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-<head>
-<title>graphics(3) - Plan 9 from User Space</title>
-<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
-</head>
-<body bgcolor=#ffffff>
-<table border=0 cellpadding=0 cellspacing=0 width=100%>
-<tr height=10><td>
-<tr><td width=20><td>
-<tr><td width=20><td><b>GRAPHICS(3)</b><td align=right><b>GRAPHICS(3)</b>
-<tr><td width=20><td colspan=2>
- <br>
-<p><font size=+1><b>NAME </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- Display, Point, Rectangle, Cursor, initdraw, geninitdraw, drawerror,
- initdisplay, closedisplay, getdefont, getwindow, gengetwindow,
- flushimage, bufimage, lockdisplay, unlockdisplay, cursorswitch,
- cursorset, openfont, buildfont, freefont, Pfmt, Rfmt, strtochan,
- chantostr, chantodepth &ndash; interactive graphics
-
-</table>
-<p><font size=+1><b>SYNOPSIS </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>#include &lt;u.h&gt;<br>
- #include &lt;libc.h&gt;<br>
- #include &lt;draw.h&gt;<br>
- #include &lt;cursor.h&gt;<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;initdraw(void (*errfun)(Display*, char*), char *font,<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- char *label)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- </table>
-
- </table>
- </font></tt>
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
-
-
- </table>
-
- </table>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;geninitdraw(char *devdir, void(*errfun)(Display*, char*),<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>char *font, char *label, char *mousedir, char *windir,<br>
- int ref)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
-
- </table>
-
- </table>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;newwindow(char *str)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>void &nbsp;&nbsp;&nbsp;drawerror(Display *d, char *msg)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>Display*initdisplay(char *devdir, char *win, void(*errfun)(Display*,
- char*))<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>void &nbsp;&nbsp;&nbsp;closedisplay(Display *d)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>Font* getdefont(Display *d)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;flushimage(Display *d, int vis)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;bufimage(Display *d, int n)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;lockdisplay(Display *d)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;unlockdisplay(Display *d)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;getwindow(Display *d, int ref)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;gengetwindow(Display *d, char *winname,<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- Image **ip, Screen **sp, int ref)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- </table>
-
- </table>
- </font></tt>
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
-
-
- </table>
-
- </table>
- <tt><font size=+1>void &nbsp;&nbsp;&nbsp;cursorswitch(Cursor *curs)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>void &nbsp;&nbsp;&nbsp;cursorset(Point p)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>Font* openfont(Display *d, char *name)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>Font* buildfont(Display *d, char *desc, char *name)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>void &nbsp;&nbsp;&nbsp;freefont(Font *f)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;Pfmt(Fmt*)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;Rfmt(Fmt*)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>ulong strtochan(char *s)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>char* chantostr(char *s, ulong chan)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;chantodepth(ulong chan)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>extern Display *display<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>extern Image &nbsp;&nbsp;&nbsp;&nbsp;*screen<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>extern Screen &nbsp;&nbsp;&nbsp;&nbsp;*_screen<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
- <tt><font size=+1>extern Font &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*font<br>
- </font></tt>
-</table>
-<p><font size=+1><b>DESCRIPTION </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- A <tt><font size=+1>Display</font></tt> structure represents a connection to the graphics device,
- <a href="../man3/draw.html"><i>draw</i>(3)</a>, holding all graphics resources associated with the connection,
- including in particular raster image data in use by the client
- program. The structure is defined (in part) as:<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>typedef<br>
- struct Display<br>
- {<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- ...<br>
- void &nbsp;&nbsp;&nbsp;&nbsp;(*error)(Display*, char*);<br>
- ...<br>
- Image &nbsp;&nbsp;&nbsp;*black;<br>
- Image &nbsp;&nbsp;&nbsp;*white;<br>
- Image &nbsp;&nbsp;&nbsp;*opaque;<br>
- Image &nbsp;&nbsp;&nbsp;*transparent;<br>
- Image &nbsp;&nbsp;&nbsp;*image;<br>
- Font &nbsp;&nbsp;&nbsp;&nbsp;*defaultfont;<br>
- Subfont*defaultsubfont;<br>
- ...<br>
-
- </table>
- };<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
-
- </table>
- A <tt><font size=+1>Point</font></tt> is a location in an Image (see below and <a href="../man3/draw.html"><i>draw</i>(3)</a>), such
- as the display, and is defined as:<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>typedef<br>
- struct Point {<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- int x;<br>
- int y;<br>
-
- </table>
- } Point;<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
-
- </table>
- The coordinate system has <i>x</i> increasing to the right and <i>y</i> increasing
- down.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- A <tt><font size=+1>Rectangle</font></tt> is a rectangular area in an image.<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>typedef<br>
- struct Rectangle {<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- Point min; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/* upper left */<br>
- Point max; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/* lower right */<br>
-
- </table>
- } Rectangle;<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
-
- </table>
- By definition, <tt><font size=+1>min.x</font></tt>&le;<tt><font size=+1>max.x</font></tt> and <tt><font size=+1>min.y</font></tt>&le;<tt><font size=+1>max.y</font></tt>. By convention, the right
- (maximum <i>x</i>) and bottom (maximum <i>y</i>) edges are excluded from the
- represented rectangle, so abutting rectangles have no points in
- common. Thus, <tt><font size=+1>max</font></tt> contains the coordinates of the first point
- beyond the rectangle.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- The <tt><font size=+1>Image</font></tt> data structure is defined in <a href="../man3/draw.html"><i>draw</i>(3)</a>.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- A <tt><font size=+1>Font</font></tt> is a set of character images, indexed by runes (see <a href="../man7/utf.html"><i>utf</i>(7)</a>).
- The images are organized into <tt><font size=+1>Subfonts</font></tt>, each containing the images
- for a small, contiguous set of runes. The detailed format of these
- data structures, which are described in detail in <a href="../man3/cachechars.html"><i>cachechars</i>(3)</a>,
- is immaterial for most applications. <tt><font size=+1>Font</font></tt> and
- <tt><font size=+1>Subfont</font></tt> structures contain two interrelated fields: <tt><font size=+1>ascent</font></tt>, the
- distance from the top of the highest character (actually the top
- of the image holding all the characters) to the baseline, and
- <tt><font size=+1>height</font></tt>, the distance from the top of the highest character to
- the bottom of the lowest character (and hence, the interline
- spacing). See <a href="../man3/cachechars.html"><i>cachechars</i>(3)</a> for more details.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- <i>Buildfont</i> parses the font description in the buffer <tt><font size=+1>desc</font></tt>, returning
- a <tt><font size=+1>Font*</font></tt> pointer that can be used by <tt><font size=+1>string</font></tt> (see <a href="../man3/draw.html"><i>draw</i>(3)</a>) to draw
- characters from the font. <i>Openfont</i> does the same, but reads the
- description from the named file. <i>Freefont</i> frees a font. The convention
- for naming font files is:
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>/lib/font/bit/</font></tt><i>name</i><tt><font size=+1>/</font></tt><i>range</i><tt><font size=+1>.</font></tt><i>size</i><tt><font size=+1>.font
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
-
- </table>
- where <i>size</i> is approximately the height in pixels of the lower
- case letters (without ascenders or descenders). <i>Range</i> gives some
- indication of which characters will be available: for example
- <tt><font size=+1>ascii</font></tt>, <tt><font size=+1>latin1</font></tt>, <tt><font size=+1>euro</font></tt>, or <tt><font size=+1>unicode</font></tt>. <tt><font size=+1>Euro</font></tt> includes most European languages,
- punctuation marks, the International Phonetic
- Alphabet, etc., but no Oriental languages. <tt><font size=+1>Unicode</font></tt> includes every
- character for which appropriate-sized images exist on the system.
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- A <i>Cursor</i> is defined:<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>typedef struct<br>
- Cursor {<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- Point offset;<br>
- uchar clr[2*16];<br>
- uchar set[2*16];<br>
-
- </table>
- } Cursor;<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
- </font></tt>
-
- </table>
- The arrays are arranged in rows, two bytes per row, left to right
- in big-endian order to give 16 rows of 16 bits each. A cursor
- is displayed on the screen by adding <tt><font size=+1>offset</font></tt> to the current mouse
- position, using <tt><font size=+1>clr</font></tt> as a mask to draw white at the pixels where
- <tt><font size=+1>clr</font></tt> is one, and then drawing black at the pixels where <tt><font size=+1>set
- </font></tt>is one.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- The routine <i>initdraw</i> connects to the display; it returns &ndash;1 if
- it fails and sets the error string. <i>Initdraw</i> sets up the global
- variables <tt><font size=+1>display</font></tt> (the <tt><font size=+1>Display</font></tt> structure representing the connection),
- <tt><font size=+1>screen</font></tt> (an <tt><font size=+1>Image</font></tt> representing the display memory itself or, if
- <a href="../man1/rio.html"><i>rio</i>(1)</a> is running, the client&#8217;s window), and <tt><font size=+1>font</font></tt> (the
- default font for text). The arguments to <i>initdraw</i> include a <i>label</i>,
- which is written to <tt><font size=+1>/dev/label</font></tt> if non-nil so that it can be used
- to identify the window when hidden (see <a href="../man1/rio.html"><i>rio</i>(1)</a>). The font is created
- by reading the named <i>font</i> file. If <tt><font size=+1>font</font></tt> is null, <i>initdraw</i> reads
- the file named in the environment variable <tt><font size=+1>$font</font></tt>; if
- <tt><font size=+1>$font</font></tt> is not set, it imports the default (usually minimal) font
- from the operating system. The global <i>font</i> will be set to point
- to the resulting <tt><font size=+1>Font</font></tt> structure. The <i>errfun</i> argument is a <i>graphics
- error function</i> to call in the event of a fatal error in the library;
- it must never return. Its arguments are the display pointer
- and an error string. If <i>errfun</i> is nil, the library provides a
- default, called <i>drawerror</i>. Another effect of <i>initdraw</i> is that
- it installs <a href="../man3/print.html"><i>print</i>(3)</a> formats <i>Pfmt</i> and <i>Rfmt</i> as <tt><font size=+1>%P</font></tt> and <tt><font size=+1>%R</font></tt> for printing
- <tt><font size=+1>Points</font></tt> and <tt><font size=+1>Rectangles</font></tt>.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- The <i>geninitdraw</i> function provides a less automated way to establish
- a connection, for programs that wish to connect to multiple displays.
- <i>Devdir</i> is the name of the directory containing the device files
- for the display (if nil, default <tt><font size=+1>/dev</font></tt>); <i>errfun</i>, <i>font</i>, and <i>label</i>
- are as in <i>initdraw</i>; <i>mousedir</i> and <i>windir</i> are the directories
- holding the <tt><font size=+1>mouse</font></tt> and <tt><font size=+1>winname</font></tt> files; and <i>ref</i> specifies the refresh
- function to be used to create the window, if running under <a href="../man1/rio.html"><i>rio</i>(1)</a>
- (see <a href="../man3/window.html"><i>window</i>(3)</a>).
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- <i>Initdisplay</i> is part of <i>geninitdraw</i>; it sets up the display structures
- but does not allocate any fonts or call <i>getwindow</i>. The arguments
- are similar to those of <i>initdraw</i>; <i>win</i> names the directory, default
- <tt><font size=+1>/dev</font></tt>, in which the files associated with the window reside. <i>Closedisplay</i>
- disconnects the display and frees the associated
- data structures. <i>Getdefont</i> builds a <tt><font size=+1>Font</font></tt> structure from in-core
- data describing a default font. None of these routines is needed
- by most programs, since <i>initdraw</i> calls them as needed.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- The data structures associated with the display must be protected
- in a multi-process program, because they assume only one process
- will be using them at a time. Multi-process programs should set
- <tt><font size=+1>display&#8722;&gt;locking</font></tt> to <tt><font size=+1>1</font></tt>, to notify the library to use a locking protocol
- for its own accesses, and call <i>lockdisplay</i> and
- <i>unlockdisplay</i> around any calls to the graphics library that will
- cause messages to be sent to the display device. <i>Initdraw</i> and
- <i>geninitdraw</i> initialize the display to the locked state.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- <i>Getwindow</i> returns a pointer to the window associated with the
- application; it is called automatically by <i>initdraw</i> to establish
- the <tt><font size=+1>screen</font></tt> pointer but must be called after each resizing of the
- window to restore the library&#8217;s connection to the window. If <tt><font size=+1>rio</font></tt>
- is not running, it returns <tt><font size=+1>display&#8722;&gt;image</font></tt>; otherwise it
- negotiates with <tt><font size=+1>rio</font></tt> by looking in <tt><font size=+1>/dev/winname</font></tt> to find the name
- of the window and opening it using <tt><font size=+1>namedimage</font></tt> (see <a href="../man3/allocimage.html"><i>allocimage</i>(3)</a>).
- The resulting window will be created using the refresh method
- <i>ref</i> (see <a href="../man3/window.html"><i>window</i>(3)</a>); this should almost always be <tt><font size=+1>Refnone</font></tt> because
- <tt><font size=+1>rio</font></tt> provides backing store for the window.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- <i>Getwindow</i> overwrites the global variables <tt><font size=+1>screen</font></tt>, a pointer to
- the <tt><font size=+1>Image</font></tt> defining the window (or the overall display, if no window
- system is running); and <tt><font size=+1>_screen</font></tt>, a pointer to the <tt><font size=+1>Screen</font></tt> representing
- the root of the window&#8217;s hierarchy. (See <a href="../man3/window.html"><i>window</i>(3)</a>. The overloading
- of the <tt><font size=+1>screen</font></tt> word is an unfortunate
- historical accident.) <i>Getwindow</i> arranges that <tt><font size=+1>screen</font></tt> point to
- the portion of the window inside the border; sophisticated clients
- may use <tt><font size=+1>_screen</font></tt> to make further subwindows. <i>Gengetwindow</i>&#8217;s extra
- arguments are the full path of the window&#8217;s <tt><font size=+1>winname</font></tt> file and pointers
- to be overwritten with the values of the
- &#8216;global&#8217; <tt><font size=+1>Image</font></tt> and <tt><font size=+1>Screen</font></tt> variables for the new window.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- The mouse cursor is always displayed. The initial cursor is an
- arrow. <i>Cursorswitch</i> causes the argument cursor to be displayed
- instead. A zero argument causes a switch back to the arrow cursor.
- <i>Cursorset</i> moves the mouse cursor to position <i>p</i>, provided (if in
- a window) that the requesting program is executing in the
- current window and the mouse is within the window boundaries;
- otherwise <i>cursorset</i> is a no-op.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- The graphics functions described in <a href="../man3/draw.html"><i>draw</i>(3)</a>, <a href="../man3/allocimage.html"><i>allocimage</i>(3)</a>, <a href="../man3/cachechars.html"><i>cachechars</i>(3)</a>,
- and <a href="../man3/subfont.html"><i>subfont</i>(3)</a> are implemented by writing commands to files under
- <tt><font size=+1>/dev/draw</font></tt> (see <a href="../man3/draw.html"><i>draw</i>(3)</a>); the writes are buffered, so the functions
- may not take effect immediately. <i>Flushimage</i> flushes the buffer,
- doing all pending graphics operations. If
- <i>vis</i> is non-zero, any changes are also copied from the &#8216;soft screen&#8217;
- (if any) in the driver to the visible frame buffer. The various
- allocation routines in the library flush automatically, as does
- the event package (see <a href="../man3/event.html"><i>event</i>(3)</a>); most programs do not need to
- call <i>flushimage</i>. It returns &ndash;1 on error.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- <i>Bufimage</i> is used to allocate space for <i>n</i> bytes in the display
- buffer. It is used by all the graphics routines to send messages
- to the display.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- The functions <i>strtochan</i> and <i>chantostr</i> convert between the channel
- descriptor strings used by <a href="../man7/image.html"><i>image</i>(7)</a> and the internal <tt><font size=+1>ulong</font></tt> representation
- used by the graphics protocol (see <a href="../man3/draw.html"><i>draw</i>(3)</a>&#8217;s <tt><font size=+1>b</font></tt> message). <tt><font size=+1>Chantostr</font></tt>
- writes at most nine bytes into the buffer pointed at by <i>s</i> and
- returns <i>s</i> on success, 0 on failure.
- <tt><font size=+1>Chantodepth</font></tt> returns the number of bits per pixel used by the format
- specified by <i>chan</i>. Both <tt><font size=+1>chantodepth</font></tt> and <tt><font size=+1>strtochan</font></tt> return 0 when
- presented with bad input.<br>
-
-</table>
-<p><font size=+1><b>EXAMPLES </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- To reconnect to the window after a resize event,<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>if(getwindow(display, Refnone) &lt; 0)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- sysfatal(&quot;resize failed: %r&quot;);<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- </table>
- </font></tt>
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
-
-
- </table>
-
- </table>
- To create and set up a new <a href="../man1/rio.html"><i>rio</i>(1)</a> window,<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>Image *screen2;<br>
- Screen *_screen2;<br>
- srvwsys = getenv(&quot;wsys&quot;);<br>
- if(srvwsys == nil)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- sysfatal(&quot;can't find $wsys: %r&quot;);<br>
-
- </table>
- rfork(RFNAMEG); /* keep mount of rio private */<br>
- fd = open(srvwsys, ORDWR);<br>
- if(fd &lt; 0)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- sysfatal(&quot;can't open $wsys: %r&quot;);<br>
-
- </table>
- /* mount creates window; see</font></tt> <i>rio</i><tt><font size=+1>(4) */<br>
- if(mount(fd, &#8722;1, &quot;/tmp&quot;, MREPL, &quot;new &#8722;dx 300&#8722;dy 200&quot;) &lt; 0)<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- sysfatal(&quot;can't mount new window: %r&quot;);<br>
-
- </table>
- if(gengetwindow(display, &quot;/tmp/winname&quot;,<br>
-
- <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- &amp;screen2, &amp;_screen2, Refnone) &lt; 0)<br>
- sysfatal(&quot;resize failed: %r&quot;);<br>
-
- </table>
- /* now open /tmp/cons, /tmp/mouse */<br>
- ...<br>
- </font></tt>
- </table>
-
-</table>
-<p><font size=+1><b>FILES </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>/usr/local/plan9/font/bit </font></tt>&nbsp;&nbsp;&nbsp;directory of fonts<br>
-
-</table>
-<p><font size=+1><b>SOURCE </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <tt><font size=+1>/usr/local/plan9/src/libdraw<br>
- </font></tt>
-</table>
-<p><font size=+1><b>SEE ALSO </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- <a href="../man1/rio.html"><i>rio</i>(1)</a>, <a href="../man3/addpt.html"><i>addpt</i>(3)</a>, <a href="../man3/allocimage.html"><i>allocimage</i>(3)</a>, <a href="../man3/cachechars.html"><i>cachechars</i>(3)</a>, <a href="../man3/subfont.html"><i>subfont</i>(3)</a>, <a href="../man3/draw.html"><i>draw</i>(3)</a>,
- <a href="../man3/event.html"><i>event</i>(3)</a>, <a href="../man3/frame.html"><i>frame</i>(3)</a>, <a href="../man3/print.html"><i>print</i>(3)</a>, <a href="../man3/window.html"><i>window</i>(3)</a>, <a href="../man3/draw.html"><i>draw</i>(3)</a>, <a href="../man7/image.html"><i>image</i>(7)</a>, <a href="../man7/font.html"><i>font</i>(7)</a><br>
-
-</table>
-<p><font size=+1><b>DIAGNOSTICS </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- An error function may call <a href="../man3/errstr.html"><i>errstr</i>(3)</a> for further diagnostics.<br>
-
-</table>
-<p><font size=+1><b>BUGS </b></font><br>
-
-<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
-
- The names <tt><font size=+1>clr</font></tt> and <tt><font size=+1>set</font></tt> in the <tt><font size=+1>Cursor</font></tt> structure are reminders of
- an archaic color map and might be more appropriately called <tt><font size=+1>white</font></tt>
- and <tt><font size=+1>black</font></tt>.
- <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
-
- These manual pages contain many references to the now-fictitious
- <tt><font size=+1>/dev/draw</font></tt>.<br>
-
-</table>
-
-<td width=20>
-<tr height=20><td>
-</table>
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