| 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)
RasterCapsScrn = GetDeviceCaps(hdcSrc, RASTE图CAPS) 'rRaste
HasPaletteScrn = RasterCapsScrn And RC_PALtTTEic1 ' Palette
PaletteSizeScrn = GetDeviceCaps(hdcSrc, SIZEPALETTE) ' Size of
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可以将屏幕保存到“c:\a.bmp”中，按Esc键退出程序。
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。
用VB编写DirectX7.0游戏六 |
