Mercurial > hg > xemacs-beta
annotate man/xemacs/display.texi @ 5797:a1808d52a34a
If the position of a window's cached point is deleted, use buffer point instead
src/ChangeLog addition:
2014-06-17 Aidan Kehoe <kehoea@parhasard.net>
* extents.h:
* window.c:
* window.c (unshow_buffer):
* window.c (Fset_window_buffer):
Use extents, rather than markers, for the window buffer point
cache, so that when the text containing that window buffer point
is deleted, the window display code uses the buffer's actual point
instead of the position that the marker had been moved to.
Fixes Michael Heinrich's problem of
http://mid.gmane.org/6zr42uxtf5.fsf@elektra.science-computing.de ,
introduced by Ben's patch of
https://bitbucket.org/xemacs/xemacs/commits/047d37eb70d70f43803 .
| author | Aidan Kehoe <kehoea@parhasard.net> |
|---|---|
| date | Tue, 17 Jun 2014 20:55:45 +0100 |
| parents | c6b1500299a7 |
| children |
| rev | line source |
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| 428 | 1 |
| 2 @node Display, Search, Registers, Top | |
| 3 @chapter Controlling the Display | |
| 4 | |
| 5 Since only part of a large buffer fits in the window, XEmacs tries to show | |
| 6 the part that is likely to be interesting. The display control commands | |
| 7 allow you to specify which part of the text you want to see. | |
| 8 | |
| 9 @table @kbd | |
| 10 @item C-l | |
| 11 Clear frame and redisplay, scrolling the selected window to center | |
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12 point vertically within it (@code{recenter-top-bottom}). |
| 428 | 13 @item C-v |
| 14 @itemx pgdn | |
| 15 @itemx next | |
| 16 Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}). | |
| 17 On most X keyboards, you can get this functionality using the key | |
| 18 labelled @samp{Page Down}, which generates either @kbd{next} or @kbd{pgdn}. | |
| 19 @item M-v | |
| 20 @itemx pgup | |
| 21 @itemx prior | |
| 22 Scroll backward (@code{scroll-down}). On most X keyboards, you can get | |
| 23 this functionality using the key labelled @samp{Page Up}, which | |
| 24 generates either @kbd{prior} or @kbd{pgup}. | |
| 25 @item @var{arg} C-l | |
| 26 Scroll so point is on line @var{arg} (@code{recenter}). | |
| 27 @item C-x < | |
| 28 @itemx C-pgdn | |
| 29 @itemx C-next | |
| 30 Scroll text in current window to the left (@code{scroll-left}). | |
| 31 @item C-x > | |
| 32 @itemx C-pgup | |
| 33 @itemx C-prior | |
| 34 Scroll to the right (@code{scroll-right}). | |
| 35 @item C-x $ | |
| 36 Make deeply indented lines invisible (@code{set-selective-display}). | |
| 37 @end table | |
| 38 | |
| 39 @menu | |
| 40 * Scrolling:: Moving text up and down in a window. | |
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41 * Recentering:: A scroll command that centers the current line. |
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42 * Automatic Scrolling:: Redisplay scrolls text automatically when needed. |
| 428 | 43 * Horizontal Scrolling:: Moving text left and right in a window. |
| 44 * Selective Display:: Hiding lines with lots of indentation. | |
| 45 * Display Vars:: Information on variables for customizing display. | |
| 46 @end menu | |
| 47 | |
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48 @node Scrolling, Recentering, Display, Display |
| 428 | 49 @section Scrolling |
| 50 | |
| 51 If a buffer contains text that is too large to fit entirely within the | |
| 52 window that is displaying the buffer, XEmacs shows a contiguous section of | |
| 53 the text. The section shown always contains point. | |
| 54 | |
| 55 @cindex scrolling | |
| 56 @dfn{Scrolling} means moving text up or down in the window so that | |
| 57 different parts of the text are visible. Scrolling forward means that text | |
| 58 moves up, and new text appears at the bottom. Scrolling backward moves | |
| 59 text down and new text appears at the top. | |
| 60 | |
| 61 Scrolling happens automatically if you move point past the bottom or top | |
| 62 of the window. You can also explicitly request scrolling with the commands | |
| 63 in this section. | |
| 64 | |
| 65 @ifinfo | |
| 66 @table @kbd | |
| 67 @item C-v | |
| 68 @itemx pgdn | |
| 69 @itemx next | |
| 70 Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}). | |
| 71 @item M-v | |
| 72 @itemx pgup | |
| 73 @itemx prior | |
| 74 Scroll backward (@code{scroll-down}). | |
| 75 @end table | |
| 76 @end ifinfo | |
| 77 | |
| 78 @kindex C-v | |
| 79 @kindex M-v | |
| 80 @kindex pgup | |
| 81 @kindex pgdn | |
| 82 @kindex next | |
| 83 @kindex prior | |
| 84 @findex scroll-up | |
| 85 @findex scroll-down | |
| 86 The scrolling commands @kbd{C-v} and @kbd{M-v} let you move all the text | |
| 87 in the window up or down a few lines. @kbd{C-v} (@code{scroll-up}) with an | |
| 88 argument shows you that many more lines at the bottom of the window, moving | |
| 89 the text and point up together as @kbd{C-l} might. @kbd{C-v} with a | |
| 90 negative argument shows you more lines at the top of the window. | |
| 91 @kbd{Meta-v} (@code{scroll-down}) is like @kbd{C-v}, but moves in the | |
| 92 opposite direction.@refill | |
| 93 | |
| 94 @vindex next-screen-context-lines | |
| 95 To read the buffer a windowful at a time, use @kbd{C-v} with no | |
| 96 argument. @kbd{C-v} takes the last two lines at the bottom of the | |
| 97 window and puts them at the top, followed by nearly a whole windowful of | |
| 98 lines not previously visible. Point moves to the new top of the window | |
| 99 if it was in the text scrolled off the top. @kbd{M-v} with no argument | |
| 100 moves backward with similar overlap. The number of lines of overlap | |
| 101 across a @kbd{C-v} or @kbd{M-v} is controlled by the variable | |
| 102 @code{next-screen-context-lines}; by default, it is two. | |
| 103 | |
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104 @node Recentering, Automatic Scrolling, Scrolling, Display |
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105 @section Recentering |
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106 |
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107 @table @kbd |
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108 @item C-l |
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109 Scroll the selected window so the current line is the center-most text |
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110 line; on subsequent consecutive invocations, make the current line the |
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111 top line, the bottom line, and so on in cyclic order. Possibly |
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112 redisplay the screen too (@code{recenter-top-bottom}). |
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113 |
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114 @item M-x recenter |
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115 Scroll the selected window so the current line is the center-most text |
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116 line. Possibly redisplay the screen too. |
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117 |
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118 @item C-M-l |
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119 Scroll heuristically to bring useful information onto the screen |
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120 (@code{reposition-window}). |
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121 @end table |
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122 |
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123 @kindex C-l |
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124 @findex recenter-top-bottom |
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125 The @kbd{C-l} (@code{recenter-top-bottom}) command @dfn{recenters} |
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126 the selected window, scrolling it so that the current screen line is |
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127 exactly in the center of the window, or as close to the center as |
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128 possible. |
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129 |
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130 Typing @kbd{C-l} twice in a row (@kbd{C-l C-l}) scrolls the window |
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131 so that point is on the topmost screen line. Typing a third @kbd{C-l} |
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132 scrolls the window so that point is on the bottom-most screen line. |
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133 Each successive @kbd{C-l} cycles through these three positions. |
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134 |
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135 @vindex recenter-positions |
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136 You can change the cycling order by customizing the list variable |
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137 @code{recenter-positions}. Each list element should be the symbol |
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138 @code{top}, @code{middle}, or @code{bottom}, or a number; an integer |
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139 means to move the line to the specified screen line, while a |
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140 floating-point number between 0.0 and 1.0 specifies a percentage of |
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141 the screen space from the top of the window. The default, |
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142 @code{(middle top bottom)}, is the cycling order described above. |
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143 Furthermore, if you change the variable @code{scroll-margin} to a |
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144 non-zero value @var{n}, @kbd{C-l} always leaves at least @var{n} |
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145 screen lines between point and the top or bottom of the window |
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146 (@pxref{Automatic Scrolling}). |
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147 |
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148 You can also give @kbd{C-l} a prefix argument. A plain prefix |
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149 argument, @kbd{C-u C-l}, simply recenters point. A positive argument |
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150 @var{n} puts point @var{n} lines down from the top of the window. An |
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151 argument of zero puts point on the topmost line. A negative argument |
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152 @var{-n} puts point @var{n} lines from the bottom of the window. When |
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153 given an argument, @kbd{C-l} does not clear the screen or cycle |
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154 through different screen positions. |
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155 |
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156 @findex recenter |
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157 The more primitive command @kbd{M-x recenter} behaves like |
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158 @code{recenter-top-bottom}, but does not cycle among screen positions. |
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159 |
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160 @node Automatic Scrolling, Horizontal Scrolling, Recentering, Display |
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161 @section Automatic Scrolling |
| 428 | 162 |
| 163 @vindex scroll-step | |
| 164 Scrolling happens automatically if point has moved out of the visible | |
| 165 portion of the text when it is time to display. Usually scrolling is | |
| 166 done to put point vertically centered within the window. However, if | |
| 167 the variable @code{scroll-step} has a non-zero value, an attempt is made to | |
| 168 scroll the buffer by that many lines; if that is enough to bring point back | |
| 169 into visibility, that is what happens. | |
| 170 | |
| 171 Scrolling happens automatically if point has moved out of the visible | |
| 172 portion of the text when it is time to display. Usually scrolling is | |
| 173 done to put point vertically centered within the window. However, if | |
| 174 the variable @code{scroll-step} has a non-zero value, an attempt is made to | |
| 175 scroll the buffer by that many lines; if that is enough to bring point back | |
| 176 into visibility, that is what happens. | |
| 177 | |
| 178 @vindex scroll-conservatively | |
| 179 If you set @code{scroll-step} to a small value because you want to use | |
| 180 arrow keys to scroll the screen without recentering, the redisplay | |
| 181 preemption will likely make XEmacs keep recentering the screen when | |
| 182 scrolling fast, regardless of @code{scroll-step}. To prevent this, set | |
| 183 @code{scroll-conservatively} to a small value, which will have the | |
| 184 result of overriding the redisplay preemption. | |
| 185 | |
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186 @node Horizontal Scrolling, Selective Display, Automatic Scrolling, Display |
| 428 | 187 @section Horizontal Scrolling |
| 188 | |
| 189 @ifinfo | |
| 190 @table @kbd | |
| 191 @item C-x < | |
| 192 Scroll text in current window to the left (@code{scroll-left}). | |
| 193 @item C-x > | |
| 194 Scroll to the right (@code{scroll-right}). | |
| 195 @end table | |
| 196 @end ifinfo | |
| 197 | |
| 198 @kindex C-x < | |
| 199 @kindex C-x > | |
| 200 @findex scroll-left | |
| 201 @findex scroll-right | |
| 202 @cindex horizontal scrolling | |
| 203 The text in a window can also be scrolled horizontally. This means that | |
| 204 each line of text is shifted sideways in the window, and one or more | |
| 205 characters at the beginning of each line are not displayed at all. When a | |
| 206 window has been scrolled horizontally in this way, text lines are truncated | |
| 207 rather than continued (@pxref{Continuation Lines}), with a @samp{$} appearing | |
| 208 in the first column when there is text truncated to the left, and in the | |
| 209 last column when there is text truncated to the right. | |
| 210 | |
| 211 The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected | |
| 212 window to the left by @var{n} columns with argument @var{n}. With no | |
| 213 argument, it scrolls by almost the full width of the window (two columns | |
| 214 less, to be precise). @kbd{C-x >} (@code{scroll-right}) scrolls | |
| 215 similarly to the right. The window cannot be scrolled any farther to | |
| 216 the right once it is displaying normally (with each line starting at the | |
| 217 window's left margin); attempting to do so has no effect. | |
| 218 | |
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recenter-top-bottom synced from GNU and new default for C-l
Mats Lidell <mats.lidell@cag.se>
parents:
428
diff
changeset
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219 @node Selective Display, Display Vars, Horizontal Scrolling, Display |
| 428 | 220 @section Selective Display |
| 221 @findex set-selective-display | |
| 222 @kindex C-x $ | |
| 223 | |
| 224 XEmacs can hide lines indented more than a certain number | |
| 225 of columns (you specify how many columns). This allows you to get an | |
| 226 overview of a part of a program. | |
| 227 | |
| 228 To hide lines, type @kbd{C-x $} (@code{set-selective-display}) with a | |
| 229 numeric argument @var{n}. (@xref{Arguments}, for information on giving | |
| 230 the argument.) Lines with at least @var{n} columns of indentation | |
| 231 disappear from the screen. The only indication of their presence are | |
| 232 three dots (@samp{@dots{}}), which appear at the end of each visible | |
| 233 line that is followed by one or more invisible ones.@refill | |
| 234 | |
| 235 The invisible lines are still present in the buffer, and most editing | |
| 236 commands see them as usual, so it is very easy to put point in the middle | |
| 237 of invisible text. When this happens, the cursor appears at the end of the | |
| 238 previous line, after the three dots. If point is at the end of the visible | |
| 239 line, before the newline that ends it, the cursor appears before the three | |
| 240 dots. | |
| 241 | |
| 242 The commands @kbd{C-n} and @kbd{C-p} move across the invisible lines | |
| 243 as if they were not there. | |
| 244 | |
| 245 To make everything visible again, type @kbd{C-x $} with no argument. | |
| 246 | |
| 247 @node Display Vars,, Selective Display, Display | |
| 248 @section Variables Controlling Display | |
| 249 | |
| 250 This section contains information for customization only. Beginning | |
| 251 users should skip it. | |
| 252 | |
| 253 @vindex no-redraw-on-reenter | |
| 254 When you reenter XEmacs after suspending, XEmacs normally clears the | |
| 255 screen and redraws the entire display. On some terminals with more than | |
| 256 one page of memory, it is possible to arrange the termcap entry so that | |
| 257 the @samp{ti} and @samp{te} strings (output to the terminal when XEmacs | |
| 258 is entered and exited, respectively) switch between pages of memory so | |
| 259 as to use one page for XEmacs and another page for other output. In that | |
| 260 case, you might want to set the variable @code{no-redraw-on-reenter} to | |
| 261 non-@code{nil} so that XEmacs will assume, when resumed, that the screen | |
| 262 page it is using still contains what XEmacs last wrote there. | |
| 263 | |
| 264 @vindex echo-keystrokes | |
| 265 The variable @code{echo-keystrokes} controls the echoing of multi-character | |
| 266 keys; its value is the number of seconds of pause required to cause echoing | |
| 267 to start, or zero, meaning don't echo at all. @xref{Echo Area}. | |
| 268 | |
| 269 @vindex ctl-arrow | |
| 270 If the variable @code{ctl-arrow} is @code{nil}, control characters in the | |
| 271 buffer are displayed with octal escape sequences, all except newline and | |
| 272 tab. If its value is @code{t}, then control characters will be printed | |
| 273 with an up-arrow, for example @kbd{^A}. | |
| 274 | |
| 275 If its value is not @code{t} and not @code{nil}, then characters whose | |
| 276 code is greater than 160 (that is, the space character (32) with its | |
| 277 high bit set) will be assumed to be printable, and will be displayed | |
| 278 without alteration. This is the default when running under X Windows, | |
| 279 since XEmacs assumes an ISO/8859-1 character set (also known as | |
| 280 ``Latin1''). The @code{ctl-arrow} variable may also be set to an | |
| 281 integer, in which case all characters whose codes are greater than or | |
| 282 equal to that value will be assumed to be printable. | |
| 283 | |
| 284 Altering the value of @code{ctl-arrow} makes it local to the current | |
| 285 buffer; until that time, the default value is in effect. @xref{Locals}. | |
| 286 | |
| 287 @vindex tab-width | |
| 288 Normally, a tab character in the buffer is displayed as whitespace which | |
| 289 extends to the next display tab stop position, and display tab stops come | |
| 290 at intervals equal to eight spaces. The number of spaces per tab is | |
| 291 controlled by the variable @code{tab-width}, which is made local by | |
| 292 changing it, just like @code{ctl-arrow}. Note that how the tab character | |
| 293 in the buffer is displayed has nothing to do with the definition of | |
| 294 @key{TAB} as a command. | |
| 295 | |
| 296 @vindex selective-display-ellipses | |
| 297 If you set the variable @code{selective-display-ellipses} to @code{nil}, | |
| 298 the three dots at the end of a line that precedes invisible | |
| 299 lines do not appear. There is no visible indication of the invisible lines. | |
| 300 This variable becomes local automatically when set. |