Created program logic.

src/main.c

@@ -16,16 +16,120 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <signal.h>
 #include <stdio.h>
+#include <time.h>
 #include <X11/Xlib.h>
 
+int run;
+void *data;
+size_t data_size;
+
+void quit() {
+	run = 0;
+}
+
+void send_selection(Display *display, XSelectionRequestEvent *sre, Atom utf8) {
+	XSelectionEvent se;
+	time_t now_tm;
+	char *now;
+
+	now_tm = time(NULL);
+	now = ctime(&now_tm);
+
+#ifdef DEBUG
+	char *an = XGetAtomName(display, sre->property);
+	printf("Sending CLIPBOARD to window 0x%1x, property '%s'\n", sre->requestor, an);
+	if(an)
+		XFree(an);
+#endif
+
+	XChangeProperty(display, sre->requestor, sre->property, utf8, 8, PropModeReplace, data, data_size);
+
+}
+
 int main() {
-	Display *display = XOpenDisplay(NULL);
+	Display *display;
+	Window clip_win, root, owner;
+	int screen;
+	Atom selection, utf8, clip_property;
+	XEvent event;
+
+	// get current X display
+	display = XOpenDisplay(NULL);
 	if(!display)
 	{
 		fprintf(stderr, "Could not open X display.\n");
 		return 1;
 	}
+	screen = DefaultScreen(display);
+	root = RootWindow(display, screen);
+
+	// create a dummy window for tinyclip
+	clip_win = XCreateSimpleWindow(display, root, -10, -10, 1, 1, 0, 0, 0);
+	XSelectInput(display, clip_win,
+			SelectionClear | SelectionRequest | SelectionNotify);
+
+	// create atoms for selections
+	selection = XInternAtom(display, "CLIPBOARD", 0);
+	utf8 = XInternAtom(display, "UTF8_STRING", 0);
+	clip_property = XInternAtom(display, "TINYCLIP", 0);
+
+	// check if there is currently someone using the clipboard
+	owner = XGetSelectionOwner(display, selection);
+	if(owner != None)
+	{
+		// take ownership of clipboard while copying contents
+#ifdef DEBUG
+		printf("Current owner: 0x%1X\n", owner);
+#endif
+		XConvertSelection(display, selection, utf8,
+				clip_property, clip_win, CurrentTime);
+	}
+	else
+	{
+		XSetSelectionOwner(display, selection, clip_win, CurrentTime);
+	}
+
+	run = 1;
+	signal(SIGINT, quit);
+
+	while(run)
+	{
+		XNextEvent(display, &event);
+		XSelectionRequestEvent *sre;
+		XSelectionEvent *se;
+		switch(event.type)
+		{
+			case SelectionClear:
+				// if someone else took the clipboard, regain ownership
+#ifdef DEBUG
+				printf("Lost selection.\n");
+#endif
+				XConvertSelection(display, selection, utf8,
+						clip_property, clip_win, CurrentTime);
+				break;
+			case SelectionNotify:
+				se = (XSelectionEvent*)&event.xselection;
+				if(se->property == None)
+					fprintf(stderr, "Conversion impossible.");
+				else
+				{
+					// TODO: handle new clipboard information
+				}
+				XSetSelectionOwner(display, selection, clip_win, CurrentTime);
+				break;
+			case SelectionRequest:
+				// respond to request for clipboard
+				sre = (XSelectionRequestEvent*) &event.xselectionrequest;
+#ifdef DEBUG
+				printf("New selection request:\n"
+						"  requestor: 0x%1x\n", sre->requestor);
+#endif
+				send_selection(display, sre, utf8);
+				break;
+		}
+	}
 
 	return 0;
 }