REFERENCE GUIDE

GetDCGetUpdateRectGetUpdateRgnGetWindowDCGrayStringInvalidateRectInvalidateRgnInvertRectReleaseDCUpdateWindowValidateRectValidateRgnRetrieves the display context for the clientarea.Copies the dimensions of a windowregion's bounding rectangle.Copies a window's update region.Retrieves the display context for an entirewindow.Writes the characters of a string using graytext.Marks a rectangle for repainting.Marks a region for repainting.Inverts the display bits of the specifiedrectangle.Releases a display context.Notifies the application when parts of awindow need redrawing.Releases the specified rectangle fromrepainting.Releases the specified region fromrepainting.How Windowsmanages thedisplayThe system display is the principal display device for allapplications running with Windows. All applications are free todisplay some form of output on the system display, but sincemany applications can run at one time, applications are notentitled to the entire system display. The complete system displaymust be shared. Windows shares the system display by carefullymanaging the access that applications have to it. Windowsensures that applications have space to display output but do notdraw in the space reserved for other applications.Windows manages the system display by using the displaycontext type. The display context is a special device context thattreats each window as a separate display surface. An applicationthat retrieves a display context for a specific window hascomplete control of the system display within that window, butcannot access or paint over any part of the display outside thewindow. With a display context, an application can use CDIpainting functions, as well as the output functions described inthis section, to draw in the given window.Chapter 1, Window manager interface functions 45