29 The Power of Inheritance and Polymorphism

Implementation: Windows classes 1043}return sWindowRep;WindowRep *WindowRep::sWindowRep = NULL;The first time that it is called, function Instance() creates the WindowRep object;subsequent calls always return a pointer to the same object.The constructor calls function Initialize() which performs any systemdependent device initialization. It then sets up the image array, and clears thescreen.WindowRep::WindowRep(){Initialize();for(int row = 0; row < CG_HEIGHT; row++)for(int col = 0; col< CG_WIDTH; col++)fImage[row][col] = ' ';Clear();}The implementation of functions like Initialize() involves the same systemdependent calls as outlined in the "Cursor Graphics" examples in Chapter 12.Some example functions are:void WindowRep::Initialize(){#if defined(SYMANTEC)/*Have to change the "mode" for the 'console' screen.Putting it in C_CBREAK allows characters to be read one byone as they are typed*/csetmode(C_CBREAK, stdin);#else/*No special initializations are needed for Borland IDE*/#endif}void WindowRep::MoveCursor(int x, int y){if((xCG_WIDTH)) return;if((yCG_HEIGHT)) return;#if defined(SYMANTEC)cgotoxy(x,y,stdout);#elsegotoxy(x,y);#endif}void WindowRep::PutCharacter(char ch){