The GMatrix Class

I designed the graph class to be reasonably simple to use so I could remember what everything meant. I also wanted something that would get a reasonably good looking graph on the screen with about 5 minutes of typing. The class definition is given by 

class GMatrix
{
  private:
    // Borland graphics information. bgi files must be available
    int    GraphDriver;
    int    GraphMode;
    int    MaxX, MaxY;
    int    MaxColors;
    int    ErrorCode;
    struct linesettingstype lineinfo;
    struct viewporttype viewinfo;


    // reference lines. can have at most 20 reference lines
    double *hrefs;
    double *vrefs;
    int nvrefs, nhrefs;

    // output a line, and pause function ESC stops program
    int  gprintf(int *xloc, int *yloc, char *fmt, ... );
    void Pause();

    // graph is stored in a VMatrix: [graphid, symbol, x, y] 4 cols
    int    graphnum;        // number of graphs in grf;
    VMatrix *grf;

    // plot a point on the screen
    void plotpoint( int ix, int iy, int symbol);

  public:

    // constructors and destructors

    GMatrix( void );
    GMatrix( VMatrix &ROp, int symbol= -' '); // ROp should be rx2 matrix
                                              // column 1 is x, col 2 is y
    ~GMatrix( void );

    // display a graph
    void Show( void );

    // add a new vector to plot
    void AddVec( VMatrix &ROp, int symbol = -' ');

    // annotation options

    strtype *title, *title2, *xname, *yname, *PathToDriver;
    boolean RectangleOn, YGridOn, XGridOn;
    void Href( double href );
    void Vref( double vref );
    int ClearHref( void ){ int t=nhrefs; nhrefs = -1; return t;}
    int ClearVref( void ){ int t=nvrefs; nvrefs = -1; return t;}

    // save the grf matrix
    void SaveGraph( char *fid ) { Writea( fid, *grf ); }
};

The graphics class is not automatically included in your project since it is machine-compiler specific. To gain access to the class you must define the global symbol VIRTGRAF. This can be done in the compiler options of the IDE, or with a -DVIRTGRAF in the command line compiler. This sets a switch in VIRT.H to include the GMatrix class definition. You must also make VIRTGRAF.CPP part of your project.

The strtype pointer PathToDriver contains the path to the BGI drivers. You tell your program where the BGI files are by a command such as *PathToDriver = "c:\\tc\\bgi". There are two things to note here. First, PathToDriver is a pointer, so you must use a '*' in front of it to store a value in it. Secondly, note the double slashes are required for the BGI autodetection function.


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