Stream Operations in Rich Edit Controls
You can use streams to transfer data into or out of a rich edit control (CRichEditCtrl). A stream is defined by an EDITSTREAM structure, which specifies a buffer and an application-defined callback function.
To read data into a rich edit control (that is, stream the data in), use the StreamIn member function. The control repeatedly calls the application-defined callback function, which transfers a portion of the data into the buffer each time.
To save the contents of a rich edit control (that is, stream the data out), you can use the StreamOut member function. The control repeatedly writes to the buffer and then calls the application-defined callback function. For each call, the callback function saves the contents of the buffer.