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

Next homework • A simple encoder/decoder program • Uses string manipulation • You may use either C++ strings or C-style strings • You will probably need to use some of each • C-style will be required for handling the command line argument (argv) • The program will use a variation of a shift cipher along with randomly embedded distracters

Coder • Usage • coder -c for encoding plain text • coder -d for decoding previously coded text • The program will be used with the Linux pipe (|) and I/O redirection (> < ) symbols so that there is no user interaction. See sample usage below. • coder –c < plain.txt • Encodes text from file “plain.txt” and outputs to screen • coder –d < coded.txt • Decodes text from file “coded.txt” and outputs to screen • cat plain.txt | coder –c • Output from cat is piped into coder where it is encoded and sent to screen • echo test it on this | coder –c > test.txt • “test it on this” is piped into coder, encoded, and sent to file “text.txt” • echo hello | coder –c | coder –d • “hello” is encoded and then decoded and then sent to the screen

Coder • Format of code is • [s][b]xx[block1]xx[block2]xx[block3]……. • [s] is a shift value 1..25 • It is used to shift all letters up by that amount • The shift wraps around in the alphabet • Upper case and lower case maintain their case in the code • [b] is the block size • Each block is a group of characters from the original plain text • xx stands for two random characters with ASCII values 33..126 that are • Inserted between blocks when encoding • Skipped over during decoding

Coder • Format of code is • [s][b]xx[block1]xx[block2]xx[block3]……. • Example: • This is a test. • Gets encoded differently based on shift and block size • Shift 22 and clock size 2 • w2/PPd*)eo6h eKfo iQw tTpa)=opiV. • Shift 24 and block size 3 • y3TtRfg.pq gibq yxZ rc>,qr.

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;

Shapes Revisited (X11 style) • ShapeX class • drawColor & setDrawColor() • drawX() draws a point at the origin • TwoDShape class • x, y, movePositX() & getPositX() • drawX() draws a point at its position • SquareX and CircleX classes • size, setSize() & getSize() • drawX() functions draw shape outlines

SquareX::drawX(…) void SquareX::drawX(ezXwindow &w) { if (size == 1) // just a point TwoDShapeX::drawX(w); else // has area, so draw Square outline { int left = x - size/2, right = x + size/2, top = y - size/2, bottom = y + size/2; w.X_draw_edge(left,top,right,top,drawColor); w.X_draw_edge(right,top,right,bottom,drawColor); w.X_draw_edge(right,bottom,left,bottom,drawColor); w.X_draw_edge(left,bottom,left,top,drawColor); } }

CircleX::drawX(…) void CircleX::drawX(ezXwindow &w) { if (size == 1) // it’s just a point TwoDShapeX::drawX(w); else // has area, so draw Circle outline { int inc(12), // must evenly divide 360 radius = size/2, startX = x + radius, startY = y; for (int a = inc; a <= 360; a += inc) { float angle = 3.14159*a/180.0; int endX = (int)round(x + radius*cos(angle)), endY = (int)round(y - radius*sin(angle)); w.X_draw_edge(startX,startY,endX,endY,drawColor); startX = endX; startY = endY; } } }

A Program using ezXwindow,SquareX & CircleX classes // ezXmvShapes08.cpp - JHS 2008 #include <unistd.h> // usleep #include <curses.h> // CURSES I/O #include <ctime> // time #include <cctype> // tolower #include <cstdlib> // system, exit rand, srand #include "shapes2008.h" #include "ezXwindow2.h" using namespace std; int main(int argc, char **argv) { // run CURSES in a small xterm, with display in an ezXwindow if (argc == 1) { // no command line arg so restart in xterm system("xterm -geometry 80x8+40+540 -e ezxms ON &"); exit(0); }

Program using ezXwindow(cont) SquareX sq; // create a Square CircleX circ; // create a Circle time_t theTime; int key, width(640), height(480), px, py, dx, dy; bool squareSelected(true); // declare and open an ezXwindow (640 x 480 pixels) ezXwindow ezWin; ezWin.X_open_win(width,height); // intitialize curses I/O initscr(); int scrwidth, scrheight; getmaxyx(stdscr, scrheight, scrwidth); raw(); cbreak(); noecho(); nodelay(stdscr,true); srand((int)time(&theTime));

Program using ezXwindow(cont) dx = 5; dy = 3; // set initial movements px = width/2; py = height/2; // set initial position sq.movePositX(px, py); // put sq in screen center sq.setSizeX(10); // set sq size circ.movePositX(px, py); // put circ in screen center circ.setSizeX(10); // set circ size int black = ezWin.X_set_color_black(), color = ezWin.X_set_color(rand()%256,rand()%256,rand()%256); do { // draw the square or circle in the ezXwindow if (squareSelected) { sq.setDrawColorX(color); sq.drawX(ezWin); // show SQUARE in Xwindow } else { circ.setDrawColorX(color); circ.drawX(ezWin); // show CIRCLE in Xwindow } ezWin.X_flush();

Program using ezXwindow(cont) // update information on CURSES screen clear(); mvprintw(0,0,"Shape:center(%3d,%3d)size(%3d)",px,py,sq.getSizeX()); mvprintw(0,scrwidth-38,"<< Shapes in ezXwindow (c) 2008 JHS >>"); mvprintw(scrheight-4,0,"(c) and (s) select circle or square"); mvprintw(scrheight-3,0,"(+) and (-) change size"); mvprintw(scrheight-2,0,"(q) quits!"); mvprintw(scrheight-1,0,"ENTER SELECTION --> "); refresh(); usleep(50000); // pause 1/20th second key = getch(); // check for keyboard input, but don't wait // erase the square or circle in the ezXwindow if (squareSelected) { sq.setDrawColorX(black); sq.drawX(ezWin); } else { circ.setDrawColorX(black); circ.drawX(ezWin); }

Program using ezXwindow(cont) if ((key == '+') && (sq.getSizeX() < 200)) { sq.setSizeX(sq.getSizeX()+2); // increase sq size circ.setSizeX(sq.getSizeX()+2); // increase circ size color = ezWin.X_set_color(rand()%256,rand()%256,rand()%256); } else if ((key == '-') && (sq.getSizeX() > 2)) { sq.setSizeX(sq.getSizeX()-2); // increase sq size circ.setSizeX(sq.getSizeX()-2); // increase circ size color = ezWin.X_set_color(rand()%256,rand()%256,rand()%256); } else if (tolower(key) == 's') squareSelected = true; // select SQUARE else if (tolower(key) == 'c') squareSelected = false; // select CIRCLE

Program using ezXwindow(cont) sq.getPositX(px,py); // get current position, both Shapes same if ((py-sq.getSizeX()/2 <= 0) || (py+sq.getSizeX()/2 >= height)) dy= -dy; // hit top or bottom wall so reverse y direction if ((px-sq.getSizeX()/2 <= 0) || (px+sq.getSizeX()/2 >= width)) dx = -dx; // hit side wall so reverse x direction sq.movePositX(px+dx, py+dy); // move SquareX circ.movePositX(px+dx, py+dy); // move CircleX } while ((key != 'q') && (key != 'Q')); // quit on input 'q' or 'Q' // clean up, and end curses I/O clear(); refresh(); endwin(); return 0; }

An ezXwindow 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