view man/lispref/dragndrop.texi @ 5142:f965e31a35f0

reduce lcrecord headers to 2 words, rename printing_unreadable_object -------------------- ChangeLog entries follow: -------------------- man/ChangeLog addition: 2010-03-13 Ben Wing <ben@xemacs.org> * internals/internals.texi (Working with Lisp Objects): * internals/internals.texi (Writing Macros): * internals/internals.texi (lrecords): More rewriting to correspond with changes from *LRECORD* to *LISP_OBJECT*. modules/ChangeLog addition: 2010-03-13 Ben Wing <ben@xemacs.org> * postgresql/postgresql.c (print_pgconn): * postgresql/postgresql.c (print_pgresult): printing_unreadable_object -> printing_unreadable_object_fmt. 2010-03-13 Ben Wing <ben@xemacs.org> * ldap/eldap.c (print_ldap): printing_unreadable_object -> printing_unreadable_object_fmt. src/ChangeLog addition: 2010-03-13 Ben Wing <ben@xemacs.org> * alloc.c (alloc_sized_lrecord_1): * alloc.c (alloc_sized_lrecord_array): * alloc.c (old_alloc_sized_lcrecord): * alloc.c (disksave_object_finalization_1): * alloc.c (mark_lcrecord_list): * alloc.c (alloc_managed_lcrecord): * alloc.c (free_managed_lcrecord): * alloc.c (tick_lcrecord_stats): * alloc.c (sweep_lcrecords_1): * buffer.c (print_buffer): * buffer.c (DEFVAR_BUFFER_LOCAL_1): * casetab.c: * casetab.c (print_case_table): * console.c (print_console): * console.c (DEFVAR_CONSOLE_LOCAL_1): * data.c (print_weak_list): * data.c (print_weak_box): * data.c (print_ephemeron): * data.c (ephemeron_equal): * database.c (print_database): * database.c (finalize_database): * device-msw.c (sync_printer_with_devmode): * device-msw.c (print_devmode): * device-msw.c (finalize_devmode): * device.c: * device.c (print_device): * elhash.c: * elhash.c (print_hash_table): * eval.c (print_subr): * eval.c (print_multiple_value): * event-stream.c (event_stream_resignal_wakeup): * events.c (clear_event_resource): * events.c (zero_event): * events.c (print_event): * extents.c: * extents.c (print_extent): * file-coding.c (print_coding_system): * font-mgr.c: * font-mgr.c (Ffc_init): * frame.c: * frame.c (print_frame): * gc.c: * gc.c (GC_CHECK_NOT_FREE): * glyphs.c: * glyphs.c (print_image_instance): * glyphs.c (print_glyph): * gui.c (print_gui_item): * gui.c (copy_gui_item): * keymap.c (print_keymap): * keymap.c (MARKED_SLOT): * lisp.h: * lisp.h (struct Lisp_String): * lisp.h (DEFUN): * lisp.h (DEFUN_NORETURN): * lrecord.h: * lrecord.h (NORMAL_LISP_OBJECT_UID): * lrecord.h (struct lrecord_header): * lrecord.h (set_lheader_implementation): * lrecord.h (struct old_lcrecord_header): * lrecord.h (struct free_lcrecord_header): * marker.c (print_marker): * mule-charset.c: * mule-charset.c (print_charset): * objects.c (print_color_instance): * objects.c (print_font_instance): * objects.c (finalize_font_instance): * print.c (print_cons): * print.c (printing_unreadable_object_fmt): * print.c (printing_unreadable_lisp_object): * print.c (external_object_printer): * print.c (internal_object_printer): * print.c (debug_p4): * print.c (ext_print_begin): * process.c (print_process): * rangetab.c (print_range_table): * rangetab.c (range_table_equal): * scrollbar.c (free_scrollbar_instance): * specifier.c (print_specifier): * specifier.c (finalize_specifier): * symbols.c (guts_of_unbound_marker): * symeval.h: * symeval.h (DEFVAR_SYMVAL_FWD): * tooltalk.c: * tooltalk.c (print_tooltalk_message): * tooltalk.c (print_tooltalk_pattern): * ui-gtk.c (ffi_object_printer): * ui-gtk.c (emacs_gtk_object_printer): * ui-gtk.c (emacs_gtk_boxed_printer): * window.c (print_window): * window.c (free_window_mirror): * window.c (debug_print_window): * xemacs.def.in.in: (1) printing_unreadable_object -> printing_unreadable_object_fmt. (2) printing_unreadable_lcrecord -> printing_unreadable_lisp_object and fix up so it no longer requires an lcrecord. These previous changes eliminate most of the remaining places where the terms `lcrecord' and `lrecord' occurred outside of specialized code. (3) Fairly major change: Reduce the number of words in an lcrecord from 3 to 2. The third word consisted of a uid that duplicated the lrecord uid, and a single free bit, which was moved into the lrecord structure. This reduces the size of the `uid' slot from 21 bits to 20 bits. Arguably this isn't enough -- we could easily have more than 1,000,000 or so objects created in a session. The answer is (a) It doesn't really matter if we overflow the uid field because it's only used for debugging, to identify an object uniquely (or pretty much so). (b) If we cared about it overflowing and wanted to reduce this, we could make it so that cons, string, float and certain other frob-block types that never print out the uid simply don't store a uid in them and don't increment the lrecord_uid_counter. (4) In conjunction with (3), create new macro NORMAL_LISP_OBJECT_UID() and use it to abstract out the differences between NEWGC and old-GC in accessing the `uid' value from a "normal Lisp Object pointer". (5) In events.c, use zero_nonsized_lisp_object() in place of custom- written equivalent. In font-mgr.c use external_object_printer() in place of custom-written equivalents.
author Ben Wing <ben@xemacs.org>
date Sat, 13 Mar 2010 05:38:08 -0600
parents bc4f2511bbea
children
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@c -*-texinfo-*-
@c This is part of the XEmacs Lisp Reference Manual.
@c Copyright (C) 1998 Oliver Graf <ograf@fga.de>
@c Original reference is (c) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
@c See the file lispref.texi for copying conditions.
@setfilename ../../info/dragndrop.texi
@node Drag and Drop, Modes, Scrollbars, Top
@chapter Drag and Drop
@cindex drag and drop

@emph{WARNING}: the Drag'n'Drop API is still under development and the
interface may change! The current implementation is considered experimental.

  Drag'n'drop is a way to transfer information between multiple applications.
To do this several GUIs define their own protocols. Examples are CDE, Motif,
KDE, MSWindows, GNOME, and many more. To catch all these protocols, XEmacs
provides a generic API.

One prime idea behind the API is to use a data interface that is
transparent for all systems. The author thinks that this is best
archived by using URL and MIME data, cause any internet enabled system
must support these for email already. XEmacs also already provides
powerful interfaces to support these types of data (tm and w3).

@menu
* Supported Protocols:: Which low-level protocols are supported.
* Drop Interface::      How XEmacs handles a drop from another application.
* Drag Interface::      Calls to initiate a drag from XEmacs.
@end menu

@node Supported Protocols
@section Supported Protocols

The current release of XEmacs only support a small set of Drag'n'drop
protocols. Some of these only support limited options available in the API.

@menu
* CDE dt::              Common Desktop Environment used on suns.
* MSWindows OLE::       Mr. Gates way of live.
* Loose ends::          The other protocols.
@end menu

@node CDE dt
@subsection CDE dt
@cindex CDE dt

CDE stands for Common Desktop Environment. It is based on the Motif
widget library. It's drag'n'drop protocol is also an abstraction of the
Motif protocol (so it might be possible, that XEmacs will also support
the Motif protocol soon).

CDE has three different types: file, buffer, and text. XEmacs only uses
file and buffer drags. The API will disallow full URL drags, only file
method URLs are passed through.

Buffer drags are always converted to plain text.

@node MSWindows OLE
@subsection MSWindows OLE
@cindex MSWindows OLE

Only allows file drags and drops.

@node Loose ends
@subsection Loose ends

The following protocols will be supported soon: Xdnd, Motif, Xde (if I
get some specs).

In particular Xdnd will be one of the protocols that can benefit from
the XEmacs API, cause it also uses MIME types to encode dragged data.

@node Drop Interface
@section Drop Interface
@cindex drop
@cindex Drop API

For each activated low-level protocol, an internal routine will catch
incoming drops and convert them to a dragdrop-drop type
misc-user-event.

This misc-user-event has its function argument set to
@code{dragdrop-drop-dispatch} and the object contains the data of the drop
(converted to URL/MIME specific data). This function will search the variable
@code{experimental-dragdrop-drop-functions} for a function that can handle the
dropped data.

To modify the drop behavior, the user can modify the variable
@code{experimental-dragdrop-drop-functions}. Each element of this list
specifies a possible handler for dropped data. The first one that can handle
the data will return @code{t} and exit. Another possibility is to set a
extent-property with the same name. Extents are checked prior to the
variable.

The customization group @code{drag-n-drop} shows all variables of user
interest.

@node Drag Interface
@section Drag Interface
@cindex drag
@cindex Drag API

This describes the drag API (not implemented yet).