Question

怎样在VB中实现全屏截图，用代码

Answer 1

截屏不难实现，关键是保存，这里我用GDI+保存图片（支持BMP，GIF，JPG，TIF，PNG等）。

窗体中的代码：
Private Declare Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Long, ByVal dwExtraInfo As Long)
Const theScreen = 1
Const theForm = 0

Private Sub Command1_Click()
Call keybd_event(vbKeySnapshot, theForm, 0, 0)
'若theForm改成theScreen则Copy整个Screen
DoEvents
Picture1.Picture = Clipboard.GetData(vbCFBitmap)
SavePic Picture1.Picture,"D:\1.gif",".gif"
End Sub

以下代码放在模块中：
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, Optional ByVal outputbuf As Long = 0) 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 CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Dest As Any, Src As Any, ByVal cb As Long) As Long

'*************************************************************************
'** 作 者 ： laviewpbt
'** 函 数 名 ： SavePic
'** 输 入 ： pic(StdPicture) - 图象句柄
'** ： FileName(String) - 保存路径
'** ： Quality(Byte) - JPG图象质量
'** ： TIFF_ColorDepth(Long) - TTF格式的颜色深度
'** ： TIFF_Compression(Long) - TTF格式的压缩比
'** 输 出 ： 无
'** 功能描述 ： 把图象保存为JPG、TIFF、PNG、GIF、BMP格式
'** 日 期 ： 2007.8.4
'** 修 改 人 ： BEN
'** 日 期 ： 2005-10-23 14.43.52
'*************************************************************************
Private Sub SavePic(ByVal pict As StdPicture, ByVal FileName As String, PicType As String, _
Optional ByVal Quality As Byte = 80, _
Optional ByVal TIFF_ColorDepth As Long = 24, _
Optional ByVal TIFF_Compression As Long = 6)
Screen.MousePointer = vbHourglass
Dim tSI As GdiplusStartupInput
Dim lRes As Long
Dim lGDIP As Long
Dim lBitmap As Long
Dim aEncParams() As Byte
On Error GoTo ErrHandle:
tSI.GdiplusVersion = 1 ' 初始化 GDI+
lRes = GdiplusStartup(lGDIP, tSI)
If lRes = 0 Then ' 从句柄创建 GDI+ 图像
lRes = GdipCreateBitmapFromHBITMAP(pict.Handle, 0, lBitmap)
If lRes = 0 Then
Dim tJpgEncoder As GUID
Dim tParams As EncoderParameters '初始化解码器的GUID标识
Select Case PicType
Case ".jpg"
CLSIDFromString StrPtr("{557CF401-1A04-11D3-9A73-0000F81EF32E}"), tJpgEncoder
tParams.count = 1 ' 设置解码器参数
With tParams.Parameter ' Quality
CLSIDFromString StrPtr("{1D5BE4B5-FA4A-452D-9CDD-5DB35105E7EB}"), .GUID ' 得到Quality参数的GUID标识
.NumberOfValues = 1
.type = 4
.Value = VarPtr(Quality)
End With
ReDim aEncParams(1 To Len(tParams))
Call CopyMemory(aEncParams(1), tParams, Len(tParams))
Case ".png"
CLSIDFromString StrPtr("{557CF406-1A04-11D3-9A73-0000F81EF32E}"), tJpgEncoder
ReDim aEncParams(1 To Len(tParams))
Case ".gif"
CLSIDFromString StrPtr("{557CF402-1A04-11D3-9A73-0000F81EF32E}"), tJpgEncoder
ReDim aEncParams(1 To Len(tParams))
Case ".tiff"
CLSIDFromString StrPtr("{557CF405-1A04-11D3-9A73-0000F81EF32E}"), tJpgEncoder
tParams.count = 2
ReDim aEncParams(1 To Len(tParams) + Len(tParams.Parameter))
With tParams.Parameter
.NumberOfValues = 1
.type = 4
CLSIDFromString StrPtr("{E09D739D-CCD4-44EE-8EBA-3FBF8BE4FC58}"), .GUID ' 得到ColorDepth参数的GUID标识
.Value = VarPtr(TIFF_Compression)
End With
Call CopyMemory(aEncParams(1), tParams, Len(tParams))
With tParams.Parameter
.NumberOfValues = 1
.type = 4
CLSIDFromString StrPtr("{66087055-AD66-4C7C-9A18-38A2310B8337}"), .GUID ' 得到Compression参数的GUID标识
.Value = VarPtr(TIFF_ColorDepth)
End With
Call CopyMemory(aEncParams(Len(tParams) + 1), tParams.Parameter, Len(tParams.Parameter))
Case ".bmp" '可以提前写保存为BMP的代码，因为并没有用GDI+
SavePicture pict, FileName
Screen.MousePointer = vbDefault
Exit Sub
End Select
lRes = GdipSaveImageToFile(lBitmap, StrPtr(FileName), tJpgEncoder, aEncParams(1)) '保存图像
GdipDisposeImage lBitmap ' 销毁GDI+图像
End If
GdiplusShutdown lGDIP '销毁 GDI+
End If
Screen.MousePointer = vbDefault
Erase aEncParams
Exit Sub
ErrHandle:
Screen.MousePointer = vbDefault
MsgBox "在保存图片的过程中发生错误:" & vbCrLf & vbCrLf & "错误号: " & err.Number & vbCrLf & "错误描述: " & err.Description, vbInformation Or vbOKOnly, "错误"
End Sub