Native Transfer

A Windows graphics suite must handle large data files and distribute them across multiple application modules. In the past, the challenge has been in transferring these large data sets without bogging down the system. OLE 2.0's Uniform Data Transfer technology makes this process more efficient.

Before OLE 2.0, applications used global memory as the medium of data transfer, and a Clipboard format (e.g., CF_TEXT or CF_BITMAP) to describe the data. Different transfers (OLE 1.0, DDE, the Clipboard, or drag and drop) required different protocols and API functions. Under OLE 2.0, a p ointer is transferred from the data source to the data recipient. The data object itself then determines a standardize d format for the transfer.

When you select a data object and drag it out of its source, the destination OLE container supports two data types -- the Native Format and the Presentation Format -- each of which might contain several additional components. The Native Format can be almost anything. Corel applications use the Corel Metafile Exchange (*.CMX) format, introduced as the clip-art format with CorelDraw 5. The Presentation Format includes elements previously supported by the Windows Clipboard (Device-Dependent Bitmap, Windows Metafile, Rich Text, and text), along with two new formats for Windows 95: Device Independent Bitmap and Extended Metafile.

When a client application accepts a data object, it selects the format of the highest quality. If the program is privy to the Native Format (which is likely if the client and server are from the same vendor), there's no need to revert to a less accurate format for the transfer.