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This is Info file ../../info/lispref.info, produced by Makeinfo version 1.68 from the input file lispref.texi. Edition History: GNU Emacs Lisp Reference Manual Second Edition (v2.01), May 1993 GNU Emacs Lisp Reference Manual Further Revised (v2.02), August 1993 Lucid Emacs Lisp Reference Manual (for 19.10) First Edition, March 1994 XEmacs Lisp Programmer's Manual (for 19.12) Second Edition, April 1995 GNU Emacs Lisp Reference Manual v2.4, June 1995 XEmacs Lisp Programmer's Manual (for 19.13) Third Edition, July 1995 XEmacs Lisp Reference Manual (for 19.14 and 20.0) v3.1, March 1996 XEmacs Lisp Reference Manual (for 19.15 and 20.1, 20.2) v3.2, April, May 1997 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc. Copyright (C) 1994, 1995 Sun Microsystems, Inc. Copyright (C) 1995, 1996 Ben Wing. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU General Public License" is included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled "GNU General Public License" may be included in a translation approved by the Free Software Foundation instead of in the original English. File: lispref.info, Node: Using Interactive, Next: Interactive Codes, Up: Defining Commands Using `interactive' ------------------- This section describes how to write the `interactive' form that makes a Lisp function an interactively-callable command. - Special Form: interactive ARG-DESCRIPTOR This special form declares that the function in which it appears is a command, and that it may therefore be called interactively (via `M-x' or by entering a key sequence bound to it). The argument ARG-DESCRIPTOR declares how to compute the arguments to the command when the command is called interactively. A command may be called from Lisp programs like any other function, but then the caller supplies the arguments and ARG-DESCRIPTOR has no effect. The `interactive' form has its effect because the command loop (actually, its subroutine `call-interactively') scans through the function definition looking for it, before calling the function. Once the function is called, all its body forms including the `interactive' form are executed, but at this time `interactive' simply returns `nil' without even evaluating its argument. There are three possibilities for the argument ARG-DESCRIPTOR: * It may be omitted or `nil'; then the command is called with no arguments. This leads quickly to an error if the command requires one or more arguments. * It may be a Lisp expression that is not a string; then it should be a form that is evaluated to get a list of arguments to pass to the command. If this expression reads keyboard input (this includes using the minibuffer), keep in mind that the integer value of point or the mark before reading input may be incorrect after reading input. This is because the current buffer may be receiving subprocess output; if subprocess output arrives while the command is waiting for input, it could relocate point and the mark. Here's an example of what *not* to do: (interactive (list (region-beginning) (region-end) (read-string "Foo: " nil 'my-history))) Here's how to avoid the problem, by examining point and the mark only after reading the keyboard input: (interactive (let ((string (read-string "Foo: " nil 'my-history))) (list (region-beginning) (region-end) string))) * It may be a string; then its contents should consist of a code character followed by a prompt (which some code characters use and some ignore). The prompt ends either with the end of the string or with a newline. Here is a simple example: (interactive "bFrobnicate buffer: ") The code letter `b' says to read the name of an existing buffer, with completion. The buffer name is the sole argument passed to the command. The rest of the string is a prompt. If there is a newline character in the string, it terminates the prompt. If the string does not end there, then the rest of the string should contain another code character and prompt, specifying another argument. You can specify any number of arguments in this way. The prompt string can use `%' to include previous argument values (starting with the first argument) in the prompt. This is done using `format' (*note Formatting Strings::.). For example, here is how you could read the name of an existing buffer followed by a new name to give to that buffer: (interactive "bBuffer to rename: \nsRename buffer %s to: ") If the first character in the string is `*', then an error is signaled if the buffer is read-only. If the first character in the string is `@', and if the key sequence used to invoke the command includes any mouse events, then the window associated with the first of those events is selected before the command is run. If the first character in the string is `_', then this command will not cause the region to be deactivated when it completes; that is, `zmacs-region-stays' will be set to `t' when the command exits successfully. You can use `*', `@', and `_' together; the order does not matter. Actual reading of arguments is controlled by the rest of the prompt string (starting with the first character that is not `*', `@', or `_'). File: lispref.info, Node: Interactive Codes, Next: Interactive Examples, Prev: Using Interactive, Up: Defining Commands Code Characters for `interactive' --------------------------------- The code character descriptions below contain a number of key words, defined here as follows: Completion Provide completion. <TAB>, <SPC>, and <RET> perform name completion because the argument is read using `completing-read' (*note Completion::.). `?' displays a list of possible completions. Existing Require the name of an existing object. An invalid name is not accepted; the commands to exit the minibuffer do not exit if the current input is not valid. Default A default value of some sort is used if the user enters no text in the minibuffer. The default depends on the code character. No I/O This code letter computes an argument without reading any input. Therefore, it does not use a prompt string, and any prompt string you supply is ignored. Even though the code letter doesn't use a prompt string, you must follow it with a newline if it is not the last code character in the string. Prompt A prompt immediately follows the code character. The prompt ends either with the end of the string or with a newline. Special This code character is meaningful only at the beginning of the interactive string, and it does not look for a prompt or a newline. It is a single, isolated character. Here are the code character descriptions for use with `interactive': `*' Signal an error if the current buffer is read-only. Special. `@' Select the window mentioned in the first mouse event in the key sequence that invoked this command. Special. `_' Do not cause the region to be deactivated when this command completes. Special. `a' A function name (i.e., a symbol satisfying `fboundp'). Existing, Completion, Prompt. `b' The name of an existing buffer. By default, uses the name of the current buffer (*note Buffers::.). Existing, Completion, Default, Prompt. `B' A buffer name. The buffer need not exist. By default, uses the name of a recently used buffer other than the current buffer. Completion, Default, Prompt. `c' A character. The cursor does not move into the echo area. Prompt. `C' A command name (i.e., a symbol satisfying `commandp'). Existing, Completion, Prompt. `d' The position of point, as an integer (*note Point::.). No I/O. `D' A directory name. The default is the current default directory of the current buffer, `default-directory' (*note System Environment::.). Existing, Completion, Default, Prompt. `e' The last mouse-button or misc-user event in the key sequence that invoked the command. No I/O. You can use `e' more than once in a single command's interactive specification. If the key sequence that invoked the command has N mouse-button or misc-user events, the Nth `e' provides the Nth such event. `f' A file name of an existing file (*note File Names::.). The default directory is `default-directory'. Existing, Completion, Default, Prompt. `F' A file name. The file need not exist. Completion, Default, Prompt. `k' A key sequence (*note Keymap Terminology::.). This keeps reading events until a command (or undefined command) is found in the current key maps. The key sequence argument is represented as a vector of events. The cursor does not move into the echo area. Prompt. This kind of input is used by commands such as `describe-key' and `global-set-key'. `K' A key sequence, whose definition you intend to change. This works like `k', except that it suppresses, for the last input event in the key sequence, the conversions that are normally used (when necessary) to convert an undefined key into a defined one. `m' The position of the mark, as an integer. No I/O. `n' A number read with the minibuffer. If the input is not a number, the user is asked to try again. The prefix argument, if any, is not used. Prompt. `N' The raw prefix argument. If the prefix argument is `nil', then read a number as with `n'. Requires a number. *Note Prefix Command Arguments::. Prompt. `p' The numeric prefix argument. (Note that this `p' is lower case.) No I/O. `P' The raw prefix argument. (Note that this `P' is upper case.) No I/O. `r' Point and the mark, as two numeric arguments, smallest first. This is the only code letter that specifies two successive arguments rather than one. No I/O. `s' Arbitrary text, read in the minibuffer and returned as a string (*note Text from Minibuffer::.). Terminate the input with either <LFD> or <RET>. (`C-q' may be used to include either of these characters in the input.) Prompt. `S' An interned symbol whose name is read in the minibuffer. Any whitespace character terminates the input. (Use `C-q' to include whitespace in the string.) Other characters that normally terminate a symbol (e.g., parentheses and brackets) do not do so here. Prompt. `v' A variable declared to be a user option (i.e., satisfying the predicate `user-variable-p'). *Note High-Level Completion::. Existing, Completion, Prompt. `x' A Lisp object, specified with its read syntax, terminated with a <LFD> or <RET>. The object is not evaluated. *Note Object from Minibuffer::. Prompt. `X' A Lisp form is read as with `x', but then evaluated so that its value becomes the argument for the command. Prompt. File: lispref.info, Node: Interactive Examples, Prev: Interactive Codes, Up: Defining Commands Examples of Using `interactive' ------------------------------- Here are some examples of `interactive': (defun foo1 () ; `foo1' takes no arguments, (interactive) ; just moves forward two words. (forward-word 2)) => foo1 (defun foo2 (n) ; `foo2' takes one argument, (interactive "p") ; which is the numeric prefix. (forward-word (* 2 n))) => foo2 (defun foo3 (n) ; `foo3' takes one argument, (interactive "nCount:") ; which is read with the Minibuffer. (forward-word (* 2 n))) => foo3 (defun three-b (b1 b2 b3) "Select three existing buffers. Put them into three windows, selecting the last one." (interactive "bBuffer1:\nbBuffer2:\nbBuffer3:") (delete-other-windows) (split-window (selected-window) 8) (switch-to-buffer b1) (other-window 1) (split-window (selected-window) 8) (switch-to-buffer b2) (other-window 1) (switch-to-buffer b3)) => three-b (three-b "*scratch*" "declarations.texi" "*mail*") => nil File: lispref.info, Node: Interactive Call, Next: Command Loop Info, Prev: Defining Commands, Up: Command Loop Interactive Call ================ After the command loop has translated a key sequence into a definition, it invokes that definition using the function `command-execute'. If the definition is a function that is a command, `command-execute' calls `call-interactively', which reads the arguments and calls the command. You can also call these functions yourself. - Function: commandp OBJECT Returns `t' if OBJECT is suitable for calling interactively; that is, if OBJECT is a command. Otherwise, returns `nil'. The interactively callable objects include strings and vectors (treated as keyboard macros), lambda expressions that contain a top-level call to `interactive', compiled-function objects made from such lambda expressions, autoload objects that are declared as interactive (non-`nil' fourth argument to `autoload'), and some of the primitive functions. A symbol is `commandp' if its function definition is `commandp'. Keys and keymaps are not commands. Rather, they are used to look up commands (*note Keymaps::.). See `documentation' in *Note Accessing Documentation::, for a realistic example of using `commandp'. - Function: call-interactively COMMAND &optional RECORD-FLAG This function calls the interactively callable function COMMAND, reading arguments according to its interactive calling specifications. An error is signaled if COMMAND is not a function or if it cannot be called interactively (i.e., is not a command). Note that keyboard macros (strings and vectors) are not accepted, even though they are considered commands, because they are not functions. If RECORD-FLAG is the symbol `lambda', the interactive calling arguments for `command' are read and returned as a list, but the function is not called on them. If RECORD-FLAG is `t', then this command and its arguments are unconditionally added to the list `command-history'. Otherwise, the command is added only if it uses the minibuffer to read an argument. *Note Command History::. - Function: command-execute COMMAND &optional RECORD-FLAG This function executes COMMAND as an editing command. The argument COMMAND must satisfy the `commandp' predicate; i.e., it must be an interactively callable function or a keyboard macro. A string or vector as COMMAND is executed with `execute-kbd-macro'. A function is passed to `call-interactively', along with the optional RECORD-FLAG. A symbol is handled by using its function definition in its place. A symbol with an `autoload' definition counts as a command if it was declared to stand for an interactively callable function. Such a definition is handled by loading the specified library and then rechecking the definition of the symbol. - Command: execute-extended-command PREFIX-ARGUMENT This function reads a command name from the minibuffer using `completing-read' (*note Completion::.). Then it uses `command-execute' to call the specified command. Whatever that command returns becomes the value of `execute-extended-command'. If the command asks for a prefix argument, it receives the value PREFIX-ARGUMENT. If `execute-extended-command' is called interactively, the current raw prefix argument is used for PREFIX-ARGUMENT, and thus passed on to whatever command is run. `execute-extended-command' is the normal definition of `M-x', so it uses the string `M-x ' as a prompt. (It would be better to take the prompt from the events used to invoke `execute-extended-command', but that is painful to implement.) A description of the value of the prefix argument, if any, also becomes part of the prompt. (execute-extended-command 1) ---------- Buffer: Minibuffer ---------- 1 M-x forward-word RET ---------- Buffer: Minibuffer ---------- => t - Function: interactive-p This function returns `t' if the containing function (the one that called `interactive-p') was called interactively, with the function `call-interactively'. (It makes no difference whether `call-interactively' was called from Lisp or directly from the editor command loop.) If the containing function was called by Lisp evaluation (or with `apply' or `funcall'), then it was not called interactively. The most common use of `interactive-p' is for deciding whether to print an informative message. As a special exception, `interactive-p' returns `nil' whenever a keyboard macro is being run. This is to suppress the informative messages and speed execution of the macro. For example: (defun foo () (interactive) (and (interactive-p) (message "foo"))) => foo (defun bar () (interactive) (setq foobar (list (foo) (interactive-p)))) => bar ;; Type `M-x foo'. -| foo ;; Type `M-x bar'. ;; This does not print anything. foobar => (nil t) File: lispref.info, Node: Command Loop Info, Next: Events, Prev: Interactive Call, Up: Command Loop Information from the Command Loop ================================= The editor command loop sets several Lisp variables to keep status records for itself and for commands that are run. - Variable: last-command This variable records the name of the previous command executed by the command loop (the one before the current command). Normally the value is a symbol with a function definition, but this is not guaranteed. The value is copied from `this-command' when a command returns to the command loop, except when the command specifies a prefix argument for the following command. - Variable: this-command This variable records the name of the command now being executed by the editor command loop. Like `last-command', it is normally a symbol with a function definition. The command loop sets this variable just before running a command, and copies its value into `last-command' when the command finishes (unless the command specifies a prefix argument for the following command). Some commands set this variable during their execution, as a flag for whatever command runs next. In particular, the functions for killing text set `this-command' to `kill-region' so that any kill commands immediately following will know to append the killed text to the previous kill. If you do not want a particular command to be recognized as the previous command in the case where it got an error, you must code that command to prevent this. One way is to set `this-command' to `t' at the beginning of the command, and set `this-command' back to its proper value at the end, like this: (defun foo (args...) (interactive ...) (let ((old-this-command this-command)) (setq this-command t) ...do the work... (setq this-command old-this-command))) - Function: this-command-keys This function returns a vector containing the key and mouse events that invoked the present command, plus any previous commands that generated the prefix argument for this command. (Note: this is not the same as in FSF Emacs, which can return a string.) *Note Events::. This function copies the vector and the events; it is safe to keep and modify them. (this-command-keys) ;; Now use `C-u C-x C-e' to evaluate that. => [#<keypress-event control-U> #<keypress-event control-X> #<keypress-event control-E>] - Variable: last-command-event This variable is set to the last input event that was read by the command loop as part of a command. The principal use of this variable is in `self-insert-command', which uses it to decide which character to insert. This variable is off limits: you may not set its value or modify the event that is its value, as it is destructively modified by `read-key-sequence'. If you want to keep a pointer to this value, you must use `copy-event'. Note that this variable is an alias for `last-command-char' in FSF Emacs. last-command-event ;; Now type `C-u C-x C-e'. => #<keypress-event control-E> - Variable: last-command-char If the value of `last-command-event' is a keyboard event, then this is the nearest character equivalent to it (or `nil' if there is no character equivalent). `last-command-char' is the character that `self-insert-command' will insert in the buffer. Remember that there is *not* a one-to-one mapping between keyboard events and XEmacs characters: many keyboard events have no corresponding character, and when the Mule feature is available, most characters can not be input on standard keyboards, except possibly with help from an input method. So writing code that examines this variable to determine what key has been typed is bad practice, unless you are certain that it will be one of a small set of characters. This variable exists for compatibility with Emacs version 18. last-command-char ;; Now use `C-u C-x C-e' to evaluate that. => ?\^E - Variable: current-mouse-event This variable holds the mouse-button event which invoked this command, or `nil'. This is what `(interactive "e")' returns. - Variable: echo-keystrokes This variable determines how much time should elapse before command characters echo. Its value must be an integer, which specifies the number of seconds to wait before echoing. If the user types a prefix key (say `C-x') and then delays this many seconds before continuing, the key `C-x' is echoed in the echo area. Any subsequent characters in the same command will be echoed as well. If the value is zero, then command input is not echoed. File: lispref.info, Node: Events, Next: Reading Input, Prev: Command Loop Info, Up: Command Loop Events ====== The XEmacs command loop reads a sequence of "events" that represent keyboard or mouse activity. Unlike in Emacs 18 and in FSF Emacs, events are a primitive Lisp type that must be manipulated using their own accessor and settor primitives. This section describes the representation and meaning of input events in detail. A key sequence that starts with a mouse event is read using the keymaps of the buffer in the window that the mouse was in, not the current buffer. This does not imply that clicking in a window selects that window or its buffer--that is entirely under the control of the command binding of the key sequence. For information about how exactly the XEmacs command loop works, *Note Reading Input::. - Function: eventp OBJECT This function returns non-`nil' if EVENT is an input event. * Menu: * Event Types:: Events come in different types. * Event Contents:: What the contents of each event type are. * Event Predicates:: Querying whether an event is of a particular type. * Accessing Mouse Event Positions:: Determining where a mouse event occurred, and over what. * Accessing Other Event Info:: Accessing non-positional event info. * Working With Events:: Creating, copying, and destroying events. * Converting Events:: Converting between events, keys, and characters. File: lispref.info, Node: Event Types, Next: Event Contents, Up: Events Event Types ----------- Events represent keyboard or mouse activity or status changes of various sorts, such as process input being available or a timeout being triggered. The different event types are as follows: key-press event A key was pressed. Note that modifier keys such as "control", "shift", and "alt" do not generate events; instead, they are tracked internally by XEmacs, and non-modifier key presses generate events that specify both the key pressed and the modifiers that were held down at the time. button-press event button-release event A button was pressed or released. Along with the button that was pressed or released, button events specify the modifier keys that were held down at the time and the position of the pointer at the time. dnd-drop event Some dragged data was released. The event provides the button that was used to drag the data, the modifier keys that were hold down, the position where the drop took place, and a lisp object containing the type and the data dropped (Note: until now only the OffiX protocol supports dnd-drop). motion event The pointer was moved. Along with the position of the pointer, these events also specify the modifier keys that were held down at the time. misc-user event A menu item was selected, or the scrollbar was used. process event Input is available on a process. timeout event A timeout has triggered. magic event Some window-system-specific action (such as a frame being resized or a portion of a frame needing to be redrawn) has occurred. The contents of this event are not accessible at the E-Lisp level, but `dispatch-event' knows what to do with an event of this type. eval event This is a special kind of event specifying that a particular function needs to be called when this event is dispatched. An event of this type is sometimes placed in the event queue when a magic event is processed. This kind of event should generally just be passed off to `dispatch-event'. *Note Dispatching an Event::. File: lispref.info, Node: Event Contents, Next: Event Predicates, Prev: Event Types, Up: Events Contents of the Different Types of Events ----------------------------------------- Every event, no matter what type it is, contains a timestamp (which is typically an offset in milliseconds from when the X server was started) indicating when the event occurred. In addition, many events contain a "channel", which specifies which frame the event occurred on, and/or a value indicating which modifier keys (shift, control, etc.) were held down at the time of the event. The contents of each event are as follows: key-press event channel timestamp key Which key was pressed. This is an integer (in the printing ASCII range: >32 and <127) or a symbol such as `left' or `right'. Note that many physical keys are actually treated as two separate keys, depending on whether the shift key is pressed; for example, the "a" key is treated as either "a" or "A" depending on the state of the shift key, and the "1" key is similarly treated as either "1" or "!" on most keyboards. In such cases, the shift key does not show up in the modifier list. For other keys, such as `backspace', the shift key shows up as a regular modifier. modifiers Which modifier keys were pressed. As mentioned above, the shift key is not treated as a modifier for many keys and will not show up in this list in such cases. button-press event button-release event channel timestamp button What button went down or up. Buttons are numbered starting at 1. modifiers Which modifier keys were pressed. The special business mentioned above for the shift key does *not* apply to mouse events. x y The position of the pointer (in pixels) at the time of the event. dnd-drop event channel timestamp button What button was used to drag. Buttons are numbered starting at 1. modifiers Which modifier keys were pressed to do the drag. x y The position of the pointer (in pixels) at the time of the event. data A lisp object containing the dropped type and data. pointer-motion event channel timestamp x y The position of the pointer (in pixels) after it moved. modifiers Which modifier keys were pressed. The special business mentioned above for the shift key does *not* apply to mouse events. misc-user event timestamp function The E-Lisp function to call for this event. This is normally either `eval' or `call-interactively'. object The object to pass to the function. This is normally the callback that was specified in the menu description. process_event timestamp process The Emacs "process" object in question. timeout event timestamp function The E-Lisp function to call for this timeout. It is called with one argument, the event. object Some Lisp object associated with this timeout, to make it easier to tell them apart. The function and object for this event were specified when the timeout was set. magic event timestamp (The rest of the information in this event is not user-accessible.) eval event timestamp function An E-Lisp function to call when this event is dispatched. object The object to pass to the function. The function and object are set when the event is created. - Function: event-type EVENT Return the type of EVENT. This will be a symbol; one of `key-press' A key was pressed. `button-press' A mouse button was pressed. `button-release' A mouse button was released. `dnd-drop' A drop occured. `motion' The mouse moved. `misc-user' Some other user action happened; typically, this is a menu selection or scrollbar action. `process' Input is available from a subprocess. `timeout' A timeout has expired. `eval' This causes a specified action to occur when dispatched. `magic' Some window-system-specific event has occurred. File: lispref.info, Node: Event Predicates, Next: Accessing Mouse Event Positions, Prev: Event Contents, Up: Events Event Predicates ---------------- The following predicates return whether an object is an event of a particular type. - Function: key-press-event-p OBJECT This is true if OBJECT is a key-press event. - Function: button-event-p OBJECT OBJECT This is true if OBJECT is a mouse button-press or button-release event. - Function: button-press-event-p OBJECT This is true if OBJECT is a mouse button-press event. - Function: button-release-event-p OBJECT This is true if OBJECT is a mouse button-release event. - Function: dnd-drop-event-p OBJECT This is true if OBJECT is a mouse dnd-drop event. - Function: motion-event-p OBJECT This is true if OBJECT is a mouse motion event. - Function: mouse-event-p OBJECT This is true if OBJECT is a mouse button-press, button-release or motion event. - Function: eval-event-p OBJECT This is true if OBJECT is an eval event. - Function: misc-user-event-p OBJECT This is true if OBJECT is a misc-user event. - Function: process-event-p OBJECT This is true if OBJECT is a process event. - Function: timeout-event-p OBJECT This is true if OBJECT is a timeout event. - Function: event-live-p OBJECT This is true if OBJECT is any event that has not been deallocated. File: lispref.info, Node: Accessing Mouse Event Positions, Next: Accessing Other Event Info, Prev: Event Predicates, Up: Events Accessing the Position of a Mouse Event --------------------------------------- Unlike other events, mouse events (i.e. motion, button-press, button-release, and dnd-drop events) occur in a particular location on the screen. Many primitives are provided for determining exactly where the event occurred and what is under that location. * Menu: * Frame-Level Event Position Info:: * Window-Level Event Position Info:: * Event Text Position Info:: * Event Glyph Position Info:: * Event Toolbar Position Info:: * Other Event Position Info:: File: lispref.info, Node: Frame-Level Event Position Info, Next: Window-Level Event Position Info, Up: Accessing Mouse Event Positions Frame-Level Event Position Info ............................... The following functions return frame-level information about where a mouse event occurred. - Function: event-frame EVENT This function returns the "channel" or frame that the given mouse motion, button press, button release, or dnd drop event occurred in. This will be `nil' for non-mouse events. - Function: event-x-pixel EVENT This function returns the X position in pixels of the given mouse event. The value returned is relative to the frame the event occurred in. This will signal an error if the event is not a mouse event. - Function: event-y-pixel EVENT This function returns the Y position in pixels of the given mouse event. The value returned is relative to the frame the event occurred in. This will signal an error if the event is not a mouse event. File: lispref.info, Node: Window-Level Event Position Info, Next: Event Text Position Info, Prev: Frame-Level Event Position Info, Up: Accessing Mouse Event Positions Window-Level Event Position Info ................................ The following functions return window-level information about where a mouse event occurred. - Function: event-window EVENT Given a mouse motion, button press, button release, or dnd drop event, compute and return the window on which that event occurred. This may be `nil' if the event occurred in the border or over a toolbar. The modeline is considered to be within the window it describes. - Function: event-buffer EVENT Given a mouse motion, button press, button release, or dnd drop event, compute and return the buffer of the window on which that event occurred. This may be `nil' if the event occurred in the border or over a toolbar. The modeline is considered to be within the window it describes. This is equivalent to calling `event-window' and then calling `window-buffer' on the result if it is a window. - Function: event-window-x-pixel EVENT This function returns the X position in pixels of the given mouse event. The value returned is relative to the window the event occurred in. This will signal an error if the event is not a mouse-motion, button-press, button-release, or dnd-drop event. - Function: event-window-y-pixel EVENT This function returns the Y position in pixels of the given mouse event. The value returned is relative to the window the event occurred in. This will signal an error if the event is not a mouse-motion, button-press, or button-release event. File: lispref.info, Node: Event Text Position Info, Next: Event Glyph Position Info, Prev: Window-Level Event Position Info, Up: Accessing Mouse Event Positions Event Text Position Info ........................ The following functions return information about the text (including the modeline) that a mouse event occurred over or near. - Function: event-over-text-area-p EVENT Given a mouse-motion, button-press, button-release, or dnd-drop event, this function returns `t' if the event is over the text area of a window. Otherwise, `nil' is returned. The modeline is not considered to be part of the text area. - Function: event-over-modeline-p EVENT Given a mouse-motion, button-press, button-release, or dnd-drop event, this function returns `t' if the event is over the modeline of a window. Otherwise, `nil' is returned. - Function: event-x EVENT This function returns the X position of the given mouse-motion, button-press, button-release, or dnd-drop event in characters. This is relative to the window the event occurred over. - Function: event-y EVENT This function returns the Y position of the given mouse-motion, button-press, button-release, or dnd-drop event in characters. This is relative to the window the event occurred over. - Function: event-point EVENT This function returns the character position of the given mouse-motion, button-press, button-release, or dnd-drop event. If the event did not occur over a window, or did not occur over text, then this returns `nil'. Otherwise, it returns an index into the buffer visible in the event's window. - Function: event-closest-point EVENT This function returns the character position of the given mouse-motion, button-press, button-release, or dnd-drop event. If the event did not occur over a window or over text, it returns the closest point to the location of the event. If the Y pixel position overlaps a window and the X pixel position is to the left of that window, the closest point is the beginning of the line containing the Y position. If the Y pixel position overlaps a window and the X pixel position is to the right of that window, the closest point is the end of the line containing the Y position. If the Y pixel position is above a window, 0 is returned. If it is below a window, the value of `(window-end)' is returned. File: lispref.info, Node: Event Glyph Position Info, Next: Event Toolbar Position Info, Prev: Event Text Position Info, Up: Accessing Mouse Event Positions Event Glyph Position Info ......................... The following functions return information about the glyph (if any) that a mouse event occurred over. - Function: event-over-glyph-p EVENT Given a mouse-motion, button-press, button-release, or dnd-drop event, this function returns `t' if the event is over a glyph. Otherwise, `nil' is returned. - Function: event-glyph-extent EVENT If the given mouse-motion, button-press, button-release, or dnd-drop event happened on top of a glyph, this returns its extent; else `nil' is returned. - Function: event-glyph-x-pixel EVENT Given a mouse-motion, button-press, button-release, or dnd-drop event over a glyph, this function returns the X position of the pointer relative to the upper left of the glyph. If the event is not over a glyph, it returns `nil'. - Function: event-glyph-y-pixel EVENT Given a mouse-motion, button-press, button-release, or dnd-drop event over a glyph, this function returns the Y position of the pointer relative to the upper left of the glyph. If the event is not over a glyph, it returns `nil'. File: lispref.info, Node: Event Toolbar Position Info, Next: Other Event Position Info, Prev: Event Glyph Position Info, Up: Accessing Mouse Event Positions Event Toolbar Position Info ........................... - Function: event-over-toolbar-p EVENT Given a mouse-motion, button-press, button-release, or dnd-drop event, this function returns `t' if the event is over a toolbar. Otherwise, `nil' is returned. - Function: event-toolbar-button EVENT If the given mouse-motion, button-press, button-release, or dnd-drop event happened on top of a toolbar button, this function returns the button. Otherwise, `nil' is returned. File: lispref.info, Node: Other Event Position Info, Prev: Event Toolbar Position Info, Up: Accessing Mouse Event Positions Other Event Position Info ......................... - Function: event-over-border-p EVENT Given a mouse-motion, button-press, button-release, or dnd-drop event, this function returns `t' if the event is over an internal toolbar. Otherwise, `nil' is returned. File: lispref.info, Node: Accessing Other Event Info, Next: Working With Events, Prev: Accessing Mouse Event Positions, Up: Events Accessing the Other Contents of Events -------------------------------------- The following functions allow access to the contents of events other than the position info described in the previous section. - Function: event-timestamp EVENT This function returns the timestamp of the given event object. - Function: event-device EVENT This function returns the device that the given event occurred on. - Function: event-key EVENT This function returns the Keysym of the given key-press event. This will be the ASCII code of a printing character, or a symbol. - Function: event-button EVENT This function returns the button-number of the given button-press or button-release event. - Function: event-modifiers EVENT This function returns a list of symbols, the names of the modifier keys which were down when the given mouse or keyboard event was produced. - Function: event-modifier-bits EVENT This function returns a number representing the modifier keys which were down when the given mouse or keyboard event was produced. - Function: event-function EVENT This function returns the callback function of the given timeout, misc-user, or eval event. - Function: event-object EVENT This function returns the callback function argument of the given timeout, misc-user, or eval event. - Function: event-process EVENT This function returns the process of the given process event. - Function: event-drag-and-drop-data EVENT This function returns a list containing the type of the drop as first element and the data of the drop as second element. File: lispref.info, Node: Working With Events, Next: Converting Events, Prev: Accessing Other Event Info, Up: Events Working With Events ------------------- XEmacs provides primitives for creating, copying, and destroying event objects. Many functions that return events take an event object as an argument and fill in the fields of this event; or they make accept either an event object or `nil', creating the event object first in the latter case. - Function: allocate-event This function returns an empty event structure. WARNING: The event object returned may be a reused one; see the function `deallocate-event'. - Function: copy-event EVENT1 &optional EVENT2 This function makes a copy of the given event object. If a second argument is given, the first event is copied into the second and the second is returned. If the second argument is not supplied (or is `nil') then a new event will be made as with `allocate-event'. - Function: deallocate-event EVENT This function allows the given event structure to be reused. You *MUST NOT* use this event object after calling this function with it. You will lose. It is not necessary to call this function, as event objects are garbage-collected like all other objects; however, it may be more efficient to explicitly deallocate events when you are sure that that is safe. File: lispref.info, Node: Converting Events, Prev: Working With Events, Up: Events Converting Events ----------------- XEmacs provides some auxiliary functions for converting between events and other ways of representing keys. These are useful when working with ASCII strings and with keymaps. - Function: character-to-event CH &optional EVENT DEVICE This function converts a numeric ASCII value to an event structure, replete with modifier bits. CH is the character to convert, and EVENT is the event object to fill in. This function contains knowledge about what the codes "mean" - for example, the number 9 is converted to the character <Tab>, not the distinct character <Control-I>. Note that CH does not have to be a numeric value, but can be a symbol such as `clear' or a list such as `(control backspace)'. If `event' is not `nil', it is modified; otherwise, a new event object is created. In both cases, the event is returned. Optional third arg DEVICE is the device to store in the event; this also affects whether the high bit is interpreted as a meta key. A value of `nil' means use the selected device but always treat the high bit as meta. Beware that `character-to-event' and `event-to-character' are not strictly inverse functions, since events contain much more information than the ASCII character set can encode. - Function: event-to-character EVENT &optional ALLOW-EXTRA-MODIFIERS ALLOW-META ALLOW-NON-ASCII This function returns the closest ASCII approximation to EVENT. If the event isn't a keypress, this returns `nil'. If ALLOW-EXTRA-MODIFIERS is non-`nil', then this is lenient in its translation; it will ignore modifier keys other than <control> and <meta>, and will ignore the <shift> modifier on those characters which have no shifted ASCII equivalent (<Control-Shift-A> for example, will be mapped to the same ASCII code as <Control-A>). If ALLOW-META is non-`nil', then the <Meta> modifier will be represented by turning on the high bit of the byte returned; otherwise, `nil' will be returned for events containing the <Meta> modifier. If ALLOW-NON-ASCII is non-`nil', then characters which are present in the prevailing character set (*note variable `character-set-property': Keymaps.) will be returned as their code in that character set, instead of the return value being restricted to ASCII. Note that specifying both ALLOW-META and ALLOW-NON-ASCII is ambiguous, as both use the high bit; <M-x> and <oslash> will be indistinguishable. - Function: events-to-keys EVENTS &optional NO-MICE Given a vector of event objects, this function returns a vector of key descriptors, or a string (if they all fit in the ASCII range). Optional arg NO-MICE means that button events are not allowed. File: lispref.info, Node: Reading Input, Next: Waiting, Prev: Events, Up: Command Loop Reading Input ============= The editor command loop reads keyboard input using the function `next-event' and constructs key sequences out of the events using `dispatch-event'. Lisp programs can also use the function `read-key-sequence', which reads input a key sequence at a time. See also `momentary-string-display' in *Note Temporary Displays::, and `sit-for' in *Note Waiting::. *Note Terminal Input::, for functions and variables for controlling terminal input modes and debugging terminal input. For higher-level input facilities, see *Note Minibuffers::. * Menu: * Key Sequence Input:: How to read one key sequence. * Reading One Event:: How to read just one event. * Dispatching an Event:: What to do with an event once it has been read. * Quoted Character Input:: Asking the user to specify a character. * Peeking and Discarding:: How to reread or throw away input events. File: lispref.info, Node: Key Sequence Input, Next: Reading One Event, Up: Reading Input Key Sequence Input ------------------ Lisp programs can read input a key sequence at a time by calling `read-key-sequence'; for example, `describe-key' uses it to read the key to describe. - Function: read-key-sequence PROMPT This function reads a sequence of keystrokes or mouse clicks and returns it as a vector of events. It keeps reading events until it has accumulated a full key sequence; that is, enough to specify a non-prefix command using the currently active keymaps. The vector and the event objects it contains are freshly created, and will not be side-effected by subsequent calls to this function. The function `read-key-sequence' suppresses quitting: `C-g' typed while reading with this function works like any other character, and does not set `quit-flag'. *Note Quitting::. The argument PROMPT is either a string to be displayed in the echo area as a prompt, or `nil', meaning not to display a prompt. If the user selects a menu item while we are prompting for a key sequence, the returned value will be a vector of a single menu-selection event (a misc-user event). An error will be signalled if you pass this value to `lookup-key' or a related function. In the example below, the prompt `?' is displayed in the echo area, and the user types `C-x C-f'. (read-key-sequence "?") ---------- Echo Area ---------- ?C-x C-f ---------- Echo Area ---------- => [#<keypress-event control-X> #<keypress-event control-F>] If an input character is an upper-case letter and has no key binding, but its lower-case equivalent has one, then `read-key-sequence' converts the character to lower case. Note that `lookup-key' does not perform case conversion in this way.