图像载入Picture前缩放/灰度处理解决方法

图像载入Picture前缩放/灰度处理
图像载入Picture前缩放OK了，灰度处理还不会，网上找的代码都是截入Picture后再灰度，有没有载入前先处理成灰度的代码，请各位大帮帮忙。

VB code

Option ExplicitPrivate Declare Function GetObject Lib "gdi32" Alias "GetObjectA" (ByVal hObject As Long, ByVal nCount As Long, lpObject As Any) As LongPrivate Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hdc As Long) As LongPrivate Declare Function SelectObject Lib "gdi32" (ByVal hdc As Long, ByVal hObject As Long) As LongPrivate Declare Function StretchBlt Lib "gdi32" (ByVal hdc 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 nSrcWidth As Long, ByVal nSrcHeight As Long, ByVal dwRop As Long) As LongPrivate Declare Function DeleteDC Lib "gdi32" (ByVal hdc As Long) As LongPrivate Type BITMAP '14 bytes    bmType As Long    bmWidth As Long    bmHeight As Long    bmWidthBytes As Long    bmPlanes As Integer    bmBitsPixel As Integer    bmBits As LongEnd TypePrivate Sub Form_Load()    Picture1.Picture = LoadPicture(App.Path & "\b.bmp")End SubPrivate Sub Command1_Click()    Dim Pic As Picture, BMP As BITMAP    Dim hdc As Long, hmemDC As Long    Set Pic = LoadPicture(App.Path & "\b.bmp")    GetObject Pic.Handle, Len(BMP), BMP    hmemDC = CreateCompatibleDC(hdc)    SelectObject hmemDC, Pic.Handle    StretchBlt Picture1.hdc, 0, 0, BMP.bmWidth * 3, BMP.bmHeight * 3, hmemDC, 0, 0, BMP.bmWidth, BMP.bmHeight, vbSrcCopy    DeleteDC hmemDC    Picture1.RefreshEnd Sub

[解决办法]
灰阶图像

Option Explicit
Private Const BI_RGB = 0&
Private Const DIB_RGB_COLORS = 0
Private Type BITMAPINFOHEADER
biSize As Long
biWidth As Long
biHeight As Long
biPlanes As Integer
biBitCount As Integer
biCompression As Long
biSizeImage As Long
biXPelsPerMeter As Long
biYPelsPerMeter As Long
biClrUsed As Long
biClrImportant As Long
End Type
Private Type RGBQUAD
rgbBlue As Byte
rgbGreen As Byte
rgbRed As Byte
rgbReserved As Byte
End Type
Private Type BITMAPINFO
bmiHeader As BITMAPINFOHEADER
bmiColors As RGBQUAD
End Type
Private Declare Function GetDIBits Lib "gdi32" (ByVal aHDC As Long, ByVal hbitmap As Long, ByVal nStartScan As Long, ByVal nNumScans As Long, lpBits As Any, lpBI As BITMAPINFO, ByVal wUsage As Long) As Long
Private Declare Function SetDIBitsToDevice Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal dx As Long, ByVal dy As Long, ByVal SrcX As Long, ByVal SrcY As Long, ByVal Scan As Long, ByVal NumScans As Long, Bits As Any, BitsInfo As BITMAPINFO, ByVal wUsage As Long) As Long

Private Sub Command1_Click()
Dim WidthSrc As Long, HeightSrc As Long
Dim PixelsSrc() As Byte
Dim Bitmap_Info As BITMAPINFO
Dim x&, y&, i&, Ret&, C As Byte
WidthSrc = 800
HeightSrc = 600
With Bitmap_Info.bmiHeader
.biSize = 40
.biWidth = WidthSrc
.biHeight = -HeightSrc
.biPlanes = 1
.biBitCount = 32
.biCompression = BI_RGB
.biSizeImage = WidthSrc * HeightSrc * 4
End With
ReDim PixelsSrc(1 To 4, 1 To WidthSrc, 1 To HeightSrc) As Byte
Ret = GetDIBits(Picture1.hdc, Picture1.Picture, 0, HeightSrc, PixelsSrc(1, 1, 1), Bitmap_Info, DIB_RGB_COLORS)
For y = 1 To HeightSrc
For x = 1 To WidthSrc
C = (9798& * PixelsSrc(3, x, y) + 19235& * PixelsSrc(2, x, y) + 3735& * PixelsSrc(1, x, y)) \ 32768
PixelsSrc(1, x, y) = C
PixelsSrc(2, x, y) = C
PixelsSrc(3, x, y) = C

Next
Next
SetDIBitsToDevice Me.hdc, 0, 0, WidthSrc, HeightSrc, 0, 0, 0, HeightSrc, PixelsSrc(1, 1, 1), Bitmap_Info, DIB_RGB_COLORS
End Sub

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