EM_STREAMIN message

Replaces the contents of a rich edit control with a stream of data provided by an application defined EditStreamCallback callback function.

wParam

Specifies the data format and replacement options. This value must be one of the following values.

Expand table

Value	Meaning
SF_RTF	RTF
SF_TEXT	Text

In addition, you can specify the following flags.

Expand table

Value	Meaning
SFF_PLAINRTF	If specified, only keywords common to all languages are streamed in. Language-specific RTF keywords in the stream are ignored. If not specified, all keywords are streamed in. You can combine this flag with the SF_RTF flag.
SFF_SELECTION	If specified, the data stream replaces the contents of the current selection. If not specified, the data stream replaces the entire contents of the control. You can combine this flag with the SF_TEXT or SF_RTF flags.
SF_UNICODE	Microsoft Rich Edit 2.0 and later: Indicates Unicode text. You can combine this flag with the SF_TEXT flag.
SF_USECODEPAGE	Rich Edit 3.0 and later: Reads UTF-8 RTF and text using other code pages. The code page is set in the high word of wParam. For example, for UTF-8 RTF, set wParam to (CP_UTF8 << 16) | SF_USECODEPAGE | SF_RTF.

lParam

Pointer to an EDITSTREAM structure. On input, the pfnCallback member of this structure must point to an application defined EditStreamCallback function. On output, the dwError member can contain a nonzero error code if an error occurred.

This message returns the number of characters read.

When you send an EM_STREAMIN message, the rich edit control makes repeated calls to the EditStreamCallback function specified by the pfnCallback member of the EDITSTREAM structure. Each time the callback function is called, it fills a buffer with data to read into the control. This continues until the callback function indicates that the stream-in operation has been completed or an error occurs.

Reference

EDITSTREAM

EditStreamCallback

EM_STREAMOUT