获得jpg文件的实际尺寸

核心提示：bask 把它编译成组件就可以用了，还支持png'I have released this source code into the public domain.You may use it'with no strings attached.'Just call GetImageSize wit

bask

把它编译成组件就可以用了，还支持png


'I have released this source code into the public domain.　You may use it
'with no strings attached.
'Just call GetImageSize with a string containing the filename, and
'it will return a user defined type 'ImageSize'　(see below)
'Return values of 0 indicate an error of some sort.　The error handling
'in this module is limited.　There is *NO* error handling on the test
'form.　This routine is limited to X or Y sizes of 32767 pixels, but that
'should not be a PRoblem.

'Check back at http://www.qtm.net/~davidc
'I may add support for more file types.

'supported in this version:
'JPEG
'GIF
'PNG

'This routine does not require any royalty fees for Unisys as it
'does nothing with the compressed part of GIF files.　It simply reads
'4 bytes to determine image size.

Option Explicit
Public WImg As Long
Public HImg As Long
Public Type ImageSize
　　Width As Long
　　Height As Long
End Type

Public Sub GetImageSize(sFileName As String)
　　On Error Resume Next　　　　'you'll want to change this
　　Dim iFN As Integer
　　Dim bTemp(3) As Byte
　　Dim lFlen As Long
　　Dim lPos As Long
　　Dim bHmsb As Byte
　　Dim bHlsb As Byte
　　Dim bWmsb As Byte
　　Dim bWlsb As Byte
　　Dim bBuf(7) As Byte
　　Dim bDone As Byte
　　Dim iCount As Integer

　　lFlen = FileLen(sFileName)
　　iFN = FreeFile
　　Open sFileName For Binary As iFN
　　Get #iFN, 1, bTemp()
　　　　
　　'PNG file
　　If bTemp(0) = &H89 And bTemp(1) = &H50 And bTemp(2) = &H4E _
　　And bTemp(3) = &H47 Then
　　　　Get #iFN, 19, bWmsb
　　　　Get #iFN, 20, bWlsb
　　　　Get #iFN, 23, bHmsb
　　　　Get #iFN, 24, bHlsb
　　　　'GetImageSize.Width = CombineBytes(bWlsb, bWmsb)
　　　　'GetImageSize.Height = CombineBytes(bHlsb, bHmsb)
　　　　WImg = CombineBytes(bWlsb, bWmsb)
　　　　HImg = CombineBytes(bHlsb, bHmsb)
　　End If
　　
　　'GIF file
　　If bTemp(0) = &H47 And bTemp(1) = &H49 And bTemp(2) = &H46 _
　　And bTemp(3) = &H38 Then
　　　　Get #iFN, 7, bWlsb
　　　　Get #iFN, 8, bWmsb
　　　　Get #iFN, 9, bHlsb
　　　　Get #iFN, 10, bHmsb
　　　　'GetImageSize.Width = CombineBytes(bWlsb, bWmsb)
　　　　'GetImageSize.Height = CombineBytes(bHlsb, bHmsb)
　　　　WImg = CombineBytes(bWlsb, bWmsb)
　　　　HImg = CombineBytes(bHlsb, bHmsb)
　　End If
　　
　　
　　'JPEG file
　　If bTemp(0) = &HFF And bTemp(1) = &HD8 And bTemp(2) = &HFF Then
　　Debug.Print "JPEG"
　　　　lPos = 3
　　　　Do
　　　　　　Do
　　　　　　　　Get #iFN, lPos, bBuf(1)
　　　　　　　　Get #iFN, lPos + 1, bBuf(2)
　　　　　　　　lPos = lPos + 1
　　　　　　Loop Until (bBuf(1) = &HFF And bBuf(2) <> &HFF) Or lPos > lFlen
　　　　
　　　　　　For iCount = 0 To 7
　　　　　　　　Get #iFN, lPos + iCount, bBuf(iCount)
　　　　　　Next iCount
　　　　　　If bBuf(0) >= &HC0 And bBuf(0) <= &HC3 Then
　　　　　　　　bHmsb = bBuf(4)
　　　　　　　　bHlsb = bBuf(5)
　　　　　　　　bWmsb = bBuf(6)
　　　　　　　　bWlsb = bBuf(7)
　　　　　　　　bDone = 1
　　　　　　Else
　　　　　　　　lPos = lPos + (CombineBytes(bBuf(2), bBuf(1))) + 1
　　　　　　End If
　　　　Loop While lPos < lFlen And bDone = 0
　　　　'GetImageSize.Width = CombineBytes(bWlsb, bWmsb)
　　　　'GetImageSize.Height = CombineBytes(bHlsb, bHmsb)
　　　　WImg = CombineBytes(bWlsb, bWmsb)
　　　　HImg = CombineBytes(bHlsb, bHmsb)
　　End If
　　Close iFN
　　
End Sub
Private Function CombineBytes(lsb As Byte, msb As Byte) As Long
　　CombineBytes = CLng(lsb + (msb * 256))
End Function