path: root/devdocs/elisp/truncation.html

 <h3 class="section">Truncation</h3>      <p>When a line of text extends beyond the right edge of a window, Emacs can <em>continue</em> the line (make it wrap to the next screen line), or <em>truncate</em> the line (limit it to one screen line). The additional screen lines used to display a long text line are called <em>continuation</em> lines. Continuation is not the same as 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. See <a href="filling">Filling</a>. </p> <p>On a graphical display, tiny arrow images in the window fringes indicate truncated and continued lines (see <a href="fringes">Fringes</a>). On a text terminal, a ‘<samp>$</samp>’ in the rightmost column of the window indicates truncation; a ‘<samp>\</samp>’ on the rightmost column indicates a line that wraps. (The display table can specify alternate characters to use for this; see <a href="display-tables">Display Tables</a>). </p> <p>Since wrapping and truncation of text contradict each other, Emacs turns off line truncation when wrapping is requested, and vice versa. </p> <dl> <dt id="truncate-lines">User Option: <strong>truncate-lines</strong>
</dt> <dd><p>If this buffer-local variable is non-<code>nil</code>, lines that extend beyond the right edge of the window are truncated; otherwise, they are continued. As a special exception, the variable <code>truncate-partial-width-windows</code> takes precedence in <em>partial-width</em> windows (i.e., windows that do not occupy the entire frame width). </p></dd>
</dl> <dl> <dt id="truncate-partial-width-windows">User Option: <strong>truncate-partial-width-windows</strong>
</dt> <dd>
 <p>This variable controls line truncation in <em>partial-width</em> windows. A partial-width window is one that does not occupy the entire frame width (see <a href="splitting-windows">Splitting Windows</a>). If the value is <code>nil</code>, line truncation is determined by the variable <code>truncate-lines</code> (see above). If the value is an integer <var>n</var>, lines are truncated if the partial-width window has fewer than <var>n</var> columns, regardless of the value of <code>truncate-lines</code>; if the partial-width window has <var>n</var> or more columns, line truncation is determined by <code>truncate-lines</code>. For any other non-<code>nil</code> value, lines are truncated in every partial-width window, regardless of the value of <code>truncate-lines</code>. </p>
</dd>
</dl> <p>When horizontal scrolling (see <a href="horizontal-scrolling">Horizontal Scrolling</a>) is in use in a window, that forces truncation. </p> <dl> <dt id="wrap-prefix">Variable: <strong>wrap-prefix</strong>
</dt> <dd>
<p>If this buffer-local variable is non-<code>nil</code>, it defines a <em>wrap prefix</em> which Emacs displays at the start of every continuation line. (If lines are truncated, <code>wrap-prefix</code> is never used.) Its value may be a string or an image (see <a href="other-display-specs">Other Display Specs</a>), or a stretch of whitespace such as specified by the <code>:width</code> or <code>:align-to</code> display properties (see <a href="specified-space">Specified Space</a>). The value is interpreted in the same way as a <code>display</code> text property. See <a href="display-property">Display Property</a>. </p> <p>A wrap prefix may also be specified for regions of text, using the <code>wrap-prefix</code> text or overlay property. This takes precedence over the <code>wrap-prefix</code> variable. See <a href="special-properties">Special Properties</a>. </p>
</dd>
</dl> <dl> <dt id="line-prefix">Variable: <strong>line-prefix</strong>
</dt> <dd>
<p>If this buffer-local variable is non-<code>nil</code>, it defines a <em>line prefix</em> which Emacs displays at the start of every non-continuation line. Its value may be a string or an image (see <a href="other-display-specs">Other Display Specs</a>), or a stretch of whitespace such as specified by the <code>:width</code> or <code>:align-to</code> display properties (see <a href="specified-space">Specified Space</a>). The value is interpreted in the same way as a <code>display</code> text property. See <a href="display-property">Display Property</a>. </p> <p>A line prefix may also be specified for regions of text using the <code>line-prefix</code> text or overlay property. This takes precedence over the <code>line-prefix</code> variable. See <a href="special-properties">Special Properties</a>. </p>
</dd>
</dl><div class="_attribution">
  <p class="_attribution-p">
    Copyright &copy; 1990-1996, 1998-2022 Free Software Foundation, Inc. <br>Licensed under the GNU GPL license.<br>
    <a href="https://www.gnu.org/software/emacs/manual/html_node/elisp/Truncation.html" class="_attribution-link">https://www.gnu.org/software/emacs/manual/html_node/elisp/Truncation.html</a>
  </p>
</div>