29 The Power of Inheritance and Polymorphism

Inheritance and Polymorphism 1044#if defined(SYMANTEC)fputc(ch, stdout);fflush(stdout);#elifputch(ch);#endif}Functions like WindowRep::Delay() and WindowRep::GetChar() similarlyrepackage code from "Cursor Graphics" example.The WindowRep::Putcharacter() function only does the cursor movementand character output operations when necessary. This function also keeps theWindowRep object's image array consistent with the screen.void WindowRep::PutCharacter(char ch, int x, int y){if((xCG_WIDTH)) return;if((yCG_HEIGHT)) return;}if(ch != fImage[y-1][x-1]) {MoveCursor(x,y);PutCharacter(ch);fImage[y-1][x-1] = ch;}The CloseDown() function clears the screen, performs any device specifictermination, then after a short delay lets the WindowRep object self destruct.void WindowRep::CloseDown(){Clear();#if defined(SYMANTEC)csetmode(C_ECHO, stdin);#endifsWindowRep = NULL;Delay(2);delete this;}WindowThe constructor for class Window initializes the simple data members like the widthand height fields. The foreground and background arrays are created. They arevectors, each element of which represents an array of characters (one row of theimage).Window::Window(int x, int y, int width, int height,char bkgd, int framed ){fX = x-1;fY = y-1;