DoEvents
bRestore = True
Loop
DoEvents
If bRestore Then
bRestore = False
Ddraw.RestoreAllSurfaces
End If
DDSBack.Lock AlphaRect, DDSBackDesc, DDLOCK_WAIT, 0
DDSBack.GetLockedArray Pict()
For Y = 0 To 479
Pict(0, Y) = 0
Pict(639, Y) = 0
Next
For X = 0 To 639
Pict(X, 477) = Rnd * 220 + 35
Pict(X, 478) = Rnd * 220 + 35
Pict(X, 479) = Rnd * 220 + 35
Next
Accum = 0
For X = 1 To 638
For Y = 0 To 477
Accum = (Accum + Pict(X, Y + 1) + Pict(X, Y + 2) _
+ Pict(X + 1, Y + 1) + Pict(X - 1, Y + 1)) \ 5
If Accum < 0 Then
Accum = 0
ElseIf Accum > 255 Then
Accum = 255
End If
Pict(X, Y) = Accum
Next
Next
For X = 0 To 639
Pict(X, 0) = 0
Pict(X, 1) = 0
Next
X = Rnd * 639
For Y = 50 To 439
Next
''''Unlock
DDSBack.Unlock AlphaRect
If DX.TickCount() - lastTime > wait Then
If Counter = 0 Then
bDrawText = True
Counter = 1
Xpos = Rnd * 200
Ypos = 300 + Rnd * 140
wait = 400
ElseIf Counter = 1 Then
MsgIndex = MsgIndex + 1
If MsgIndex > 5 Then MsgIndex = 0
bDrawText = False
Counter = 0
wait = 2000
End If
lastTime = DX.TickCount
End If
''''Draw Text to the backbuffer
If bDrawText Then
On Error Resume Next
DDSBack.DrawText Xpos, Ypos, Msg(MsgIndex), False
On Error GoTo 0
End If
MainForm.Form_Paint
Wend
TerminateDX
End
End Sub
Function ExModeActive() As Boolean
Dim TestCoopRes As Long
TestCoopRes = Ddraw.TestCooperativeLevel
Select Case TestCoopRes
Case DDERR_NOEXCLUSIVEMODE
ExModeActive = False
Case DD_OK
ExModeActive = True
End Select
End Function
Public Sub InitializeDX()
MainForm.Left = 0
MainForm.Top = 0
MainForm.Height =640 * Screen.TwipsPerPixelY
MainForm.Width = 480 * Screen.TwipsPerPixelX
MainForm.Show
''''建立DirectDraw对象
Set Ddraw = DX.DirectDrawCreate("")
''''设定DirectDraw对象的协作层
Ddraw.SetCooperativeLevel MainForm.hWnd, DDSCL_EXCLUSIVE Or DDSCL_FULLSCREEN '''' DDSCL_NORMAL
''''设定显示模式位640×480×8位颜色
Ddraw.SetDisplayMode 640, 480, 8, 0, DDSDM_DEFAULT
''''设定DDSFrontDesc为主平面
With DDSFrontDesc
.lFlags = DDSD_CAPS
.ddsCaps.lCaps = DDSCAPS_PRIMARYSURFACE ''''Or DDSCAPS_SYSTEMMEMORY
End With
''''设定DDSBackDesc为后台缓冲平面
With DDSBackDesc
.ddsCaps.lCaps = DDSCAPS_SYSTEMMEMORY
.lFlags = DDSD_CAPS Or DDSD_WIDTH Or DDSD_HEIGHT
.lWidth = 640
.lHeight = 480
End With
''''建立平面
Set DDSFront = Ddraw.CreateSurface(DDSFrontDesc)
Set DDSBack = Ddraw.CreateSurface(DDSBackDesc)
Set Clipper = Ddraw.CreateClipper(0)
Clipper.SetHWnd MainForm.hWnd
DDSFront.SetClipper Clipper
DDSBack.SetClipper Clipper
DoEvents
Exit Sub
ERRoUT:
If Not (Ddraw Is Nothing) Then
Ddraw.RestoreDisplayMode
Ddraw.SetCooperativeLevel MainForm.hWnd, DDSCL_NORMAL
DoEvents
End If
MsgBox “无法对DirectDraw进行初始化 ”＋Chr(13)＋“也许你的显示卡不支持 640×480×8 显示模式 ”
End
End Sub
Public Sub TerminateDX()
''''子程序TerminateDX回复原来的显示模式并且释放所有的DirectDraw有关对象
Ddraw.RestoreDisplayMode
Ddraw.SetCooperativeLevel MainForm.hWnd, DDSCL_NORMAL
DoEvents
Set Clipper = Nothing
Set DDSBack = Nothing
Set DDSFront = Nothing
Set Ddraw = Nothing
Set DX = Nothing
End Sub
在工程文件中再加入一个Module，这个Module主要定义与图像保存相关的操作，在建立的Module中加入以下代码：
Option Explicit
Option Base 0
Private Type PALETTEENTRY
peRed As Byte
peGreen As Byte
peBlue As Byte
peFlags As Byte
End Type
Private Type LOGPALETTE
palVersion As Integer
palNumEntries As Integer
palPalEntry(255) As PALETTEENTRY '''' Enough for 256 colors.
End Type
Private Type GUID
Data1 As Long
Data2 As Integer
Data3 As Integer
Data4(7) As Byte
End Type
Private Const RASTERCAPS As Long = 38
Private Const RC_PALETTE As Long = &H100
Private Const SIZEPALETTE As Long = 104
Private Declare Function CreateCompatibleDC Lib "GDI32" (ByVal hDC As Long) As Long
Private Declare Function CreateCompatibleBitmap Lib "GDI32" (ByVal hDC As Long, ByVal nWidth As Long, ByVal nHeight As Long) As Long
Private Declare Function GetDeviceCaps Lib "GDI32" (ByVal hDC As Long, ByVal iCapabilitiy As Long) As Long
Private Declare Function GetSystemPaletteEntries Lib "GDI32" (ByVal hDC As Long, ByVal wStartIndex As Long, ByVal wNumEntries As Long, lpPaletteEntries As PALETTEENTRY) As Long
Private Declare Function CreatePalette Lib "GDI32" (lpLogPalette As LOGPALETTE) As Long
Private Declare Function SelectObject Lib "GDI32" (ByVal hDC As Long, ByVal hObject As Long) As Long
Private Declare Function BitBlt Lib "GDI32" (ByVal hDCDest As Long, ByVal Xdest As Long, ByVal Ydest As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hdcSrc As Long, ByVal XSrc As Long, ByVal Ysrc As Long, ByVal dwRop As Long) As Long
Private Declare Function DeleteDC Lib "GDI32" (ByVal hDC As Long) As Long
Private Declare Function GetForegroundWindow Lib "USER32" () As Long
Private Declare Function SelectPalette Lib "GDI32" (ByVal hDC As Long, ByVal hPalette As Long, ByVal bForceBackground As Long) As Long
Private Declare Function RealizePalette Lib "GDI32" (ByVal hDC As Long) As Long
Private Declare Function GetWindowDC Lib "USER32" (ByVal hWnd As Long) As Long
Private Declare Function GetDC Lib "USER32" (ByVal hWnd As Long) As Long
Private Declare Function GetWindowRect Lib "USER32" (ByVal hWnd As Long, lpRect As RECT) As Long
Private Declare Function ReleaseDC Lib "USER32" (ByVal hWnd As Long, ByVal hDC As Long) As Long
Private Declare Function GetDesktopWindow Lib "USER32" () As Long
Private Type PicBmp
Size As Long
Type As Long
hBmp As Long
hPal As Long
Reserved As Long
End Type
Private Declare Function OleCreatePictureIndirect Lib “olepro32.dll” (PicDesc As PicBmp, RefIID As GUID, ByVal fPictureOwnsHandle As Long, Ipic As Ipicture) As Long
Public Function SaveTohBmp(ByVal hdcSrc As Long, ByVal LeftSrc As Long, ByVal TopSrc As Long, ByVal WidthSrc As Long, ByVal HeightSrc As Long) As Picture
Dim hDCMemory As Long
Dim hBmp As Long
Dim hBmpPrev As Long
Dim r As Long
Dim hPal As Long
Dim hPalPrev As Long
Dim RasterCapsScrn As Long
Dim HasPaletteScrn As Long
Dim PaletteSizeScrn As Long
Dim LogPal As LOOGPALETTE
''''建立一个内存图形设备句柄
hDCMemory=CreateCompatibleDC(hdcSrc)
''''建立一个bitmap并保存到hDCMemory中
hBmp = CreateCompatibleBitmap(hdcSrc, WidthSrc, HeightSrc)
hBmpPrev = SelectObject(hDCMemory, hBmp)
'''' Get screen properties.
RasterCapsScrn = GetDeviceCaps(hdcSrc, RASTERCAPS) ''''Raste capabilities.
HasPaletteScrn = RasterCapsScrn And RC_PALtTTEic1 '''' Palette support.
PaletteSizeScrn = GetDeviceCaps(hdcSrc, SIZEPALETTE) '''' Size of palette.
If HasPaletteScrn And (PaletteSizeScrn = 256) Then
''''建立系统调色板的拷贝
LogPal.palVersion = &H300
LogPal.palNumEntries = 256
r = GetSystemPaletteEntries(hdcSrc, 0, 256, LogPal.palPalEntry(0))
hPal = CreatePalette(LogPal)
hPalPrev = SelectPalette(hDCMemory, hPal, 0)
r = RealizePalette(hDCMemory)
End If
''''将屏幕图形拷贝到内存图形设备句柄中
r = BitBlt(hDCMemory, 0, 0, WidthSrc, HeightSrc, hdcSrc, LeftSrc, TopSrc, vbSrcCopy)
hBmp = SelectObject(hDCMemory, hBmpPrev)
If HasPaletteScrn And (PaletteSizeScrn = 256) Then
hPal = SelectPalette(hDCMemory, hPalPrev, 0)
End If
''''释放图形设备句柄
r = DeleteDC(hDCMemory)
Debug.Print r
''''调用CreateBitmapPicture函数从指定的bitmap对象和调色板中建立一个picture对象
Set SaveTohBmp = CreateBitmapPicture(hBmp, hPal)
End Function
Public Function CreateBitmapPicture(ByVal hBmp As Long, ByVal hPal As Long) As Picture
Dim r As Long
Dim Pic As PicBmp
Dim Ipic As Ipicture
Dim IID_Idispatch As GUID
''''填充Idispatch界面
With IID_Idispatch
.Data1 = &H20400
.Data4(0) = &HC0
.Data4(7) = &H46
End With
''''填充Pic结构
With Pic
.Size = Len(Pic) '''' Length of structure.
.Type = vbPicTypeBitmap '''' Type of Picture (bitmap).
.hBmp = hBmp '''' Handle to bitmap.
.hPal = hPal '''' Handle to palette (may be null).
End With
''''建立Picture对象
r = OleCreatePictureIndirect(Pic, IID_Idispatch, 1, Ipic)
''''返回Picture对象
Set CreateBitmapPicture = Ipic
End Function
运行程序，在屏幕上会出现一些火焰字的特效，按Enter键可以将屏幕保存到“c:\a.bmp”中，按Esc键退出程序回到Windows。
在上面的程序中，程序首先建立一个DirectDraw对象，然后设置该对象的协作层为全屏协作模式，接下来设置显示模式为640×480×8位颜色，建立一个前台DirectDrawSurface对象和一个后台缓冲DirectDrawSurface对象，建立和设置DirectDrawClipper对象。
在主程序段中，程序首先对前台绘图平面的调色板（DirectDrawPalette）对象进行操作以改变显示的文字的颜色，然后对后台缓冲绘图平面进行字节操作，以产生文字弥散的效果，然后再将后台缓冲绘图平面翻转到前台。当用户按下Enter键之后，程序获得与前台绘图平面相兼容的图形设备句柄，然后再调用Windows API函数将绘图平面内存中的内容保存到Windows位图文件中。
上面粗略地介绍了DirectX7 SDK的新特性以及初步的DirectDraw编程，希望对大家能有所帮助。以上的程序在Windows98、VB6.0下运行通过。
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