Windows Programming
Assignment No.1
Group 4

Submitted To: Submitted By: E.R. Mandeep Kumar Zennia 81307113049 I.T.

Q.NO.1 What is device context? Explain how it is used.
Ans.
Device Context:
A data structure in Windows programming that is used to define the attributes of text and images that are output to the screen or printer. The device context (DC) is maintained by GDI. A DC, which is a handle to the structure, is obtained before output is written and released after the elements have been written. One of the advantages of windows is its device independence. Device independence means that same program should be able to work using different devices like keyboard, screen, printer etc without modification to the program. Windows take care of the hardware allowing the programmer to concentrate on the program itself.
How is it used: Windows program do not send data directly to the screen or printer. Instead, the program contains a handle (ID value) for the screen or printer’s device context. The output data is sent to the device context (DC) and then windows take care of sending it to the real hardware. The part of windows that converts the windows graphics function calls to the actual commands sent to the hardware is the GDI (Graphics Device Interface). He GDI is program file called GDI.EXE that is stored in the Windows System Directory. The Windows Environment will load GDI.EXE into memory when it is needed for graphical output.

Getting and Releasing the handle of Device Context: To get the handle of DC : GetDC(hWnd)