barrier/synergy/CXWindowsScreen.cpp

#include "CXWindowsScreen.h"
#include "CThread.h"
#include "CLock.h"
#include "TMethodJob.h"
#include "CLog.h"
#include "CString.h"
#include "CStopwatch.h"
#include <string.h>
#include <assert.h>
#include <X11/X.h>
#include <X11/Xatom.h>
#include <set>

//
// CXWindowsScreen
//

static const UInt32 kMaxRequestSize = 4096;

CXWindowsScreen::CXWindowsScreen() :
								m_display(NULL),
								m_root(None),
								m_w(0), m_h(0),
								m_stop(false)
{
	// do nothing
}

CXWindowsScreen::~CXWindowsScreen()
{
	assert(m_display == NULL);
}

void					CXWindowsScreen::openDisplay()
{
	assert(m_display == NULL);

	// open the display
	log((CLOG_DEBUG "XOpenDisplay(%s)", "NULL"));
	m_display = XOpenDisplay(NULL);	// FIXME -- allow non-default
	if (m_display == NULL)
		throw int(5);	// FIXME -- make exception for this

	// get default screen
	m_screen = DefaultScreen(m_display);
	Screen* screen = ScreenOfDisplay(m_display, m_screen);

	// get screen size
	m_w = WidthOfScreen(screen);
	m_h = HeightOfScreen(screen);
	log((CLOG_INFO "display size: %dx%d", m_w, m_h));

	// get the root window
	m_root = RootWindow(m_display, m_screen);

	// get some atoms
	m_atomTargets      = XInternAtom(m_display, "TARGETS", False);
	m_atomMultiple     = XInternAtom(m_display, "MULTIPLE", False);
	m_atomTimestamp    = XInternAtom(m_display, "TIMESTAMP", False);
	m_atomAtom         = XInternAtom(m_display, "ATOM", False);
	m_atomAtomPair     = XInternAtom(m_display, "ATOM_PAIR", False);
	m_atomInteger      = XInternAtom(m_display, "INTEGER", False);
	m_atomData         = XInternAtom(m_display, "DESTINATION", False);
	m_atomINCR         = XInternAtom(m_display, "INCR", False);
	m_atomString       = XInternAtom(m_display, "STRING", False);
	m_atomText         = XInternAtom(m_display, "TEXT", False);
	m_atomCompoundText = XInternAtom(m_display, "COMPOUND_TEXT", False);
	m_atomSynergyTime  = XInternAtom(m_display, "SYNERGY_TIME", False);

	// clipboard atoms
	m_atomClipboard[kClipboardClipboard] =
								XInternAtom(m_display, "CLIPBOARD", False);
	m_atomClipboard[kClipboardSelection] = XA_PRIMARY;

	// let subclass prep display
	onOpenDisplay();
}

void					CXWindowsScreen::closeDisplay()
{
	assert(m_display != NULL);

	// let subclass close down display
	onCloseDisplay();

	// clear out the clipboard request lists
	for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
		CClipboardInfo& clipboard = m_clipboards[id];
		for (CRequestMap::iterator index = clipboard.m_requests.begin();
								index != clipboard.m_requests.end(); ++index) {
			CRequestList* list = index->second;
			for (CRequestList::iterator index2 = list->begin();
								index2 != list->end(); ++index2) {
				delete *index2;
			}
			delete list;
		}
		clipboard.m_requests.clear();
	}

	// close the display
	XCloseDisplay(m_display);
	m_display = NULL;
	log((CLOG_DEBUG "closed display"));
}

int						CXWindowsScreen::getScreen() const
{
	assert(m_display != NULL);
	return m_screen;
}

Window					CXWindowsScreen::getRoot() const
{
	assert(m_display != NULL);
	return m_root;
}

void					CXWindowsScreen::getScreenSize(
								SInt32* w, SInt32* h) const
{
	assert(m_display != NULL);
	assert(w != NULL && h != NULL);

	*w = m_w;
	*h = m_h;
}

Cursor					CXWindowsScreen::createBlankCursor() const
{
	// this seems just a bit more complicated than really necessary

	// get the closet cursor size to 1x1
	unsigned int w, h;
	XQueryBestCursor(m_display, m_root, 1, 1, &w, &h);

	// make bitmap data for cursor of closet size.  since the cursor
	// is blank we can use the same bitmap for shape and mask:  all
	// zeros.
	const int size = ((w + 7) >> 3) * h;
	char* data = new char[size];
	memset(data, 0, size);

	// make bitmap
	Pixmap bitmap = XCreateBitmapFromData(m_display, m_root, data, w, h);

	// need an arbitrary color for the cursor
	XColor color;
	color.pixel = 0;
	color.red   = color.green = color.blue = 0;
	color.flags = DoRed | DoGreen | DoBlue;

	// make cursor from bitmap
	Cursor cursor = XCreatePixmapCursor(m_display, bitmap, bitmap,
								&color, &color, 0, 0);

	// don't need bitmap or the data anymore
	delete[] data;
	XFreePixmap(m_display, bitmap);

	return cursor;
}

bool					CXWindowsScreen::getEvent(XEvent* xevent) const
{
	// wait for an event in a cancellable way and don't lock the
	// display while we're waiting.
	m_mutex.lock();
	while (!m_stop && XPending(m_display) == 0) {
		m_mutex.unlock();
		CThread::sleep(0.05);
		m_mutex.lock();
	}
	if (m_stop) {
		m_mutex.unlock();
		return false;
	}
	else {
		XNextEvent(m_display, xevent);
		m_mutex.unlock();
		return true;
	}
}

void					CXWindowsScreen::doStop()
{
	CLock lock(&m_mutex);
	m_stop = true;
}

ClipboardID				CXWindowsScreen::getClipboardID(Atom selection)
{
	for (ClipboardID id = 0; id < kClipboardEnd; ++id)
		if (selection == m_atomClipboard[id])
			return id;
	return kClipboardEnd;
}

bool					CXWindowsScreen::lostClipboard(
								Atom selection, Time timestamp)
{
	for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
		if (selection == m_atomClipboard[id]) {
			// note the time
			CLock lock(&m_mutex);
			m_clipboards[id].m_lostClipboard = timestamp;
			log((CLOG_INFO "lost clipboard %d ownership at %d", id, timestamp));
			return true;
		}
	}
	return false;
}

bool					CXWindowsScreen::setDisplayClipboard(
								ClipboardID id,
								const IClipboard* clipboard,
								Window requestor, Time timestamp)
{
	CLock lock(&m_mutex);

	XSetSelectionOwner(m_display, m_atomClipboard[id], requestor, timestamp);
	if (XGetSelectionOwner(m_display, m_atomClipboard[id]) == requestor) {
		// we got the selection
		log((CLOG_INFO "grabbed clipboard at %d", timestamp));
		m_clipboards[id].m_lostClipboard = CurrentTime;
		if (clipboard != NULL) {
			// save clipboard to serve requests
			CClipboard::copy(&m_clipboards[id].m_clipboard,
								clipboard, timestamp);
		}
		else {
			// clear clipboard
			if (m_clipboards[id].m_clipboard.open(timestamp)) {
				m_clipboards[id].m_clipboard.close();
			}
		}

		return true;
	}

	return false;
}

void					CXWindowsScreen::getDisplayClipboard(
								ClipboardID id,
								IClipboard* clipboard,
								Window requestor, Time timestamp) const
{
	assert(clipboard != NULL);
	assert(requestor != None);

	// FIXME -- don't update clipboard object if clipboard hasn't changed

	// clear the clipboard object
	if (!clipboard->open(timestamp))
		return;

	// block others from using the display while we get the clipboard.
	// in particular, this prevents the event thread from stealing the
	// selection notify event we're expecting.
	CLock lock(&m_mutex);
	Atom selection = m_atomClipboard[id];

	// ask the selection for all the formats it has.  some owners return
	// the TARGETS atom and some the ATOM atom when TARGETS is requested.
	Atom format;
	CString targets;
	if (getDisplayClipboard(selection, m_atomTargets,
								requestor, timestamp, &format, &targets) &&
		(format == m_atomTargets || format == XA_ATOM)) {
		// get each target (that we can interpret).  some owners return
		// some targets multiple times in the list so don't try to get
		// those multiple times.
		const Atom* targetAtoms = reinterpret_cast<const Atom*>(targets.data());
		const SInt32 numTargets = targets.size() / sizeof(Atom);
		std::set<IClipboard::EFormat> clipboardFormats;
		std::set<Atom> targets;
		log((CLOG_INFO "getting selection %d with %d targets", id, numTargets));
		for (SInt32 i = 0; i < numTargets; ++i) {
			Atom format = targetAtoms[i];
			log((CLOG_DEBUG1 " source target %d", format));

			// skip already handled targets
			if (targets.count(format) > 0) {
				log((CLOG_DEBUG1 "  skipping handled target %d", format));
				continue;
			}

			// mark this target as done
			targets.insert(format);

			// determine the expected clipboard format
			IClipboard::EFormat expectedFormat = getFormat(format);

			// if we can use the format and we haven't already retrieved
			// it then get it
			if (expectedFormat == IClipboard::kNumFormats) {
				log((CLOG_DEBUG1 "  no format for target", format));
				continue;
			}
			if (clipboardFormats.count(expectedFormat) > 0) {
				log((CLOG_DEBUG1 "  skipping handled format %d", expectedFormat));
				continue;
			}

			CString data;
			if (!getDisplayClipboard(selection, format,
							requestor, timestamp, &format, &data)) {
				log((CLOG_DEBUG1 "  no data for target", format));
				continue;
			}

			// use the actual format, not the expected
			IClipboard::EFormat actualFormat = getFormat(format);
			if (actualFormat == IClipboard::kNumFormats) {
				log((CLOG_DEBUG1 "  no format for target", format));
				continue;
			}
			if (clipboardFormats.count(actualFormat) > 0) {
				log((CLOG_DEBUG1 "  skipping handled format %d", actualFormat));
				continue;
			}

			// add to clipboard and note we've done it
			clipboard->add(actualFormat, data);
			clipboardFormats.insert(actualFormat);
			log((CLOG_INFO "  added format %d for target %d", actualFormat, format));
		}
	}
	else {
		// non-ICCCM conforming selection owner.  try TEXT format.
		// FIXME
		log((CLOG_DEBUG1 "selection doesn't support TARGETS, format is %d", format));
	}

	// done with clipboard
	clipboard->close();
}

bool					CXWindowsScreen::getDisplayClipboard(
								Atom selection, Atom type,
								Window requestor, Time timestamp,
								Atom* outputType, CString* outputData) const
{
	assert(outputType != NULL);
	assert(outputData != NULL);

	// FIXME -- this doesn't work to retrieve Motif selections.

	// delete data property
	XDeleteProperty(m_display, requestor, m_atomData);

	// request data conversion
	XConvertSelection(m_display, selection, type,
								m_atomData, requestor, timestamp);

	// wait for the selection notify event.  can't just mask out other
	// events because X stupidly doesn't provide a mask for selection
	// events, so we use a predicate to find our event.  we also set
	// a time limit for a response so we're not screwed by a bad
	// clipboard owner.
	CStopwatch timer(true);
	XEvent xevent;
	while (XCheckIfEvent(m_display, &xevent,
								&CXWindowsScreen::findSelectionNotify,
								(XPointer)&requestor) != True) {
		// return false if we've timed-out
		if (timer.getTime() >= 0.2)
			return false;

		// wait a bit
		CThread::sleep(0.05);
	}
	assert(xevent.type                 == SelectionNotify);
	assert(xevent.xselection.requestor == requestor);

	// make sure the transfer worked
	Atom property = xevent.xselection.property;
	if (property == None) {
		// cannot convert
		*outputType = type;
		log((CLOG_DEBUG "selection conversion failed for %d", type));
		return false;
	}

	// get the data and discard the property
	SInt32 datumSize;
	CString data;
	bool okay = getData(requestor, property, outputType, &datumSize, &data);
	XDeleteProperty(m_display, requestor, property);

	// fail if we couldn't get the data
	if (!okay) {
		log((CLOG_DEBUG "can't get data for selection format %d", type));
		return false;
	}

	// handle INCR type specially.  it means we'll be receiving the data
	// piecemeal so we just loop until we've collected all the data.
	if (*outputType == m_atomINCR) {
		log((CLOG_DEBUG1 "selection data for format %d is incremental", type));
		// the data is a lower bound on the amount of data to be
		// transferred.  use it as a hint to size our buffer.
		UInt32 size;
		switch (datumSize) {
		  case 8:
			size = *(reinterpret_cast<const UInt8*>(data.data()));
			break;

		  case 16:
			size = *(reinterpret_cast<const UInt16*>(data.data()));
			break;

		  case 32:
			size = *(reinterpret_cast<const UInt32*>(data.data()));
			break;

		  default:
			assert(0 && "invalid datum size");
		}

		// empty the buffer and reserve the lower bound
		data.erase();
		data.reserve(size);

		// look for property notify events with the following
		CPropertyNotifyInfo filter;
		filter.m_window   = requestor;
		filter.m_property = property;

		// now enter the INCR loop
		bool error = false;
		*outputType = (Atom)0;
		for (;;) {
			// wait for more data
			while (XCheckIfEvent(m_display, &xevent,
								&CXWindowsScreen::findPropertyNotify,
								(XPointer)&filter) != True) {
				// wait a bit
				CThread::sleep(0.05);
			}
			assert(xevent.type             == PropertyNotify);
			assert(xevent.xproperty.window == requestor);
			assert(xevent.xproperty.atom   == property);

			// get the additional data then delete the property to
			// ask the clipboard owner for the next chunk.
			Atom newType;
			CString newData;
			okay = getData(requestor, property, &newType, NULL, &newData);
			XDeleteProperty(m_display, requestor, property);

			// transfer has failed if we can't get the data
			if (!okay)
				error = true;

			// a zero length property means we got the last chunk
			if (newData.size() == 0)
				break;

			// if this is the first chunk then save the type.  otherwise
			// note that the new type is the same as the first chunk's
			// type.  if they're not the the clipboard owner is busted
			// but we have to continue the transfer because there's no
			// way to cancel it.
			if (*outputType == (Atom)0)
				*outputType = newType;
			else if (*outputType != newType)
				error = true;

			// append the data
			data += newData;
		}

		// if there was an error we could say the transferred failed
		// but we'll be liberal in what we accept.
		if (error) {
			log((CLOG_WARN "ICCCM violation by clipboard owner"));
//			return false;
		}
	}

	*outputData = data;
	return true;
}

bool					CXWindowsScreen::getData(
								Window window, Atom property,
								Atom* type, SInt32* datumSize,
								CString* data) const
{
	assert(type != NULL);
	assert(data != NULL);

	// clear out any existing data
	data->erase();

	// read the property
	long offset = 0;
	long length = 8192 / 4;
	for (;;) {
		// get more data
		int actualDatumSize;
		unsigned long numItems, bytesLeft;
		unsigned char* rawData;
		const int result = XGetWindowProperty(m_display, window, property,
								offset, length, False, AnyPropertyType,
								type, &actualDatumSize,
								&numItems, &bytesLeft,
								&rawData);
		if (result != Success) {
			// failed
			return false;
		}

		// save datum size
		if (datumSize != NULL)
			*datumSize = (SInt32)actualDatumSize;
		const SInt32 bytesPerDatum = (SInt32)actualDatumSize / 8;

		// advance read pointer.  since we can only read at offsets that
		// are multiples of 4 byte we take care to write multiples of 4
		// bytes to data, except when we've retrieved the last chunk.
		SInt32 quadCount = (numItems * bytesPerDatum) / 4;
		offset += quadCount;

		// append data
		if (bytesLeft == 0)
			data->append((char*)rawData, bytesPerDatum * numItems);
		else
			data->append((char*)rawData, 4 * quadCount);

		// done with returned data
		XFree(rawData);

		// done if no data is left
		if (bytesLeft == 0)
			return true;
	}
}

IClipboard::EFormat		CXWindowsScreen::getFormat(Atom src) const
{
	// FIXME -- handle more formats (especially mime-type-like formats
	// and various character encodings like unicode).
	if (src == XA_STRING ||
		src == m_atomText ||
		src == m_atomCompoundText)
		return IClipboard::kText;
	return IClipboard::kNumFormats;
}

Bool					CXWindowsScreen::findSelectionNotify(
								Display*, XEvent* xevent, XPointer arg)
{
	Window requestor = *reinterpret_cast<Window*>(arg);
	return (xevent->type                 == SelectionNotify &&
			xevent->xselection.requestor == requestor) ? True : False;
}

Bool					CXWindowsScreen::findPropertyNotify(
								Display*, XEvent* xevent, XPointer arg)
{
	CPropertyNotifyInfo* filter = reinterpret_cast<CPropertyNotifyInfo*>(arg);
	return (xevent->type             == PropertyNotify &&
			xevent->xproperty.window == filter->m_window &&
			xevent->xproperty.atom   == filter->m_property &&
			xevent->xproperty.state  == PropertyNewValue) ? True : False;
}

void					CXWindowsScreen::addClipboardRequest(
								Window owner, Window requestor,
								Atom selection, Atom target,
								Atom property, Time time)
{
	bool success = false;

	// see if it's a selection we know about
	ClipboardID id;
	for (id = 0; id < kClipboardEnd; ++id)
		if (selection == m_atomClipboard[id])
			break;

	// mutex the display
	CLock lock(&m_mutex);

	// a request for multiple targets is special
	if (id != kClipboardEnd) {
		// check time we own the selection against the requested time
		if (!wasOwnedAtTime(id, owner, time)) {
			// fail for time we didn't own selection
		}
		else if (target == m_atomMultiple) {
			// add a multiple request
			if (property != None) {
				success = sendClipboardMultiple(id, requestor, property, time);
			}
		}
		else {
			// handle remaining request formats
			success = sendClipboardData(id, requestor, target, property, time);
		}
	}

	// send success or failure
	sendNotify(requestor, selection, target, success ? property : None, time);
}

void					CXWindowsScreen::processClipboardRequest(
								Window requestor,
								Atom property, Time /*time*/)
{
	CLock lock(&m_mutex);

	// check every clipboard
	for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
		CClipboardInfo& clipboard = m_clipboards[id];

		// find the request list
		CRequestMap::iterator index = clipboard.m_requests.find(requestor);
		if (index == clipboard.m_requests.end()) {
			// this clipboard isn't servicing this requestor window
			continue;
		}
		CRequestList* list = index->second;
		assert(list != NULL);

		// find the property in the list
		CRequestList::iterator index2;
		for (index2 = list->begin(); index2 != list->end(); ++index2) {
			if ((*index2)->m_property == property) {
				break;
			}
		}
		if (index2 == list->end()) {
			// this clipboard isn't waiting on this property
			continue;
		}
		CClipboardRequest* request = *index2;
		assert(request != NULL);

		// compute amount of data to send
		assert(request->m_sent <= request->m_data.size());
		UInt32 count = request->m_data.size() - request->m_sent;
		if (count > kMaxRequestSize) {
			// limit maximum chunk size
			count = kMaxRequestSize;

			// make it a multiple of the size
			count &= ~((request->m_size >> 3) - 1);
		}

		// send more data
		// FIXME -- handle Alloc errors (by returning false)
		XChangeProperty(m_display, request->m_requestor, request->m_property,
								request->m_type, request->m_size,
								PropModeReplace,
								reinterpret_cast<const unsigned char*>(
									request->m_data.data() + request->m_sent),
								count / (request->m_size >> 3));

		// account for sent data
		request->m_sent += count;

		// if we sent zero bytes then we're done sending this data.  remove
		// it from the list and, if the list is empty, the list from the
		// map.  also stop watching the requestor for events.
		if (count == 0) {
			list->erase(index2);
			delete request;
			if (list->empty()) {
				clipboard.m_requests.erase(index);
				delete list;
			}
			XSelectInput(m_display, requestor, getEventMask(requestor));
		}

		// request has been serviced
		break;
	}
}

void					CXWindowsScreen::destroyClipboardRequest(
								Window requestor)
{
	CLock lock(&m_mutex);

	// check every clipboard
	for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
		CClipboardInfo& clipboard = m_clipboards[id];

		// find the request list
		CRequestMap::iterator index = clipboard.m_requests.find(requestor);
		if (index == clipboard.m_requests.end()) {
			continue;
		}
		CRequestList* list = index->second;
		assert(list != NULL);

		// destroy every request in the list
		for (CRequestList::iterator index2 = list->begin();
								index2 != list->end(); ++index2) {
			delete *index2;
		}

		// remove and destroy the list
		clipboard.m_requests.erase(index);
		delete list;
	}

	// note -- we don't stop watching the window for events because
	// we're called in response to the window being destroyed.
}

bool					CXWindowsScreen::sendClipboardData(
								ClipboardID id,
								Window requestor, Atom target,
								Atom property, Time time)
{
	if (target == m_atomTargets) {
		return sendClipboardTargets(id, requestor, property, time);
	}
	else if (target == m_atomTimestamp) {
		return sendClipboardTimestamp(id, requestor, property, time);
	}
	else {
		// compute the type and size for the requested target and
		// convert the data from the clipboard.
		Atom type = None;
		int size = 0;
		CString data;
		if (target == m_atomText || target == m_atomString) {
			if (m_clipboards[id].m_clipboard.has(IClipboard::kText)) {
				type = m_atomString;
				size = 8;
				data = m_clipboards[id].m_clipboard.get(IClipboard::kText);
			}
		}

		// fail if we don't recognize or can't handle the target
		if (type == None || size == 0) {
			return false;
		}

		if (data.size() > kMaxRequestSize) {
			log((CLOG_DEBUG1 "handling clipboard request for %d as INCR", target));

			// get the appropriate list, creating it if necessary
			CRequestList* list = m_clipboards[id].m_requests[requestor];
			if (list == NULL) {
				list = new CRequestList;
				m_clipboards[id].m_requests[requestor] = list;
			}

			// create request object
			CClipboardRequest* request = new CClipboardRequest;
			request->m_data      = data;
			request->m_sent      = 0;
			request->m_requestor = requestor;
			request->m_property  = property;
			request->m_type      = type;
			request->m_size      = size;

			// add request to request list
			list->push_back(request);

			// start watching requestor for property changes and
			// destruction, in addition to other events required by
			// the subclass.
			XSelectInput(m_display, requestor,
								getEventMask(requestor) |
									StructureNotifyMask |
									PropertyChangeMask);

			// FIXME -- handle Alloc errors (by returning false)
			// set property to INCR
			const UInt32 zero = 0;
			XChangeProperty(m_display, requestor, property,
								m_atomINCR,
								8 * sizeof(zero),
								PropModeReplace,
								reinterpret_cast<const unsigned char*>(&zero),
								1);
		}
		else {
			log((CLOG_DEBUG1 "handling clipboard request for %d", target));

			// FIXME -- handle Alloc errors (by returning false)
			XChangeProperty(m_display, requestor, property,
								type, size,
								PropModeReplace,
								reinterpret_cast<const unsigned char*>(
									data.data()),
								data.size() / (size >> 3));
		}
		return true;
	}
	return false;
}

bool					CXWindowsScreen::sendClipboardMultiple(
								ClipboardID id,
								Window requestor,
								Atom property, Time time)
{
	log((CLOG_DEBUG1 "handling clipboard request for MULTIPLE"));

	// get the list of requested formats
	Atom type;
	SInt32 size;
	CString data;
	if (!getData(requestor, property, &type, &size, &data)) {
		type = 0;
	}

	// we only handle atom pair type
	bool success = false;
	if (type == m_atomAtomPair) {
		// check each format, replacing ones we can't do with None.  set
		// the property for each to the requested data (for small requests)
		// or INCR (for large requests).
		bool updated = false;
		UInt32 numRequests = data.size() / (2 * sizeof(Atom));
		for (UInt32 index = 0; index < numRequests; ++index) {
			// get request info
			const Atom* request = reinterpret_cast<const Atom*>(data.data());
			const Atom target   = request[2 * index + 0];
			const Atom property = request[2 * index + 1];

			// handle target
			if (property != None) {
				if (!sendClipboardData(id, requestor, target, property, time)) {
					// couldn't handle target.  change property to None.
					const Atom none = None;
					data.replace((2 * index + 1) * sizeof(Atom), sizeof(Atom),
								reinterpret_cast<const char*>(&none),
								sizeof(none));
					updated = true;
				}
				else {
					success = true;
				}
			}
		}

		// update property if we changed it
		if (updated) {
			// FIXME -- handle Alloc errors (by returning false)
			XChangeProperty(m_display, requestor, property,
								m_atomAtomPair,
								8 * sizeof(Atom),
								PropModeReplace,
								reinterpret_cast<const unsigned char*>(
									data.data()),
								data.length());
		}
	}

	// send notify
	sendNotify(requestor, m_atomClipboard[id], m_atomMultiple,
								success ? property : None, time);
	return success;
}

bool					CXWindowsScreen::sendClipboardTargets(
								ClipboardID id,
								Window requestor,
								Atom property, Time /*time*/)
{
	log((CLOG_DEBUG1 "handling request for TARGETS"));

	// count the number of targets, plus TARGETS and MULTIPLE
	SInt32 numTargets = 2;
	if (m_clipboards[id].m_clipboard.has(IClipboard::kText)) {
		numTargets += 2;
	}

	// construct response
	Atom* response = new Atom[numTargets];
	SInt32 count = 0;
	response[count++] = m_atomTargets;
	response[count++] = m_atomMultiple;
	if (m_clipboards[id].m_clipboard.has(IClipboard::kText)) {
		response[count++] = m_atomText;
		response[count++] = m_atomString;
	}

	// send response (we assume we can transfer the entire list at once)
	// FIXME -- handle Alloc errors (by returning false)
	XChangeProperty(m_display, requestor, property,
								m_atomAtom,
								8 * sizeof(Atom),
								PropModeReplace,
								reinterpret_cast<unsigned char*>(response),
								count);

	// done with our response
	delete[] response;

	return true;
}

bool					CXWindowsScreen::sendClipboardTimestamp(
								ClipboardID id,
								Window requestor,
								Atom property, Time /*time*/)
{
	log((CLOG_DEBUG1 "handling clipboard request for TIMESTAMP"));

	// FIXME -- handle Alloc errors (by returning false)
	Time time = m_clipboards[id].m_clipboard.getTime();
	XChangeProperty(m_display, requestor, property,
								m_atomInteger,
								32,
								PropModeReplace,
								reinterpret_cast<unsigned char*>(time),
								1);
	return true;
}

void					CXWindowsScreen::sendNotify(
								Window requestor, Atom selection,
								Atom target, Atom property, Time time)
{
	XEvent event;
	event.xselection.type      = SelectionNotify;
	event.xselection.display   = m_display;
	event.xselection.requestor = requestor;
	event.xselection.selection = selection;
	event.xselection.target    = target;
	event.xselection.property  = property;
	event.xselection.time      = time;
	XSendEvent(m_display, requestor, False, 0, &event);
}

bool					CXWindowsScreen::wasOwnedAtTime(
								ClipboardID id, Window window, Time time) const
{
	const CClipboardInfo& clipboard = m_clipboards[id];

	// not owned if we've never owned the selection
	if (clipboard.m_clipboard.getTime() == CurrentTime)
		return false;

	// if time is CurrentTime then return true if we still own the
	// selection and false if we do not.  else if we still own the
	// selection then get the current time, otherwise use
	// m_lostClipboard as the end time.
	Time lost = clipboard.m_lostClipboard;
	if (lost == CurrentTime)
		if (time == CurrentTime)
			return true;
		else
			lost = getCurrentTimeNoLock(window);
	else
		if (time == CurrentTime)
			return false;

	// compare time to range
	Time duration = clipboard.m_lostClipboard - clipboard.m_clipboard.getTime();
	Time when     = time - clipboard.m_clipboard.getTime();
	return (/*when >= 0 &&*/ when < duration);
}

Time					CXWindowsScreen::getCurrentTime(Window window) const
{
	CLock lock(&m_mutex);
	return getCurrentTimeNoLock(window);
}

Time					CXWindowsScreen::getCurrentTimeNoLock(
								Window window) const
{
	// select property events on window
	// note -- this will break clipboard transfer if used on a requestor
	// window, so don't do that.
	XSelectInput(m_display, window, getEventMask(window) | PropertyChangeMask);

	// do a zero-length append to get the current time
	unsigned char dummy;
	XChangeProperty(m_display, window, m_atomSynergyTime,
								m_atomInteger, 8,
								PropModeAppend,
								&dummy, 0);

	// look for property notify events with the following
	CPropertyNotifyInfo filter;
	filter.m_window   = window;
	filter.m_property = m_atomSynergyTime;

	// wait for reply
	XEvent xevent;
	while (XCheckIfEvent(m_display, &xevent,
								&CXWindowsScreen::findPropertyNotify,
								(XPointer)&filter) != True) {
		// wait a bit
		CThread::sleep(0.05);
	}
	assert(xevent.type             == PropertyNotify);
	assert(xevent.xproperty.window == window);
	assert(xevent.xproperty.atom   == m_atomSynergyTime);

	// restore event mask
	XSelectInput(m_display, window, getEventMask(window));

	return xevent.xproperty.time;
}


//
// CXWindowsScreen::CClipboardInfo
//

CXWindowsScreen::CClipboardInfo::CClipboardInfo() :
								m_clipboard(),
								m_lostClipboard(CurrentTime),
								m_requests()
{
	// do nothing
}


//
// CXWindowsScreen::CDisplayLock
//

CXWindowsScreen::CDisplayLock::CDisplayLock(const CXWindowsScreen* screen) :
								m_mutex(&screen->m_mutex),
								m_display(screen->m_display)
{
	assert(m_display != NULL);

	m_mutex->lock();
}

CXWindowsScreen::CDisplayLock::~CDisplayLock()
{
	m_mutex->unlock();
}

CXWindowsScreen::CDisplayLock::operator Display*() const
{
	return m_display;
}