The functions described below affect the current video mode, coordinate systems, clipping regions, viewports, and windows. For more information, use Help.
Erases the text or graphics screen and fills it with the current background color (note that setting the video mode automatically clears the screen). Pass one of the constants _GCLEARSCREEN, _GVIEWPORT, or _GWINDOW. No return value.
Converts viewport coordinates to physical coordinates. Pass an x and y coordinate from the viewport. The function returns an _xycoord structure, which includes an x and a y position from the physical screen.
Obtains the status of the current graphics environment. Pass it the address of a structure of type _videoconfig. See “Reading the _videoconfig Structure”.
Converts physical coordinates to viewport coordinates. Pass two integers: an x and y coordinate. The function returns an _xycoord structure containing the equivalent position within the viewport.
Converts window coordinates to viewport coordinates. Pass two doubles that name points within the window. Returns the equivalent viewport coordinates as an _xycoord structure.
Converts window coordinates to viewport coordinates in an _xycoord structure. Pass a _wxycoord structure.
Converts viewport coordinates to window coordinates. Pass two integers representing viewport coordinates. Returns a _wxycoord structure.
Limits graphic output to part of the screen, called the “clipping region.” Pass four values: the x and y coordinate of the upper-left corner (on the physical screen) and the coordinates of the lower-right corner. The default clipping region is the entire screen. See “Physical Coordinates”.
Selects an operating mode for the display screen. Pass a constant, such as _HRES16COLOR. Returns 0 if the video mode selected is not supported by the hardware. See “Setting a Video Mode”.
Sets the video mode and the number of rows for text operations. Pass two values: a video mode and the desired number of text rows (25, 30, 43, 50, or 60). Pass the symbolic constant _MAXTEXTROWS to get the largest available number of rows. Returns the number of rows or 0 if unsuccessful.
Repositions the viewport origin. Pass an x and y position: the physical screen location that will become the new origin. Returns the previous origin in an _xycoord structure.
Creates a viewport, including a clipping region and a new origin in the upper-left corner of the viewport. Subsequent calls to graphics routines will be limited to the viewport area. Pass four short integers that indicate the physical screen locations of the x and y coordinates in the upper-left and lower-right corners of the viewport. No return value.
Defines a window coordinate system. Pass five values: a short invert flag (TRUE or FALSE) and four doubles that represent the extreme values in the upper-left and lower-right portions of the current viewport. See “Window Coordinates”.