScrSaverRect

'Show the Screen Saver
SetWindowPos frmMain.hwnd, 0, 0, 0, ScrSaverRect.Right, ScrSaverRect.Bottom, SWP_SHOWWINDOW

'Make the cursor dissapear
ShowCursor False

'Initialize these two mouse variables, used in
'the shut down procedure
CurrentMouseX = 0
CurrentMouseY = 0

'Send a message telling Windows that a Screen
'Saver is now active
SystemParametersInfo SPI_SETSCREENSAVEACTIVE, 0, ByVal 0&, 0

'Disable System Keys
SystemParametersInfo SPI_SCREENSAVERRUNNING, True, TempBoolean, 0

'Disable the system taskbar
TaskbarhWnd = FindWindow("Shell_traywnd", "")

'If you're not getting a handle, you have some
'hardcore system problems to work through.
'Nonetheless, here is a bit of error trapping
If TaskbarhWnd <> 0 Then
TaskBarEnabled = IsWindowEnabled(TaskbarhWnd)

'Check if the Task bar is already disabled
If TaskBarEnabled = 1 Then
Taskbar = EnableWindow(TaskbarhWnd, 0)
End If
End If
Else
'Preview mode
frmMain.Caption = "PREVIEW"
GetClientRect targethWnd, ScrSaverRect


'Pull the current style of frmMain
WindowStyle = GetWindowLong(frmMain.hwnd, GWL_STYLE)

'Next, add an or value to allow you to do a
'switch between the previous style and WS_CHILD
WindowStyle = WindowStyle Or WS_CHILD

'Now we'll switch the style over to thew new
'style (WS_CHILD)
SetWindowLong frmMain.hwnd, GWL_STYLE, WindowStyle

'Set the preview window as frmMain's parent
SetParent frmMain.hwnd, targethWnd

'Set the Display to be a parent window
SetWindowLong frmMain.hwnd, GWL_HWNDPARENT, targethWnd

'Show the Preview
SetWindowPos frmMain.hwnd, HWND_TOP, 0, 0, ScrSaverRect.Right, ScrSaverRect.Bottom, SWP_NOZORDER Or SWP_NOACTIVATE Or SWP_SHOWWINDOW
End If
End Sub

Public Sub EraseBackground()
'If you want to make your Screen Saver's background
'that of windows at this moment, uncomment the next
'line:
'DesktopWindow

'Otherwise, set the background of frmMain (Picture
'or Background, depending on whether the background
'is a colour or a picture)
frmMain.BackColor = vbWhite
End Sub

Private Sub DesktopWindow()
'I still can't quite get this Sub Procedure to
'work. If you know of a way to pull the current
'Desktop's image, please get in touch with me

'This will hold the value of the current Display
'Device Context
Dim ScreenDC As Long
Dim DisplayMode As DEVMODE

'Get the Display Device Context
ScreenDC = CreateDC("DISPLAY" & Chr(0), 0, 0, DisplayMode)

'Transfer the Display DC to frmmain.Picture
BitBlt frmMain.hdc, 0, 0, (Screen.Width / Screen.TwipsPerPixelX), (Screen.Height / Screen.TwipsPerPixelY), ScreenDC, 0, 0, vbSrcCopy
End Sub

Public Sub ShutDown()
'Used to check the current mode (Regular or Preview)
Dim CurrentDesktopRect As RECT
'Will tell us whether or not a correct password
'was entered
Dim CorrectPassword As Boolean
'Used in the SPI call to enable system keys, not
'used for anything else
Dim TempBoolean As Boolean
'Used to get the handle and status of the Task Bar
Dim Taskbar As Long, TaskbarhWnd As Long
'Holds the current cursor position
Dim MousePos As POINTAPI
'Used to shutdown all forms
Dim FRM As Form

'First we check to make sure we are running in
'regular mode
GetClientRect GetDesktopWindow, CurrentDesktopRect

'Only in regular mode will the Screen Saver's rect
'structure be equal to that of the Current Desktop
If Not (ScrSaverRect.Right = CurrentDesktopRect.Right) Then
Exit Sub
End If

'This will allow one grace move
GetCursorPos MousePos

If (CurrentMouseX = 0) And (CurrentMouseY = 0) Then
'Exit if this is just the first move
CurrentMouseX = MousePos.x
CurrentMouseY = MousePos.y
Exit Sub
End If

'Pause all Screen Saver Activities
frmMain.Timer1.Enabled = False

'Show the cursor
ShowCursor True

'Now make them enter the password
CorrectPassword = VerifyScreenSavePwd(frmMain.hwnd)

'If it is correct, shut down, otherwise, reset
If CorrectPassword = False Then
'Reset everything

'Diable the form or it will trap a MouseMove
'Event again
frmMain.Enabled = False

'Reset cursor variables
CurrentMouseX = 0
CurrentMouseY = 0

'Hide cursor
ShowCursor False

'Enable Screen Saver
frmMain.Enabled = True

'Restart events
frmMain.Timer1.Enabled = True

Exit Sub
End If

'Tell the system that the Screen Saver is shutting
'down
SystemParametersInfo SPI_SETSCREENSAVEACTIVE, 1, ByVal 0&, 0

'Enable the system taskbar
TaskbarhWnd = FindWindow("Shell_traywnd", "")

If TaskbarhWnd <> 0 Then
Taskbar = EnableWindow(TaskbarhWnd, 1)
End If

'Enable System Keys
SystemParametersInfo SPI_SCREENSAVERRUNNING, False, TempBoolean, 0

'Clear whatever forms you may have opened
For Each FRM In Forms
Unload FRM
Next

End
End Sub

Private Sub StartUp()
'If App.PrevInstance = True Then End
End Sub

[Dynamic]

Thank TechnoFantasy(www.applevb.com), 我给你加分了。