JPG 操作模块代码

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Attribute VB_Name = "mIntelJPEGLibrary"

Option Explicit

'Powered by barenx

Private Enum IJLERR

'// The following "error" values indicate an "OK" condition.

IJL_OK = 0

IJL_INTERRUPT_OK = 1

IJL_ROI_OK = 2

'// The following "error" values indicate an error has occurred.

IJL_EXCEPTION_DETECTED = -1

IJL_INVALID_ENCODER = -2

IJL_UNSUPPORTED_SUBSAMPLING = -3

IJL_UNSUPPORTED_BYTES_PER_PIXEL = -4

IJL_MEMORY_ERROR = -5

IJL_BAD_HUFFMAN_TABLE = -6

IJL_BAD_QUANT_TABLE = -7

IJL_INVALID_JPEG_PROPERTIES = -8

IJL_ERR_FILECLOSE = -9

IJL_INVALID_FILENAME = -10

IJL_ERROR_EOF = -11

IJL_PROG_NOT_SUPPORTED = -12

IJL_ERR_NOT_JPEG = -13

IJL_ERR_COMP = -14

IJL_ERR_SOF = -15

IJL_ERR_DNL = -16

IJL_ERR_NO_HUF = -17

IJL_ERR_NO_QUAN = -18

IJL_ERR_NO_FRAME = -19

IJL_ERR_MULT_FRAME = -20

IJL_ERR_DATA = -21

IJL_ERR_NO_IMAGE = -22

IJL_FILE_ERROR = -23

IJL_INTERNAL_ERROR = -24

IJL_BAD_RST_MARKER = -25

IJL_THUMBNAIL_DIB_TOO_SMALL = -26

IJL_THUMBNAIL_DIB_WRONG_COLOR = -27

IJL_RESERVED = -99

End Enum

Private Enum IJLIOTYPE

IJL_SETUP = -1&

''// Read JPEG parameters (i.e., height, width, channels,

''// sampling, etc.) from a JPEG bit stream.

IJL_JFILE_READPARAMS = 0&

IJL_JBUFF_READPARAMS = 1&

''// Read a JPEG Interchange Format image.

IJL_JFILE_READWHOLEIMAGE = 2&

IJL_JBUFF_READWHOLEIMAGE = 3&

''// Read JPEG tables from a JPEG Abbreviated Format bit stream.

IJL_JFILE_READHEADER = 4&

IJL_JBUFF_READHEADER = 5&

''// Read image info from a JPEG Abbreviated Format bit stream.

IJL_JFILE_READENTROPY = 6&

IJL_JBUFF_READENTROPY = 7&

''// Write an entire JFIF bit stream.

IJL_JFILE_WRITEWHOLEIMAGE = 8&

IJL_JBUFF_WRITEWHOLEIMAGE = 9&

''// Write a JPEG Abbreviated Format bit stream.

IJL_JFILE_WRITEHEADER = 10&

IJL_JBUFF_WRITEHEADER = 11&

''// Write image info to a JPEG Abbreviated Format bit stream.

IJL_JFILE_WRITEENTROPY = 12&

IJL_JBUFF_WRITEENTROPY = 13&

''// Scaled Decoding Options:

''// Reads a JPEG image scaled to 1/2 size.

IJL_JFILE_READONEHALF = 14&

IJL_JBUFF_READONEHALF = 15&

''// Reads a JPEG image scaled to 1/4 size.

IJL_JFILE_READONEQUARTER = 16&

IJL_JBUFF_READONEQUARTER = 17&

''// Reads a JPEG image scaled to 1/8 size.

IJL_JFILE_READONEEIGHTH = 18&

IJL_JBUFF_READONEEIGHTH = 19&

''// Reads an embedded thumbnail from a JFIF bit stream.

IJL_JFILE_READTHUMBNAIL = 20&

IJL_JBUFF_READTHUMBNAIL = 21&

End Enum

Private Type JPEG_CORE_PROPERTIES_VB

UseJPEGPROPERTIES As Long '// default = 0

'// DIB specific I/O data specifiers.

DIBBytes As Long '; '// default = NULL 4

DIBWidth As Long '; '// default = 0 8

DIBHeight As Long '; '// default = 0 12

DIBPadBytes As Long '; '// default = 0 16

DIBChannels As Long '; '// default = 3 20

DIBColor As Long '; '// default = IJL_BGR 24

DIBSubsampling As Long '; '// default = IJL_NONE 28

'// JPEG specific I/O data specifiers.

JPGFile As Long 'LPTSTR JPGFile; 32 '// default = NULL

JPGBytes As Long '; '// default = NULL 36

JPGSizeBytes As Long '; '// default = 0 40

JPGWidth As Long '; '// default = 0 44

JPGHeight As Long '; '// default = 0 48

JPGChannels As Long '; '// default = 3

JPGColor As Long '; '// default = IJL_YCBCR

JPGSubsampling As Long '; '// default = IJL_411

JPGThumbWidth As Long ' ; '// default = 0

JPGThumbHeight As Long '; '// default = 0

'// JPEG conversion properties.

cconversion_reqd As Long '; '// default = TRUE

upsampling_reqd As Long '; '// default = TRUE

jquality As Long '; '// default = 75. 100 is my preferred quality setting.

'// Low-level properties - 20,000 bytes. If the whole structure

' is written out then VB fails with an obscure error message

' "Too Many Local Variables" !

' These all default if they are not otherwise specified so there

' is no trouble.

jprops(0 To 19999) As Byte

End Type

Private Declare Function ijlInit Lib "ijl10.dll" (jcprops As Any) As Long

Private Declare Function ijlFree Lib "ijl10.dll" (jcprops As Any) As Long

Private Declare Function ijlRead Lib "ijl10.dll" (jcprops As Any, ByVal ioType As Long) As Long

Private Declare Function ijlWrite Lib "ijl10.dll" (jcprops As Any, ByVal ioType As Long) As Long

Private Declare Function ijlGetLibVersion Lib "ijl10.dll" () As Long

Private Declare Function ijlGetErrorString Lib "ijl10.dll" (ByVal code As Long) As Long

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" ( _

lpvDest As Any, lpvSource As Any, ByVal cbCopy As Long)

Private Declare Function GlobalAlloc Lib "kernel32" (ByVal wFlags As Long, ByVal dwBytes As Long) As Long

Private Declare Function GlobalFree Lib "kernel32" (ByVal hMem As Long) As Long

Private Declare Function GlobalLock Lib "kernel32" (ByVal hMem As Long) As Long

Private Declare Function GlobalUnlock Lib "kernel32" (ByVal hMem As Long) As Long

Public Const GMEM_DDESHARE = &H2000

Public Const GMEM_DISCARDABLE = &H100

Public Const GMEM_DISCARDED = &H4000

Public Const GMEM_FIXED = &H0

Public Const GMEM_INVALID_HANDLE = &H8000

Public Const GMEM_LOCKCOUNT = &HFF

Public Const GMEM_MODIFY = &H80

Public Const GMEM_MOVEABLE = &H2

Public Const GMEM_NOCOMPACT = &H10

Public Const GMEM_NODISCARD = &H20

Public Const GMEM_NOT_BANKED = &H1000

Public Const GMEM_NOTIFY = &H4000

Public Const GMEM_SHARE = &H2000

Public Const GMEM_VALID_FLAGS = &H7F72

Public Const GMEM_ZEROINIT = &H40

Public Const GPTR = (GMEM_FIXED Or GMEM_ZEROINIT)

Public Function LoadJPG(ByRef cDib As cDIBSection, ByVal sFile As String) As Boolean

Dim tJ As JPEG_CORE_PROPERTIES_VB

Dim bFile() As Byte

Dim lR As Long

Dim lPtr As Long

Dim lJPGWidth As Long, lJPGHeight As Long

lR = ijlInit(tJ)

If lR = IJL_OK Then

' Write the filename to the jcprops.JPGFile member:

bFile = StrConv(sFile, vbFromUnicode)

ReDim Preserve bFile(0 To UBound(bFile) + 1) As Byte

bFile(UBound(bFile)) = 0

lPtr = VarPtr(bFile(0))

CopyMemory tJ.JPGFile, lPtr, 4

' Read the JPEG file parameters:

lR = ijlRead(tJ, IJL_JFILE_READPARAMS)

If lR <> IJL_OK Then

' Throw error

MsgBox "Failed to read JPG", vbExclamation

Else

' Get the JPGWidth ...

lJPGWidth = tJ.JPGWidth

' .. & JPGHeight member values:

lJPGHeight = tJ.JPGHeight

' Create a buffer of sufficient size to hold the image:

If cDib.Create(lJPGWidth, lJPGHeight) Then

' Store DIBWidth:

tJ.DIBWidth = lJPGWidth

' Store DIBHeight:

tJ.DIBHeight = -lJPGHeight

' Store Channels:

tJ.DIBChannels = 3&

' Store DIBBytes (pointer to uncompressed JPG data):

tJ.DIBBytes = cDib.DIBSectionBitsPtr

' Now decompress the JPG into the DIBSection:

lR = ijlRead(tJ, IJL_JFILE_READWHOLEIMAGE)

If lR = IJL_OK Then

' That's it! cDib now contains the uncompressed JPG.

LoadJPG = True

Else

' Throw error:

MsgBox "Cannot read Image Data from file.", vbExclamation

End If

Else

' failed to create the DIB...

End If

' Ensure we have freed memory:

ijlFree tJ

Else

' Throw error:

MsgBox "Failed to initialise the IJL library: " & lR, vbExclamation

End If

End Function

Public Function SaveJPG(ByRef cDib As cDIBSection, ByVal sFile As String) As Boolean

Dim tJ As JPEG_CORE_PROPERTIES_VB

Dim bFile() As Byte

Dim lPtr As Long

Dim lR As Long

lR = ijlInit(tJ)

If lR = IJL_OK Then

' Set up the DIB information:

' Store DIBWidth:

tJ.DIBWidth = cDib.Width

' Store DIBHeight:

tJ.DIBHeight = -cDib.Height

' Store DIBBytes (pointer to uncompressed JPG data):

tJ.DIBBytes = cDib.DIBSectionBitsPtr

' Set up the JPEG information:

' Store JPGFile:

bFile = StrConv(sFile, vbFromUnicode)

ReDim Preserve bFile(0 To UBound(bFile) + 1) As Byte

bFile(UBound(bFile)) = 0

lPtr = VarPtr(bFile(0))

CopyMemory tJ.JPGFile, lPtr, 4

' Store JPGWidth:

tJ.JPGWidth = cDib.Width

' .. & JPGHeight member values:

tJ.JPGHeight = cDib.Height

tJ.jquality = 90

' Write the image:

lR = ijlWrite(tJ, IJL_JFILE_WRITEWHOLEIMAGE)

If lR = IJL_OK Then

SaveJPG = True

Else

' Throw error

MsgBox "Failed to save to JPG", vbExclamation

End If

' Ensure we have freed memory:

ijlFree tJ

Else

' Throw error:

MsgBox "Failed to initialise the IJL library: " & lR, vbExclamation

End If

End Function

JPG 操作模块 代码

JPG 操作模块代码