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DtDndProtocol(4)
CDE
NAME
DtDndProtocol - drag and drop matching and transfer protocols
DESCRIPTION
The drag and drop protocols provide policy for matching and data transfer
between the drag initiator and the drop receiver of file names, selected
text spans and application-defined structured data formats.
The drag and drop protocols use the standard X11 selection targets, where
available, with the addition of several new selection targets where
required.
These protocols provide for the transfer of the following types of data:
· Selected Text
· File Names
· Buffers
PROTOCOL OVERVIEW
Each protocol consists of the following:
Drag and Drop API Protocol
Each protocol described corresponds to a specific DtDndProtocol enumeration
value.
Export/Import Targets
The Motif drag and drop API provides support for matching of the data
transfer protocol between the drag initiator and the various drop
receivers. This allows the user to determine readily which drop sites will
accept the dragged data.
The drag initiator sets the XmNexportTargets resource of the XmDragContext
to the list of target atoms that describe the data being dragged. The drop
receiver sets the XmNimportTargets resource of the XmDropSite to the list
of target atoms that describe the data that it will accept. The Motif drag
and drop subsystem allows drops when the XmNexportTargets and
XmNimportTargets have at least one target in common.
Data Transfer Protocol
Once the drag initiator has dropped on the drop receiver, the transfer of
data is begun. The transfer is accomplished using X selections and is
controlled by the drop receiver.
The drop receiver starts all transfers by converting the selection into the
ICCCM TARGETS target to get the set of available selection targets. (See
the for a description of converting targets). It then chooses the
appropriate selections from that set and requests that the drag initiator
convert each requested selection. Each protocol has a set of selection
targets that are used to transfer all the necessary data. These target
conversions are usually initiated by calling XmDropTransferStart.
Move Completion
When the operation of the drop is XmDROP_MOVE, the drop receiver must
complete the move using an appropriate method. For most data transfers,
this is accomplished by converting the selection into the ICCCM DELETE
target to tell the drag initiator that it may delete the data. For most
file name transfers, this is accomplished via the file system.
TEXT TRANSFER PROTOCOL
The text transfer protocol is used to exchange text selections.
Drag and Drop API
This is the protocol used when a DtDndProtocol of DtDND_TEXT_TRANSFER is
specified.
Export/Import Targets
The export or import targets are any of the following; the target
describing the character encoding of the text selection, COMPOUND_TEXT,
STRING or TEXT.
Data Transfer Protocol
The transfer of text selections follows the protocols described in the
ICCCM manual. If the character encoding of the drag initiator and drop
receiver are the same, that target should be converted to get the text
selection. If the character encoding are different, the drop receiver
should attempt to convert the standard text targets in the following order:
COMPOUND_TEXT, STRING or TEXT.
Move Completion
The move is completed by converting the selection into the ICCCM DELETE
target.
FILE NAME TRANSFER PROTOCOL
The transfer protocol is used to exchange file names.
Drag and Drop API
This is the protocol used when a DtDndProtocol of DtDND_FILENAME_TRANSFER
is specified.
Export/Import Targets
The export or import targets are FILE_NAME and, optionally, _DT_NETFILE if
capable of providing the file name in network canonical form using
tt_file_netfile(3) and tt_netfile_file(3).
Data Transfer Protocol
If the ICCCM HOST_NAME target is in the list of target atoms, it is
converted. If the returned host name is different than the host name for
the drop receiver and the _DT_NETFILE target is in the list of target
atoms, it is converted. The drag initiator uses tt_file_netfile(3) to
encode the file names and the drop receiver uses tt_netfile_file(3) to
decode the file names.
If the hosts are the same for both the drag initiator and the drop receiver
or either the HOST_NAME or the _DT_NETFILE targets are not in the list of
target atoms from the drag initiator, the drop receiver converts the ICCCM
FILE_NAME target. No encoding of the file names occurs in this case.
Move Completion
Moves of file names can be accomplished atomically using standard file
system operations. Drop receivers are encouraged to use the file system.
The drop receiver may alternatively choose to use the ICCCM DELETE target
to complete the XmDROP_MOVE and the drag initiator must be ready to comply.
BUFFER TRANSFER PROTOCOL
The transfer protocol is used to exchange memory buffers.
Drag and Drop API
This is the protocol used when a DtDndProtocol of DtDND_BUFFER_TRANSFER is
specified.
Export/Import Targets
The export and import targets are _DT_BUFFER_DATA, _DT_BUFFER_LENGTHS and,
optionally, _DT_BUFFER_NAMES.
Data Transfer Protocol
The _DT_BUFFER_DATA and _DT_BUFFER_LENGTHS targets are converted to
transfer the buffer data.
The data of the buffers is encoded into the _DT_BUFFER_DATA target as an
array of bytes. The lengths in bytes of each buffer are encoded into
_DT_BUFFER_LENGTHS. Each length is used to index into the _DT_BUFFER_DATA
array.
If the _DT_BUFFER_NAMES target is available, it is converted to transfer
the names of the buffers.
Move Completion
The move is completed by converting the selection into the ICCCM DELETE
target.
SELECTION TARGETS
The following table describes the selection targets used in the drag and
drop data matching and transfer protocols.
Atom Type Description
ATOM
TARGETS
A list of valid target
atoms. See ICCCM
section 2.6.2.
NULL
DELETE
Used to delete the
dropped data. If the
drop receiver wishes to
perform a move
operation on the data,
after copying the data
it should
request conversion of
the DELETE target.
COMPOUND_TEXT
COMPOUND_TEXT
The text selection in
compound text format.
See ICCCM section
2.7.1.
STRING
STRING
The text selection in
ISO Latin-1 format. See
ICCCM section 2.7.1.
TEXT
TEXT
The text selection in
the format preferred by
the selection holder.
TEXT
HOST_NAME
The name of the machine
running the client
as seen from the
machine
running the server. See
ICCCM section 2.6.2.
TEXT
FILE_NAME
The full path name of
the files. See ICCCM
section 2.6.2.
TEXT
_DT_NETFILE
The full pathname of
the files,
each encoded using
tt_file_netfile(3) and
decoded using
tt_netfile_file(3).
_DT_BUFFER_DATA
_DT_BUFFER_DATA
The buffer data in an
array of bytes.
INTEGER
_DT_BUFFER_LENGTHS
The lengths in bytes of
each buffer in the
_DT_BUFFER_NAMES array.
STRING
_DT_BUFFER_NAMES
The names of each
buffer, suitable for
use
as a file name.
SEE ALSO
DtDnd(5), DtDndDragStart(3), DtDndVaDragStart(3), DtDndVaDropRegister(3),
DtDndDropUnregister(3), XmDragContext(3X), XmDragStart(3X), XmDropSite(3X),
tt_file_netfile(3), tt_netfile_file(3), X11/R5 Inter-Client
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Index for
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Alphabetical
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