VB6结合GDI+实现内存(Stream)压缩/解压缩JPG(JPEG)图像

优快云论坛vb版中有一个讨论内存压缩JPEG的帖子，在此我贴出解决代码。

代码原理原本就简单，所以注释也很简单。

希望能帮助到苦苦思索的朋友们。(魏滔序原创，转帖请注明出处。)

 

首先要下载一个IStream库，用该库可以减少代码量，如果直接全部用API也未尝不可。

IStream下载地址：IStream.zip

 

下面是代码，可以贴在一个模块中：

Option Explicit '常量声明 Private Const ClsidJPEG As String = "{557CF401-1A04-11D3-9A73-0000F81EF32E}" Private Const EncoderParameterValueTypeLong As Long = 4& Private Const EncoderQuality As String = "{1D5BE4B5-FA4A-452D-9CDD-5DB35105E7EB}" Private Const GdiPlusVersion As Long = 1& '结构声明 Private Type GUID Data1 As Long Data2 As Integer Data3 As Integer Data4(0 To 7) As Byte End Type Private Type IID Data1 As Long Data2 As Integer Data3 As Integer Data4(0 To 7) As Byte End Type Private Type PICTDESC cbSizeOfStruct As Long picType As Long hgdiObj As Long hPalOrXYExt 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(15) As EncoderParameter End Type Private Type GDIPlusSt