add examples for 1-5-Events

x/1-5-Events/animation.min.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    animation.cpp   Ball bouncing in window (minimal version)
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <cstdlib>
+#include <iostream>
+#include <unistd.h>
+#include <sys/time.h>
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+
+
+// get microseconds
+unsigned long now() {
+	timeval tv;
+	gettimeofday(&tv, NULL);
+	return tv.tv_sec * 1000000 + tv.tv_usec;
+}
+
+
+using namespace std;
+
+Display* display;
+Window window;
+
+// frames per second to run animation loop
+int FPS = 60;
+
+int main( int argc, char *argv[] ) {
+	display = XOpenDisplay("");
+	if (display == NULL) exit (-1);
+	int screennum = DefaultScreen(display);
+	long background = WhitePixel(display, screennum);
+	long foreground = BlackPixel(display, screennum);
+	window = XCreateSimpleWindow(display, DefaultRootWindow(display),
+	                             10, 10, 300, 200, 2, foreground, background);
+	XSelectInput(display, window,
+	             ButtonPressMask | KeyPressMask); // select events
+	XMapRaised(display, window);
+	XFlush(display);
+
+	XEvent event; // save the event here
+
+	// ball postition, size, and velocity
+	XPoint ballPos;
+	ballPos.x = 50;
+	ballPos.y = 50;
+	int ballSize = 50;
+	XPoint ballDir;
+	ballDir.x = 3;
+	ballDir.y = 3;
+
+	// create gc for drawing
+	GC gc = XCreateGC(display, window, 0, 0);
+
+	// time of last window paint
+	unsigned long lastRepaint = 0;
+
+	XWindowAttributes w;
+	XGetWindowAttributes(display, window, &w);
+
+	// event loop
+	while ( true ) {
+
+		// TRY THIS
+		// comment out this conditional to see what happens when
+		// events block (run the program and keep pressing the mouse)
+		if (XPending(display) > 0) { 
+			XNextEvent( display, &event ); 
+
+			switch ( event.type ) {
+
+			// mouse button press
+        	case ButtonPress:
+	            cout << "CLICK" << endl;
+            	break;
+
+			case KeyPress: // any keypress
+			    KeySym key;
+				char text[10];
+          		int i = XLookupString( (XKeyEvent*)&event, text, 10, &key, 0 );
+            	if ( i == 1 && text[0] == 'q' ) {
+                	XCloseDisplay(display);
+                	exit(0);
+            	}
+				break;
+			}
+		}
+
+		unsigned long end = now();	// get time in microsecond
+
+		if (end - lastRepaint > 1000000 / FPS) { 
+
+			// clear background
+			XClearWindow(display, window);
+
+			// draw ball from centre
+			XFillArc(display, window, gc, 
+				ballPos.x - ballSize/2, 
+				ballPos.y - ballSize/2, 
+				ballSize, ballSize,
+				0, 360*64);
+
+			// update ball position
+			ballPos.x += ballDir.x;
+			ballPos.y += ballDir.y;
+
+			// bounce ball
+			if (ballPos.x + ballSize/2 > w.width ||
+				ballPos.x - ballSize/2 < 0)
+				ballDir.x = -ballDir.x;
+			if (ballPos.y + ballSize/2 > w.height ||
+				ballPos.y - ballSize/2 < 0)
+				ballDir.y = -ballDir.y;
+
+			XFlush( display );
+
+			lastRepaint = now(); // remember when the paint happened
+		}
+
+		// IMPORTANT: sleep for a bit to let other processes work
+		if (XPending(display) == 0) {
+			usleep(1000000 / FPS - (end - lastRepaint));
+		}
+
+
+	}
+	XCloseDisplay(display);
+}

x/1-5-Events/doublebuffer1.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    doublebuffer1.cpp   How to do double buffering (minimal version using animation.cpp)
+    				    Note, it's pretty hard to see any difference.
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <cstdlib>
+#include <iostream>
+#include <unistd.h>
+#include <sys/time.h>
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+
+// get microseconds
+unsigned long now() {
+	timeval tv;
+	gettimeofday(&tv, NULL);
+	return tv.tv_sec * 1000000 + tv.tv_usec;
+}
+
+
+using namespace std;
+
+Display* display;
+Window window;
+
+// frames per second to run animation loop
+int FPS = 60;
+
+int main( int argc, char *argv[] ) {
+	display = XOpenDisplay("");
+	if (display == NULL) exit (-1);
+	int screennum = DefaultScreen(display);
+	long background = WhitePixel(display, screennum);
+	long foreground = BlackPixel(display, screennum);
+	window = XCreateSimpleWindow(display, DefaultRootWindow(display),
+	                             10, 10, 300, 200, 2, foreground, background);
+	XSelectInput(display, window,
+	             ButtonPressMask | KeyPressMask); // select events
+	XMapRaised(display, window);
+	XFlush(display);
+
+	XEvent event; // save the event here
+
+	// ball postition, size, and velocity
+	XPoint ballPos;
+	ballPos.x = 50;
+	ballPos.y = 50;
+	int ballSize = 50;
+	XPoint ballDir;
+	ballDir.x = 3;
+	ballDir.y = 3;
+
+	// create gc for drawing
+	GC gc = XCreateGC(display, window, 0, 0);
+
+
+	// time of last window paint
+	unsigned long lastRepaint = 0;
+
+	XWindowAttributes w;
+	XGetWindowAttributes(display, window, &w);
+
+	// DOUBLE BUFFER
+	// create bimap (pximap) to us a other buffer
+	int depth = DefaultDepth(display, DefaultScreen(display));
+	Pixmap	buffer = XCreatePixmap(display, window, w.width, w.height, depth);
+
+	bool useBuffer = true;
+
+	// event loop
+	while ( true ) {
+
+		// TRY THIS
+		// comment out this conditional to see what happens when
+		// events block (run the program and keep pressing the mouse)
+		if (XPending(display) > 0) {
+			XNextEvent( display, &event );
+
+			switch ( event.type ) {
+
+			// mouse button press
+			case ButtonPress:
+				useBuffer = !useBuffer;
+				cout << "double buffer " << useBuffer << endl;
+				break;
+
+			case KeyPress: // any keypress
+				KeySym key;
+				char text[10];
+				int i = XLookupString( (XKeyEvent*)&event, text, 10, &key, 0 );
+				if ( i == 1 && text[0] == 'q' ) {
+					XCloseDisplay(display);
+					exit(0);
+				}
+				break;
+			}
+		}
+
+		unsigned long end = now();
+
+		if (end - lastRepaint > 1000000 / FPS) {
+
+			Pixmap pixmap;
+
+			if (useBuffer) {
+
+				pixmap = buffer;
+				// draw into the buffer
+				// note that a window and a pixmap are “drawables”
+				XSetForeground(display, gc, WhitePixel(display, DefaultScreen(display)));
+				XFillRectangle(display, pixmap, gc,
+				               0, 0, w.width, w.height);
+			} else {
+				pixmap = window;
+				// clear background
+				XClearWindow(display, pixmap);
+			}
+
+			// draw ball from centre
+			XSetForeground(display, gc, BlackPixel(display, DefaultScreen(display)));
+			XFillArc(display, pixmap, gc,
+			         ballPos.x - ballSize / 2,
+			         ballPos.y - ballSize / 2,
+			         ballSize, ballSize,
+			         0, 360 * 64);
+
+			// update ball position
+			ballPos.x += ballDir.x;
+			ballPos.y += ballDir.y;
+
+			// bounce ball
+			if (ballPos.x + ballSize / 2 > w.width ||
+			        ballPos.x - ballSize / 2 < 0)
+				ballDir.x = -ballDir.x;
+			if (ballPos.y + ballSize / 2 > w.height ||
+			        ballPos.y - ballSize / 2 < 0)
+				ballDir.y = -ballDir.y;
+
+			// copy buffer to window
+			if (useBuffer) {
+				XCopyArea(display, pixmap, window, gc,
+				          0, 0, w.width, w.height,  // region of pixmap to copy
+				          0, 0); // position to put top left corner of pixmap in window
+			}
+
+			XFlush( display );
+
+			lastRepaint = now(); // remember when the paint happened
+		}
+
+		// IMPORTANT: sleep for a bit to let other processes work
+		if (XPending(display) == 0) {
+			usleep(1000000 / FPS - (end - lastRepaint));
+		}
+
+
+	}
+	XCloseDisplay(display);
+}

x/1-5-Events/doublebuffer2.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    doublebuffer2.cpp   Adds many balls to animation to make doublebuffering
+    					effect more obvious.
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <cstdlib>
+#include <iostream>
+#include <unistd.h>
+#include <sys/time.h>
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+#include <vector>
+
+
+// get microseconds
+unsigned long now() {
+	timeval tv;
+	gettimeofday(&tv, NULL);
+	return tv.tv_sec * 1000000 + tv.tv_usec;
+}
+
+
+using namespace std;
+
+Display* display;
+Window window;
+
+// frames per second to run animation loop
+int FPS = 60;
+
+int main( int argc, char *argv[] ) {
+	display = XOpenDisplay("");
+	if (display == NULL) exit (-1);
+	int screennum = DefaultScreen(display);
+	long background = WhitePixel(display, screennum);
+	long foreground = BlackPixel(display, screennum);
+	window = XCreateSimpleWindow(display, DefaultRootWindow(display),
+	                             10, 10, 300, 200, 2, foreground, background);
+	XSelectInput(display, window,
+	             ButtonPressMask | KeyPressMask); // select events
+	XMapRaised(display, window);
+	XFlush(display);
+
+	XEvent event; // save the event here
+
+	// ball postition, size, and velocity
+	vector<XPoint> ballPos;
+	vector<XPoint> ballDir;
+	int numBalls = 1000;
+
+	for (int i = 0; i < numBalls; i++) {
+		XPoint bp;
+		bp.x = rand() % 300;
+		bp.y = rand() % 200;
+		XPoint bd;
+		bd.x = rand() % 3;
+		bd.y = rand() % 3;
+		ballPos.push_back(bp);
+		ballDir.push_back(bd);
+	}
+
+	// XPoint ballPos;
+	// ballPos.x = 50;
+	// ballPos.y = 50;
+	int ballSize = 10;
+	// XPoint ballDir;
+	// ballDir.x = 3;
+	// ballDir.y = 3;
+
+	// create gc for drawing
+	GC gc = XCreateGC(display, window, 0, 0);
+
+
+	// time of last window paint
+	unsigned long lastRepaint = 0;
+
+	XWindowAttributes w;
+	XGetWindowAttributes(display, window, &w);
+
+	// DOUBLE BUFFER
+	// create bimap (pximap) to us a other buffer
+	int depth = DefaultDepth(display, DefaultScreen(display));
+	Pixmap	buffer = XCreatePixmap(display, window, w.width, w.height, depth);
+
+	bool useBuffer = true;
+
+	// event loop
+	while ( true ) {
+
+		// TRY THIS
+		// comment out this conditional to see what happens when
+		// events block (run the program and keep pressing the mouse)
+		if (XPending(display) > 0) {
+			XNextEvent( display, &event );
+
+			switch ( event.type ) {
+
+			// mouse button press
+			case ButtonPress:
+				useBuffer = !useBuffer;
+				cout << "double buffer " << useBuffer << endl;
+				break;
+
+			case KeyPress: // any keypress
+				KeySym key;
+				char text[10];
+				int i = XLookupString( (XKeyEvent*)&event, text, 10, &key, 0 );
+				if ( i == 1 && text[0] == 'q' ) {
+					XCloseDisplay(display);
+					exit(0);
+				}
+				break;
+			}
+		}
+
+		unsigned long end = now();
+
+		if (end - lastRepaint > 1000000 / FPS) {
+
+			Pixmap pixmap;
+
+			if (useBuffer) {
+
+				pixmap = buffer;
+				// draw into the buffer
+				// note that a window and a pixmap are “drawables”
+				XSetForeground(display, gc, WhitePixel(display, DefaultScreen(display)));
+				XFillRectangle(display, pixmap, gc,
+				               0, 0, w.width, w.height);
+			} else {
+				pixmap = window;
+				// clear background
+				XClearWindow(display, pixmap);
+			}
+
+
+			for (int i = 0; i < numBalls; i++) {
+
+
+				// draw ball from centre
+				XSetForeground(display, gc, BlackPixel(display, DefaultScreen(display)));
+				XFillArc(display, pixmap, gc,
+				         ballPos[i].x - ballSize / 2,
+				         ballPos[i].y - ballSize / 2,
+				         ballSize, ballSize,
+				         0, 360 * 64);
+
+				// update ball position
+				ballPos[i].x += ballDir[i].x;
+				ballPos[i].y += ballDir[i].y;
+
+				// bounce ball
+				if (ballPos[i].x + ballSize / 2 > w.width ||
+				        ballPos[i].x - ballSize / 2 < 0)
+					ballDir[i].x = -ballDir[i].x;
+				if (ballPos[i].y + ballSize / 2 > w.height ||
+				        ballPos[i].y - ballSize / 2 < 0)
+					ballDir[i].y = -ballDir[i].y;
+			}
+
+			// copy buffer to window
+			if (useBuffer) {
+				XCopyArea(display, pixmap, window, gc,
+				          0, 0, w.width, w.height,  // region of pixmap to copy
+				          0, 0); // position to put top left corner of pixmap in window
+			}
+
+			XFlush( display );
+
+			lastRepaint = now(); // remember when the paint happened
+		}
+
+		// IMPORTANT: sleep for a bit to let other processes work
+		if (XPending(display) == 0) {
+			usleep(1000000 / FPS - (end - lastRepaint));
+		}
+
+
+	}
+	XCloseDisplay(display);
+}

x/1-5-Events/eventloop.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    eventloop     Displays text at cursor location on mouse button press
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <iostream>
+#include <list>
+#include <cstdlib>
+#include <vector>
+
+//#include <string>
+//#include <sstream>
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+using namespace std;
+
+
+const int Border = 5;
+const int BufferSize = 10;
+
+int count_click = 0;
+
+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() );
+    }
+
+    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
+    }
+
+    Polyline(int x, int y) {
+        add_point(x, y);
+    }
+
+    // add another point to the line
+    void add_point(int x, int y) {
+        XPoint p; 
+        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
+};
+
+// Function to put out a message on error exits.
+void error( string str ) {
+    cerr << str << endl;
+    exit(0);
+}
+
+// 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 );
+}
+
+
+
+// The loop responding to events from the user.
+void eventloop(XInfo& xinfo) {
+    XEvent event;
+    KeySym key;
+    char text[BufferSize];
+    list<Displayable*> dList;        
+
+    Polyline* polyline = NULL;
+
+    while ( true ) {
+        XNextEvent( xinfo.display, &event );
+
+        switch ( event.type ) {
+
+        // add item where mouse clicked
+        case ButtonPress:
+            // output to console
+            cout << "ButtonPress at " << event.xbutton.time << endl;
+
+            // add a new text object to the display list
+            dList.push_back(new Text(
+                event.xbutton.x, event.xbutton.y, "CLICK"));                
+            // start a new polyline to draw
+            polyline = new Polyline(event.xbutton.x, event.xbutton.y);
+            dList.push_back(polyline);
+            repaint( dList, xinfo );
+            break;
+
+        // add item where mouse moved
+        case MotionNotify:
+
+            // add the point to the drawing
+            if (polyline != NULL) {
+                polyline->add_point(event.xmotion.x, 
+                    event.xmotion.y);
+
+            }
+            repaint( dList, xinfo );
+
+            break;
+        /*
+         * Exit when 'q' is typed.
+         * Arguments for XLookupString :
+         *                 event - the keyboard event
+         *                 text - buffer into which text will be written
+         *                 BufferSize - size of text buffer
+         *                 key - workstation independent key symbol
+         *                 0 - pointer to a composeStatus structure
+         */
+        case KeyPress:
+            int i = XLookupString( 
+                (XKeyEvent*)&event, text, BufferSize, &key, 0 );
+            cout << "KeySym " << key
+                 << " text='" << text << "'"
+                 << " at " << event.xkey.time
+
+                 << endl;
+            if ( i == 1 && text[0] == 'q' ) {
+                cout << "Terminated normally." << endl;
+                XCloseDisplay(xinfo.display);
+                return;
+            }
+
+            switch(key){
+                case XK_Up:
+                    cout << "Up" << endl;
+                    break;
+                case XK_Down:
+                    cout << "Down" << endl;
+                    break;
+                case XK_Left:
+                    cout << "Left" << endl;
+                    break;
+                case XK_Right:
+                    cout << "Right" << endl;
+                    break;
+                }
+
+            break;
+        }
+    }
+}
+
+//  Create the window;  initialize X.
+void initX(int argc, char* argv[], XInfo& xinfo) {
+
+    xinfo.display = XOpenDisplay( "" );
+    if ( !xinfo.display ) {
+        error( "Can't open display." );
+    }
+
+    int screen = DefaultScreen( xinfo.display );
+    unsigned long background = WhitePixel( xinfo.display, screen );
+    unsigned long foreground = BlackPixel( xinfo.display, screen );
+
+ 
+    XSizeHints hints;
+    hints.x = 100;
+    hints.y = 100;
+    hints.width = 400;
+    hints.height = 300;
+    hints.flags = PPosition | PSize;
+    xinfo.window = XCreateSimpleWindow( xinfo.display, DefaultRootWindow( xinfo.display ),
+                                        hints.x, hints.y, hints.width, hints.height,
+                                        Border, foreground, background );
+    XSetStandardProperties( xinfo.display, xinfo.window, "eventloop", "eventloop", None,
+                            argv, argc, &hints );
+
+
+    xinfo.gc = XCreateGC (xinfo.display, xinfo.window, 0, 0 );
+    XSetBackground( xinfo.display, xinfo.gc, background );
+    XSetForeground( xinfo.display, xinfo.gc, foreground );
+
+    // Tell the window manager what input events you want.
+    // ButtomMotionMask: The client application receives MotionNotify events only when at least one button is pressed.
+    XSelectInput( xinfo.display, xinfo.window,
+                  ButtonPressMask | KeyPressMask | ButtonMotionMask );
+
+    XMapRaised( xinfo.display, xinfo.window );
+}
+
+
+
+int main ( int argc, char* argv[] ) {
+    XInfo xinfo;
+    initX(argc, argv, xinfo);
+    eventloop(xinfo);
+}

x/1-5-Events/eventloop.min.cpp

+/*
+CS 349 Code Examples: X Windows and XLib
+
+    eventloop.min.cpp   Demos events by displaying mouse motion events
+    					to console (minimal version)
+
+- - - - - - - - - - - - - - - - - - - - - -
+
+See associated makefile for compiling instructions
+
+*/
+
+#include <cstdlib>
+#include <iostream>
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+using namespace std;
+
+Display* display;
+Window window;
+
+int main( int argc, char *argv[] ) {
+	display = XOpenDisplay("");
+	if (display == NULL) exit (-1);
+	int screennum = DefaultScreen(display);
+	long background = WhitePixel(display, screennum);
+	long foreground = BlackPixel(display, screennum);
+	window = XCreateSimpleWindow(display, DefaultRootWindow(display),
+	                             10, 10, 300, 200, 2, foreground, background);
+	XSelectInput(display, window,
+	             PointerMotionMask | KeyPressMask); // select events
+	XMapRaised(display, window);
+	XFlush(display);
+	XEvent event; // save the event here
+	while ( true ) { // event loop until 'exit'
+		XNextEvent( display, &event ); // wait for next event
+		cout << event.type << " ";
+
+		switch ( event.type ) {
+		case MotionNotify: // mouse movement
+			cout << event.xmotion.x << ","
+			     << event.xmotion.y << endl;
+			break;
+		case KeyPress: // any keypress
+			exit(0);
+			break;
+		}
+	}
+	XCloseDisplay(display);
+}

x/1-5-Events/makefile

+# super simple makefile
+# call it using 'make NAME=name_of_code_file_without_extension'
+# (assumes a .cpp extension)
+NAME = "eventloop.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