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Commit bf87f8bb authored by Ulrich Sibiller's avatar Ulrich Sibiller Committed by Mike Gabriel
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Clipboard.c: add loads of comments

parent e985f711
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Showing with 195 additions and 32 deletions
nx-X11/programs/Xserver/hw/nxagent/Clipboard.c
View file @ bf87f8bb
......@@ -82,14 +82,19 @@ const int nxagentMaxSelections = 2;
typedef struct _SelectionOwner
{
Atom selection;
ClientPtr client;
Window window;
WindowPtr windowPtr;
Time lastTimeChanged;
Atom selection; /* _external_ Atom */
ClientPtr client; /* internal client */
Window window; /* internal window id */
WindowPtr windowPtr; /* internal window struct */
Time lastTimeChanged; /* internal time */
} SelectionOwner;
/*
* this contains the last selection owner in nxagent. The
* lastTimeChanged is always an internal time. If .client is NULL the
* owner is outside nxagent. .selection will _always_ contain the
* external atom of the selection
*/
static SelectionOwner *lastSelectionOwner;
static Atom nxagentLastRequestedSelection;
......@@ -438,6 +443,11 @@ int SendSelectionNotifyEventToClient(ClientPtr client,
return SendEventToClient(client, &x);
}
/*
* Check if target is a valid content type target sent by the real X
* server, like .e.g XA_STRING or UTF8_STRING. Other, non content type
* targets like "TARGETS" or "TIMESTAMP" will return false.
*/
Bool nxagentValidServerTargets(Atom target)
{
if (target == XA_STRING)
......@@ -565,6 +575,11 @@ int nxagentFindCurrentSelectionIndex(Atom sel)
return i;
}
/*
* This is called from Events.c dispatch loop on reception of a
* SelectionClear event. We receive this event if someone on the real
* X server claims the selection ownership.
*/
void nxagentClearSelection(XEvent *X)
{
#ifdef DEBUG
......@@ -585,6 +600,7 @@ void nxagentClearSelection(XEvent *X)
{
if (lastSelectionOwner[i].client != NULL)
{
/* send a SelectionClear event to (our) previous owner */
xEvent x = {0};
x.u.u.type = SelectionClear;
x.u.selectionClear.time = GetTimeInMillis();
......@@ -594,6 +610,11 @@ void nxagentClearSelection(XEvent *X)
SendEventToClient(lastSelectionOwner[i].client, &x);
}
/*
* set the root window with the NullClient as selection owner. Our
* clients asking for the owner via XGetSelectionOwner() will get
* these for an answer
*/
CurrentSelections[i].window = screenInfo.screens[0]->root->drawable.id;
CurrentSelections[i].client = NullClient;
......@@ -634,6 +655,13 @@ void nxagentReplyRequestSelection(XEvent *X, Bool success)
NXFlushDisplay(nxagentDisplay, NXFlushLink);
}
/*
* This is called from Events.c dispatch loop on reception of a
* SelectionRequest event, meaning a client of the real X server wants
* to have the selection content. The real X server knows the nxagent
* as selection owner. But in reality one of our windows is the owner,
* so we must pass the request on to the real owner.
*/
void nxagentRequestSelection(XEvent *X)
{
#ifdef DEBUG
......@@ -664,6 +692,15 @@ void nxagentRequestSelection(XEvent *X)
return;
}
/*
* check if this request needs special treatment by checking
* if any of the following is true:
* - this is a special request like TARGETS or TIMESTAMP
* - lastServerRequestor in non-NULL (= we are currenty in the transfer phase)
* - the selection in this request is none we own.
* In all cases we'll send back a SelectionNotify event with an
* appropriate answer
*/
if (!nxagentValidServerTargets(X->xselectionrequest.target) ||
(lastServerRequestor != None) ||
((X->xselectionrequest.selection != lastSelectionOwner[nxagentPrimarySelection].selection) &&
......@@ -687,6 +724,15 @@ FIXME: Do we need this?
*/
if (X->xselectionrequest.target == serverTARGETS)
{
/*
* the selection request target is TARGETS. The requestor is
* asking for a list of supported data formats. Currently
* there's only one format we support: XA_STRING
*
* The selection does not matter here, we will return this for
* PRIMARY and CLIPBOARD.
*/
Atom targets[] = {XA_STRING};
int numTargets = 1;
......@@ -714,6 +760,17 @@ FIXME: Do we need this?
}
else if (X->xselectionrequest.target == serverTIMESTAMP)
{
/*
* Section 2.6.2 of the ICCCM states:
* TIMESTAMP - To avoid some race conditions, it is important
* that requestors be able to discover the timestamp the owner
* used to acquire ownership. Until and unless the protocol is
* changed so that a GetSelectionOwner request returns the
* timestamp used to acquire ownership, selection owners must
* support conversion to TIMESTAMP, returning the timestamp they
* used to obtain the selection.
*/
int i = nxagentFindLastSelectionOwnerIndex(X->xselectionrequest.selection);
if (i < nxagentMaxSelections)
{
......@@ -737,9 +794,13 @@ FIXME: Do we need this?
}
/*
* This is necessary in nxagentGetClipboardWindow.
* reaching this means the request is neither a special request nor
* invalid. We can process it now.
*/
/*
* This is required for nxagentGetClipboardWindow.
*/
nxagentLastRequestedSelection = X->xselectionrequest.selection;
/* find the index of the requested selection */
......@@ -748,6 +809,10 @@ FIXME: Do we need this?
{
if ((lastClientWindowPtr != NULL) && (lastSelectionOwner[i].client != NULL))
{
/*
* Request the real X server to transfer the selection content
* to the NX_CUT_BUFFER_CLIENT property of the serverWindow.
*/
XConvertSelection(nxagentDisplay, CurrentSelections[i].selection,
X->xselectionrequest.target, serverCutProperty,
serverWindow, lastClientTime);
......@@ -758,9 +823,18 @@ FIXME: Do we need this?
}
else
{
/*
* if one of our clients owns the selection we ask it to copy
* the selection to the clientCutProperty on nxagent's root
* window
*/
if (lastSelectionOwner[i].client != NULL &&
nxagentOption(Clipboard) != ClipboardClient)
{
/*
* store who on the real X server requested the data and how
* and where it wants to have it
*/
lastServerProperty = X->xselectionrequest.property;
lastServerRequestor = X->xselectionrequest.requestor;
lastServerTarget = X->xselectionrequest.target;
......@@ -815,6 +889,7 @@ FIXME: Do we need this?
}
/*
* end current selection transfer by sending a notification to the
* client and resetting the corresponding variables and the state
* machine. If success is False send a None reply, meaning "request
* denied/failed"
......@@ -1118,6 +1193,11 @@ void nxagentCollectPropertyEvent(int resource)
SAFE_XFree(pszReturnData);
}
/*
* This is _only_ called from Events.c dispatch loop on reception of a
* SelectionNotify event from the real X server. These events are
* sent out by nxagent itself!
*/
void nxagentNotifySelection(XEvent *X)
{
if (agentClipboardStatus != 1)
......@@ -1143,6 +1223,14 @@ void nxagentNotifySelection(XEvent *X)
if (lastClientWindowPtr != NULL)
{
/*
* We reach here after a paste inside the nxagent, triggered by
* the XConvertSelection call in nxagentConvertSelection(). This
* means that data we need has been transferred to the
* serverCutProperty of the serverWindow (our window on the real X
* server). We now need to transfer it to the original requestor,
* which is stored in the lastClient* variables.
*/
if ((lastClientStage == SelectionStageNone) && (X->xselection.property == serverCutProperty))
{
#ifdef DEBUG
......@@ -1181,6 +1269,7 @@ void nxagentNotifySelection(XEvent *X)
int i = nxagentFindLastSelectionOwnerIndex(X->xselection.selection);
if (i < nxagentMaxSelections)
{
/* if the last owner was an internal one */
if ((lastSelectionOwner[i].client != NULL) &&
(lastSelectionOwner[i].windowPtr != NULL) &&
(X->xselection.property == serverClientCutProperty))
......@@ -1191,6 +1280,7 @@ void nxagentNotifySelection(XEvent *X)
unsigned long ulReturnBytesLeft;
unsigned char *pszReturnData = NULL;
/* first get size values ... */
int result = GetWindowProperty(lastSelectionOwner[i].windowPtr, clientCutProperty, 0, 0, False,
AnyPropertyType, &atomReturnType, &resultFormat,
&ulReturnItems, &ulReturnBytesLeft, &pszReturnData);
......@@ -1206,6 +1296,7 @@ void nxagentNotifySelection(XEvent *X)
}
else
{
/* ... then use the size values for the actual request */
result = GetWindowProperty(lastSelectionOwner[i].windowPtr, clientCutProperty, 0,
ulReturnBytesLeft, False, AnyPropertyType, &atomReturnType,
&resultFormat, &ulReturnItems, &ulReturnBytesLeft,
......@@ -1230,6 +1321,7 @@ void nxagentNotifySelection(XEvent *X)
PropModeReplace,
pszReturnData,
ulReturnItems);
/* Fill the property on the initial requestor with the requested data */
#ifdef DEBUG
{
......@@ -1252,6 +1344,14 @@ void nxagentNotifySelection(XEvent *X)
*/
}
/*
* inform the initial requestor that the requested data has
* arrived in the desired property. If we have been unable to
* get the data from the owner XChangeProperty will not have
* been called and lastServerProperty will be None which
* effectively will send a "Request denied" to the initial
* requestor.
*/
XSelectionEvent eventSelection = {
.requestor = lastServerRequestor,
.selection = X->xselection.selection,
......@@ -1275,10 +1375,10 @@ void nxagentNotifySelection(XEvent *X)
}
/*
* Acquire selection so we don't get selection
* requests from real X clients.
* Let nxagent's serverWindow acquire the selection. All requests from
* the real X server (or its clients) will be sent to this window. The
* real X server never communicates with our windows directly.
*/
void nxagentResetSelectionOwner(void)
{
if (lastServerRequestor != None)
......@@ -1314,22 +1414,31 @@ void nxagentResetSelectionOwner(void)
lastClientWindowPtr = NULL;
SetClientSelectionStage(None);
/* Hmm, this is already None when reaching this */
lastServerRequestor = None;
return;
}
#ifdef NXAGENT_CLIPBOARD
/*
* The callback is called from dix. This is the normal operation
* mode. The callback is also called when nxagent gets XFixes events
* from the real X server. In that case the Trap is set and the
* callback will do nothing.
*/
void nxagentSetSelectionCallback(CallbackListPtr *callbacks, void *data,
void *args)
{
/*
* Only act if the Trap is unset. The trap indicates that we are
* triggered by a clipboard event originating from the real X
* server. In that case we do not want to propagate back changes to
* the real X server, because it already knows about them and we
* Only act if the trap is unset. The trap indicates that we are
* triggered by an XFixes clipboard event originating from the real
* X server. In that case we do not want to propagate back changes
* to the real X server, because it already knows about them and we
* would end up in an infinite loop of events. If there was a better
* way to identify that situation during Callback processing we
* way to identify that situation during callback processing we
* could get rid of the Trap...
*/
if (nxagentExternalClipboardEventTrap != 0)
......@@ -1388,6 +1497,10 @@ void nxagentSetSelectionCallback(CallbackListPtr *callbacks, void *data,
}
#endif
/*
* This is called from the nxagentSetSelectionCallback, so it is using
* internal Atoms
*/
void nxagentSetSelectionOwner(Selection *pSelection)
{
if (agentClipboardStatus != 1)
......@@ -1437,13 +1550,16 @@ void nxagentSetSelectionOwner(Selection *pSelection)
/*
* inform the real X server that our serverWindow is the
* clipboard owner. The real owner window (inside nxagent) is
* stored in lastSelectionOwner.window.
* lastSelectionOwner.windowPtr points to the struct that
* contains all information about the owner window
* clipboard owner.
*/
XSetSelectionOwner(nxagentDisplay, lastSelectionOwner[i].selection, serverWindow, CurrentTime);
/*
* The real owner window (inside nxagent) is stored in
* lastSelectionOwner.window. lastSelectionOwner.windowPtr
* points to the struct that contains all information about the
* owner window.
*/
nxagentStoreSelectionOwner(&lastSelectionOwner[i], pSelection);
}
}
......@@ -1477,10 +1593,9 @@ FIXME
void nxagentNotifyConvertFailure(ClientPtr client, Window requestor,
Atom selection, Atom target, Time time)
{
/*
FIXME: Why this pointer can be not a valid
client pointer?
*/
/*
* Check if the client is still valid.
*/
if (clients[client -> index] != client)
{
#ifdef WARNING
......@@ -1493,6 +1608,13 @@ FIXME: Why this pointer can be not a valid
SendSelectionNotifyEventToClient(client, time, requestor, selection, target, None);
}
/*
* This is called from dix (ProcConvertSelection) if an nxagent client
* issues a ConvertSelection request. So all the Atoms are internal
* return codes:
* 0: let dix process the request
* 1: don't let dix process the request
*/
int nxagentConvertSelection(ClientPtr client, WindowPtr pWin, Atom selection,
Window requestor, Atom property, Atom target, Time time)
{
......@@ -1502,19 +1624,14 @@ int nxagentConvertSelection(ClientPtr client, WindowPtr pWin, Atom selection,
return 0;
}
/*
* There is a client owner on the agent side, let normal stuff happen.
*/
/*
* Only for PRIMARY and CLIPBOARD selections.
*/
for (int i = 0; i < nxagentMaxSelections; i++)
{
if ((selection == CurrentSelections[i].selection) &&
(lastSelectionOwner[i].client != NULL))
{
/*
* There is a client owner on the agent side, let normal dix stuff happen.
*/
return 0;
}
}
......@@ -1569,6 +1686,10 @@ int nxagentConvertSelection(ClientPtr client, WindowPtr pWin, Atom selection,
return 1;
}
/*
* The selection request target is TARGETS. The requestor is asking
* for a list of supported data formats. Currently there's 4 of them.
*/
if (target == clientTARGETS)
{
/* --- Order changed by dimbor (prevent sending COMPOUND_TEXT to client --- */
......@@ -1596,11 +1717,28 @@ int nxagentConvertSelection(ClientPtr client, WindowPtr pWin, Atom selection,
return 1;
}
/*
* Section 2.6.2 of the ICCCM states:
* "TIMESTAMP - To avoid some race conditions, it is important
* that requestors be able to discover the timestamp the owner
* used to acquire ownership. Until and unless the protocol is
* changed so that a GetSelectionOwner request returns the
* timestamp used to acquire ownership, selection owners must
* support conversion to TIMESTAMP, returning the timestamp they
* used to obtain the selection."
*/
if (target == MakeAtom("TIMESTAMP", 9, 1))
{
int i = nxagentFindCurrentSelectionIndex(selection);
if (i < NumCurrentSelections)
{
/*
* "If the specified property is not None, the owner should place
* the data resulting from converting the selection into the
* specified property on the requestor window and should set the
* property's type to some appropriate value, which need not be
* the same as the specified target."
*/
ChangeWindowProperty(pWin,
property,
XA_INTEGER,
......@@ -1620,7 +1758,7 @@ int nxagentConvertSelection(ClientPtr client, WindowPtr pWin, Atom selection,
if (lastClientClientPtr == client && (GetTimeInMillis() - lastClientReqTime < 5000))
{
/*
* The same client made consecutive requests of clipboard contents
* The same client made consecutive requests of clipboard content
* with less than 5 seconds time interval between them.
*/
......@@ -1647,6 +1785,10 @@ int nxagentConvertSelection(ClientPtr client, WindowPtr pWin, Atom selection,
{
lastClientWindowPtr = pWin;
SetClientSelectionStage(None);
/*
* store the original requestor, we need that later after
* serverCutProperty contains the desired selection content
*/
lastClientRequestor = requestor;
lastClientClientPtr = client;
lastClientTime = time;
......@@ -1663,6 +1805,10 @@ int nxagentConvertSelection(ClientPtr client, WindowPtr pWin, Atom selection,
selection = lastSelectionOwner[nxagentClipboardSelection].selection;
}
/*
* we only convert to either UTF8 or XA_STRING, despite accepting
* TEXT and COMPOUND_TEXT.
*/
if (target == clientUTF8_STRING)
{
#ifdef DEBUG
......@@ -1700,6 +1846,23 @@ int nxagentConvertSelection(ClientPtr client, WindowPtr pWin, Atom selection,
return 0;
}
/*
* This is _only_ called from ProcSendEvent in NXevents.c. It is used
* to send a SelectionNotify event to our server window which will
* trigger the dispatch loop in Events.c to run nxagentNotifySelection
* which in turn will take care of transferring the selection content
* from the owning client to to a property of the server window.
*
* Returning 1 here means the client request will not be further
* handled by dix. Returning 0 means a SelectionNotify event being
* pushed out to our clients.
*
* From https://tronche.com/gui/x/xlib/events/client-communication/selection.html:
* "This event is generated by the X server in response to a
* ConvertSelection protocol request when there is no owner for the
* selection. When there is an owner, it should be generated by the
* owner of the selection by using XSendEvent()."
*/
int nxagentSendNotify(xEvent *event)
{
#ifdef DEBUG
......
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