OleLoadPicture解释

OleLoadPicture

Creates a new picture object and initializes it from the contents of a stream. This is equivalent to calling OleCreatePictureIndirect(NULL, ...) followed by IPersistStream::Load.

STDAPI OleLoadPicture(

  IStream * pStream,

               //Pointer to the stream that contains picture's data

               //指向包含图片数据的流

  LONG lSize,  //Number of bytes read from the stream

               //读取pStream字节的长度

  BOOL fRunmode,

               //The opposite of the initial value of the picture's

               // property

               //与图片属性的初始化值相反

  REFIID riid, //Reference to the identifier of the interface

               // describing the type of interface pointer to return

               //接口的参考类型,返回描述类型接口指针

  VOID ppvObj  //Address of output variable that receives interface

               // pointer requested in riid

               //返回指向需要riid的接口指针,为输出值

);

Parameters

pStream

[in] Pointer to the stream that contains the picture's data.

lSize

[in] Number of bytes that should be read from the stream, or zero if the entire stream should be read.

fRunmode

[in] The opposite of the initial value of the KeepOriginalFormat property. If TRUE, KeepOriginalFormat is set to FALSE and vice-versa.

//主要是和KeepOriginalFormat的属性相反

riid

[in] Reference to the identifier of the interface describing the type of interface pointer to return in ppvObj.

ppvObj

[out] Address of pointer variable that receives the interface pointer requested in riid. Upon successful return, *ppvObj contains the requested interface pointer on the storage of the object identified by the moniker. If *ppvObj is non-NULL, this function calls IUnknown::AddRef on the interface; it is the caller's responsibility to call IUnknown::Release. If an error occurs, *ppvObj is set to NULL.

Return Values

This function supports the standard return values E_OUTOFMEMORY and E_UNEXPECTED, as well as the following:

S_OK

The picture was created successfully.

E_POINTER

The address in pStream or ppvObj is not valid. For example, either may be NULL.

E_NOINTERFACE

The object does not support the interface specified in riid.

Remarks

The stream must be in BMP (bitmap), WMF (metafile), or ICO (icon) format. A picture object created using OleLoadPicture always has ownership of its internal resources (fOwn==TRUE is implied).