judging by low bandwidth footprint I am guessing that TeamViewer doesn't just transmit the screen pixel by pixel. So what api would such a tool use to obtain graphics features for efficient transmission? Are there open source apps like "poor man's TeamViewer" demonstrating this in code?
ETA: I am not asking for "specific api" for "complex task". My question boils down to "how does TeamViewer work, in terms of obtaining graphics info from Windows?"