intov.html

unix 下的C开发手册,还用详细的例程。

is ISO/IEC 10646-1:1993.
<p>
A complex character can be written to the screen; if it does not include a
spacing character, any non-spacing characters are associated with the
spacing complex character that exists at the specified screen position.  When
the application reads information back from the screen, it obtains spacing
complex characters.
<p>
The
<b>cchar_t</b>
data type represents a complex character and its rendition.
When a
<b>cchar_t</b>
represents a non-spacing complex character (that is, when there is no spacing
character within the complex character), then its rendition is not used; when
it is written to the screen, it uses the rendition specified by the spacing
character already displayed.
<p>
An object of type <b>cchar_t</b> can be initialised using
<i><a href="setcchar.html">setcchar()</a></i>
and its contents can be extracted using
<i><a href="getcchar.html">getcchar()</a></i>.
The behaviour of functions that take a <b>cchar_t</b> input argument is
undefined if the application provides a <b>cchar_t</b> value that was not
initialised in this way or obtained from a Curses
function that has a <b>cchar_t</b> output argument.
<h4><a name = "tag_001_003_006">&nbsp;</a>Window Properties</h4>
<xref type="3" name="wprops"></xref>
Associated with each window are the following properties that affect the
placing of characters into the window (see
<xref href=wrendition><a href="#tag_001_004_004">
Rendition of Characters Placed into a Window
</a></xref>).
<h5><a name = "tag_001_003_006_001">&nbsp;</a>Window Rendition</h5>
Each window has a rendition, which is combined with the rendition component of
the window's background property described below.
<h5><a name = "tag_001_003_006_002">&nbsp;</a>Window Background</h5>
Each window has a background property.  The background property specifies:
<ul>
<p>
<li>
A spacing complex character (the background character) that will be used in a
variety of situations where visible information is deleted from the screen.
<p>
<li>
A rendition to use in displaying the background character in those
situations, and in other situations specified in
<xref href=wrendition><a href="#tag_001_004_004">
Rendition of Characters Placed into a Window
</a></xref>.
<p>
</ul>
<h3><a name = "tag_001_004">&nbsp;</a>Conceptual Operations</h3>
<xref type="2" name="displaymodel"></xref>
<h4><a name = "tag_001_004_001">&nbsp;</a>Screen Addressing</h4>
Many Curses functions use a coordinate pair.  In the
<b>DESCRIPTION</b>,
coordinate locations are represented as (<i>y</i>, <i>x</i>) since the <i>y</i>
argument always precedes the <i>x</i> argument in the function call.
These coordinates denote a line/column position, not a character position.
<p>
The coordinate <i>y</i> always refers to the row (of the window), and <i>x</i>
always refers to the column.  The first row and the first column is number 0,
not 1.
The position (0, 0) is the window's
<i>origin</i>.
<p>
For example, for terminals that display the ISO 8859-1 character set (with
left-to-right writing), (0, 0) represents the upper left-hand corner of the
screen.
<p>
Functions that start with
<i>mv</i>
take arguments that specify a (<i>y</i>, <i>x</i>) position and move the cursor
(as though
<i><a href="move.html">move()</a></i>
were called) before performing the requested action.  As part of the requested
action, further cursor movement may occur, specified on the respective
reference manual page.
<h4><a name = "tag_001_004_002">&nbsp;</a>Basic Character Operations</h4>
<h5><a name = "tag_001_004_002_001">&nbsp;</a>Adding (Overwriting)</h5>
The Curses functions that contain the word add, such as
<i><a href="addch.html">addch()</a></i>,
actually specify one or more characters to replace (overwrite) characters
already in the window.
If these functions specify only non-spacing
characters, they are appended to a spacing character already in the window;
see also
<xref href=zerowidth><a href="#tag_001_003_005">
Non-spacing Characters
</a></xref>.
<p>
When replacing a multi-column character with a character that requires fewer
columns, the new character is added starting at the specified or implied
column position.  All columns that the former multi-column character
occupied that the new character does not require are <i>orphaned columns</i>,
which are filled using the background character and rendition.
<p>
Replacing a character with a character that requires more columns also
replaces one or more subsequent characters on the line.  This process may also
produce orphaned columns.
<h5><a name = "tag_001_004_002_002">&nbsp;</a>Truncation, Wrapping and Scrolling</h5>
<xref type="5" name="truncation"></xref>
<p>
If the application specifies a character or a string of characters
such that writing them to a window would extend beyond the end of the line
(for example, if the application tries to deposit any multi-column character
at the last column in a line),
&nbsp;the behaviour depends on whether the function supports line wrapping:
<ul>
<p>
<li>
If the function does not wrap, it fails.
<p>
<li>
If the function wraps, then it places one or more characters in the window at
the start of the next line, beginning with the first character
that would not completely fit on the original line.
<p>
If the final character on the line is a multi-column character that does not
completely fit on the line, the entire character wraps to the next line and
columns at the end of the original line may be orphaned.
<p>
If the original line was the last line in the window, the wrap may cause a
scroll to occur:
<ul>
<p>
<li>
If scrolling is enabled, a scroll occurs.  The contents of the first line of
the window are lost.  The contents of each remaining line in the window move
to the previous line.  The last line of the window is filled with any
characters that wrapped.  Any remaining space on the last line is
filled with the background character and rendition.
<p>
<li>
If scrolling is disabled, any characters that would extend beyond
the last column of the last line are truncated.
<p>
</ul>
<p>
The
<i><a href="scrollok.html">scrollok()</a></i>
function enables and disables scrolling.
<p>
</ul>
<p>
Some <i>add</i> functions move the cursor just beyond the end of the last
character added.  If this position is beyond the end of a line, it causes
wrapping and scrolling under the conditions specified in the second bullet
above.
<h5><a name = "tag_001_004_002_003">&nbsp;</a>Insertion</h5>
Insertion functions (such as
<i><a href="insch.html">insch()</a></i>)
insert characters immediately before the character at the specified or implied
cursor position.
<p>
The insertion shifts all characters that were formerly at or beyond the
cursor position on the cursor line toward the end of that line.  The
disposition of the characters that would thus extend beyond the end of the
line depends on whether the function supports wrapping:
<ul>
<p>
<li>
If the function does not wrap, those characters are removed from the window.
This may produce orphaned columns.
<p>
<li>
If the function supports wrapping, the effect is as described above in
<xref href=truncation><a href="#tag_001_004_002_002">
Truncation, Wrapping and Scrolling
</a></xref>
(except that the overwriting discussed in the final dash is an insertion).
<p>
</ul>
<p>
If multi-column characters are displayed, some cursor positions are within a
multi-column character but not at the beginning of a character.  Any request
to insert data at a position that is not the beginning of a multi-column
character will be adjusted so that the actual cursor position is at the
beginning of the multi-column character in which the requested position occurs.
<p>
There are no warning indications relative to cursor relocation.
The application should not maintain an image of the cursor position, since
this constitutes placing terminal-specific information in the application and
defeats the purpose of using Curses.
<p>
Portable applications cannot assume that a cursor position specified in an
insert function is a reusable indication of the actual cursor position.
<h5><a name = "tag_001_004_002_004">&nbsp;</a>Deletion</h5>
Deletion functions (such as
<i><a href="delch.html">delch()</a></i>)
delete the simple
&nbsp;or complex
&nbsp;character at the specified or implied cursor position,
&nbsp;no matter which column of the character this is.
&nbsp;All column positions are replaced by
the background character and rendition and the cursor is not relocated.
If a character-deletion operation would cause a previous wrapping operation to
be undone, then the results are unspecified.
<h5><a name = "tag_001_004_002_005">&nbsp;</a>Window Operations</h5>
Overlapping a window (that is, placing one window on top of another)
and overwriting a window
(that is, copying the contents of one window into another) follows
the operation of overwriting
&nbsp;multi-column
&nbsp;glyphs around its edge.  Any orphaned columns are handled as in the
character operations.
<h5><a name = "tag_001_004_002_006">&nbsp;</a>Characters that Straddle the Subwindow Border</h5>
A subwindow can be defined such that multi-column characters straddle the
subwindow border.  The character operations deal with these straddling
characters as follows:
<ul>
<p>
<li>
Reading the subwindow with a function such as
<i><a href="in_wch.html">in_wch()</a></i>
reads the entire straddling character.
<p>
<li>
Adding, inserting or deleting in the subwindow deletes the entire straddling
character before the requested operation begins and does not relocate the
cursor.
<p>
<li>
Scrolling lines in the subwindow has the following effects:
<ul>
<p>
<li>
A straddling character at the start of the line is completely erased before
the scroll operation begins.
<p>
<li>
A straddling character at the end of the line moves in the direction of the
scroll and continues to straddle the subwindow border.  Column positions
outside the subwindow at the straddling character's former position are
orphaned unless another straddling character scrolls into those positions.
<p>
</ul>
<p>
</ul>
<p>
If the application calls a function such as
<i><a href="border.html">border()</a></i>,
the above situations do not occur because writing the border on the subwindow
deletes any straddling characters.
<p>
In the above cases involving multi-column characters, operations confined to a
subwindow can modify the screen outside the subwindow.  Therefore, saving a
subwindow, performing operations within the subwindow, and then restoring the
subwindow may disturb the appearance of the screen.  To overcome these
effects (for example, for pop-up windows), the application should refresh
the entire screen.
<h4><a name = "tag_001_004_003">&nbsp;</a>Special Characters</h4>
<xref type="3" name="specialchars"></xref>
Some functions process special characters as specified below.
<p>
In functions that do not move the cursor based on the
information placed in the window, these special characters would only be used
within a string in order to affect the placement of subsequent characters; the
cursor movement specified below does not persist in the visible cursor beyond
the end of the operation.  In functions that do move the cursor, these special
characters can be used to affect the placement of subsequent characters and to
achieve movement of the visible cursor.
<dl compact>

<dt>&lt;backspace&gt;<dd><index term="backspace, special processing"></index>
Unless the cursor was already in column 0, &lt;backspace&gt; moves the cursor one
column toward the start of the current line and any characters after the
&lt;backspace&gt; are added or inserted starting there.

<dt>&lt;carriage return&gt;<dd><br>
Unless the cursor was already in column 0, &lt;carriage return&gt; moves the cursor
to the start of the current line.  Any characters after the &lt;carriage return&gt;
are added or inserted starting there.

<dt>&lt;newline&gt;<dd><index term="newline, special processing"></index>
In an add operation, Curses adds the background character into successive
columns until reaching the end of the line.  Scrolling occurs as described in
<xref href=truncation><a href="#tag_001_004_002_002">
Truncation, Wrapping and Scrolling
</a></xref>.
Any characters after the &lt;newline&gt; character are added, starting at the
start of the new line.

In an insert operation, &lt;newline&gt; erases the remainder of the current
line with the background character, effectively a
<i><a href="wclrtoeol.html">wclrtoeol()</a></i>,
and
moves the cursor to the start of a new line.  When scrolling is 
enabled, advancing the cursor to a new line may cause scrolling as
described in
<xref href=truncation><a href="#tag_001_004_002_002">
Truncation, Wrapping and Scrolling
</a></xref>.
Any characters after the &lt;newline&gt; character are inserted at the start of the new
line.

The
<i><a href="filter.html">filter()</a></i>
function may inhibit this processing.

<dt>&lt;tab&gt;<dd>Tab characters in text move subsequent characters to the next horizontal tab
stop.  By default, tab stops are in column 0, 8, 16, and so on.

In an insert or add operation, Curses inserts or adds, respectively, the
background character into successive columns until reaching the next tab stop.
If there are no more tab stops in the current line, wrapping and scrolling