add x examples for 1-4 drawing

x/1-4-Drawing/clipping.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    displaylist     Demos Displayable class and display list
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <iostream>
+#include <list>
+#include <cstdlib>
+#include <vector>
+/*
+ * Header files for X functions
+ */
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+#include <unistd.h> // needed for sleep
+
+using namespace std;
+
+/*
+ * Information to draw on the window.
+ */
+struct XInfo {
+  Display*  display;
+  Window   window;
+  GC       gc;
+};
+
+
+/*
+ * An abstract class representing displayable things.
+ */
+class Displayable {
+public:
+  virtual void paint(XInfo& xinfo) = 0;
+};
+
+/*
+ * A text displayable
+ */
+class Text : public Displayable {
+public:
+  virtual void paint(XInfo& xinfo) {
+    XDrawImageString( xinfo.display, xinfo.window, xinfo.gc,
+                      this->x, this->y, this->s.c_str(), this->s.length() );
+  }
+
+  // constructor
+  Text(int x, int y, string s): x(x), y(y), s(s)  {}
+
+private:
+  int x;
+  int y;
+  string s; // string to show
+};
+
+/*
+ * A displayable polyline
+ */
+class Polyline : public Displayable {
+public:
+  virtual void paint(XInfo& xinfo) {
+
+    // CLIPPING CODE HERE!
+    // =====================================
+    
+    // create a clip window
+    XRectangle clip_rect;
+
+    clip_rect.x = 50;
+    clip_rect.y = 50;
+    clip_rect.width = 200;
+    clip_rect.height = 200;
+
+    // clips all drawings that use the same GC after this call ...
+    XSetClipRectangles(xinfo.display, xinfo.gc, 
+      0, 0, &clip_rect, 1, Unsorted);
+
+    XDrawLines(xinfo.display, xinfo.window, xinfo.gc,
+               &points[0], points.size(),  // vector of points
+               CoordModeOrigin ); // use absolute coordinates
+
+    // turn clipping off again
+    XSetClipMask(xinfo.display, xinfo.gc, None);
+
+    // =====================================
+    // to here
+  }
+
+  // constructor
+  Polyline(int x, int y) {
+    add_point(x, y);
+  }
+
+  // add another point to the line
+  void add_point(int x, int y) {
+    XPoint p; // XPoint is a built in struct
+    p.x = x;
+    p.y = y;
+    points.push_back(p);
+  }
+
+private:
+  // need to use a vector to dynamically add points
+  vector < XPoint > points; // XPoint is a built in struct
+};
+
+
+
+/*
+ * A face displayable
+ */
+class Face : public Displayable {
+public:
+  virtual void paint(XInfo& xinfo) {
+
+    // create a simple graphics context
+    GC gc = XCreateGC(xinfo.display, xinfo.window, 0, 0);
+    int screen = DefaultScreen( xinfo.display );
+    XSetForeground(xinfo.display, gc, BlackPixel(xinfo.display, screen));
+    XSetBackground(xinfo.display, gc, WhitePixel(xinfo.display, screen));
+    XSetFillStyle(xinfo.display,  gc, FillSolid);
+    XSetLineAttributes(xinfo.display, gc,
+                       3,       // 3 is line width
+                       LineSolid, CapButt, JoinRound);         // other line options
+
+
+    // draw head
+    XFillArc(xinfo.display, xinfo.window, gc,
+             x - (d / 2), y - (d / 2), d, d, 0, 360 * 64);
+
+    XSetForeground(xinfo.display, gc, WhitePixel(xinfo.display, screen));
+
+    // draw mouth either smiling or serious
+    if (smile) {
+      int dd = d / 2;
+      XDrawArc(xinfo.display, xinfo.window, gc,
+               x - (dd / 2), y - (dd / 2), dd, dd, 210 * 64, 120 * 64);
+    } else {
+      int dd = d / 3;
+      XDrawLine(xinfo.display, xinfo.window, gc,
+                x - dd, y + dd / 2, x + dd, y + dd / 2);
+    }
+  }
+
+  // constructor
+  Face(int x, int y, int d, bool smile): x(x), y(y), d(d), smile(smile) {}
+
+private:
+  int x;
+  int y;
+  int d; // diameter
+  bool smile; // is smiling
+};
+
+
+
+/*
+ * Function to put out a message on error exits.
+ */
+void error( string str ) {
+  cerr << str << endl;
+  exit(0);
+}
+
+
+/*
+ * Create a window
+ */
+void initX(int argc, char* argv[], XInfo& xinfo) {
+
+
+  /*
+  * Display opening uses the DISPLAY  environment variable.
+  * It can go wrong if DISPLAY isn't set, or you don't have permission.
+  */
+  xinfo.display = XOpenDisplay( "" );
+  if ( !xinfo.display ) {
+    error( "Can't open display." );
+  }
+
+  /*
+  * Find out some things about the display you're using.
+  */
+  // DefaultScreen is as macro to get default screen index
+  int screen = DefaultScreen( xinfo.display );
+
+  unsigned long white, black;
+  white = XWhitePixel( xinfo.display, screen );
+  black = XBlackPixel( xinfo.display, screen );
+
+  xinfo.window = XCreateSimpleWindow(
+                   xinfo.display,       // display where window appears
+                   DefaultRootWindow( xinfo.display ), // window's parent in window tree
+                   10, 10,                  // upper left corner location
+                   300, 300,                  // size of the window
+                   5,               // width of window's border
+                   black,           // window border colour
+                   white );             // window background colour
+
+  // extra window properties like a window title
+  XSetStandardProperties(
+    xinfo.display,    // display containing the window
+    xinfo.window,   // window whose properties are set
+    "clipping",  // window's title
+    "CL",       // icon's title
+    None,       // pixmap for the icon
+    argv, argc,     // applications command line args
+    None );         // size hints for the window
+
+  /*
+   * Put the window on the screen.
+   */
+  XMapRaised( xinfo.display, xinfo.window );
+
+  XFlush(xinfo.display);
+
+  // give server time to setup
+  sleep(1);
+}
+
+/*
+ * Function to repaint a display list
+ */
+void repaint( list<Displayable*> dList, XInfo& xinfo) {
+  list<Displayable*>::const_iterator begin = dList.begin();
+  list<Displayable*>::const_iterator end = dList.end();
+
+  XClearWindow(xinfo.display, xinfo.window);
+  while ( begin != end ) {
+    Displayable* d = *begin;
+    d->paint(xinfo);
+    begin++;
+  }
+  XFlush(xinfo.display);
+}
+
+
+int main( int argc, char* argv[] ) {
+
+  XInfo xinfo;
+
+  initX(argc, argv, xinfo);
+
+  // create a simple graphics context
+  GC gc = XCreateGC(xinfo.display, xinfo.window, 0, 0);
+  int screen = DefaultScreen( xinfo.display );
+  XSetForeground(xinfo.display, gc, BlackPixel(xinfo.display, screen));
+  XSetBackground(xinfo.display, gc, WhitePixel(xinfo.display, screen));
+
+  // load a larger font
+  XFontStruct * font;
+  font = XLoadQueryFont (xinfo.display, "12x24");
+  XSetFont (xinfo.display, gc, font->fid);
+
+  xinfo.gc = gc;
+
+  // list of Displayables
+  list<Displayable*> dList;
+
+  Polyline* polyline = new Polyline(0, 0);
+  for (int i = 0; i < 100; i++) {
+    polyline->add_point(rand() % 300, rand() % 300);
+  }
+
+  // try changing the order or commenting out these lines
+
+  dList.push_back(new Text(50, 50, "ABC"));
+
+  dList.push_back(new Text(130, 100, "DEF"));
+
+  dList.push_back(new Text(200, 200, "GHI"));
+
+  dList.push_back(new Face(200, 200, 50, false));
+
+  dList.push_back(polyline);
+
+  // paint everything in the display list
+  repaint(dList, xinfo);
+
+  XFlush(xinfo.display);
+
+  std::cout << "ENTER2exit"; std::cin.get(); // wait for input
+  XCloseDisplay(xinfo.display);
+
+}
\ No newline at end of file

x/1-4-Drawing/displaylist.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    displaylist     Demos Displayable class and display list technique
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <iostream>
+#include <list>
+#include <cstdlib>
+#include <vector>
+/*
+ * Header files for X functions
+ */
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+#include <unistd.h> // needed for sleep
+
+using namespace std;
+
+/*
+ * Information to draw on the window.
+ */
+struct XInfo {
+  Display*  display;
+  Window   window;
+  GC       gc;
+};
+
+
+/*
+ * An abstract class representing displayable things.
+ */
+class Displayable {
+public:
+  virtual void paint(XInfo& xinfo) = 0;
+};
+
+/*
+ * A text displayable
+ */
+class Text : public Displayable {
+public:
+  virtual void paint(XInfo& xinfo) {
+    XDrawImageString( xinfo.display, xinfo.window, xinfo.gc,
+                      this->x, this->y, this->s.c_str(), this->s.length() );
+  }
+
+  // constructor
+  Text(int x, int y, string s): x(x), y(y), s(s)  {}
+
+private:
+  int x;
+  int y;
+  string s; // string to show
+};
+
+/*
+ * A displayable polyline
+ */
+class Polyline : public Displayable {
+public:
+  virtual void paint(XInfo& xinfo) {
+    // note the trick to pass a stl vector as an C array
+    XDrawLines(xinfo.display, xinfo.window, xinfo.gc,
+               &points[0], points.size(),  // vector of points
+               CoordModeOrigin ); // use absolute coordinates
+  }
+
+  // constructor
+  Polyline(int x, int y) {
+    add_point(x, y);
+  }
+
+  // add another point to the line
+  void add_point(int x, int y) {
+    XPoint p; // XPoint is a built in struct
+    p.x = x;
+    p.y = y;
+    points.push_back(p);
+  }
+
+private:
+  // need to use a vector to dynamically add points
+  vector < XPoint > points; // XPoint is a built in struct
+};
+
+
+
+/*
+ * A face displayable
+ */
+class Face : public Displayable {
+public:
+  virtual void paint(XInfo& xinfo) {
+
+     // create a simple graphics context
+    GC gc = XCreateGC(xinfo.display, xinfo.window, 0, 0);
+    int screen = DefaultScreen( xinfo.display );
+    XSetForeground(xinfo.display, gc, BlackPixel(xinfo.display, screen));
+    XSetBackground(xinfo.display, gc, WhitePixel(xinfo.display, screen));
+    XSetFillStyle(xinfo.display,  gc, FillSolid);
+    XSetLineAttributes(xinfo.display, gc,
+                       3,       // 3 is line width
+                       LineSolid, CapButt, JoinRound);         // other line options
+
+
+    // draw head
+    XFillArc(xinfo.display, xinfo.window, gc,
+             x - (d / 2), y - (d / 2), d, d, 0, 360 * 64);
+
+    XSetForeground(xinfo.display, gc, WhitePixel(xinfo.display, screen));
+
+    // draw mouth either smiling or serious
+    if (smile) {
+      int dd = d / 2;
+      XDrawArc(xinfo.display, xinfo.window, gc,
+               x - (dd / 2), y - (dd / 2), dd, dd, 210 * 64, 120 * 64);
+    } else {
+      int dd = d / 3;
+      XDrawLine(xinfo.display, xinfo.window, gc,
+                x - dd, y + dd / 2, x + dd, y + dd / 2);
+    }
+  }
+
+  // constructor
+  Face(int x, int y, int d, bool smile): x(x), y(y), d(d), smile(smile) {}
+
+private:
+  int x;
+  int y;
+  int d; // diameter
+  bool smile; // is smiling
+};
+
+
+
+/*
+ * Function to put out a message on error exits.
+ */
+void error( string str ) {
+  cerr << str << endl;
+  exit(0);
+}
+
+
+/*
+ * Create a window
+ */
+void initX(int argc, char* argv[], XInfo& xinfo) {
+
+
+  /*
+  * Display opening uses the DISPLAY  environment variable.
+  * It can go wrong if DISPLAY isn't set, or you don't have permission.
+  */
+  xinfo.display = XOpenDisplay( "" );
+  if ( !xinfo.display ) {
+    error( "Can't open display." );
+  }
+
+  /*
+  * Find out some things about the display you're using.
+  */
+  // DefaultScreen is as macro to get default screen index
+  int screen = DefaultScreen( xinfo.display );
+
+  unsigned long white, black;
+  white = XWhitePixel( xinfo.display, screen );
+  black = XBlackPixel( xinfo.display, screen );
+
+  xinfo.window = XCreateSimpleWindow(
+                   xinfo.display,       // display where window appears
+                   DefaultRootWindow( xinfo.display ), // window's parent in window tree
+                   10, 10,                  // upper left corner location
+                   300, 300,                  // size of the window
+                   5,               // width of window's border
+                   black,           // window border colour
+                   white );             // window background colour
+
+  // extra window properties like a window title
+  XSetStandardProperties(
+    xinfo.display,    // display containing the window
+    xinfo.window,   // window whose properties are set
+    "displaylist",  // window's title
+    "DL",       // icon's title
+    None,       // pixmap for the icon
+    argv, argc,     // applications command line args
+    None );         // size hints for the window
+
+  /*
+   * Put the window on the screen.
+   */
+  XMapRaised( xinfo.display, xinfo.window );
+
+  XFlush(xinfo.display);
+
+  // give server time to setup
+  sleep(1);
+}
+
+/*
+ * Function to repaint a display list
+ */
+void repaint( list<Displayable*> dList, XInfo& xinfo) {
+  list<Displayable*>::const_iterator begin = dList.begin();
+  list<Displayable*>::const_iterator end = dList.end();
+
+  XClearWindow(xinfo.display, xinfo.window);
+  while ( begin != end ) {
+    Displayable* d = *begin;
+    d->paint(xinfo);
+    begin++;
+  }
+  XFlush(xinfo.display);
+}
+
+
+int main( int argc, char* argv[] ) {
+
+  XInfo xinfo;
+
+  initX(argc, argv, xinfo);
+
+  // create a simple graphics context
+  GC gc = XCreateGC(xinfo.display, xinfo.window, 0, 0);
+  int screen = DefaultScreen( xinfo.display );
+  XSetForeground(xinfo.display, gc, BlackPixel(xinfo.display, screen));
+  XSetBackground(xinfo.display, gc, WhitePixel(xinfo.display, screen));
+
+  // load a larger font
+  XFontStruct * font;
+  font = XLoadQueryFont (xinfo.display, "12x24");
+  XSetFont (xinfo.display, gc, font->fid);
+
+  xinfo.gc = gc;
+
+   // list of Displayables
+  list<Displayable*> dList;
+
+  Polyline* polyline = new Polyline(0, 0);
+  for (int i = 0; i < 100; i++) {
+    polyline->add_point(rand() % 300, rand() % 300);
+  }
+
+  // try changing the order or commenting out these lines
+
+
+  dList.push_back(new Text(50, 50, "ABC"));
+
+  dList.push_back(new Text(130, 100, "DEF"));
+
+  dList.push_back(new Text(200, 200, "GHI"));
+
+  dList.push_back(new Face(200, 200, 50, false));
+
+  dList.push_back(polyline);
+
+
+  // paint everything in the display list
+  repaint(dList, xinfo);
+
+  XFlush(xinfo.display);
+
+  std::cout << "ENTER2exit"; std::cin.get(); // wait for input
+  XCloseDisplay(xinfo.display);
+
+}
\ No newline at end of file

x/1-4-Drawing/drawing.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    drawing     Demos drawing functions and graphics contexts
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <iostream>
+#include <list>
+#include <cstdlib>
+#include <unistd.h>
+
+// Header files for X functions
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+using namespace std;
+
+// handy struct to save display, window, and screen
+struct XInfo {
+	Display	 *display;
+	int		 screen;
+	Window	 window;
+};
+
+// Function to put out a message on error and exits
+void error( string str ) {
+	cerr << str << endl;
+	exit(0);
+}
+
+void drawRectanglesInCorners(XInfo &xinfo, GC gc) {
+	Display  *display = xinfo.display;
+	Window   win = xinfo.window;
+
+	XWindowAttributes windowInfo;
+	XGetWindowAttributes(display, win, &windowInfo);
+	// max x and y coordinate
+	unsigned int maxHeight = windowInfo.height - 1;
+	unsigned int maxWidth = windowInfo.width - 1;
+
+	// draw rectangles in each corner of the window 
+	int s = 32; // rectangle size
+	XDrawRectangle(display, win, gc, 0, 0, s, s); // top left
+	XDrawRectangle(display, win, gc, 0, maxHeight - s, s, s); // bottom left
+	XDrawRectangle(display, win, gc, maxWidth - s, 0, s, s); // top right
+	XDrawRectangle(display, win, gc, maxWidth - s, maxHeight - s, s, s); // bottom right
+}
+
+void drawStuff(XInfo &xinfo, GC gc, int x, int y) {
+	Display  *display = xinfo.display;
+	Window   win = xinfo.window;
+
+	// draw two intersecting lines, one horizontal and one vertical,
+	// which intersect at point "x,y".                            
+	XDrawLine(display, win, gc, x, y - 30, x, y + 200);
+	XDrawLine(display, win, gc, x - 30, y, x + 200, y);
+
+	// now use the XDrawArc() function to draw a circle whose diameter
+	// is 30 pixels, and whose center is at location 'x,y'.        
+	XDrawArc(display, win, gc, x - (30 / 2), y - (30 / 2), 30, 30, 0, 360 * 64);
+
+	// draw a small triangle at the top-left corner of the window.
+	// the triangle is made of a set of consecutive lines, whose  
+	// end-point pixels are specified in the 'points' array.      
+	{
+		XPoint points[] = {
+			{x + 200, y + 50},
+			{x + 250, y + 80},
+			{x + 200, y + 80},
+			{x + 200, y + 50}
+		};
+		int npoints = sizeof(points) / sizeof(XPoint);
+
+		XDrawLines(display, win, gc, points, npoints, CoordModeOrigin);
+	}
+
+	// draw a rectangle whose top-left corner is at 'x+120,y+50', its width is 
+	// 50 pixels, and height is 60 pixels.                                  
+	XDrawRectangle(display, win, gc, x + 120, y + 50, 50, 60);
+
+	// draw a filled rectangle of the same size as above, to the left of the 
+	// previous rectangle.                                                   
+	XFillRectangle(display, win, gc, x + 60, y + 50, 50, 60);
+}
+
+
+// Initialize X and create a window
+void initX(int argc, char *argv[], XInfo &xinfo) {
+
+	XSizeHints hints;
+	unsigned long white, black;
+
+
+	// Display opening uses the DISPLAY	environment variable.
+	// It can go wrong if DISPLAY isn't set, or you don't have permission.
+	xinfo.display = XOpenDisplay( "" );
+	if ( !xinfo.display )	{
+		error( "Can't open display." );
+	}
+
+	// Find out some things about the display you're using.
+	xinfo.screen = DefaultScreen( xinfo.display );
+
+	white = XWhitePixel( xinfo.display, xinfo.screen );
+	black = XBlackPixel( xinfo.display, xinfo.screen );
+
+	hints.x = 100;
+	hints.y = 100;
+	hints.width = 600;
+	hints.height = 600;
+	hints.flags = PPosition | PSize;
+
+	xinfo.window = XCreateSimpleWindow(
+	                   xinfo.display,				// display where window appears
+	                   DefaultRootWindow( xinfo.display ), // window's parent in window tree
+	                   hints.x, hints.y,			// upper left corner location
+	                   hints.width, hints.height,	// size of the window
+	                   5,						// width of window's border
+	                   black,						// window border colour
+	                   white );					// window background colour
+
+	XSetStandardProperties(
+	    xinfo.display,		// display containing the window
+	    xinfo.window,		// window whose properties are set
+	    "drawing",			// window's title
+	    "SD",				// icon's title
+	    None,				// pixmap for the icon
+	    argv, argc,			// applications command line args
+	    &hints );			// size hints for the window
+
+	// Put the window on the screen.
+	XMapRaised( xinfo.display, xinfo.window );
+
+	XFlush(xinfo.display);
+	
+    // give server time to setup before sending drawing commands
+    sleep(1);
+}
+
+
+
+/*
+ * Start executing here.
+ *	 First initialize window.
+ *	 Next loop responding to events.
+ *	 Exit forcing window manager to clean up - cheesy, but easy.
+ */
+int main ( int argc, char *argv[] ) {
+	XInfo xinfo;
+
+	initX(argc, argv, xinfo);
+
+	// an array of graphics contexts to demo
+	GC  gc[3];
+
+	// Create 3 Graphics Contexts
+	int i = 0;
+	gc[i] = XCreateGC(xinfo.display, xinfo.window, 0, 0);
+	XSetForeground(xinfo.display, gc[i], BlackPixel(xinfo.display, xinfo.screen));
+	XSetBackground(xinfo.display, gc[i], WhitePixel(xinfo.display, xinfo.screen));
+	XSetFillStyle(xinfo.display, gc[i], FillSolid);
+	XSetLineAttributes(xinfo.display, gc[i],
+	                   1, LineSolid, CapButt, JoinRound);
+
+	i = 1;
+	gc[i] = XCreateGC(xinfo.display, xinfo.window, 0, 0);
+	XSetForeground(xinfo.display, gc[i], BlackPixel(xinfo.display, xinfo.screen));
+	XSetBackground(xinfo.display, gc[i], WhitePixel(xinfo.display, xinfo.screen));
+	XSetFillStyle(xinfo.display, gc[i], FillSolid);
+	XSetLineAttributes(xinfo.display, gc[i],
+	                   7, LineSolid, CapRound, JoinMiter);
+
+	i = 2;
+	gc[i] = XCreateGC(xinfo.display, xinfo.window, 0, 0);
+	XSetForeground(xinfo.display, gc[i], BlackPixel(xinfo.display, xinfo.screen));
+	XSetBackground(xinfo.display, gc[i], WhitePixel(xinfo.display, xinfo.screen));
+	XSetFillStyle(xinfo.display, gc[i], FillSolid);
+	XSetLineAttributes(xinfo.display, gc[i],
+	                   7, LineOnOffDash, CapButt, JoinBevel);
+
+	// make the drawing
+	drawRectanglesInCorners(xinfo, gc[1]);
+	drawStuff(xinfo, gc[0], 50, 50);
+	drawStuff(xinfo, gc[1], 150, 200);
+	drawStuff(xinfo, gc[2], 250, 350);
+
+	// flush all pending requests to the X server.
+	XFlush(xinfo.display);
+
+	// wait for user input to quit
+	cout << "press ENTER to exit";
+	cin.get();
+
+	XCloseDisplay(xinfo.display);
+}

x/1-4-Drawing/drawing.min.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    drawing.min     Demos drawing and graphics context (minimal version).
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <cstdlib>
+#include <iostream>
+#include <X11/Xlib.h>
+
+#include <unistd.h> // needed for sleep
+
+Display* display;
+Window window;
+
+int main( int argc, char* argv[] ) {
+    // see openwindow.min for the setup code ...
+    display = XOpenDisplay("");
+    if (!display) exit (-1);
+    int screen = XDefaultScreen(display);
+    int w = 300;
+    int h = 300;
+    window = XCreateSimpleWindow(display,
+                                 DefaultRootWindow(display),
+                                 10, 10, w, h, 2,
+                                 XBlackPixel(display, screen),
+                                 XWhitePixel(display, screen));
+    XMapRaised(display, window);
+    XFlush(display);
+
+    // give server 10ms to get set up before sending drawing commands
+    usleep(10 * 1000);  
+
+
+    // drawing demo with graphics context here ...
+    GC gc = XCreateGC(display, window, 0, 0);       // create a graphics context
+    XSetForeground(display, gc, XBlackPixel(display, screen));
+    XSetBackground(display, gc, XWhitePixel(display, screen));
+    XSetFillStyle(display,  gc, FillSolid);
+    XSetLineAttributes(display, gc,
+                       3,       // 3 is line width
+                       LineSolid, CapButt, JoinRound);         // other line options
+
+    // draw some things
+    XDrawLine(display, window, gc, 10, 10, w - 10, h - 10);
+    XFillRectangle(display, window, gc, 50, 50, w - (2 * 50), h - (2 * 50));
+    XSetForeground(display, gc, XWhitePixel(display, screen));
+    XDrawLine(display, window, gc, w - 10, 10, 10, h - 10);
+
+    XFlush(display);
+
+    std::cout << "ENTER2exit"; std::cin.get(); // wait for input
+    XCloseDisplay(display);
+}

x/1-4-Drawing/makefile

+# super simple makefile
+# call it using 'make NAME=name_of_code_file_without_extension'
+# (assumes a .cpp extension)
+NAME = "drawing.min"
+
+# Add $(MAC_OPT) to the compile line for macOS 
+# (should be ignored by Linux, set to nothing if causing problems)
+MAC_OPT = -I/opt/X11/include
+
+all:
+	@echo "Compiling..."
+	g++ -o $(NAME) $(NAME).cpp -L/opt/X11/lib -lX11 -lstdc++ $(MAC_OPT)
+
+run: all
+	@echo "Running..."
+	./$(NAME) 
+
+clean:
+	-rm *o