CSE 20232 Lecture 32 – Coding, X11, Inheritance, & Makefiles

CSE 20232Lecture 32 – Coding, X11, Inheritance, & Makefiles • Coding and decoding – next assignment • X11 windows (Xlib) • Makefiles in a bit more detail • Examples: • X11 Move & show program • (Square:TwoDShape:Shape) • X11 image display

Coding and Decoding • Some ASCII basics • ASCII code is listed in Appendix B, page 1231 • Digits ‘0’..’9’ are ASCII codes 48..57 • Letters ‘A’..’Z’ are ASCII codes 65..90 • Letters ‘a’..’z’ are ASCII codes 97..122 • Some easy tasks • Convert digit to equivalent number • (e.g., ‘5’  5) • Given char ch = ‘5’; … int value = ch – ‘0’; • Convert number to equivalent ASCII character • (e.g., 4  ‘4’) • Given int value = 4; … char ch = (char)(value + ‘0’);

Coding and Decoding • Shifting a letter n=5 positions in the alphabet • ABCDEFGHIJKLMNOPQRSTUVWXYZ (plain text) • FGHIJKLMNOPQRSTUVWXYZABCDE (coded text) • Approach # 1: Add n to ASCII code for letter and if result is greater than code for ‘Z’, then subtract 26 char letter = ‘W’; int shift = 5; char codeLetter = letter + n; if (codeLetter > ‘Z’) codeLetter = codeLetter - 26; • Approach # 2: Use modular arithmetic to add the relative position of the new letter in the alphabet to the position of ‘A’ char letter = ‘W’; int shift = 5; int codeLtrPos = ((letter – ’A’) + n) % 26; char codeLetter = ‘A’ + codeLtrPos;

Coding and Decoding • Shifting a letter n=5 positions in the alphabet • ABCDEFGHIJKLMNOPQRSTUVWXYZ (plain text) • FGHIJKLMNOPQRSTUVWXYZABCDE (coded text) • Decoding: If letter was coded by shifting n=5 positions right, then decode • (1) by shifting r = -n or -5 positions left or … • (2) by shifting 26 – n = 26 - 5 = 21 positions further right • Correct for shifts past end of alphabet as previously shown

XWindows (X11) • Here is a brief intro to X Windows (for more see wikipedia.org) • The X Window System (commonly X11 or X) is a protocol and associated software to provide windowing on bitmap displays. • It provides the standard toolkit and protocol to build graphical user interfaces (GUIs) on Unix, Linux, and is supported by most other modern operating systems. • X provides the basic framework for a GUI environment: • drawing and moving windows on the screen • interacting with a mouse and/or keyboard. • X does not specify a particular user interface so different programs may present radically different interfaces.

Xlib • Xlib is the basic X function library for creating X applications • It involves … • Creating and managing displays, windows, graphics contexts, color maps, … • Detecting and queuing events from mouse, keyboard, … • Handling resizing and hiding/exposing of windows

ezXwindows • For our last program I have created a simplified version of Xlib (ezXwindows) • It allows you to … • Open a window • Change colors • Draw using lines • Example programs • ezXmandel.cpp – shows Mandelbrot image • ezXshowShapes.cpp – shows bouncing box

ezXwindows class class ezXwindow { public: // create an ezXwindow object (includes dynamic // allocation of WinStuff structure) ezXwindow(void); // call X_close_win() if the window is actually still // open and then destroy the ezXwindow object // (delete WinStuff structure) ~ezXwindow(void);

ezXwindows class // handle all details of opening an X11/Xlib window of // specified size. Initial foreground color is system // white, and background color is system black. This // function MUST BE CALLED BEFORE any actual changes // of colors, or drawing can be performed. void X_open_win(int width=SCREEN_WIDTH, int height=SCREEN_HEIGHT); // handle all details of closing X11/Xlib window and // freeing resources void X_close_win(void); // indicates whether X11 window has be opened bool isOpen(void) const;

ezXwindows class // indicates whether current foreground color is // system black bool isBlack(void) const; // indicates whether current foreground color is // system white bool isWhite(void) const; // sets current foreground color to (r,g,b) color // specified and returns the index (color number) of // the window's Colormap entry int X_set_color(int r, int g, int b);

ezXwindows class // sets current foreground color to system black and // return the index (color number) of the window's // Colormap entry int X_set_color_black(void); // sets current foreground color to system white and // return the index (color number) of the window's // Colormap entry int X_set_color_white(void); // sets foreground color as specified and draws an edge // from x1,y1 to x2,y2 in the current foreground color void X_draw_edge(double x0, double y0, double x1, double y1, int color);

ezXwindows class // sends buffered output to window X_flush(); private: WinStuff *X; // pointer to the X window structure bool Open; // true means X window is open bool black, white; // color is system black or // system white or custom };

WinStuff structure details #define NIL 0 #define SCREEN_WIDTH 640 #define SCREEN_HEIGHT 480 #define MAXCOLOR 255 typedef struct { XColor pC; // a color Colormap m_map; // a colormap Display *dpy; // the display Window w; // the window GC gc; // the graphics context double midX, midY; // middle of screen double scale; // minimum screen dimension int blackColor, whiteColor; // default background & // foreground colors } WinStuff;

Program using Squares // ezXdrawShapes.cpp - JHS 2006 #include <iostream> #include <curses.h> #include <ctime> #include "shapes2006.h" #include "ezXwindow.h“ // new, for X11 window using namespace std; int main() { Square sq; time_t theTime; int key, width, height, px, py, dx, dy; // declare and open an ezXwindow (790 x 250) pixels ezXwindow ezWin; ezWin.X_open_win(790,250); // intitialize curses I/O initscr(); getmaxyx(stdscr, height, width); raw(); cbreak(); noecho(); nodelay(stdscr,true); srand((int)time(&theTime));

Program using Squares sq.movePosit(width/2, height/2); // put sq in screen center sq.setSize(10); // set sq size dx = 2; dy = 1; // set initial movements do { sq.getPosit(px,py); // get current position of Shape // clear screen, show sq, position & size and wait 1/5 sec clear(); sq.draw(); // position ad draw the square in the ezXwindow int half = sq.getSize()/2; int Lx = 10*(px-half), Uy = 10*(py-half), Rx = 10*(px+half), Ly = 10*(py+half); int color = ezWin.X_set_color(rand()%256,rand()%256,rand()%256); ezWin.X_draw_edge(Lx,Uy,Lx,Ly, color); // left side ezWin.X_draw_edge(Lx,Ly,Rx,Ly, color); // bottom ezWin.X_draw_edge(Rx,Ly,Rx,Uy, color); // right side ezWin.X_draw_edge(Rx,Uy,Lx,Uy, color); // top ezWin.X_flush(); // show buffer

Program using Squares // display location and prompt user inputs mvprintw(0,0,"Square: center(%3d,%3d) size(%3d)", px, py, sq.getSize()); mvprintw(0,width-29,"<< The Square (c) 2006 JHS >>"); mvprintw(height-1,0, "ENTER: (+) or (-) to change size or (q) to quit! "); refresh(); usleep(100000); // pause 1/10th second key = getch(); // check for keyboard input, but don't wait if ((key == '+') && (sq.getSize() < 20)) sq.setSize(sq.getSize()+2); // increase sq size if ((key == '-') && (sq.getSize() > 2)) sq.setSize(sq.getSize()-2); // decrease sq size if ((py-sq.getSize()/2 <= 0) || (py+sq.getSize()/2 >= height)) { dy= -dy; // hit top or bottom wall so reverse y direction sq.setDrawChar((char)(33+rand()%94)); // change draw char }

Program using Squares if ((px-sq.getSize()/2 <= 0) || (px+sq.getSize()/2 >= width-1)) dx = -dx; // hit side wall so reverse x direction // erase the square in the ezXwindow color = ezWin.X_set_color_black(); // draw in black ezWin.X_draw_edge(Lx,Uy,Lx,Ly, color); ezWin.X_draw_edge(Lx,Ly,Rx,Ly, color); ezWin.X_draw_edge(Rx,Ly,Rx,Uy, color); ezWin.X_draw_edge(Rx,Uy,Lx,Uy, color); sq.movePosit(px+dx, py+dy); // move sq } while ((key != 'q') && (key != 'Q')); // quit on 'q' or 'Q‘ clear(); refresh(); endwin(); // clean up, and end curses I/O return 0; }

Program to display images // ezXimage.cpp -- JHS 10/24/2003 & 11/19/2006 #include <iostream> #include <fstream> #include "ezXwindow.h" using namespace std; #define ROWS 1024 #define COLUMNS 1024 bool load(string filename, unsigned char image[ROWS][COLUMNS][3], int &width, int &height); int main (void) { unsigned char image[ROWS][COLUMNS][3]; int width; int height; string filename; ezXwindow ezWin; // for the X11 display

Program to display images system("clear"); system("ls *.ppm"); cout << "\nChoose file to display: “; cin >> filename; cin.get(); if (! load(filename, image, width, height)) return 1; // open window and draw image from the array ezWin.X_open_win(width,height); for (int r=0;r<height;r+=1) for (int c=0;c<width;c+=1) ezWin.X_draw_edge( c, r, c, r+1, ezWin.X_set_color( image[r][c][0], image[r][c][1], image[r][c][2])); ezWin.X_flush(); cout << "Hit ENTER to exit!"; cin.get(); return 0; }

Program to display images(load function) bool load(string filename, unsigned char image[ROWS][COLUMNS][3], int &width, int &height) { int maxcolor; string comment, magicNum; cout << "Loading file \"" << filename << "\"\n"; ifstream infile(filename.c_str()); if (infile.fail()) { infile.clear(); cout << "ERROR: load failed.\n"; return false; } getline(infile,magicNum); if (magicNum != "P6") return false;

Program to display images(load function) while(infile.peek() == '#') getline(infile, comment); infile >> width >> height >> maxcolor; infile.get(); for (int r=0;r<height;r++) for (int c=0;c<width;c++) { image[r][c][0] = infile.get(); image[r][c][1] = infile.get(); image[r][c][2] = infile.get(); } infile.clear(); infile.close(); return true; }

More on Makefiles • MACRO • A name associated with a value to be used later • Useful macros • List of compiler options • List of libraries to be linked to program • Alternate locations for includes and libraries • $@ is the current target • $^ is a list of the current dependencies

Sample Makefile # Makefile for ezXimage # JHS 2006 Notre Dame # here are some useful macros for COMMON items SOURCES = ezXimage.cpp ezXwindow.cpp OBJECTS = ezXimage.o ezXwindow.o HEADERS = ezXwindow.h LIBS = -L/usr/X11R6/lib -lX11 -lm INCLUDES = -I/usr/include/X11 ezXimage : $(OBJECTS) g++ -o $@ $^ $(LIBS) ezXimage.o : ezXimage.cpp ezXwindow.h g++ -c ezXimage.cpp $(INCLUDES) ezXwindow.o : ezXwindow.cpp ezXwindow.h g++ -c ezXwindow.cpp $(INCLUDES)

CSE 20232 Lecture 32 – Coding, X11, Inheritance, & Makefiles