Question

VB 高手帮忙 想做个程序截屏后自动将图由bmp转成jpg

我是用以下代码来截图的 保存的是bmp格式图片，3.7M大小，想知道怎样转成jpg格式
Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function 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) As Long

Me.AutoRedraw = True
BitBlt Me.hDC, 0, 0, Screen.Width, Screen.Height, GetDC(0), 0, 0, vbSrcCopy
sFile$ = "D:\zhuatu\" & Format(Now, "mm-dd(hhmmss)") & ".jpg"
SavePicture Me.Image, sFile

各位大侠，麻烦尽量给我能直接用的代码，我是VB小菜，谢谢

Answer 1

Option Explicit

Private Type GUID
Data1 As Long
Data2 As Integer
Data3 As Integer
Data4(0 To 7) As Byte
End Type

Private Type GdiplusStartupInput
GdiplusVersion As Long
DebugEventCallback As Long
SuppressBackgroundThread As Long
SuppressExternalCodecs As Long
End Type

Private Type EncoderParameter
GUID As GUID
NumberOfValues As Long
type As Long
Value As Long
End Type

Private Type EncoderParameters
Count As Long
Parameter As EncoderParameter
End Type

Private Declare Function GdiplusStartup Lib "GDIPlus" (token As Long, inputbuf As GdiplusStartupInput, ByVal outputbuf As Long) As Long
Private Declare Function GdiplusShutdown Lib "GDIPlus" (ByVal token As Long) As Long
Private Declare Function GdipCreateBitmapFromHBITMAP Lib "GDIPlus" (ByVal hbm As Long, ByVal hpal As Long, Bitmap As Long) As Long
Private Declare Function GdipDisposeImage Lib "GDIPlus" (ByVal Image As Long) As Long
Private Declare Function GdipSaveImageToFile Lib "GDIPlus" (ByVal Image As Long, ByVal FileName As Long, clsidEncoder As GUID, encoderParams As Any) As Long
Private Declare Function CLSIDFromString Lib "ole32" (ByVal str As Long, id As GUID) As Long
Private Declare Function GdipCreateBitmapFromFile Lib "GDIPlus" (ByVal FileName As Long, Bitmap As Long) As Long

Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hDC As Long) As Long
Private Declare Function AbortDoc Lib "gdi32" (ByVal hDC As Long) As Long
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 DeleteDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) 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 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) As Long

Private Function HBmp2JPG(ByVal hBmp As Long, ByVal FileName As String, Optional ByVal quality As Byte = 80) As Boolean
Dim tSI As GdiplusStartupInput
Dim lRes As Long
Dim lGDIP As Long
Dim lBitmap As Long

'初始化 GDI+
tSI.GdiplusVersion = 1
lRes = GdiplusStartup(lGDIP, tSI, 0)

If lRes = 0 Then
'从句柄创建 GDI+ 图像
lRes = GdipCreateBitmapFromHBITMAP(hBmp, 0, lBitmap)
If lRes = 0 Then
Dim tJpgEncoder As GUID
Dim tParams As EncoderParameters
'初始化解码器的GUID标识
CLSIDFromString StrPtr("{557CF401-1A04-11D3-9A73-0000F81EF32E}"), tJpgEncoder

'设置解码器参数
tParams.Count = 1
With tParams.Parameter ' Quality
'得到Quality参数的GUID标识
CLSIDFromString StrPtr("{1D5BE4B5-FA4A-452D-9CDD-5DB35105E7EB}"), .GUID
.NumberOfValues = 1
.type = 4
.Value = VarPtr(quality)
End With
'保存图像
lRes = GdipSaveImageToFile(lBitmap, StrPtr(FileName), tJpgEncoder, tParams)
'销毁GDI+图像
GdipDisposeImage lBitmap
End If
'销毁 GDI+
GdiplusShutdown lGDIP
End If
HBmp2JPG = IIf(lRes, False, True)
End Function

Sub CaptureScreen(FileName As String)
Dim hDC As Long
Dim hDCmem As Long
Dim hBmp As Long
Dim hBmpPrev As Long
hDC = GetDC(0)
hDCmem = CreateCompatibleDC(hDC)
hBmp = CreateCompatibleBitmap(hDC, Screen.Width / Screen.TwipsPerPixelX, Screen.Height / Screen.TwipsPerPixelY)
hBmpPrev = SelectObject(hDCmem, hBmp)
BitBlt hDCmem, 0, 0, Screen.Width / Screen.TwipsPerPixelX, Screen.Height / Screen.TwipsPerPixelY, hDC, 0, 0, vbSrcCopy
SelectObject hDCmem, hBmpPrev
DeleteDC hDCmem
ReleaseDC 0, hDC
If HBmp2JPG(hBmp, FileName, 60) Then
MsgBox "抓屏成功，JPG文件保存在" & FileName
Else
MsgBox "抓屏失败"
End If
DeleteObject hBmp
End Sub

Private Sub Command1_Click()
CaptureScreen "c:\test.jpg"
End Sub