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<pre><a name="line-1"></a><span class='hs-comment'>{-
<a name="line-2"></a>Copyright (c) 2008, 2009
<a name="line-3"></a>Russell O'Connor
<a name="line-4"></a>
<a name="line-5"></a>Permission is hereby granted, free of charge, to any person obtaining a copy
<a name="line-6"></a>of this software and associated documentation files (the "Software"), to deal
<a name="line-7"></a>in the Software without restriction, including without limitation the rights
<a name="line-8"></a>to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
<a name="line-9"></a>copies of the Software, and to permit persons to whom the Software is
<a name="line-10"></a>furnished to do so, subject to the following conditions:
<a name="line-11"></a>
<a name="line-12"></a>The above copyright notice and this permission notice shall be included in
<a name="line-13"></a>all copies or substantial portions of the Software.
<a name="line-14"></a>
<a name="line-15"></a>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
<a name="line-16"></a>IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
<a name="line-17"></a>FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
<a name="line-18"></a>AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
<a name="line-19"></a>LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
<a name="line-20"></a>OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
<a name="line-21"></a>THE SOFTWARE.
<a name="line-22"></a>-}</span>
<a name="line-23"></a><span class='hs-comment'>-- |Datatypes for representing the human perception of colour.</span>
<a name="line-24"></a><span class='hs-comment'>-- Includes common operations for blending and compositing colours.</span>
<a name="line-25"></a><span class='hs-comment'>-- The most common way of creating colours is either by name</span>
<a name="line-26"></a><span class='hs-comment'>-- (see "Data.Colour.Names") or by giving an sRGB triple </span>
<a name="line-27"></a><span class='hs-comment'>-- (see "Data.Colour.SRGB").</span>
<a name="line-28"></a><span class='hs-comment'>--</span>
<a name="line-29"></a><span class='hs-comment'>-- Methods of specifying Colours can be found in </span>
<a name="line-30"></a><span class='hs-comment'>--</span>
<a name="line-31"></a><span class='hs-comment'>-- - "Data.Colour.SRGB"</span>
<a name="line-32"></a><span class='hs-comment'>--</span>
<a name="line-33"></a><span class='hs-comment'>-- - "Data.Colour.SRGB.Linear"</span>
<a name="line-34"></a><span class='hs-comment'>--</span>
<a name="line-35"></a><span class='hs-comment'>-- - "Data.Colour.CIE"</span>
<a name="line-36"></a><span class='hs-comment'>--</span>
<a name="line-37"></a><span class='hs-comment'>-- Colours can be specified in a generic 'Data.Colour.RGBSpace.RGBSpace'</span>
<a name="line-38"></a><span class='hs-comment'>-- by using</span>
<a name="line-39"></a><span class='hs-comment'>--</span>
<a name="line-40"></a><span class='hs-comment'>-- - "Data.Colour.RGBSpace"</span>
<a name="line-41"></a>
<a name="line-42"></a><span class='hs-varop'>--TODO</span>
<a name="line-43"></a><span class='hs-comment'>-- - "Data.Colour.HDTV"</span>
<a name="line-44"></a><span class='hs-comment'>--</span>
<a name="line-45"></a><span class='hs-comment'>-- - "Data.Colour.SDTV"</span>
<a name="line-46"></a>
<a name="line-47"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Colour</span>
<a name="line-48"></a> <span class='hs-layout'>(</span>
<a name="line-49"></a><span class='hs-comment'>-- *Interfacing with Other Libraries\' Colour Spaces</span>
<a name="line-50"></a><span class='hs-comment'>--</span>
<a name="line-51"></a><span class='hs-comment'>-- |Executive summary: Always use "Data.Colour.SRGB" when interfacing with</span>
<a name="line-52"></a><span class='hs-comment'>-- other libraries.</span>
<a name="line-53"></a><span class='hs-comment'>-- Use 'Data.Colour.SRGB.toSRGB24' \/ 'Data.Colour.SRGB.sRGB24' when</span>
<a name="line-54"></a><span class='hs-comment'>-- interfacing with libraries wanting 'Data.Word.Word8' per channel.</span>
<a name="line-55"></a><span class='hs-comment'>-- Use 'Data.Colour.SRGB.toSRGB' \/ 'Data.Colour.SRGB.sRGB' when</span>
<a name="line-56"></a><span class='hs-comment'>-- interfacing with libraries wanting 'Double' or 'Float' per channel.</span>
<a name="line-57"></a><span class='hs-comment'>--</span>
<a name="line-58"></a><span class='hs-comment'>-- Interfacing with the colour for other libraries, such as cairo</span>
<a name="line-59"></a><span class='hs-comment'>-- (<<a href="http://www.haskell.org/gtk2hs/archives/category/cairo/">http://www.haskell.org/gtk2hs/archives/category/cairo/</a>>) and OpenGL</span>
<a name="line-60"></a><span class='hs-comment'>-- (<<a href="http://hackage.haskell.org/cgi-bin/hackage-scripts/package/OpenGL">http://hackage.haskell.org/cgi-bin/hackage-scripts/package/OpenGL</a>>),</span>
<a name="line-61"></a><span class='hs-comment'>-- can be a challenge because these libraries often do not use colour spaces</span>
<a name="line-62"></a><span class='hs-comment'>-- in a consistent way.</span>
<a name="line-63"></a><span class='hs-comment'>-- The problem is that these libraries work in a device dependent colour</span>
<a name="line-64"></a><span class='hs-comment'>-- space and give no indication what the colour space is.</span>
<a name="line-65"></a><span class='hs-comment'>-- For most devices this colours space is implicitly the non-linear sRGB</span>
<a name="line-66"></a><span class='hs-comment'>-- space.</span>
<a name="line-67"></a><span class='hs-comment'>-- However, to make matters worse, these libraries also do their</span>
<a name="line-68"></a><span class='hs-comment'>-- compositing and blending in the device colour space.</span>
<a name="line-69"></a><span class='hs-comment'>-- Blending and compositing ought to be done in a linear colour space,</span>
<a name="line-70"></a><span class='hs-comment'>-- but since the device space is typically non-linear sRGB, these libraries</span>
<a name="line-71"></a><span class='hs-comment'>-- typically produce colour blends that are too dark.</span>
<a name="line-72"></a><span class='hs-comment'>--</span>
<a name="line-73"></a><span class='hs-comment'>-- (Note that "Data.Colour" is a device /independent/ colour space, and</span>
<a name="line-74"></a><span class='hs-comment'>-- produces correct blends. </span>
<a name="line-75"></a><span class='hs-comment'>-- e.g. compare @toSRGB (blend 0.5 lime red)@ with @RGB 0.5 0.5 0@)</span>
<a name="line-76"></a><span class='hs-comment'>--</span>
<a name="line-77"></a><span class='hs-comment'>-- Because these other colour libraries can only blend in device colour</span>
<a name="line-78"></a><span class='hs-comment'>-- spaces, they are fundamentally broken and there is no \"right\" way</span>
<a name="line-79"></a><span class='hs-comment'>-- to interface with them.</span>
<a name="line-80"></a><span class='hs-comment'>-- For most libraries, the best one can do is assume they are working</span>
<a name="line-81"></a><span class='hs-comment'>-- with an sRGB colour space and doing incorrect blends. </span>
<a name="line-82"></a><span class='hs-comment'>-- In these cases use "Data.Colour.SRGB" to convert to and from the</span>
<a name="line-83"></a><span class='hs-comment'>-- colour coordinates. This is the best advice for interfacing with cairo.</span>
<a name="line-84"></a><span class='hs-comment'>--</span>
<a name="line-85"></a><span class='hs-comment'>-- When using OpenGL, the choice is less clear.</span>
<a name="line-86"></a><span class='hs-comment'>-- Again, OpenGL usually does blending in the device colour space.</span>
<a name="line-87"></a><span class='hs-comment'>-- However, because blending is an important part of proper shading, one</span>
<a name="line-88"></a><span class='hs-comment'>-- may want to consider that OpenGL is working in a linear colour space,</span>
<a name="line-89"></a><span class='hs-comment'>-- and the resulting rasters are improperly displayed.</span>
<a name="line-90"></a><span class='hs-comment'>-- This is born out by the fact that OpenGL extensions that support</span>
<a name="line-91"></a><span class='hs-comment'>-- sRGB do so by converting sRGB input\/output to linear colour coordinates</span>
<a name="line-92"></a><span class='hs-comment'>-- for processing by OpenGL.</span>
<a name="line-93"></a><span class='hs-comment'>--</span>
<a name="line-94"></a><span class='hs-comment'>-- The best way to use OpenGL, is to use proper sRGB surfaces for textures</span>
<a name="line-95"></a><span class='hs-comment'>-- and rendering.</span>
<a name="line-96"></a><span class='hs-comment'>-- These surfaces will automatically convert to and from OpenGL's linear</span>
<a name="line-97"></a><span class='hs-comment'>-- colour space.</span>
<a name="line-98"></a><span class='hs-comment'>-- In this case, use "Data.Colour.SRGB.Linear" to interface OpenGL's linear</span>
<a name="line-99"></a><span class='hs-comment'>-- colour space.</span>
<a name="line-100"></a><span class='hs-comment'>--</span>
<a name="line-101"></a><span class='hs-comment'>-- If not using proper surfaces with OpenGL, then you have a choice between</span>
<a name="line-102"></a><span class='hs-comment'>-- having OpenGL do improper blending or improper display</span>
<a name="line-103"></a><span class='hs-comment'>-- If you are using OpenGL for 3D shading, I recommend using</span>
<a name="line-104"></a><span class='hs-comment'>-- "Data.Colour.SRGB.Linear" (thus choosing improper OpenGL display).</span>
<a name="line-105"></a><span class='hs-comment'>-- If you are not using OpenGL for 3D shading, I recommend using</span>
<a name="line-106"></a><span class='hs-comment'>-- "Data.Colour.SRGB" (thus choosing improper OpenGL blending).</span>
<a name="line-107"></a>
<a name="line-108"></a><span class='hs-comment'>-- *Colour type</span>
<a name="line-109"></a> <span class='hs-conid'>Colour</span>
<a name="line-110"></a> <span class='hs-layout'>,</span><span class='hs-varid'>colourConvert</span>
<a name="line-111"></a> <span class='hs-layout'>,</span><span class='hs-varid'>black</span>
<a name="line-112"></a>
<a name="line-113"></a> <span class='hs-layout'>,</span><span class='hs-conid'>AlphaColour</span>
<a name="line-114"></a> <span class='hs-layout'>,</span><span class='hs-varid'>opaque</span><span class='hs-layout'>,</span> <span class='hs-varid'>withOpacity</span>
<a name="line-115"></a> <span class='hs-layout'>,</span><span class='hs-varid'>transparent</span>
<a name="line-116"></a> <span class='hs-layout'>,</span><span class='hs-varid'>alphaColourConvert</span>
<a name="line-117"></a> <span class='hs-layout'>,</span><span class='hs-varid'>alphaChannel</span>
<a name="line-118"></a>
<a name="line-119"></a> <span class='hs-comment'>-- *Colour operations</span>
<a name="line-120"></a> <span class='hs-comment'>-- |These operations allow combine and modify existing colours</span>
<a name="line-121"></a> <span class='hs-layout'>,</span><span class='hs-conid'>AffineSpace</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-varid'>blend</span>
<a name="line-122"></a>
<a name="line-123"></a> <span class='hs-layout'>,</span><span class='hs-conid'>ColourOps</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-124"></a> <span class='hs-layout'>,</span><span class='hs-varid'>dissolve</span><span class='hs-layout'>,</span> <span class='hs-varid'>atop</span>
<a name="line-125"></a> <span class='hs-layout'>)</span>
<a name="line-126"></a><span class='hs-keyword'>where</span>
<a name="line-127"></a>
<a name="line-128"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Char</span>
<a name="line-129"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Colour</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span>
<a name="line-130"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Colour</span><span class='hs-varop'>.</span><span class='hs-conid'>SRGB</span><span class='hs-varop'>.</span><span class='hs-conid'>Linear</span>
<a name="line-131"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Colour</span><span class='hs-varop'>.</span><span class='hs-conid'>CIE</span><span class='hs-varop'>.</span><span class='hs-conid'>Chromaticity</span> <span class='hs-layout'>(</span><span class='hs-varid'>app_prec</span><span class='hs-layout'>,</span> <span class='hs-varid'>infix_prec</span><span class='hs-layout'>)</span>
<a name="line-132"></a>
<a name="line-133"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Fractional</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Show</span> <span class='hs-layout'>(</span><span class='hs-conid'>Colour</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-134"></a> <span class='hs-varid'>showsPrec</span> <span class='hs-varid'>d</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showParen</span> <span class='hs-layout'>(</span><span class='hs-varid'>d</span> <span class='hs-varop'>></span> <span class='hs-varid'>app_prec</span><span class='hs-layout'>)</span> <span class='hs-varid'>showStr</span>
<a name="line-135"></a> <span class='hs-keyword'>where</span>
<a name="line-136"></a> <span class='hs-varid'>showStr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showString</span> <span class='hs-varid'>linearConstructorQualifiedName</span>
<a name="line-137"></a> <span class='hs-varop'>.</span> <span class='hs-varid'>showString</span> <span class='hs-str'>" "</span> <span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-varid'>showsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>app_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-138"></a> <span class='hs-varop'>.</span> <span class='hs-varid'>showString</span> <span class='hs-str'>" "</span> <span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-varid'>showsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>app_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>g</span><span class='hs-layout'>)</span>
<a name="line-139"></a> <span class='hs-varop'>.</span> <span class='hs-varid'>showString</span> <span class='hs-str'>" "</span> <span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-varid'>showsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>app_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-140"></a> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Colour</span><span class='hs-varop'>.</span><span class='hs-conid'>SRGB</span><span class='hs-varop'>.</span><span class='hs-conid'>Linear</span><span class='hs-varop'>.</span><span class='hs-conid'>RGB</span> <span class='hs-varid'>r</span> <span class='hs-varid'>g</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Colour</span><span class='hs-varop'>.</span><span class='hs-conid'>SRGB</span><span class='hs-varop'>.</span><span class='hs-conid'>Linear</span><span class='hs-varop'>.</span><span class='hs-varid'>toRGB</span> <span class='hs-varid'>c</span>
<a name="line-141"></a>
<a name="line-142"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Fractional</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Read</span> <span class='hs-layout'>(</span><span class='hs-conid'>Colour</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-143"></a> <span class='hs-varid'>readsPrec</span> <span class='hs-varid'>d</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>readParen</span> <span class='hs-layout'>(</span><span class='hs-varid'>d</span> <span class='hs-varop'>></span> <span class='hs-varid'>app_prec</span><span class='hs-layout'>)</span>
<a name="line-144"></a> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Colour</span><span class='hs-varop'>.</span><span class='hs-conid'>SRGB</span><span class='hs-varop'>.</span><span class='hs-conid'>Linear</span><span class='hs-varop'>.</span><span class='hs-varid'>rgb</span> <span class='hs-varid'>r0</span> <span class='hs-varid'>g0</span> <span class='hs-varid'>b0</span><span class='hs-layout'>,</span><span class='hs-varid'>t</span><span class='hs-layout'>)</span>
<a name="line-145"></a> <span class='hs-keyglyph'>|</span><span class='hs-layout'>(</span><span class='hs-varid'>name</span><span class='hs-layout'>,</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>mylex</span> <span class='hs-varid'>r</span>
<a name="line-146"></a> <span class='hs-layout'>,</span><span class='hs-varid'>name</span> <span class='hs-varop'>`elem`</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>linearConstructorName</span>
<a name="line-147"></a> <span class='hs-layout'>,</span><span class='hs-varid'>linearConstructorQualifiedName</span><span class='hs-keyglyph'>]</span>
<a name="line-148"></a> <span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>r0</span><span class='hs-layout'>,</span><span class='hs-varid'>s0</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>app_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>s</span>
<a name="line-149"></a> <span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>g0</span><span class='hs-layout'>,</span><span class='hs-varid'>s1</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>app_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>s0</span>
<a name="line-150"></a> <span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>b0</span><span class='hs-layout'>,</span><span class='hs-varid'>t</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>app_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>s1</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span>
<a name="line-151"></a> <span class='hs-keyword'>where</span>
<a name="line-152"></a> <span class='hs-varid'>mylex</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span>
<a name="line-153"></a> <span class='hs-varop'>.</span> <span class='hs-varid'>span</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>isAlphaNum</span> <span class='hs-varid'>c</span> <span class='hs-varop'>||</span> <span class='hs-varid'>c</span> <span class='hs-varop'>`elem`</span> <span class='hs-str'>"._'"</span><span class='hs-layout'>)</span>
<a name="line-154"></a> <span class='hs-varop'>.</span> <span class='hs-varid'>dropWhile</span> <span class='hs-varid'>isSpace</span>
<a name="line-155"></a>
<a name="line-156"></a><a name="linearConstructorQualifiedName"></a><span class='hs-definition'>linearConstructorQualifiedName</span> <span class='hs-keyglyph'>=</span> <span class='hs-str'>"Data.Colour.SRGB.Linear.rgb"</span>
<a name="line-157"></a><a name="linearConstructorName"></a><span class='hs-definition'>linearConstructorName</span> <span class='hs-keyglyph'>=</span> <span class='hs-str'>"rgb"</span>
<a name="line-158"></a>
<a name="line-159"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Fractional</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Show</span> <span class='hs-layout'>(</span><span class='hs-conid'>AlphaColour</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-160"></a> <span class='hs-varid'>showsPrec</span> <span class='hs-varid'>d</span> <span class='hs-varid'>ac</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>a</span> <span class='hs-varop'>==</span> <span class='hs-num'>0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showString</span> <span class='hs-str'>"transparent"</span>
<a name="line-161"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showParen</span> <span class='hs-layout'>(</span><span class='hs-varid'>d</span> <span class='hs-varop'>></span> <span class='hs-varid'>infix_prec</span><span class='hs-layout'>)</span> <span class='hs-varid'>showStr</span>
<a name="line-162"></a> <span class='hs-keyword'>where</span>
<a name="line-163"></a> <span class='hs-varid'>showStr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>infix_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>c</span>
<a name="line-164"></a> <span class='hs-varop'>.</span> <span class='hs-varid'>showString</span> <span class='hs-str'>" `withOpacity` "</span>
<a name="line-165"></a> <span class='hs-varop'>.</span> <span class='hs-varid'>showsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>infix_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>a</span>
<a name="line-166"></a> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>alphaChannel</span> <span class='hs-varid'>ac</span>
<a name="line-167"></a> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>colourChannel</span> <span class='hs-varid'>ac</span>
<a name="line-168"></a>
<a name="line-169"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Fractional</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Read</span> <span class='hs-layout'>(</span><span class='hs-conid'>AlphaColour</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-170"></a> <span class='hs-varid'>readsPrec</span> <span class='hs-varid'>d</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>transparent</span><span class='hs-layout'>,</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>|</span><span class='hs-layout'>(</span><span class='hs-str'>"transparent"</span><span class='hs-layout'>,</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lex</span> <span class='hs-varid'>r</span><span class='hs-keyglyph'>]</span>
<a name="line-171"></a> <span class='hs-varop'>++</span> <span class='hs-varid'>readParen</span> <span class='hs-layout'>(</span><span class='hs-varid'>d</span> <span class='hs-varop'>></span> <span class='hs-varid'>infix_prec</span><span class='hs-layout'>)</span>
<a name="line-172"></a> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>c</span> <span class='hs-varop'>`withOpacity`</span> <span class='hs-varid'>o</span><span class='hs-layout'>,</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span>
<a name="line-173"></a> <span class='hs-keyglyph'>|</span><span class='hs-layout'>(</span><span class='hs-varid'>c</span><span class='hs-layout'>,</span><span class='hs-varid'>r0</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>infix_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span>
<a name="line-174"></a> <span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-str'>"`"</span><span class='hs-layout'>,</span><span class='hs-varid'>r1</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lex</span> <span class='hs-varid'>r0</span>
<a name="line-175"></a> <span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-str'>"withOpacity"</span><span class='hs-layout'>,</span><span class='hs-varid'>r2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lex</span> <span class='hs-varid'>r1</span>
<a name="line-176"></a> <span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-str'>"`"</span><span class='hs-layout'>,</span><span class='hs-varid'>r3</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lex</span> <span class='hs-varid'>r2</span>
<a name="line-177"></a> <span class='hs-layout'>,</span><span class='hs-layout'>(</span><span class='hs-varid'>o</span><span class='hs-layout'>,</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readsPrec</span> <span class='hs-layout'>(</span><span class='hs-varid'>infix_prec</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>r3</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span>
</pre></body>
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