Mercurial > hg > xemacs-beta
comparison man/lispref/windows.texi @ 2289:7fa4bc78a35d
[xemacs-hg @ 2004-09-21 02:59:59 by james]
Darryl Okahata's patch to add current-pixel-row.
| author | james |
|---|---|
| date | Tue, 21 Sep 2004 03:00:27 +0000 |
| parents | 33f0f28b945c |
| children | 61aaa5e258b0 |
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| 2288:63d767a4650c | 2289:7fa4bc78a35d |
|---|---|
| 1047 @section Windows and Point | 1047 @section Windows and Point |
| 1048 @cindex window position | 1048 @cindex window position |
| 1049 @cindex window point | 1049 @cindex window point |
| 1050 @cindex position in window | 1050 @cindex position in window |
| 1051 @cindex point in window | 1051 @cindex point in window |
| 1052 @cindex cursor in window | |
| 1052 | 1053 |
| 1053 Each window has its own value of point, independent of the value of | 1054 Each window has its own value of point, independent of the value of |
| 1054 point in other windows displaying the same buffer. This makes it useful | 1055 point in other windows displaying the same buffer. This makes it useful |
| 1055 to have multiple windows showing one buffer. | 1056 to have multiple windows showing one buffer. |
| 1056 | 1057 |
| 1095 @end defun | 1096 @end defun |
| 1096 | 1097 |
| 1097 @defun set-window-point window position | 1098 @defun set-window-point window position |
| 1098 This function positions point in @var{window} at position | 1099 This function positions point in @var{window} at position |
| 1099 @var{position} in @var{window}'s buffer. | 1100 @var{position} in @var{window}'s buffer. |
| 1101 @end defun | |
| 1102 | |
| 1103 @defun current-pixel-row &optional window pos | |
| 1104 @defunx current-pixel-column &optional window pos | |
| 1105 @cindex cursor pixel row | |
| 1106 @cindex window point pixel row | |
| 1107 @cindex cursor pixel column | |
| 1108 @cindex window point pixel column | |
| 1109 The function, @code{current-pixel-row}, returns the vertical location, | |
| 1110 in pixels, of the point @var{pos} within the specified @var{window}; | |
| 1111 similarly, @code{current-pixel-column} returns the corresponding | |
| 1112 horizontal location. The position returned is that of the upper-left | |
| 1113 corner of the cursor, and is relative to the upper-left location of the | |
| 1114 window. If @var{window} is @code{nil}, the function uses the selected | |
| 1115 window. If @var{pos} is @code{nil}, the value of @code{window-point} is | |
| 1116 used. | |
| 1117 | |
| 1118 Note that the coordinates are relative to the current XEmacs window, and | |
| 1119 are not relative to the XEmacs X11 window. To obtain the coordinates | |
| 1120 relative to the X11 window, you must also take into account the spacings | |
| 1121 of any menubars, gutters, toolbars, margins, etc., as well as any window | |
| 1122 offsets. The function, @code{window-pixel-edges} (@pxref{Position of | |
| 1123 Window}), can be used to help calculate the location relative to the | |
| 1124 frame. | |
| 1125 | |
| 1126 @emph{Important note}: in order for these functions to return a correct, | |
| 1127 non-nil value, two criteria @emph{must} be satisfied: | |
| 1128 | |
| 1129 @itemize @bullet | |
| 1130 | |
| 1131 @item | |
| 1132 The location of @code{pos} must be visible within the specified window. | |
| 1133 If @var{pos} is outside the visible area, @code{nil} is returned. | |
| 1134 | |
| 1135 @item | |
| 1136 As the pixel location is determined from the redisplay tables, the | |
| 1137 redisplay tables must be up-to-date. In other words, the XEmacs | |
| 1138 window(s), as seen by the user, must be correct (to improve performance, | |
| 1139 XEmacs generally defers display updates until control returns back to | |
| 1140 the idle loop). To insure that the redisplay tables are up-to-date, one | |
| 1141 of the following must generally be done @emph{before} calling | |
| 1142 @code{current-pixel-row} or @code{current-pixel-column}: | |
| 1143 | |
| 1144 @itemize @bullet | |
| 1145 | |
| 1146 @item | |
| 1147 If the window in question is not in a new frame, you can force a | |
| 1148 redisplay using @code{(sit-for 0)}. See @code{sit-for} in | |
| 1149 @ref{Waiting}. | |
| 1150 | |
| 1151 @item | |
| 1152 If the window in question is in a new frame, you must call code like the | |
| 1153 following: | |
| 1154 | |
| 1155 @example | |
| 1156 @group | |
| 1157 (while (not (frame-visible-p frame)) | |
| 1158 (sleep-for .5)) | |
| 1159 @end group | |
| 1160 @end example | |
| 1161 | |
| 1162 @end itemize | |
| 1163 | |
| 1164 @end itemize | |
| 1165 | |
| 1166 If one of these is not done, the return value may be incorrect, even if | |
| 1167 it is non-nil. | |
| 1168 | |
| 1100 @end defun | 1169 @end defun |
| 1101 | 1170 |
| 1102 @node Window Start | 1171 @node Window Start |
| 1103 @section The Window Start Position | 1172 @section The Window Start Position |
| 1104 | 1173 |