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<html>
<head>
<title>NX Graphics Subsystem</title>
<meta name="author" content="Gregory Nutt">
</head>

<body background="backgd.gif">
<hr><hr>
<table width ="100%">
  <tr align="center" bgcolor="#e4e4e4">
    <td>
      <h1><big><font color="#3c34ec">
        <i>NX Graphics Subsystem</i>
      </font></big></h1>
      <p>Last Updated: December 5, 2008</p>
    </td>
  </tr>
</table>
<hr><hr>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
    <td>
      <h1>Table of Contents</h1>
    </td>
  </tr>
</table>

<table width="100%">
<tr>
  <td align="left" valign="top">
  <p>
   <big><b>1.0</b> <a href="#Introduction">Introduction</a></big>
  </p>
  <ul>
    <p>
     <i><b>1.1</b> <a href="#Overview">Overview</a><br></i>
     <i><b>1.2</b> <a href="#Objectives">Objectives</a></i><br>
     <i><b>1.3</b> <a href="#Organization">Organization</a></i>
    </p>
    <p>
      <ul>
        <i>1.3.1 <a href="#nxgl1">NX Graphics Library (<code>NXGL</code>)</a></i><br>
        <i>1.3.2 <a href="#nx1">NX (NXSU and NXMU)</a></i><br>
        <i>1.3.3 <a href="#nxtk1">NX Tool Kit (<code>NXTK</code>)</a></i><br>
        <i>1.3.4 <a href="#nxfonts1">NX Fonts Support (<code>NXFONTS</code>)</a></i><br>
        <i>1.3.5 <a href="#nxwidgets1">NX Widgets (<code>NXWIDGETS</code>)</a></i>
      </ul>
    </p>
  </ul>
  <p>
    <big><b>2.0</b> <a href="#nxapis">NX User APIs</a></big>
  </p>
  <ul>
    <p>
      <i><b>2.1</b> <a href="#nxheaders">NX Header Files</a></i><br>
      <i><b>2.2</b> <a href="#nxgl2">NX Graphics Library (<code>NXGL</code>)</a></i>
    </p>
    <p>
      <ul>
        <i>2.2.1 <a href="#nxgltypes">NXGL Types</a></i><br>
        <i>2.2.1 <a href="#nxglrgb2yuv"><code>nxgl_rgb2yuv()</code></a></i><br>
        <i>2.2.2 <a href="#nxglyuv2rgb"><code>nxgl_yuv2rgb()</code></a></i><br>
        <i>2.2.3 <a href="#nxglrectcopy"><code>nxgl_rectcopy()</code></a></i><br>
        <i>2.2.4 <a href="#nxglrectoffset"><code>nxgl_rectoffset()</code></a></i><br>
        <i>2.2.5 <a href="#nxglvectoradd"><code>nxgl_vectoradd()</code></a></i><br>
        <i>2.2.6 <a href="#nxglvectorsubtract"><code>nxgl_vectorsubtract()</code></a></i><br>
        <i>2.2.7 <a href="#nxglrectintersect"><code>nxgl_rectintersect()</code></a></i><br>
        <i>2.2.8 <a href="#nxglrectunion"><code>nxgl_rectunion()</code></a></i><br>
        <i>2.2.9 <a href="#nxglnonintersecting"><code>nxgl_nonintersecting()</code></a></i><br>
        <i>2.2.10 <a href="#nxglrectoverlap"><code>nxgl_rectoverlap()</code></a></i><br>
        <i>2.2.11 <a href="#nxglrectinside"><code>nxgl_rectinside()</code></a></i><br>
        <i>2.2.12 <a href="#nxglrectsize"><code>nxgl_rectsize()</code></a></i><br>
        <i>2.2.13 <a href="#nxglnullrect"><code>nxgl_nullrect()</code></a></i><br>
        <i>2.2.14 <a href="#nxglrunoffset"><code>nxgl_runoffset()</code></a></i><br>
        <i>2.2.15 <a href="#nxglruncopy"><code>nxgl_runcopy()</code></a></i><br>
        <i>2.2.16 <a href="#nxgltrapoffset"><code>nxgl_trapoffset()</code></a></i><br>
        <i>2.2.17 <a href="#nxgltrapcopy"><code>nxgl_trapcopy()</code></a></i><br>
        <i>2.2.18 <a href="#nxglcolorcopy"><code>nxgl_colorcopy</code></a></i>
      </ul>
     </p>
   <p>
     <i><b>2.3</b> <a href="#nx2">NX</a></i>
   </p>
   <p>
     <ul>
        <i>2.3.1 <a href="#nxppdefs">Pre-Processor Definitions</a></i><br>
        <i>2.3.2 <a href="#nxtypes">NX Types</a></i><br>
        <i>2.3.3 <a href="#nxtypes">NX Server Callbacks</a></i>
        <p>
          <ul>
            <i>2.3.3.1 <a href="#nxcbredraw"><code>redraw()</code></a></i><br>
            <i>2.3.3.2 <a href="#nxcbposition"><code>position()</code></a></i><br>
            <i>2.3.3.3 <a href="#nxcbmousein"><code>mousein()</code></a></i><br>
            <i>2.3.3.4 <a href="#nxcbkbdin"><code>kbdin()</code></a></i>
          </ul>
        <p>
        <i>2.3.4 <a href="#nxruninstance"><code>nx_runinstance()</code> (and <code>nx_run()<code> macro)</a></i><br>
        <i>2.3.5 <a href="#nxconnectinstance"><code>nx_connectinstance()</code> (and <code>nx_connect()</code> macro)</a></i><br>
        <i>2.3.6 <a href="#nxopen"><code>nx_open()</code></a></i><br>
        <i>2.3.7 <a href="#nxdisconnect"><code>nx_disconnect()</code></a></i><br>
        <i>2.3.8 <a href="#nxclose"><code>nx_close()</code></a></i><br>
        <i>2.3.9 <a href="#nxeventhandler"><code>nx_eventhandler()</code></a></i><br>
        <i>2.3.10 <a href="#nxeventnotify"><code>nx_eventnotify()</code></a></i><br>
        <i>2.3.11 <a href="#nxopenwindow"><code>nx_openwindow()</code></a></i><br>
        <i>2.3.12 <a href="#nxclosewindow"><code>nx_closewindow()</code></a></i><br>
        <i>2.3.13 <a href="#nxrequestbkgd"><code>nx_requestbkgd()</code></a></i><br>
        <i>2.3.14 <a href="#nxreleasebkgd"><code>nx_releasebkgd()</code></a></i><br>
        <i>2.3.15 <a href="#nxgetposition"><code>nx_getposition()</code></a></i><br>
        <i>2.3.16 <a href="#nxsetposition"><code>nx_setposition()</code></a></i><br>
        <i>2.3.17 <a href="#nxsetsize"><code>nx_setsize()</code></a></i><br>
        <i>2.3.18 <a href="#nxraise"><code>nx_raise()</code></a></i><br>
        <i>2.3.19 <a href="#nxlower"><code>nx_lower()</code></a></i><br>
        <i>2.3.20 <a href="#nxfill"><code>nx_fill()</code></a></i><br>
        <i>2.3.21 <a href="#nxfilltrapezoid"><code>nx_filltrapezoid()</code></a></i><br>
        <i>2.3.22 <a href="#nxglrgb2yuv"><code>nx_setbgcolor()</code></a></i><br>
        <i>2.3.23 <a href="#nxmove"><code>nx_move()</code></a></i><br>
        <i>2.3.24 <a href="#nxbitmap"><code>nx_bitmap()</code></a></i><br>
        <i>2.3.25 <a href="#nxkbdin"><code>nx_kbdin()</code></a></i><br>
        <i>2.3.26 <a href="#nxmousein"><code>nx_mousein()</code></a></i><br>
     </ul>
   </p>
  </td>
  <td align="left" valign="top">
   <p>
     <i><b>2.4</b> <a href="#nxtk2">NX Tool Kit (<code>NXTK</code>)</a></i>
   </p>
   <p>
     <ul>
        <i>2.4.1 <a href="#nxtktypes"><code>NXTK Types()</code></a></i><br>
        <i>2.4.2 <a href="#nxtkopenwindow"><code>nxtk_openwindow()</code></a></i><br>
        <i>2.4.3 <a href="#nxtkclosewindow"><code>nxtk_closewindow()</code></a></i><br>
        <i>2.4.4 <a href="#nxtkgetposition"><code>nxtk_getposition()</code></a></i><br>
        <i>2.4.5 <a href="#nxtksetposition"><code>nxtk_setposition()</code></a></i><br>
        <i>2.4.6 <a href="#nxtksetsize"><code>nxtk_setsize()</code></a></i><br>
        <i>2.4.7 <a href="#nxtkraise"><code>nxtk_raise()</code></a></i><br>
        <i>2.4.8 <a href="#nxtklower"><code>nxtk_lower()</code></a></i><br>
        <i>2.4.9 <a href="#nxtkfillwindow"><code>nxtk_fillwindow()</code></a></i><br>
        <i>2.4.10 <a href="#nxtkfilltrapwindow"><code>nxtk_filltrapwindow()</code></a></i><br>
        <i>2.4.11 <a href="#nxtkmovewindow"><code>nxtk_movewindow()</code></a></i><br>
        <i>2.4.12 <a href="#nxtkbitmapwindow"><code>nxtk_bitmapwindow()</code></a></i><br>
        <i>2.4.13 <a href="#nxtkopentoolbar"><code>nxtk_opentoolbar()</code></a></i><br>
        <i>2.4.14 <a href="#nxtkclosetoolbar"><code>nxtk_closetoolbar()</code></a></i><br>
        <i>2.4.15 <a href="#nxtkfilltoolbar"><code>nxtk_filltoolbar()</code></a></i><br>
        <i>2.4.16 <a href="#nxtkfilltraptoolbar"><code>nxtk_filltraptoolbar()</code></a></i><br>
        <i>2.4.17 <a href="#nxtkmovetoolbar"><code>nxtk_movetoolbar()</code></a></i><br>
        <i>2.4.18 <a href="#nxtkbitmaptoolbar"><code>nxtk_bitmaptoolbar()</code></a></i>
     </ul>
   </p>
   <p>
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     <i><b>2.5</b> <a href="#nxfonts2">NX Fonts Support (<code>NXFONTS</code>)</a></i>
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   </p>
   <p>
     <ul>
        <i>2.5.1 <a href="#nxfontstypes"><code>NXFONTS Types()</code></a></i><br>
        <i>2.5.2 <a href="#nxfgetfontset"><code>nxf_getfontset()</code></a></i><br>
        <i>2.5.3 <a href="#nxfgetbitmap"><code>nxf_getbitmap()</code></a></i><br>
        <i>2.5.4 <a href="#nxfconvertbpp"><code>nxf_convert_*bpp()</code></a></i>
     </ul>
   </p>
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   <p>
     <i><b>2.6</b> <a href="#samplecode">Sample Code</a></i>
   </p>
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  </ul>
  <p>
    <big><b>Appendix A</b> <a href="#grapicsdirs"><code>graphics/</code> Directory Structure</a></big><br>
    <big><b>Appendix B</b> <a href="#nxconfigs">NX Configuration Options</a></big>
  </p>
  <p>
    <ul>
      <i><b>B.1</b> <a href="#nxgenconfig">General Configuration Settings</a></i><br>
      <i><b>B.2</b> <a href="#nxglconfig">NXGL Configuration Settings</a></i><br>
      <i><b>B.3</b> <a href="#nxconfig">NX Configuration Settings</a></i><br>
      <i><b>B.4</b> <a href="#nxmuconfig">NX Multi-User (Only) Configuration Settings</a></i><br>
      <i><b>B.5</b> <a href="#nxtkconfig">NXTK Configuration Settings</a></i><br>
      <i><b>B.6</b> <a href="#nxfpmtsconfig">NXFONTS Configuration Settings</a></i>
    </ul>
  </p>
  <p>
    <big><b>Appendix C</b> <a href="#testcoverage">NX Test Coverage</a></big>
  </p>
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    <ul>
      <i><b>Table C.1:</b> <a href="#nxglibcoverage">NXGLIB API Test Coverage</a></i><br>
      <i><b>Table C.2:</b> <a href="#nxcbcoverage">NX Server Callbacks Test Coverage</a></i><br>
      <i><b>Table C.3:</b> <a href="#nxcoverage">NX API Test Coverage</a></i><br>
      <i><b>Table C.4:</b> <a href="#nxtkcoverage">NXTK API Test Coverage</a></i><br>
      <i><b>Table C.5:</b> <a href="#nxfontscoverage">NXFONTS API Test Coverage</a></i><br>
    </ul>
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  </td>
  </tr>
</table>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
    <td>
      <h1>1.0 <a name="Introduction">Introduction</a></h1>
    </td>
  </tr>
</table>

<h2>1.1 <a name="Overview">Overview</a></h2>
<p>
  This document describes the tiny graphics support included in NuttX.
  It includes an overview description of that graphics support, detailed
  descriptions of the NuttX graphics APIs, and discussion of code organization,
  and OS configuration options.
</p>

<center><table width="480">
  <tr>
    <td><a name="screenshot"><img src="NuttXScreenShot.jpg"></a></td>
  </tr>
  <tr>
    <td><small>Figure 1.
    This sceen shot shows the final frame for the NuttX example at <code>examples/nx</code>
    running on the simulated, Linux x86 platform with simulated framebuffer output to
    an X window.
    This picture shows to framed windows with (blank) toolbars.
    Each window has displayed text as received from the NX keyboard interface
    The second window has just been raised to the top of the display.
    </small>
  </tr>
</table></center>


<h2>1.2 <a name="Objectives">Objectives</a></h2>

<p>
  The objective of this development was to provide a tiny windowing system in the
  spirit of X, but greatly scaled down and appropriate for most resource-limited
  embedded environments.
  The current NX implementation supports the general following, high-level features:
</p>
<ul>
  <li><b>Virtual Vertical Graphics Space</b>.
    Windows that reside in a virtual, <i>vertical</i> space so that it makes
    sense to talk about one window being on top of another and obcuring the
    window below it.
  </li>
  <li><b>Client/Server Model</b>.
    A standard client server/model was adopted.  NX may be considered a server
    and other logic that presents the windows are NX clients.
  </li>
  <li><b>Single- and Multi-User Support</b>.
    NX includes <i>front-end</i> logic to either a simple single-thread/single-user
    architecture or a separate NX server thread that can serve multiple NX client threads.
    In the single-user case, the NX <i>server</i> is simply a set of library
    calls;  in the multi-user case, NX is a server thread/daemon the serializes
    graphics operations from multiple clients.
    Other some unique start-up/connection logic, the APIs supported by the single-user
    and multi-user front-ends are identical.
    Providing both front-ends is consistent with the NuttX commitment to scalability.
  </li>
  <li><b>Minimal Graphics Toolset</b>.
    The actual implementation of the graphics operations is performed by common,
    <i>back-end</i> logic.  This back-end supports only a primitive set of graphic
    and rendering operations.
  </li>
  <li><b>Framebuffer Device Interface</b>.
    NX supports any graphics device using the NuttX framebuffer <i>driver</i>
    interface.
    (However, the dependency of NX on framebuffer drivers is minimal and the
    logic could be extended to other interfaces -- such as a serial LCD -- with
    some minimal effort).
  <li><b>Transparent to NX Client</b>.
    The window client on &quot;sees&quot; the sub-window that is operates in
    and does not need to be concerned with the virtual, vertical space (other
    that to respond to <i>redraw</i> requests from NX when needed).
  </li>
  <li><b>Framed Windows and Toolbars</b>.
    NX also adds the capability to support windows with frames and toolbars on
    top of the basic windowing support.
    These are windows such as those shown in the
    <a href="#screenshot">screenshot</a> above.
    These framed windows sub-divide one one window into three relatively independent
    subwindows:  A frame, the contained window and an (optional) toolbar window.
  </li>
  <li><b>Mouse Support</b>.
    NX provides support for a mouse or other X/Y pointing devices.
    APIs are provided to allow external devices to give X/Y position information
    and mouse button presses to NX.
    NX will then provide the mouse input to the relevant window clients via callbacks.
    Client windows only receive the mouse input callback if the mouse is positioned over a visible
    portion of the client window; X/Y position is provided to the client in the relative
    coordinate system of the client window.
  </li>
  <li><b>Keyboard input</b>.
    NX also supports keyboard/keypad devices.
    APIs are provided to allow external devices to give keypad information to NX.
    NX will then provide the mouse input to the top window on the display (the window
    that has the <i>focus</i>) via a callback function.
  </li>
</ul>

<h2>1.3 <a name="Organization">Organization</a></h2>

<p>
  NX is organized into 6 (and perhaps someday 7 or 8) logical modules.
  These logical modules also correspond to the directory organization.
  That NuttX directory organization is discussed in 
  <a href="#grapicsdirs">Appendix B</a> of this document.
  The logic modules are discussed in the following sub-paragraphs.
</p>

<p>
  <center><img src="NXOrganization.gif" width="60%"></center>
</p>

<h3>1.3.1 <a name="nxgl1">NX Graphics Library (<code>NXGL</code>)</a></h3>

<p>
  NXGLIB is a standalone library that contains low-level graphics utilities and
  direct framebuffer rendering logic. NX is built on top NXGLIB.
</p>

<h3>1.3.2 <a name="nx1">NX (<code>NXSU</code> and <code>NXMU</code>)</a></h3>

<p>
  NX is the tiny NuttX windowing system for raw windows (i.e., simple regions of
  graphics memory).
  NX includes both a small-footprint, single user implementaton (NXSU) and a somewhat
  larger multi-user implentation (NXMU as described below).
  Both conform to the same APIs as defined in <code>include/nuttx/nx.h</code> and, hence,
  are interchangable<sup>1</sup>.
  NX can be used without NXWIDGETS and without NXTOOLKIT for raw window displays.
</p>

<p>
  <sup>1</sup><small>NXMU and NXSU are interchangeable other than (1) certain start-up
  and intialization APIs (as described below), and (2) timing.  With NXSU, NX APIs
  execute immediately; with NXMU, NX APIs defer and serialize the operations and, hence,
  introduce different timing and potential race conditions that you would not experience
  with NXSU.</small>
</p>

<p><b>NXNULL?</b>
  At one time, I also envisoned a <i>NULL</i> front-end that did not support windowing
  at all but, rather, simply provided the entire framebuffer memory as one dumb window.
  This has the advantage that the same NX APIs can be used on the one dumb window as
  for the other NX windows.
  This would be in the NuttX spirit of scalability.
</p>
<p>
  However, the same end result can be obtained by using the
  <a href="nxrequestbkgd"><code>nx_requestbkgd()</code></a> API.
  It still may be possible to reduce the footprint in this usage case by developing
  and even thinner NXNULL front-end.
  That is a possible future development.
</p>

<h3>1.3.3 <a name="nxtk1">NX Tool Kit (<code>NXTK</code>)</a></h3>

<p>
  NXTK is a s set of C graphics tools that provide higher-level window drawing
  operations.
  This is the module where the framed windows and toolbar logic is implemented.
  NXTK is built on top of NX and does not depend on NXWIDGETS.
</p>

<h3>1.3.4 <a name="nxfonts1">NX Fonts Support (<code>NXFONTS</code>)</a></h3>

<p>
  A set of C graphics tools for present (bitmap) font images.
  The font implementation is at a very low level or graphics operation,
  comparable to the logic in NXGLIB.
  NXFONTS does not depend on any NX module other than some utilities and types from NXGLIB.
</p>

<h3>1.3.5 <a name="nxwidgets1">NX Widgets (<code>NXWIDGETS</code>)</a></h3>

<p>
  I had originally planned a high level, C++, object-oriented library for
  object-oriented access to graphics <i>widgets</i>.
  However, C++ compilers are not available for some of the targets supported by NuttX.
  So I have decided to implement the entire solution in  C.
  That decision makes the solution somewhat more difficult to work with, but supports all platforms.
</p>
<p>
  At this point, the amount of C in the implementation would make conversion to C++ a
  more difficult job.
  I leave the C++ widget interface to any contributor who may have an interest in such things.
</p>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
    <td>
      <h1>2.0 <a name="nxapis">NX User APIs</a></h1>
    </td>
  </tr>
</table>

<h2>2.1 <a name="nxheaders">NX Header Files</a></h2>

<ul><dl>
  <dt><code>include/nuttx/nxglib.h
    <dd>Describes the NXGLIB C interfaces
  <dt><code>include/nuttx/nx.h
    <dd>Describes the NX C interfaces
  <dt><code>include/nutt/nxtk.h
    <dd>Describe the NXTOOLKIT C interfaces
  <dt><code>include/nutt/nxfont.h
    <dd>Describe sthe NXFONT C interfaces
  <dt><code>include/nuttx/nxwidgets.h
    <dd>Will describe the NXWIDGETS classes (no longer planned)
</dl></ul>

<h2>2.2 <a name="nxgl2">NX Graphics Library (<code>NXGL</code>)</a></h2>

<p>
  NXGL provides many APIs, some available for use internally by NX and
  others for use by applications as well.
  Only those APIs intended for application usage are documented here
  See <code>include/nuttx/nxglib.h</code> for the full set of APIs;
  those APIs might be of interest if you are rendering directly into
  framebuffer memory.
</p>

<h3>2.2.1 <a name="nxgltypes">NXGL Types</a></h3>

<p>
  <code>nxgl_mxpixel_t</code>.
  Holds one device pixel.
  NXGLIB will select the smallest size for the <code>nxgl_mxpixel_t</code>
  that just contains the pixel:  <code>byte</code> if 16, 24, and 32 resolution
  support is disabled, <code>uint16</code> if 24, and 32 resolution
  support is disabled, or <code>uint32</code>.
</p>

<p>
  <code>nxgl_coord_t</b>
  A given coordinate is limited to the screen height an width.  If either
  of those values exceed 32,767 pixels, then the following will have to need
  to change:
</p>
<ul><pre>
typedef sint16 nxgl_coord_t;
</pre></ul>

<p>
  <code>struct nxgl_point_s</code>. Describes a point on the display:
</p>
<ul><pre>
struct nxgl_point_s
{
  nxgl_coord_t x;         /* X position, range: 0 to screen width - 1 */
  nxgl_coord_t y;         /* Y position, range: 0 to screen height - 1 */
};
</pre></ul>

<p>
  <code>struct nxgl_size_s</code>. Describes the size of a rectangular region.
</p>
<ul><pre>
struct nxgl_size_s
{
  nxgl_coord_t w;        /* Width in pixels */
  nxgl_coord_t h;        /* Height in rows */
};
</pre></ul>

<p>
  <code>struct nxgl_rect_s</code>. Describes a positioned rectangle on the display.
</p>
<ul><pre>
struct nxgl_rect_s
{
  struct nxgl_point_s pt1; /* Upper, left-hand corner */
  struct nxgl_point_s pt2; /* Lower, right-hand corner */
};
</pre></ul>

<p>
  <code>struct nxgl_run_s</code>.
  Describes a run, i.e., a horizontal line.  Note that the start/end positions
  have fractional precision.  This is necessary for good joining of trapezoids
  when a more complex shape is decomposed into trapezoids
</p>
<ul><pre>
struct nxgl_run_s
{
  b16_t        x1;        /* Left X position, range: 0 to x2 */
  b16_t        x2;        /* Right X position, range: x1 to screen width - 1 */
  nxgl_coord_t y;         /* Top Y position, range: 0 to screen height - 1 */
};
</pre></ul>

<p>
  <code>struct nxgl_trapezoid_s</code>.
  Describes a horizontal trapezoid on the display in terms the run at the
  top of the trapezoid and the run at the bottom
</p>
<ul><pre>
struct nxgl_trapezoid_s
{
  struct nxgl_run_s top;  /* Top run */
  struct nxgl_run_s bot;  /* bottom run */
};
</pre></ul>

<h3>2.2.1 <a name="nxglrgb2yuv"><code>nxgl_rgb2yuv()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_rgb2yuv(ubyte r, ubyte g, ubyte b, ubyte *y, ubyte *u, ubyte *v);
</pre></ul>
<p>
  <b>Description:</b>
  Convert 8-bit RGB triplet to 8-bit YUV triplet.
</p>

<h3>2.2.2 <a name="nxglyuv2rgb"><code>nxgl_yuv2rgb()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_yuv2rgb(ubyte y, ubyte u, ubyte v, ubyte *r, ubyte *g, ubyte *b);
</pre></ul>
<p>
  <b>Description:</b>
  Convert 8-bit RGB triplet to 8-bit YUV triplet.
</p>

<h3>2.2.3 <a name="nxglrectcopy"><code>nxgl_rectcopy()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_rectcopy(FAR struct nxgl_rect_s *dest,
                   FAR const struct nxgl_rect_s *src);
</pre></ul>
<p>
  <b>Description:</b>
  This is essentially <code>memcpy()</code>for rectangles.  We don't do structure
  assignments because some compilers are not good at that.
</p>

<h3>2.2.4 <a name="nxglrectoffset"><code>nxgl_rectoffset()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_rectoffset(FAR struct nxgl_rect_s *dest,
                     FAR const struct nxgl_rect_s *src,
                     nxgl_coord_t dx, nxgl_coord_t dy);
</pre></ul>
<p>
  <b>Description:</b>
   Offset the rectangle position by the specified dx, dy values.
</p>

<h3>2.2.5 <a name="nxglvectoradd"><code>nxgl_vectoradd()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_vectoradd(FAR struct nxgl_point_s *dest,
                    FAR const struct nxgl_point_s *v1,
                    FAR const struct nxgl_point_s *v2);
</pre></ul>
<p>
  <b>Description:</b>
  Add two 2x1 vectors and save the result to a third.
</p>

<h3>2.2.6 <a name="nxglvectorsubtract"><code>nxgl_vectorsubtract()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_vectsubtract(FAR struct nxgl_point_s *dest,
                       FAR const struct nxgl_point_s *v1,
                       FAR const struct nxgl_point_s *v2);
</pre></ul>
<p>
  <b>Description:</b>
  Add subtract vector <code>v2</code> from vector <code>v1</code> and return the result in vector dest.
</p>

<h3>2.2.7 <a name="nxglrectintersect"><code>nxgl_rectintersect()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_rectintersect(FAR struct nxgl_rect_s *dest,
                        FAR const struct nxgl_rect_s *src1,
                        FAR const struct nxgl_rect_s *src2);
</pre></ul>
<p>
  <b>Description:</b>
   Return the rectangle representing the intersection of the two rectangles.
</p>

<h3>2.2.8 <a name="nxglrectunion"><code>nxgl_rectunion()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_rectunion(FAR struct nxgl_rect_s *dest,
                    FAR const struct nxgl_rect_s *src1,
                    FAR const struct nxgl_rect_s *src2);
</pre></ul>
<p>
  <b>Description:</b>
  Given two rectanges, <code>src1</code> and <code>src2</code>, return the larger rectangle that 
  contains both, <code>dest</code>.
</p>

<h3>2.2.9 <a name="nxglnonintersecting"><code>nxgl_nonintersecting()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
nxgl_nonintersecting(FAR struct nxgl_rect_s result[4],
                     FAR const struct nxgl_rect_s *rect1,
                     FAR const struct nxgl_rect_s *rect2);
</pre></ul>
<p>
  <b>Description:</b>
  Return the regions of rectangle <code>rect1</code> that do not intersect with
  <code>rect2</code>.  This will four rectangles, some of which may be
  degenerate (and can be picked off with <a href="#nxglnullrect"><code>nxgl_nullrect()<code></a>).
</p>

<h3>2.2.10 <a name="nxglrectoverlap"><code>nxgl_rectoverlap()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
boolean nxgl_rectoverlap(FAR struct nxgl_rect_s *rect1,
                         FAR struct nxgl_rect_s *rect2);
</pre></ul>
<p>
  <b>Description:</b>
  Return TRUE if the two rectangles overlap.
</p>

<h3>2.2.11 <a name="nxglrectinside"><code>nxgl_rectinside()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
boolean nxgl_rectinside(FAR const struct nxgl_rect_s *rect,
                        FAR const struct nxgl_point_s *pt);
</pre></ul>
<p>
  <b>Description:</b>
  Return TRUE if the point <code>pt</code> lies within <code>rect</code>.
</p>

<h3>2.2.12 <a name="nxglrectsize"><code>nxgl_rectsize()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_rectsize(FAR struct nxgl_size_s *size,
                   FAR const struct nxgl_rect_s *rect);
</pre></ul>
<p>
  <b>Description:</b>
  Return the size of the specified rectangle.
</p>

<h3>2.2.13 <a name="nxglnullrect"><code>nxgl_nullrect()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
boolean nxgl_nullrect(FAR const struct nxgl_rect_s *rect);
</pre></ul>
<p>
  <b>Description:</b>
   Return TRUE if the area of the retangle is &lt;= 0.
</p>

<h3>2.2.14 <a name="nxglrunoffset"><code>nxgl_runoffset()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_runoffset(FAR struct nxgl_run_s *dest,
                    FAR const struct nxgl_run_s *src,
                    nxgl_coord_t dx, nxgl_coord_t dy);
</pre></ul>
<p>
  <b>Description:</b>
  Offset the run position by the specified <code>dx</code>, <code>dy</code> values.
</p>

<h3>2.2.15 <a name="nxglruncopy"><code>nxgl_runcopy()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_runcopy(FAR struct nxgl_run_s *dest,
                  FAR const struct nxgl_run_s *src);
</pre></ul>
<p>
  <b>Description:</b>
  This is essentially <code>memcpy()</code>for runs.  We don't do structure assignments
  because some compilers are not good at that.
</p>

<h3>2.2.16 <a name="nxgltrapoffset"><code>nxgl_trapoffset()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_trapoffset(FAR struct nxgl_trapezoid_s *dest,
                     FAR const struct nxgl_trapezoid_s *src,
                     nxgl_coord_t dx, nxgl_coord_t dy);
</pre></ul>
<p>
  <b>Description:</b>
  Offset the trapezoid position by the specified <code>dx</code>, <code>dy</code> values.
</p>

<h3>2.2.1 <a name="nxgltrapcopy"><code>nxgl_trapcopy()</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
void nxgl_trapcopy(FAR struct nxgl_trapezoid_s *dest,
                   FAR const struct nxgl_trapezoid_s *src);
</pre></ul>
<p>
  <b>Description:</b>
  This is essentially <code>memcpy()</code>for trapezoids.  We don't do structure
  assignments because some compilers are not good at that.
</p>

<h3>2.2.1 <a name="nxglcolorcopy"><code>nxgl_colorcopy</code></a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
nxgl_colorcopy(nxgl_mxpixel_t dest[CONFIG_NX_NPLANES],
               const nxgl_mxpixel_t src[CONFIG_NX_NPLANES]);
</pre></ul>
<p>
  <b>Description:</b>
  This is essentially <code>memcpy()</code>for colors.  This does very little for us
  other than hide all of the conditional compilation for planar colors
  in one place.
</p>

<h2>2.3 <a name="nx2">NX</a></h2>

<h3>2.3.1 <a name="nxppdefs">Pre-Processor Definitions</a></h3>

<p>
  The default server message queue name used by the
  <a href="#nxruninstance"><code>nx_run()</code></a> macro:
</p>
<ul><pre>
#define NX_DEFAULT_SERVER_MQNAME "/dev/nxs"
</pre></ul>

<p>
  Mouse button bits:
</p>
<ul><pre>
#define NX_MOUSE_NOBUTTONS    0x00
#define NX_MOUSE_LEFTBUTTON   0x01
#define NX_MOUSE_CENTERBUTTON 0x02
#define NX_MOUSE_RIGHTBUTTON  0x04
</pre></ul>

<h3>2.3.2 <a name="nxtypes">NX Types</a></h3>

<p>
  The interface to the NX server is managed using a opaque handle:
</p>
<ul><pre>
typedef FAR void *NXHANDLE;
</pre></ul>

<p>
  The interface to a specific window is managed using an opaque handle:
</p>
<ul><pre>
typedef FAR void *NXWINDOW;
</pre></ul>

<p>
  These define callbacks that must be provided to
  <a href="#nxopenwindow"><code>nx_openwindow()</code></a>.
  In the multi-user model, these callbacks will be invoked as part of the
  processing performed by
  <a href="#nxeventhandler"><code>nx_eventhandler()</code></a>.
</p>
<ul><pre>
struct nx_callback_s
{
  void (*redraw)(NXWINDOW hwnd, FAR const struct nxgl_rect_s *rect,
                 boolean more, FAR void *arg);
  void (*position)(NXWINDOW hwnd, FAR const struct nxgl_size_s *size,
                   FAR const struct nxgl_point_s *pos,
                   FAR const struct nxgl_rect_s *bounds,
                   FAR void *arg);
#ifdef CONFIG_NX_MOUSE
  void (*mousein)(NXWINDOW hwnd, FAR const struct nxgl_point_s *pos,
                  ubyte buttons, FAR void *arg);
#endif
#ifdef CONFIG_NX_KBD
  void (*kbdin)(NXWINDOW hwnd, ubyte nch, FAR const ubyte *ch, FAR void *arg);
#endif
};
</pre></ul>

<h3>2.3.3 <a name="nxtypes">NX Server Callbacks</a></h3>

<h4>2.3.3.1 <a name="nxcbredraw"><code>redraw()</code></a></h4>
<p><b>Callback Function Prototype:</b></p>
<ul><pre>
void redraw(NXWINDOW hwnd, FAR const struct nxgl_rect_s *rect,
            boolean more, FAR void *arg);
</pre></ul>
<p>
  <b>Description:</b>
  NX requests that the client re-draw the portion of the window within
  with rectangle.
</p>
<p>
  <b>Input Parameters:</b>
  <ul><dl>
    <dt><code>hwnd</code>
    <dd>The handle created by <a href="#nxopenwindow"><code>nx_openwindow()</code></a>
      or <a href="#nxrequestbkgd"><code>nx_requestbkgd()</code></a>
    <dt><code>rect</code>
    <dd>The rectangle that needs to be re-drawn (in window relative coordinates)
    <dt><code>more</code>
    <dd>TRUE: More re-draw requests will follow
    <dt><code>arg</code>
    <dd>User provided argument (see <a href="#nxopenwindow"><code>nx_openwindow()</code></a>)
  </dl></ul>
</p>
<p>
  <b>Returned Value:</b> None
</p>

<h4>2.3.3.2 <a name="nxcbposition"><code>position()</code></a></h4>
<p><b>Callback Function Prototype:</b></p>
<ul><pre>
void position(NXWINDOW hwnd, FAR const struct nxgl_size_s *size,
              FAR const struct nxgl_point_s *pos,
              FAR const struct nxgl_rect_s *bounds,
              FAR void *arg);
</pre></ul>
<p>
  <b>Description:</b>
  The size or position of the window has changed (or the window was
  just created with zero size.
</p>
<p>
  <b>Input Parameters:</b>
  <ul><dl>
    <dt><code>hwnd</code>
    <dd>The handle created by <a href="#nxopenwindow"><code>nx_openwindow()</code></a>
      or <a href="#nxrequestbkgd"><code>nx_requestbkgd()</code></a>
    <dt><code>size</code>
    <dd>The size of the window
    <dt><code>pos</code>
    <dd>The position of the upper left hand corner of the window on
      the overall display
    <dt><code>bounds</code>
    <dd>The bounding rectangle that the describes the entire display
    <dt><code>arg</code>
    <dd>User provided argument (see <a href="#nxopenwindow"><code>nx_openwindow()</code></a>)
  </dl></ul>
</p>
<p>
  <b>Returned Value:</b> None
</p>

<h4>2.3.3.3 <a name="nxcbmousein"><code>mousein()</code></a></h4>
<p><b>Callback Function Prototype:</b></p>
<ul><pre>
#ifdef CONFIG_NX_MOUSE
void mousein(NXWINDOW hwnd, FAR const struct nxgl_point_s *pos,
             ubyte buttons, FAR void *arg);
#endif
</pre></ul>
<p>
  <b>Description:</b>
  New mouse data is available for the window
</p>
<p>
  <b>Input Parameters:</b>
  <ul><dl>
    <dt><code>hwnd</code>
    <dd>The handle created by <a href="#nxopenwindow"><code>nx_openwindow()</code></a>
      or <a href="#nxrequestbkgd"><code>nx_requestbkgd()</code></a>
    <dt><code>pos</code>
    <dd>The (x,y) position of the mouse
    <dt><code>buttons</code>
    <dd>See <code>NX_MOUSE_*</code> definitions
    <dt><code>arg</code>
    <dd>User provided argument (see <a href="#nxopenwindow"><code>nx_openwindow()</code></a>)
  </dl></ul>
</p>
<p>
  <b>Returned Value:</b> None
</p>

<h4>2.3.3.4 <a name="nxcbkbdin"><code>kbdin()</code></a></h4>
<p><b>Callback Function Prototype:</b></p>
<ul><pre>
#ifdef CONFIG_NX_KBD
void (*kbdin)(NXWINDOW hwnd, ubyte nch, FAR const ubyte *ch, FAR void *arg);
#endif
</pre></ul>
<p>
  <b>Description:</b>
  New keyboard/keypad data is available for the window.
</p>
<p>
  <b>Input Parameters:</b>
  <ul><dl>
    <dt><code>hwnd</code>
    <dd>The handle created by <a href="#nxopenwindow"><code>nx_openwindow()</code></a>
      or <a href="#nxrequestbkgd"><code>nx_requestbkgd()</code></a>
    <dt><code>nch</code>
    <dd>The number of characters that are available in ch[]
    <dt><code>ch</code>
    <dd>The array of characters
    <dt><code>arg</code>
    <dd>User provided argument (see <a href="#nxopenwindow"><code>nx_openwindow()</code></a>)
  </dl></ul>
</p>
<p>
  <b>Returned Value:</b> NOne
</p>

<h3>2.3.4 <a name="nxruninstance"><code>nx_runinstance()</code> (and <code>nx_run()<code> macro)</a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
#include &lt;nuttx/nx.h&gt;

#ifdef CONFIG_NX_MULTIUSER
int nx_runinstance(FAR const char *mqname, FAR struct fb_vtable_s *fb);
#define nx_run(fb) nx_runinstance(NX_DEFAULT_SERVER_MQNAME, fb)
#endif
</pre></ul>
<p>
  <b>Description:</b>
  This is the server entry point.  It does not return; the calling thread
  is dedicated to supporting NX server.
</p>
<p>
  NOTE that multiple instances of the NX server may run at the same time,
  with different callback and message queue names.  <code>nx_run()</code> is simply
  a macro that can be used when only one server instance is required.  In
  that case, a default server name is used.
</p>
<p>
  Multiple user mode only!
</p>
<p>
  <b>Input Parameters:</b>
  <ul><dl>
    <dt><code>mqname</code>
    <dd>
     - The name for the server incoming message queue
    <dt><code>fb</code>
    <dd>Vtable &quot;object&quot; of the framebuffer &quot;driver&quot; to use
  </dl></ul>
</p>
<p>
  <b>Returned Value:</b>
  This function usually does not return.  If it does return, it will
  return <code>ERROR</code> and <code>errno</code> will be set appropriately.
</p>

<h3>2.3.5 <a name="nxconnectinstance"><code>nx_connectinstance()</code> (and <code>nx_connect()</code> macro)</a></h3>
<p><b>Function Prototype:</b></p>
<ul><pre>
#include &lt;nuttx/nxglib.h&gt;
#include &lt;nuttx/nx.h&gt;

#ifdef CONFIG_NX_MULTIUSER
NXHANDLE nx_connectinstance(FAR const char *svrmqname);
#define nx_connect(cb) nx_connectinstance(NX_DEFAULT_SERVER_MQNAME)
#endif
</pre></ul>
<p>
  <b>Description:</b>
  Open a connection from a client to the NX server.  One one client
  connection is normally needed per thread as each connection can host
  multiple windows.
</p>
<p>
  NOTES:
</p>
<ul>
  <li>
    This function returns before the connection is fully instantiated.
    it is necessary to wait for the connection event before using the
    returned handle.
  </li>
  <li>
    Multiple instances of the NX server may run at the same time,
    each with different message queue names.
  </li>
  <li>
    <code>nx_connect()</code> is simply a macro that can be used when only one
    server instance is required.  In that case, a default server name
    is used.
  </li>
</ul>
<p>
  Multiple user mode only!
</p>
<p>
  <b>Input Parameters:</b>
  <ul><dl>
    <dt><code>svrmqname</code>
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