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authorscuri <scuri>2008-10-17 06:10:33 +0000
committerscuri <scuri>2008-10-17 06:10:33 +0000
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+<!doctype HTML PUBLIC "-//IETF//DTD HTML//EN">
+<html>
+ <head>
+ <title>Color Coding</title>
+ <meta http-equiv="Content-Language" content="en-us">
+ <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
+ <link rel="stylesheet" type="text/css" href="../../style.css">
+ </head>
+ <body>
+ <h2 align="center">Color Coding</h2>
+ <p>The library's color system is RGB. In order to simplify some functions, a
+ compact representation was created for the 3 values. To make a conversion from
+ this representation to the 3 separate values and vice-versa, use functions
+ <b> <font>cdDecodeColor</font></b>
+ and <b> <font>cdEncodeColor</font></b>.
+ </p>
+ <p>When the canvas used does not support more than 8 bpp of color resolution, you
+ can use function <b> <font>Palette</font></b> to give the driver an idea of which
+ colors to prioritize. <b> <font>Palette</font>'s</b> behavior is driver dependent.</p>
+ <p>There are some predefined colors:</p>
+ <pre>CD_RED = (255, 0, 0)
+CD_DARK_RED = (128, 0, 0)
+CD_GREEN = (0 ,255, 0)
+CD_DARK_GREEN = ( 0,128, 0)
+CD_BLUE = ( 0, 0,255)
+CD_DARK_BLUE = ( 0, 0,128)
+CD_YELLOW = (255,255, 0)
+CD_DARK_YELLOW = (128,128, 0)
+CD_MAGENTA = (255, 0,255)
+CD_DARK_MAGENTA = (128, 0,128)
+CD_CYAN = ( 0,255,255)
+CD_DARK_CYAN = ( 0,128,128)
+CD_WHITE = (255,255,255)
+CD_BLACK = ( 0, 0 , 0)
+CD_DARK_GRAY = (128,128,128)
+CD_GRAY = (192,192,192)
+</pre>
+ <hr>
+ <pre class="function"><span class="mainFunction">long int <a name="cdEncodeColor">cdEncodeColor</a>(unsigned char red, unsigned char green, unsigned char blue) [in C]</span>
+
+cd.EncodeColor(r, g, b: number) -&gt; (old_color: lightuserdata) [in Lua]</pre>
+ <p>Returns a codified triple (<em>r,g,b</em>) in a long integer such as <b><tt>0x00RRGGBB</tt></b>,
+ where <tt><b>RR</b> </tt>are the red components, <b><tt>GG</tt></b> are the
+ green ones and <b><tt>BB</tt></b> are the blue ones. The code is used in the CD
+ library to define colors. It can be used without an active canvas.</p>
+ <pre class="function"><span class="mainFunction">void <a name="cdDecodeColor">cdDecodeColor</a>(long int color, unsigned char *red, unsigned char *green, unsigned char *blue) [in C]</span>
+
+cd.DecodeColor(color: lightuserdata) -&gt; (r, g, b: number) [in Lua]</pre>
+ <p>Returns the red, green and blue components of a color in the CD library. Can
+ be used without an active canvas.</p>
+ <pre class="function"><span class="mainFunction">long int <a name="cdEncodeAlpha">cdEncodeAlpha</a>(long int color, unsigned char alpha) [in C]</span>
+
+cd.EncodeAlpha(color: lightuserdata, alpha: number) -&gt; (color: lightuserdata) [in Lua]</pre>
+ <p>Returns the given color coded with the alpha information. ATENTION: At the
+ moment only the Win32 with GDI+ and the IMAGERGB drivers support alpha
+ components in color coding. Se in <a href="../drv/gdiplus.html">Windows Using
+ GDI+ Base Driver</a> and <a href="../drv/irgb.html">IMAGERGB driver</a>. The
+ internal representation of the component is inverted, because the default value
+ must be 0 and opaque for backward compatibility, so you should use the <strong>cdDecodeAlpha</strong>
+ function ot the <strong>cdAlpha</strong> macro to retrieve the alpha component.</p>
+ <pre class="function"><span class="mainFunction">unsigned char <a name="cdDecodeAlpha">cdDecodeAlpha</a>(long int color) [in C]</span>
+
+cd.DecodeAlpha(color: lightuserdata) -&gt; (a: number) [in Lua]</pre>
+ <p>Returns the alpha component of a color in the CD library. Can be used without
+ an active canvas. 0 is transparent, 255 is opaque.</p>
+ <pre class="function"><span class="mainFunction">unsigned char <a name="cdRed0">cdAlpha</a>(long int color); [in C]</span>
+
+cd.Alpha(color: lightuserdata) -&gt; (r: number) [in Lua]</pre>
+ <p>Macro that returns the alpha component of a color in the CD library. Can be
+ used without an active canvas.</p>
+ <pre class="function"><span class="mainFunction">unsigned char <a name="cdRed">cdRed</a>(long int color); [in C]</span>
+
+cd.Red(color: lightuserdata) -&gt; (r: number) [in Lua]</pre>
+ <p>Macro that returns the red component of a color in the CD library. Can be used
+ without an active canvas.</p>
+ <pre class="function"><span class="mainFunction">unsigned char <a name="cdGreen">cdGreen</a>(long int color); [in C]</span>
+
+cd.Green(color: lightuserdata) -&gt; (g: number) [in Lua]</pre>
+ <p>Macro that returns the green component of a color in the CD library. Can be
+ used without an active canvas.</p>
+ <pre class="function"><span class="mainFunction">unsigned char <a name="cdBlue">cdBlue</a>(long int color); [in C]</span>
+
+cd.Blue(color: lightuserdata) -&gt; (b: number) [in Lua]</pre>
+ <p>Macro that returns the blue component of a color in the CD library. Can be
+ used without an active canvas.</p>
+ <hr>
+ <pre class="function"><span class="mainFunction">int <a name="cdGetColorPlanes">cdCanvasGetColorPlanes</a>(cdCanvas* canvas); [in C]</span>
+
+canvas:GetColorPlanes() -&gt; (bpp: number) [in Lua]</pre>
+ <p>Returns a given number, for instance <i>p</i>, which defines the number of
+ colors supported by the current device as <i>2<sup>p</sup></i>, representing
+ the number of bits by pixel.
+ </p>
+ <pre class="function"><span class="mainFunction">void <a name="cdPalette">cdCanvasPalette</a>(cdCanvas* canvas, int n, const long int *color, int mode); [in C]</span>
+
+canvas:Palette(palette: cdPalette; mode: number) [in Lua]</pre>
+ <p>In systems limited to 256 palette colors, this function aims at adding&nbsp; <b><tt>
+ n</tt></b> colors to the system's palette. In such systems, the colors
+ demanded forward or backward which are not in the palette are approximated to
+ the closest available color. The type can be <tt><b>CD_FORCE</b> </tt>or <b><tt>CD_POLITE</tt></b>.
+ <b><tt>CD_FORCE</tt></b> ignores the system colors and interface elements,
+ since the menus and dialogues may be in illegible colors, but there will be
+ more colors available. <tt><b>CD_POLITE</b></tt> is the recommended type. It
+ must always be used before drawing. It cannot be queried.</p>
+
+<h3><a name="Palette">Palette</a></h3>
+
+ <pre class="function"><a name="cdCreatePalette">cd.CreatePalette</a>(size: number) -&gt; (palette: cdPalette) [in Lua Only]</pre>
+ <p>Creates a palette.</p>
+ <pre class="function"><a name="cdKillPalette">cd.KillPalette</a>(palette: cdPalette) [in Lua Only]</pre>
+ <p>Destroys the created palette and liberates allocated memory. If this
+ function is not called in Lua, the garbage collector will call it.</p>
+
+<h3>Palette <a name="DataAccess">Data Access</a></h3>
+
+ <p>Data access in Lua is done directly using the array access operators. The
+ colors can have their values checked or changed directly as if they
+ were Lua tables:</p>
+
+ <pre>palette[index] = cd.EncodeColor(r, g, b)
+count = #palette
+...
+color = palette[index]
+r, g, b = cd.DecodeColor(color)</pre>
+
+ <p>Notice that the type of value returned or received by
+ <font size="3">palette[index]</font><font size="2"> </font>is a
+ <font>lightuserdata</font>, the same type used with functions <b>
+ <font size="3">cdEncodeColor</font></b>, <b>
+ <font size="3">cdDecodeColor</font></b>, <b>
+ <font size="3">cdPixel</font></b>, <b>
+ <font size="3">cdForeground</font></b><font size="2">
+ </font>and <b> <font size="3">cdBackground</font></b>.</p>
+
+
+ </body>
+</html> \ No newline at end of file