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This is Info file ../../info/lispref.info, produced by Makeinfo-1.63 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 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc. Copyright (C) 1994, 1995 Sun Microsystems, Inc. Copyright (C) 1995 Amdahl Corporation. Copyright (C) 1995 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: Glyph Properties, Next: Glyph Convenience Functions, Prev: Creating Glyphs, Up: Glyph Functions Glyph Properties ---------------- The following symbols have predefined meanings: `image' The image used to display the glyph. `baseline' Percent above baseline that glyph is to be displayed. `contrib-p' Whether the glyph contributes to the height of the line it's on. `face' Face of this glyph (*not* a specifier). - Function: set-glyph-property GLYPH PROPERTY VALUE &optional LOCALE TAG-SET HOW-TO-ADD This function changes a property of a GLYPH. For built-in properties, the actual value of the property is a specifier and you cannot change this; but you can change the specifications within the specifier, and that is what this function will do. For user-defined properties, you can use this function to either change the actual value of the property or, if this value is a specifier, change the specifications within it. If PROPERTY is a built-in property, the specifications to be added to this property can be supplied in many different ways: If VALUE is a simple instantiator (e.g. a string naming a pixmap filename) or a list of instantiators, then the instantiator(s) will be added as a specification of the property for the given LOCALE (which defaults to `global' if omitted). If VALUE is a list of specifications (each of which is a cons of a locale and a list of instantiators), then LOCALE must be `nil' (it does not make sense to explicitly specify a locale in this case), and specifications will be added as given. If VALUE is a specifier (as would be returned by `glyph-property' if no LOCALE argument is given), then some or all of the specifications in the specifier will be added to the property. In this case, the function is really equivalent to `copy-specifier' and LOCALE has the same semantics (if it is a particular locale, the specification for the locale will be copied; if a locale type, specifications for all locales of that type will be copied; if `nil' or `all', then all specifications will be copied). HOW-TO-ADD should be either `nil' or one of the symbols `prepend', `append', `remove-tag-set-prepend', `remove-tag-set-append', `remove-locale', `remove-locale-type', or `remove-all'. See `copy-specifier' and `add-spec-to-specifier' for a description of what each of these means. Most of the time, you do not need to worry about this argument; the default behavior usually is fine. In general, it is OK to pass an instance object (e.g. as returned by `glyph-property-instance') as an instantiator in place of an actual instantiator. In such a case, the instantiator used to create that instance object will be used (for example, if you set a font-instance object as the value of the `font' property, then the font name used to create that object will be used instead). If some cases, however, doing this conversion does not make sense, and this will be noted in the documentation for particular types of instance objects. If PROPERTY is not a built-in property, then this function will simply set its value if LOCALE is `nil'. However, if LOCALE is given, then this function will attempt to add VALUE as the instantiator for the given LOCALE, using `add-spec-to-specifier'. If the value of the property is not a specifier, it will automatically be converted into a `generic' specifier. - Function: glyph-property GLYPH PROPERTY &optional LOCALE This function returns GLYPH's value of the given PROPERTY. If LOCALE is omitted, the GLYPH's actual value for PROPERTY will be returned. For built-in properties, this will be a specifier object of a type appropriate to the property (e.g. a font or color specifier). For other properties, this could be anything. If LOCALE is supplied, then instead of returning the actual value, the specification(s) for the given locale or locale type will be returned. This will only work if the actual value of PROPERTY is a specifier (this will always be the case for built-in properties, but not or not may apply to user-defined properties). If the actual value of PROPERTY is not a specifier, this value will simply be returned regardless of LOCALE. The return value will be a list of instantiators (e.g. vectors specifying pixmap data), or a list of specifications, each of which is a cons of a locale and a list of instantiators. Specifically, if LOCALE is a particular locale (a buffer, window, frame, device, or `global'), a list of instantiators for that locale will be returned. Otherwise, if LOCALE is a locale type (one of the symbols `buffer', `window', `frame', or `device'), the specifications for all locales of that type will be returned. Finally, if LOCALE is `all', the specifications for all locales of all types will be returned. The specifications in a specifier determine what the value of PROPERTY will be in a particular "domain" or set of circumstances, which is typically a particular Emacs window along with the buffer it contains and the frame and device it lies within. The value is derived from the instantiator associated with the most specific locale (in the order buffer, window, frame, device, and `global') that matches the domain in question. In other words, given a domain (i.e. an Emacs window, usually), the specifier for PROPERTY will first be searched for a specification whose locale is the buffer contained within that window; then for a specification whose locale is the window itself; then for a specification whose locale is the frame that the window is contained within; etc. The first instantiator that is valid for the domain (usually this means that the instantiator is recognized by the device [i.e. the X server or TTY device] that the domain is on). The function `glyph-property-instance' actually does all this, and is used to determine how to display the glyph. - Function: glyph-property-instance GLYPH PROPERTY &optional DOMAIN DEFAULT NO-FALLBACK This function returns the instance of GLYPH's PROPERTY in the specified DOMAIN. Under most circumstances, DOMAIN will be a particular window, and the returned instance describes how the specified property actually is displayed for that window and the particular buffer in it. Note that this may not be the same as how the property appears when the buffer is displayed in a different window or frame, or how the property appears in the same window if you switch to another buffer in that window; and in those cases, the returned instance would be different. The returned instance will typically be an image-instance object or a string (*this is slated to change in 19.13*), and you can query it using the appropriate object-specific functions. For example, you could use `image-instance-depth' to find out the depth (number of color planes) of a pixmap displayed in a particular window. The results might be different from the results you would get for another window (perhaps the user specified a different image for the frame that window is on; or perhaps the same image was specified but the window is on a different X server, and that X server has different color capabilities from this one). DOMAIN defaults to the selected window if omitted. DOMAIN can be a frame or device, instead of a window. The value returned for a such a domain is used in special circumstances when a more specific domain does not apply; for example, a frame value might be used for coloring a toolbar, which is conceptually attached to a frame rather than a particular window. The value is also useful in determining what the value would be for a particular window within the frame or device, if it is not overridden by a more specific specification. If PROPERTY does not name a built-in property, its value will simply be returned unless it is a specifier object, in which case it will be instanced using `specifier-instance'. Optional arguments DEFAULT and NO-FALLBACK are the same as in `specifier-instance'. *Note Specifiers::. File: lispref.info, Node: Glyph Convenience Functions, Prev: Glyph Properties, Up: Glyph Functions Glyph Convenience Functions --------------------------- - Function: glyph-image GLYPH &optional LOCALE - Function: set-glyph-image GLYPH SPEC &optional LOCALE TAG-SET HOW-TO-ADD - Function: glyph-image-instance GLYPH &optional DOMAIN DEFAULT NO-FALLBACK - Function: glyph-contrib-p GLYPH &optional LOCALE This function returns whether GLYPH contributes to its line height. GLYPH and LOCALE are as in `glyph-property'. - Function: set-glyph-contrib-p GLYPH SPEC &optional LOCALE TAG-SET HOW-TO-ADD - Function: glyph-contrib-p-instance GLYPH &optional DOMAIN DEFAULT NO-FALLBACK - Function: glyph-baseline GLYPH &optional LOCALE - Function: set-glyph-baseline GLYPH SPEC &optional LOCALE TAG-SET HOW-TO-ADD - Function: glyph-baseline-instance GLYPH &optional DOMAIN DEFAULT NO-FALLBACK File: lispref.info, Node: Images, Next: Cursors, Prev: Glyph Functions, Up: Glyphs Images ====== * Menu: * Image Specifiers:: Specifying how an image will appear. * Image Instantiator Conversion:: Conversion is applied to image instantiators at the time they are added to an image specifier or at the time they are passed to `make-image-instance'. * Image Instances:: What an image specifier gets instanced as. File: lispref.info, Node: Image Specifiers, Next: Image Instantiator Conversion, Up: Images Image Specifiers ---------------- An image specifier is used for images (pixmaps and the like). It is used to describe the actual image in a glyph. It is instanced as an image-instance. An image instantiator should be a string or a vector of the form `[TYPE :KEYWORD VALUE ...]' i.e. a type symbol followed by zero or more alternating keyword-value pairs. TYPE should be one of `nothing' (Don't display anything; no keywords are valid for this.) `string' (Display this image as a text string.) `formatted-string' (Display this image as a text string, with replaceable fields; #### not implemented in 19.13.) `xbm' (An X bitmap; only if X support was compiled into this XEmacs.) `xpm' (An XPM pixmap; only if XPM support was compiled into this XEmacs.) `xface' (An X-Face bitmap, used to encode people's faces in e-mail messages; only if X-Face support was compiled into this XEmacs.) `autodetect' (XEmacs tries to guess what format the data is in. If X support exists, the data string will be checked to see if it names a filename. If so, and this filename contains XBM or XPM data, the appropriate sort of pixmap will be created. Otherwise, the image will be displayed as a string. If no X support exists, the image will always be displayed as a string.) The valid keywords are: `:data' (Inline data. For most formats above, this should be a string. For XBM images, this should be a cons of three elements: width, height, and a string of bit data.) `:file' (Data is contained in a file. The value is the name of this file. If both `:data' and `:file' are specified, the image is created from what is specified in `:data' and the string in `:file' becomes the value of the `image-instance-file-name' function when applied to the resulting image-instance.) `:mask-data' (Only for XBM images. This specifies a mask to be used with the bitmap. The format is a cons of width, height, and bits, like for `:data'.) `:mask-file' (Only for XBM images. This specifies a file containing the mask data.) `:color-symbols' (Only for XPM images. This specifies an alist that maps strings that specify symbolic color names to the actual color to be used for that symbolic color (in the form of a string or a color-specifier object). If this is not specified, the contents of `xpm-color-symbols' are used to generate the alist.) If instead of a vector, the instantiator is a string, it will be looked up according to the specs in the `device-type-image-conversion-list' for the device type of the domain over which the image is being instantiated. If the instantiator is a string, it will be read in at the time that the instantiator is added to the image, and the instantiator will be converted into one of the `[FILENAME ...]' forms. This implies that the file must exist when the instantiator is added to the image, but does not need to exist at any other time (e.g. it may be a temporary file). - Function: image-specifier-p OBJECT This function returns non-`nil' if OBJECT is an image specifier. - Variable: xpm-color-symbols This variable holds definitions of logical color-names used when reading XPM files. Elements of this list should be of the form `(COLOR-NAME FORM-TO-EVALUATE)'. The COLOR-NAME should be a string, which is the name of the color to define; the FORM-TO-EVALUATE should evaluate to a color specifier object, or a string to be passed to `make-color-instance' (*note Colors::.). If a loaded XPM file references a symbolic color called COLOR-NAME, it will display as the computed color instead. The default value of this variable defines the logical color names `"foreground"' and `"background"' to be the colors of the `default' face. - Variable: x-bitmap-file-path A list of the directories in which X bitmap files may be found. If nil, this is initialized from the `"*bitmapFilePath"' resource. This is used by the `make-image-instance' function (however, note that if the environment variable `XBMLANGPATH' is set, it is consulted first). File: lispref.info, Node: Image Instantiator Conversion, Next: Image Instances, Prev: Image Specifiers, Up: Images Image Instantiator Conversion ----------------------------- - Function: set-device-type-image-conversion-list DEVICE-TYPE LIST This function sets the image-conversion-list for devices of the given DEVICE-TYPE. The image-conversion-list specifies how image instantiators that are strings should be interpreted. Each element of the list should be a list of two elements (a regular expression string and a vector) or a list of three elements (the preceding two plus an integer index into the vector). The string is converted to the vector associated with the first matching regular expression. If a vector index is specified, the string itself is substituted into that position in the vector. Note: The conversion above is applied when the image instantiator is added to an image specifier, not when the specifier is actually instantiated. Therefore, changing the image-conversion-list only affects newly-added instantiators. Existing instantiators in glyphs and image specifiers will not be affected. - Function: device-type-image-conversion-list DEVICE-TYPE This function returns the image-conversion-list for devices of the given DEVICE-TYPE. File: lispref.info, Node: Image Instances, Prev: Image Instantiator Conversion, Up: Images Image Instances --------------- Image-instance objects encapsulate the way a particular image (pixmap, etc.) is displayed on a particular device. In most circumstances, you do not need to directly create image instances; use a glyph or an image- specifier instead. (Most functions and data structures that want an image are designed to take either a glyph or an image-specifier.) - Function: image-instance-p OBJECT This function returns non-`nil' if OBJECT is an image instance. - Function: make-image-instance DATA &optional DEVICE FORCE-MONO NOERROR This function creates a new image-instance object. - Function: colorize-image-instance IMAGE-INSTANCE FOREGROUND BACKGROUND This function makes the image instance be displayed in the given colors. Image instances come in two varieties: bitmaps, which are 1 bit deep which are rendered in the prevailing foreground and background colors; and pixmaps, which are of arbitrary depth (including 1) and which have the colors explicitly specified. This function converts a bitmap to a pixmap. If the image instance was a pixmap already, nothing is done (and `nil' is returned). Otherwise `t' is returned. - Function: image-instance-depth IMAGE-INSTANCE This function returns the depth of the image instance. This is 0 for a bitmap, or a positive integer for a pixmap. - Function: image-instance-file-name IMAGE-INSTANCE This function returns the file name from which the given image instance was read, or `nil' if the image instance was created from Lisp data (the lisp data is not retained, since it usually won't be needed again and might be quite large). - Function: image-instance-height IMAGE-INSTANCE This function returns the height of the image instance, in pixels. - Function: image-instance-width IMAGE-INSTANCE This function returns the width of the image instance, in pixels. - Function: set-image-instance-hotspot IMAGE-INSTANCE X Y This function sets the image instance's hotspot. This is a point relative to the origin of the pixmap. When a pixmap is used as a cursor or similar pointing indicator, the hotspot is the point on the pixmap that sits over the location that the pointer points to. This is, for example, the tip of the arrow or the center of the crosshairs. - Function: image-instance-hotspot-x IMAGE-INSTANCE This function returns the X coordinate of the image instance's hotspot. - Function: image-instance-hotspot-y IMAGE-INSTANCE This function returns the Y coordinate of the image instance's hotspot. File: lispref.info, Node: Cursors, Prev: Images, Up: Glyphs Cursors ======= Cursors are scheduled to be overhauled in 19.13. Watch this space for more info. File: lispref.info, Node: Annotations, Next: Display, Prev: Glyphs, Up: Top Annotations *********** An "annotation" is a pixmap or string that is not part of a buffer's text but is displayed next to a particular location in a buffer. Annotations are implemented using extents (*note Extents::.); but you can work with annotations without knowing how extents work. * Menu: * Annotation Basics:: * Annotation Primitives:: * Margin Primitives:: * Annotation Hooks:: File: lispref.info, Node: Annotation Basics, Next: Annotation Primitives, Up: Annotations Annotation Basics ================= Marginal annotations are notes associated with a particular location in a buffer. They may be displayed in a margin created on the left-hand side of the frame, in any whitespace at the beginning of a line, or inside of the text itself. Every annotation may have an associated action to be performed when the annotation is selected. The term "annotation" is used to refer to an individual note. The term "margin" is generically used to refer to the whitespace before the first character on a line. `annotation' Each annotation has the following characteristics: GLYPH This may be either a bitmap/pixmap object or a string. FACE The face with which to display the glyph. ACTION If non-nil this field must contain a function capable of being the first argument to `funcall'. This function is evaluated with a single argument, the value of the DATA field, each time the annotation is selected. DATA Not used internally. This field can contain any Elisp object. It is passed as the lone argument to ACTION described above. TYPE Valid types are: `bitmap', `pixmap' and `string'. The margin is divided into "outside" and "inside". The outside margin is space on the left side of the frame which normal text cannot be displayed in. The inside margin is that space between the leftmost point text can be displayed and where the first character actually is. There are four different "layout types" which affect the exact location an annotation appears. `outside-margin' The annotation is placed, left-justified, into the outside margin area. If the outside margin is not wide enough for an annotation to fit it is not displayed. `inside-margin' The annotation is placed, left-justified, into the inside margin area. If the inside margin is not wide enough for the annotation to fit it will be displayed using any available outside margin space if and only if the variable `use-left-overflow' is non-`nil'. `whitespace' The annotation is placed, right-justified, into the inside margin area. This puts the annotation as close as possible to the first non-whitespace character on a line. If the inside margin is not wide enough for the annotation to fit it will be displayed if and only if the variable `use-left-overflow' is non-`nil'. `text' The annotation is placed at the position it is inserted. It will create enough space for itself inside of the text area. It does not take up a place in the logical buffer, only in the display of the buffer. The current layout policy is that all `whitespace' annotations are displayed first. Next, all `inside-margin' annotations are displayed using any remaining space. Finally as many `outside-margin' annotations are displayed as possible. The `text' annotations will always display as they create their own space to display in. File: lispref.info, Node: Annotation Primitives, Next: Margin Primitives, Prev: Annotation Basics, Up: Annotations Annotation Primitives ===================== - Function: make-annotation GLYPH &optional POSITION LAYOUT BUFFER Create a marginal annotation with GLYPH, which may be a bitmap/pixmap or a string at position POS. Use layout policy LAYOUT and place the annotation in buffer BUFFER. If POS is `nil', point is used. If LAYOUT is `nil', `whitespace' is used. If BUFFER is `nil', the current buffer is used. Returns the newly created annotation. - Function: delete-annotation ANNOTATION Remove ANNOTATION from its buffer. This does not modify the buffer text. Returns the annotation deleted. - Function: annotationp ANNOTATION Return `t' if ANNOTATION is an annotation, `nil' otherwise. - Function: annotation-visible ANNOTATION Return `t' if there is enough available space to display ANNOTATION, `nil' otherwise. - Function: annotation-at &optional POSITION BUFFER Return the annotation at POSITION in BUFFER. If POSITION is `nil' point is used. If BUFFER is `nil' the current buffer is used. - Function: annotation-layout ANNOTATION Return the layout policy of ANNOTATION. - Function: set-annotation-layout ANNOTATION LAYOUT Set the layout policy of ANNOTATION to LAYOUT. - Function: annotation-type ANNOTATION Returns the display type of ANNOTATION. The type will be one of following symbols: `' pixmap `' bitmap `' string `' nil (object is not an annotation) - Function: annotation-width ANNOTATION Return the width of ANNOTATION in pixels. - Function: annotation-glyph ANNOTATION If ANNOTATION is of type `string' return the string. Otherwise return the bitmap or pixmap object of the glyph representing ANNOTATION. - Function: set-annotation-glyph ANNOTATION GLYPH &optional LAYOUT Set the glyph image of ANNOTATION to GLYPH. If LAYOUT is non-`nil' set the layout policy of ANNOTATION to LAYOUT. Returns the new value of `annotation-glyph'. - Function: annotation-data ANNOTATION Return the data associated with ANNOTATION. - Function: set-annotation-data ANNOTATION DATA Set the data field of ANNOTATION to DATA. Returns DATA. - Function: annotation-action ANNOTATION Return the action associated with ANNOTATION. - Function: set-annotation-action ANNOTATION ACTION Set the action field of ANNOTATION to ACTION. Returns ACTION. - Function: annotation-face ANNOTATION Return the face associated with ANNOTATION. - Function: set-annotation-face ANNOTATION FACE Set the face associated with ANNOTATION to FACE. - Function: annotations-in-region START END BUFFER Return a list of all annotations in BUFFER which are between START and END inclusively. - Function: annotation-at &optional POSITION BUFFER Return a list of all annotations at POSITION in BUFFER. If POSITION is `nil' point is used. If BUFFER is `nil' the current buffer is used. - Function: annotation-list &optional BUFFER Returns a list of all annotations in BUFFER. If BUFFER is `nil', the current buffer is used. - Function: all-annotations Returns a list of all annotations in all buffers in existence. File: lispref.info, Node: Margin Primitives, Next: Annotation Hooks, Prev: Annotation Primitives, Up: Annotations Margin Primitives ================= It is possible to set values for both a left and a right hand side margin. Only the left side has been implemented. All margin settings are buffer-local at the moment. - Function: set-buffer-left-margin-width WIDTH &optional BUFFER Set the width, in characters, of the left outside margin of BUFFER to WIDTH. If BUFFER is `nil', the current buffer is used. Returns the new width. - Function: set-buffer-right-margin-width WIDTH &optional BUFFER Set the width, in characters, of the right outside margin of BUFFER to WIDTH. If BUFFER is `nil', the current buffer is used. Returns the new width. - Function: buffer-left-margin-width &optional BUFFER Return the width of the left outside margin, in characters, of BUFFER. If BUFFER is `nil', the current buffer is used. - Function: buffer-right-margin-width &optional BUFFER Return the width of the right outside margin, in characters, of BUFFER. If BUFFER is `nil', the current buffer is used. - Function: buffer-left-margin-pixwidth &optional BUFFER Return the width of the left outside margin, in pixels, of BUFFER. If BUFFER is `nil', the current buffer is used. - Function: buffer-right-margin-pixwidth &optional BUFFER Return the width of the right outside margin, in pixels, of BUFFER. If BUFFER is `nil', the current buffer is used. - Variable: use-left-overflow If non-`nil' use the left outside margin as extra whitespace when displaying `whitespace' and `inside-margin' annotations. Defaults to `nil'. The margin colors are controlled by the faces `left-margin' and `right-margin'. These can be set using the X resources `Emacs*left-margin*background' and `Emacs*left-margin*foreground'. Likewise for the right margin. File: lispref.info, Node: Annotation Hooks, Prev: Margin Primitives, Up: Annotations Annotation Hooks ================ The following three hooks are provided for use with the marginal annotations: *`before-delete-annotation-hook'* This hook is called immediately before an annotation is destroyed. It is passed a single argument, the annotation being destroyed. *`after-delete-annotation-hook'* This hook is called immediately after an annotation is destroyed. It may contain any number of functions to run. No arguments are passed to any of the functions on the hook. *`make-annotation-hook'* This hook is called immediately after an annotation is created. It is passed a single argument, the newly created annotation. File: lispref.info, Node: Display, Next: Processes, Prev: Annotations, Up: Top Emacs Display ************* This chapter describes a number of other features related to the display that XEmacs presents to the user. * Menu: * Refresh Screen:: Clearing the screen and redrawing everything on it. * Truncation:: Folding or wrapping long text lines. * The Echo Area:: Where messages are displayed. * Invisible Text:: Hiding part of the buffer text. * Selective Display:: Hiding part of the buffer text (the old way). * Overlay Arrow:: Display of an arrow to indicate position. * Temporary Displays:: Displays that go away automatically. * Blinking:: How XEmacs shows the matching open parenthesis. * Usual Display:: The usual conventions for displaying nonprinting chars. * Display Tables:: How to specify other conventions. * Beeping:: Audible signal to the user. File: lispref.info, Node: Refresh Screen, Next: Truncation, Up: Display Refreshing the Screen ===================== The function `redraw-frame' redisplays the entire contents of a given frame. *Note Frames::. - Function: redraw-frame FRAME This function clears and redisplays frame FRAME. Even more powerful is `redraw-display': - Command: redraw-display &optional DEVICE This function redraws all frames on DEVICE marked as having their image garbled. DEVICE defaults to the selected device. If DEVICE is `t', all devices will have their frames checked. Processing user input takes absolute priority over redisplay. If you call these functions when input is available, they do nothing immediately, but a full redisplay does happen eventually--after all the input has been processed. Normally, suspending and resuming XEmacs also refreshes the screen. Some terminal emulators record separate contents for display-oriented programs such as XEmacs and for ordinary sequential display. If you are using such a terminal, you might want to inhibit the redisplay on resumption. *Note Suspending XEmacs::. - Variable: no-redraw-on-reenter This variable controls whether XEmacs redraws the entire screen after it has been suspended and resumed. Non-`nil' means yes, `nil' means no. The above functions do not actually cause the display to be updated; rather, they clear out the internal display records that XEmacs maintains, so that the next time the display is updated it will be redrawn from scratch. Normally this occurs the next time that `next-event' or `sit-for' is called; however, a display update will not occur if there is input pending. *Note Command Loop::. - Command: force-redisplay This function causes an immediate update of the display in all circumstances, whether or not input is pending. (This function does not exist in FSF Emacs.) - Function: force-cursor-redisplay This function causes an immediate update of the cursor on the selected frame. (This function does not exist in FSF Emacs.) File: lispref.info, Node: Truncation, Next: The Echo Area, Prev: Refresh Screen, Up: Display Truncation ========== When a line of text extends beyond the right edge of a window, the line can either be truncated or continued on the next line. When a line is truncated, this is normally shown with a `\' in the rightmost column of the window on X displays, and with a `$' on TTY devices. When a line is continued or "wrapped" onto the next line, this is shown with a curved arrow in the rightmost column of the window (or with a `\' on TTY devices). The additional screen lines used to display a long text line are called "continuation" lines. Normally, whenever line truncation is in effect for a particular window, a horizontal scrollbar is displayed in that window if the device supports scrollbars. *Note Scrollbars::. Note that continuation is different from filling; continuation happens on the screen only, not in the buffer contents, and it breaks a line precisely at the right margin, not at a word boundary. *Note Filling::. - User Option: truncate-lines This buffer-local variable controls how XEmacs displays lines that extend beyond the right edge of the window. If it is non-`nil', then XEmacs does not display continuation lines; rather each line of text occupies exactly one screen line, and a backslash appears at the edge of any line that extends to or beyond the edge of the window. The default is `nil'. If the variable `truncate-partial-width-windows' is non-`nil', then truncation is always used for side-by-side windows (within one frame) regardless of the value of `truncate-lines'. - User Option: default-truncate-lines This variable is the default value for `truncate-lines', for buffers that do not have local values for it. - User Option: truncate-partial-width-windows This variable controls display of lines that extend beyond the right edge of the window, in side-by-side windows (*note Splitting Windows::.). If it is non-`nil', these lines are truncated; otherwise, `truncate-lines' says what to do with them. The backslash and curved arrow used to indicate truncated or continued lines are only defaults, and can be changed. These images are actually glyphs (*note Glyphs::.). XEmacs provides a great deal of flexibility in how glyphs can be controlled. (This differs from FSF Emacs, which uses display tables to control these images.) - Variable: truncation-glyph This variable holds the glyph that is displayed at the end of truncated lines. - Variable: continuation-glyph This variable holds the glyphs that is displayed at the end of wrapped lines. File: lispref.info, Node: The Echo Area, Next: Invisible Text, Prev: Truncation, Up: Display The Echo Area ============= The "echo area" is used for displaying messages made with the `message' primitive, and for echoing keystrokes. It is not the same as the minibuffer, despite the fact that the minibuffer appears (when active) in the same place on the screen as the echo area. The `XEmacs Reference Manual' specifies the rules for resolving conflicts between the echo area and the minibuffer for use of that screen space (*note The Minibuffer: (emacs)Minibuffer.). Error messages appear in the echo area; see *Note Errors::. You can write output in the echo area by using the Lisp printing functions with `t' as the stream (*note Output Functions::.), or as follows: - Function: message STRING &rest ARGUMENTS This function displays a one-line message in the echo area. The argument STRING is similar to a C language `printf' control string. See `format' in *Note String Conversion::, for the details on the conversion specifications. `message' returns the constructed string. In batch mode, `message' prints the message text on the standard error stream, followed by a newline. If STRING is `nil', `message' clears the echo area. If the minibuffer is active, this brings the minibuffer contents back onto the screen immediately. (message "Minibuffer depth is %d." (minibuffer-depth)) -| Minibuffer depth is 0. => "Minibuffer depth is 0." ---------- Echo Area ---------- Minibuffer depth is 0. ---------- Echo Area ---------- Almost all the messages displayed in the echo area are also recorded in the `*Messages*' buffer. - User Option: message-log-max This variable specifies how many lines to keep in the `*Messages*' buffer. The value `t' means there is no limit on how many lines to keep. The value `nil' disables message logging entirely. Here's how to display a message and prevent it from being logged: (let (message-log-max) (message ...)) - 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 (such as `C-x') and then delays this many seconds before continuing, the prefix key 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. - Variable: cursor-in-echo-area This variable controls where the cursor appears when a message is displayed in the echo area. If it is non-`nil', then the cursor appears at the end of the message. Otherwise, the cursor appears at point--not in the echo area at all. The value is normally `nil'; Lisp programs bind it to `t' for brief periods of time. File: lispref.info, Node: Invisible Text, Next: Selective Display, Prev: The Echo Area, Up: Display Invisible Text ============== You can make characters "invisible", so that they do not appear on the screen, with the `invisible' property. This can be either a text property or a property of an overlay. In the simplest case, any non-`nil' `invisible' property makes a character invisible. This is the default case--if you don't alter the default value of `buffer-invisibility-spec', this is how the `invisibility' property works. This feature is much like selective display (*note Selective Display::.), but more general and cleaner. More generally, you can use the variable `buffer-invisibility-spec' to control which values of the `invisible' property make text invisible. This permits you to classify the text into different subsets in advance, by giving them different `invisible' values, and subsequently make various subsets visible or invisible by changing the value of `buffer-invisibility-spec'. Controlling visibility with `buffer-invisibility-spec' is especially useful in a program to display the list of entries in a data base. It permits the implementation of convenient filtering commands to view just a part of the entries in the data base. Setting this variable is very fast, much faster than scanning all the text in the buffer looking for properties to change. - Variable: buffer-invisibility-spec This variable specifies which kinds of `invisible' properties actually make a character invisible. `t' A character is invisible if its `invisible' property is non-`nil'. This is the default. a list Each element of the list makes certain characters invisible. Ultimately, a character is invisible if any of the elements of this list applies to it. The list can have two kinds of elements: `ATOM' A character is invisible if its `invisible' propery value is ATOM or if it is a list with ATOM as a member. `(ATOM . t)' A character is invisible if its `invisible' propery value is ATOM or if it is a list with ATOM as a member. Moreover, if this character is at the end of a line and is followed by a visible newline, it displays an ellipsis. Ordinarily, commands that operate on text or move point do not care whether the text is invisible. However, the user-level line motion commands explicitly ignore invisible newlines. File: lispref.info, Node: Selective Display, Next: Overlay Arrow, Prev: Invisible Text, Up: Display Selective Display ================= "Selective display" is a pair of features that hide certain lines on the screen. The first variant, explicit selective display, is designed for use in a Lisp program. The program controls which lines are hidden by altering the text. Outline mode has traditionally used this variant. It has been partially replaced by the invisible text feature (*note Invisible Text::.); there is a new version of Outline mode which uses that instead. In the second variant, the choice of lines to hide is made automatically based on indentation. This variant is designed to be a user-level feature. The way you control explicit selective display is by replacing a newline (control-j) with a carriage return (control-m). The text that was formerly a line following that newline is now invisible. Strictly speaking, it is temporarily no longer a line at all, since only newlines can separate lines; it is now part of the previous line. Selective display does not directly affect editing commands. For example, `C-f' (`forward-char') moves point unhesitatingly into invisible text. However, the replacement of newline characters with carriage return characters affects some editing commands. For example, `next-line' skips invisible lines, since it searches only for newlines. Modes that use selective display can also define commands that take account of the newlines, or that make parts of the text visible or invisible. When you write a selectively displayed buffer into a file, all the control-m's are output as newlines. This means that when you next read in the file, it looks OK, with nothing invisible. The selective display effect is seen only within XEmacs. - Variable: selective-display This buffer-local variable enables selective display. This means that lines, or portions of lines, may be made invisible. * If the value of `selective-display' is `t', then any portion of a line that follows a control-m is not displayed. * If the value of `selective-display' is a positive integer, then lines that start with more than that many columns of indentation are not displayed. When some portion of a buffer is invisible, the vertical movement commands operate as if that portion did not exist, allowing a single `next-line' command to skip any number of invisible lines. However, character movement commands (such as `forward-char') do not skip the invisible portion, and it is possible (if tricky) to insert or delete text in an invisible portion. In the examples below, we show the *display appearance* of the buffer `foo', which changes with the value of `selective-display'. The *contents* of the buffer do not change. (setq selective-display nil) => nil ---------- Buffer: foo ---------- 1 on this column 2on this column 3n this column 3n this column 2on this column 1 on this column ---------- Buffer: foo ---------- (setq selective-display 2) => 2 ---------- Buffer: foo ---------- 1 on this column 2on this column 2on this column 1 on this column ---------- Buffer: foo ---------- - Variable: selective-display-ellipses If this buffer-local variable is non-`nil', then XEmacs displays `...' at the end of a line that is followed by invisible text. This example is a continuation of the previous one. (setq selective-display-ellipses t) => t ---------- Buffer: foo ---------- 1 on this column 2on this column ... 2on this column 1 on this column ---------- Buffer: foo ---------- You can use a display table to substitute other text for the ellipsis (`...'). *Note Display Tables::. File: lispref.info, Node: Overlay Arrow, Next: Temporary Displays, Prev: Selective Display, Up: Display The Overlay Arrow ================= The "overlay arrow" is useful for directing the user's attention to a particular line in a buffer. For example, in the modes used for interface to debuggers, the overlay arrow indicates the line of code about to be executed. - Variable: overlay-arrow-string This variable holds the string to display to call attention to a particular line, or `nil' if the arrow feature is not in use. Despite its name, the value of this variable can be either a string or a glyph (*note Glyphs::.). - Variable: overlay-arrow-position This variable holds a marker that indicates where to display the overlay arrow. It should point at the beginning of a line. The arrow text appears at the beginning of that line, overlaying any text that would otherwise appear. Since the arrow is usually short, and the line usually begins with indentation, normally nothing significant is overwritten. The overlay string is displayed only in the buffer that this marker points into. Thus, only one buffer can have an overlay arrow at any given time. You can do the same job by creating an extent with a `begin-glyph' property. *Note Extent Properties::. File: lispref.info, Node: Temporary Displays, Next: Blinking, Prev: Overlay Arrow, Up: Display Temporary Displays ================== Temporary displays are used by commands to put output into a buffer and then present it to the user for perusal rather than for editing. Many of the help commands use this feature. - Special Form: with-output-to-temp-buffer BUFFER-NAME FORMS... This function executes FORMS while arranging to insert any output they print into the buffer named BUFFER-NAME. The buffer is then shown in some window for viewing, displayed but not selected. The string BUFFER-NAME specifies the temporary buffer, which need not already exist. The argument must be a string, not a buffer. The buffer is erased initially (with no questions asked), and it is marked as unmodified after `with-output-to-temp-buffer' exits. `with-output-to-temp-buffer' binds `standard-output' to the temporary buffer, then it evaluates the forms in FORMS. Output using the Lisp output functions within FORMS goes by default to that buffer (but screen display and messages in the echo area, although they are "output" in the general sense of the word, are not affected). *Note Output Functions::. The value of the last form in FORMS is returned. ---------- Buffer: foo ---------- This is the contents of foo. ---------- Buffer: foo ---------- (with-output-to-temp-buffer "foo" (print 20) (print standard-output)) => #<buffer foo> ---------- Buffer: foo ---------- 20 #<buffer foo> ---------- Buffer: foo ---------- - Variable: temp-buffer-show-function If this variable is non-`nil', `with-output-to-temp-buffer' calls it as a function to do the job of displaying a help buffer. The function gets one argument, which is the buffer it should display. In Emacs versions 18 and earlier, this variable was called `temp-buffer-show-hook'. - Function: momentary-string-display STRING POSITION &optional CHAR MESSAGE This function momentarily displays STRING in the current buffer at POSITION. It has no effect on the undo list or on the buffer's modification status. The momentary display remains until the next input event. If the next input event is CHAR, `momentary-string-display' ignores it and returns. Otherwise, that event remains buffered for subsequent use as input. Thus, typing CHAR will simply remove the string from the display, while typing (say) `C-f' will remove the string from the display and later (presumably) move point forward. The argument CHAR is a space by default. The return value of `momentary-string-display' is not meaningful. You can do the same job in a more general way by creating an extent with a begin-glyph property. *Note Extent Properties::. If MESSAGE is non-`nil', it is displayed in the echo area while STRING is displayed in the buffer. If it is `nil', a default message says to type CHAR to continue. In this example, point is initially located at the beginning of the second line: ---------- Buffer: foo ---------- This is the contents of foo. -!-Second line. ---------- Buffer: foo ---------- (momentary-string-display "**** Important Message! ****" (point) ?\r "Type RET when done reading") => t ---------- Buffer: foo ---------- This is the contents of foo. **** Important Message! ****Second line. ---------- Buffer: foo ---------- ---------- Echo Area ---------- Type RET when done reading ---------- Echo Area ---------- This function works by actually changing the text in the buffer. As a result, if you later undo in this buffer, you will see the message come and go.