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<title>Graphics/Gloss/Data/Extent.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE PatternGuards #-}</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='hs-comment'>-- | Represents an integral rectangular area of the 2D plane.</span>
<a name="line-4"></a><span class='hs-comment'>-- Using `Int`s (instead of `Float`s) for the bounds means we can safely</span>
<a name="line-5"></a><span class='hs-comment'>-- compare extents for equality.</span>
<a name="line-6"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Gloss</span><span class='hs-varop'>.</span><span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Extent</span>
<a name="line-7"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>Extent</span>
<a name="line-8"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Coord</span>
<a name="line-9"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>makeExtent</span>
<a name="line-10"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>takeExtent</span>
<a name="line-11"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>squareExtent</span>
<a name="line-12"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>sizeOfExtent</span>
<a name="line-13"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>isUnitExtent</span>
<a name="line-14"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>coordInExtent</span>
<a name="line-15"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>pointInExtent</span>
<a name="line-16"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>centerCoordOfExtent</span>
<a name="line-17"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>cutQuadOfExtent</span>
<a name="line-18"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>quadOfCoord</span>
<a name="line-19"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>pathToCoord</span>
<a name="line-20"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>intersectSegExtent</span>
<a name="line-21"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>touchesSegExtent</span><span class='hs-layout'>)</span>
<a name="line-22"></a><span class='hs-keyword'>where</span>
<a name="line-23"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Gloss</span><span class='hs-varop'>.</span><span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Point</span>
<a name="line-24"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Gloss</span><span class='hs-varop'>.</span><span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Quad</span>
<a name="line-25"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Gloss</span><span class='hs-varop'>.</span><span class='hs-conid'>Geometry</span><span class='hs-varop'>.</span><span class='hs-conid'>Line</span>
<a name="line-26"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Maybe</span>
<a name="line-27"></a>
<a name="line-28"></a>
<a name="line-29"></a><a name="Extent"></a><span class='hs-comment'>-- | A rectangular area of the 2D plane.</span>
<a name="line-30"></a><a name="Extent"></a><span class='hs-comment'>-- We keep the type abstract to ensure that invalid extents cannot be</span>
<a name="line-31"></a><a name="Extent"></a><span class='hs-comment'>-- constructed.</span>
<a name="line-32"></a><a name="Extent"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Extent</span>
<a name="line-33"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Extent</span> <span class='hs-conid'>Int</span> <span class='hs-conid'>Int</span> <span class='hs-conid'>Int</span> <span class='hs-conid'>Int</span>
<a name="line-34"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-35"></a>
<a name="line-36"></a>
<a name="line-37"></a><a name="Coord"></a><span class='hs-comment'>-- | An integral coordinate.</span>
<a name="line-38"></a><a name="Coord"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Coord</span>
<a name="line-39"></a> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-conid'>Int</span><span class='hs-layout'>)</span>
<a name="line-40"></a>
<a name="line-41"></a>
<a name="line-42"></a><a name="makeExtent"></a><span class='hs-comment'>-- | Construct an extent.</span>
<a name="line-43"></a><span class='hs-comment'>-- The north value must be > south, and east > west, else `error`.</span>
<a name="line-44"></a><span class='hs-definition'>makeExtent</span>
<a name="line-45"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ y max (north)</span>
<a name="line-46"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ y min (south)</span>
<a name="line-47"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ x max (east)</span>
<a name="line-48"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ x min (west)</span>
<a name="line-49"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span>
<a name="line-50"></a>
<a name="line-51"></a><span class='hs-definition'>makeExtent</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-varid'>w</span>
<a name="line-52"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>n</span> <span class='hs-varop'>>=</span> <span class='hs-varid'>s</span><span class='hs-layout'>,</span> <span class='hs-varid'>e</span> <span class='hs-varop'>>=</span> <span class='hs-varid'>w</span>
<a name="line-53"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-varid'>w</span>
<a name="line-54"></a>
<a name="line-55"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-56"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"Graphics.Gloss.Geometry.Extent.makeExtent: invalid extent"</span>
<a name="line-57"></a>
<a name="line-58"></a>
<a name="line-59"></a><a name="takeExtent"></a><span class='hs-comment'>-- | Take the NSEW components of an extent.</span>
<a name="line-60"></a><span class='hs-definition'>takeExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-conid'>Int</span><span class='hs-layout'>)</span>
<a name="line-61"></a><span class='hs-definition'>takeExtent</span> <span class='hs-layout'>(</span><span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span>
<a name="line-62"></a> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span><span class='hs-layout'>,</span> <span class='hs-varid'>s</span><span class='hs-layout'>,</span> <span class='hs-varid'>e</span><span class='hs-layout'>,</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span>
<a name="line-63"></a>
<a name="line-64"></a>
<a name="line-65"></a><a name="squareExtent"></a><span class='hs-comment'>-- | A square extent of a given size.</span>
<a name="line-66"></a><span class='hs-definition'>squareExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span>
<a name="line-67"></a><span class='hs-definition'>squareExtent</span> <span class='hs-varid'>i</span>
<a name="line-68"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Extent</span> <span class='hs-varid'>i</span> <span class='hs-num'>0</span> <span class='hs-varid'>i</span> <span class='hs-num'>0</span>
<a name="line-69"></a>
<a name="line-70"></a>
<a name="line-71"></a><a name="sizeOfExtent"></a><span class='hs-comment'>-- | Get the width and height of an extent.</span>
<a name="line-72"></a><span class='hs-definition'>sizeOfExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-conid'>Int</span><span class='hs-layout'>)</span>
<a name="line-73"></a><span class='hs-definition'>sizeOfExtent</span> <span class='hs-layout'>(</span><span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span>
<a name="line-74"></a> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-comment'>-</span> <span class='hs-varid'>w</span><span class='hs-layout'>,</span> <span class='hs-varid'>n</span> <span class='hs-comment'>-</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span>
<a name="line-75"></a>
<a name="line-76"></a>
<a name="line-77"></a><a name="isUnitExtent"></a><span class='hs-comment'>-- | Check if an extent is a square with a width and height of 1.</span>
<a name="line-78"></a><span class='hs-definition'>isUnitExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-79"></a><span class='hs-definition'>isUnitExtent</span> <span class='hs-varid'>extent</span>
<a name="line-80"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sizeOfExtent</span> <span class='hs-varid'>extent</span> <span class='hs-varop'>==</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span>
<a name="line-81"></a>
<a name="line-82"></a>
<a name="line-83"></a><a name="coordInExtent"></a><span class='hs-comment'>-- | Check whether a coordinate lies inside an extent.</span>
<a name="line-84"></a><span class='hs-definition'>coordInExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Coord</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-85"></a><span class='hs-definition'>coordInExtent</span> <span class='hs-layout'>(</span><span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-86"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span> <span class='hs-varop'>>=</span> <span class='hs-varid'>w</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>x</span> <span class='hs-varop'><</span> <span class='hs-varid'>e</span>
<a name="line-87"></a> <span class='hs-varop'>&&</span> <span class='hs-varid'>y</span> <span class='hs-varop'>>=</span> <span class='hs-varid'>s</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>y</span> <span class='hs-varop'><</span> <span class='hs-varid'>n</span>
<a name="line-88"></a>
<a name="line-89"></a>
<a name="line-90"></a><a name="pointInExtent"></a><span class='hs-comment'>-- | Check whether a point lies inside an extent.</span>
<a name="line-91"></a><span class='hs-definition'>pointInExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Point</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-92"></a><span class='hs-definition'>pointInExtent</span> <span class='hs-layout'>(</span><span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-93"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>n'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>n</span>
<a name="line-94"></a> <span class='hs-varid'>s'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>s</span>
<a name="line-95"></a> <span class='hs-varid'>e'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>e</span>
<a name="line-96"></a> <span class='hs-varid'>w'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>w</span>
<a name="line-97"></a>
<a name="line-98"></a> <span class='hs-keyword'>in</span> <span class='hs-varid'>x</span> <span class='hs-varop'>>=</span> <span class='hs-varid'>w'</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>x</span> <span class='hs-varop'><=</span> <span class='hs-varid'>e'</span>
<a name="line-99"></a> <span class='hs-varop'>&&</span> <span class='hs-varid'>y</span> <span class='hs-varop'>>=</span> <span class='hs-varid'>s'</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>y</span> <span class='hs-varop'><=</span> <span class='hs-varid'>n'</span>
<a name="line-100"></a>
<a name="line-101"></a>
<a name="line-102"></a><a name="centerCoordOfExtent"></a><span class='hs-comment'>-- | Get the coordinate that lies at the center of an extent.</span>
<a name="line-103"></a><span class='hs-definition'>centerCoordOfExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-conid'>Int</span><span class='hs-layout'>)</span>
<a name="line-104"></a><span class='hs-definition'>centerCoordOfExtent</span> <span class='hs-layout'>(</span><span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span>
<a name="line-105"></a> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span> <span class='hs-varid'>w</span> <span class='hs-varop'>+</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-comment'>-</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span> <span class='hs-varop'>`div`</span> <span class='hs-num'>2</span>
<a name="line-106"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>s</span> <span class='hs-varop'>+</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-comment'>-</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-varop'>`div`</span> <span class='hs-num'>2</span><span class='hs-layout'>)</span>
<a name="line-107"></a>
<a name="line-108"></a>
<a name="line-109"></a><a name="cutQuadOfExtent"></a><span class='hs-comment'>-- | Cut one quadrant out of an extent.</span>
<a name="line-110"></a><span class='hs-definition'>cutQuadOfExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Quad</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span>
<a name="line-111"></a><span class='hs-definition'>cutQuadOfExtent</span> <span class='hs-varid'>quad</span> <span class='hs-layout'>(</span><span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span>
<a name="line-112"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>hheight</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-comment'>-</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-varop'>`div`</span> <span class='hs-num'>2</span>
<a name="line-113"></a> <span class='hs-varid'>hwidth</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-comment'>-</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span> <span class='hs-varop'>`div`</span> <span class='hs-num'>2</span>
<a name="line-114"></a> <span class='hs-keyword'>in</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>quad</span> <span class='hs-keyword'>of</span>
<a name="line-115"></a> <span class='hs-conid'>NW</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-layout'>(</span><span class='hs-varid'>s</span> <span class='hs-varop'>+</span> <span class='hs-varid'>hheight</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-comment'>-</span> <span class='hs-varid'>hwidth</span><span class='hs-layout'>)</span> <span class='hs-varid'>w</span>
<a name="line-116"></a> <span class='hs-conid'>NE</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span> <span class='hs-varid'>n</span> <span class='hs-layout'>(</span><span class='hs-varid'>s</span> <span class='hs-varop'>+</span> <span class='hs-varid'>hheight</span><span class='hs-layout'>)</span> <span class='hs-varid'>e</span> <span class='hs-layout'>(</span><span class='hs-varid'>w</span> <span class='hs-varop'>+</span> <span class='hs-varid'>hwidth</span><span class='hs-layout'>)</span>
<a name="line-117"></a> <span class='hs-conid'>SW</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-comment'>-</span> <span class='hs-varid'>hheight</span><span class='hs-layout'>)</span> <span class='hs-varid'>s</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-comment'>-</span> <span class='hs-varid'>hwidth</span><span class='hs-layout'>)</span> <span class='hs-varid'>w</span>
<a name="line-118"></a> <span class='hs-conid'>SE</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-comment'>-</span> <span class='hs-varid'>hheight</span><span class='hs-layout'>)</span> <span class='hs-varid'>s</span> <span class='hs-varid'>e</span> <span class='hs-layout'>(</span><span class='hs-varid'>w</span> <span class='hs-varop'>+</span> <span class='hs-varid'>hwidth</span><span class='hs-layout'>)</span>
<a name="line-119"></a>
<a name="line-120"></a>
<a name="line-121"></a><a name="quadOfCoord"></a><span class='hs-comment'>-- | Get the quadrant that this coordinate lies in, if any.</span>
<a name="line-122"></a><span class='hs-definition'>quadOfCoord</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Coord</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-conid'>Quad</span>
<a name="line-123"></a><span class='hs-definition'>quadOfCoord</span> <span class='hs-varid'>extent</span> <span class='hs-varid'>coord</span>
<a name="line-124"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>listToMaybe</span>
<a name="line-125"></a> <span class='hs-varop'>$</span> <span class='hs-varid'>filter</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>q</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>coordInExtent</span> <span class='hs-layout'>(</span><span class='hs-varid'>cutQuadOfExtent</span> <span class='hs-varid'>q</span> <span class='hs-varid'>extent</span><span class='hs-layout'>)</span> <span class='hs-varid'>coord</span><span class='hs-layout'>)</span>
<a name="line-126"></a> <span class='hs-varop'>$</span> <span class='hs-varid'>allQuads</span>
<a name="line-127"></a>
<a name="line-128"></a>
<a name="line-129"></a><a name="pathToCoord"></a><span class='hs-comment'>-- | Constuct a path to a particular coordinate in an extent.</span>
<a name="line-130"></a><span class='hs-definition'>pathToCoord</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Coord</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Quad</span><span class='hs-keyglyph'>]</span>
<a name="line-131"></a><span class='hs-definition'>pathToCoord</span> <span class='hs-varid'>extent</span> <span class='hs-varid'>coord</span>
<a name="line-132"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isUnitExtent</span> <span class='hs-varid'>extent</span>
<a name="line-133"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-conid'>[]</span>
<a name="line-134"></a>
<a name="line-135"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-136"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>quad</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>quadOfCoord</span> <span class='hs-varid'>extent</span> <span class='hs-varid'>coord</span>
<a name="line-137"></a> <span class='hs-varid'>rest</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>pathToCoord</span> <span class='hs-layout'>(</span><span class='hs-varid'>cutQuadOfExtent</span> <span class='hs-varid'>quad</span> <span class='hs-varid'>extent</span><span class='hs-layout'>)</span> <span class='hs-varid'>coord</span>
<a name="line-138"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-varid'>quad</span> <span class='hs-conop'>:</span> <span class='hs-varid'>rest</span>
<a name="line-139"></a>
<a name="line-140"></a>
<a name="line-141"></a><a name="intersectSegExtent"></a><span class='hs-comment'>-- | If a line segment (P1-P2) intersects the outer edge of an extent then</span>
<a name="line-142"></a><span class='hs-comment'>-- return the intersection point, that is closest to P1, if any.</span>
<a name="line-143"></a><span class='hs-comment'>-- If P1 is inside the extent then `Nothing`.</span>
<a name="line-144"></a><span class='hs-comment'>--</span>
<a name="line-145"></a><span class='hs-comment'>-- @</span>
<a name="line-146"></a><span class='hs-comment'>-- P2</span>
<a name="line-147"></a><span class='hs-comment'>-- /</span>
<a name="line-148"></a><span class='hs-comment'>-- ----/-</span>
<a name="line-149"></a><span class='hs-comment'>-- | / |</span>
<a name="line-150"></a><span class='hs-comment'>-- + |</span>
<a name="line-151"></a><span class='hs-comment'>-- /------</span>
<a name="line-152"></a><span class='hs-comment'>-- / </span>
<a name="line-153"></a><span class='hs-comment'>-- P1</span>
<a name="line-154"></a><span class='hs-comment'>-- @</span>
<a name="line-155"></a><span class='hs-comment'>-- </span>
<a name="line-156"></a><span class='hs-definition'>intersectSegExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Point</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Point</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-conid'>Point</span>
<a name="line-157"></a><span class='hs-definition'>intersectSegExtent</span> <span class='hs-varid'>p1</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-varid'>x1</span><span class='hs-layout'>,</span> <span class='hs-varid'>y1</span><span class='hs-layout'>)</span> <span class='hs-varid'>p2</span> <span class='hs-layout'>(</span><span class='hs-conid'>Extent</span> <span class='hs-varid'>n'</span> <span class='hs-varid'>s'</span> <span class='hs-varid'>e'</span> <span class='hs-varid'>w'</span><span class='hs-layout'>)</span>
<a name="line-158"></a> <span class='hs-comment'>-- starts below extent</span>
<a name="line-159"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>y1</span> <span class='hs-varop'><</span> <span class='hs-varid'>s</span>
<a name="line-160"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>pos</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>intersectSegHorzSeg</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-varid'>s</span> <span class='hs-varid'>w</span> <span class='hs-varid'>e</span>
<a name="line-161"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>pos</span>
<a name="line-162"></a>
<a name="line-163"></a> <span class='hs-comment'>-- starts above extent</span>
<a name="line-164"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>y1</span> <span class='hs-varop'>></span> <span class='hs-varid'>n</span>
<a name="line-165"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>pos</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>intersectSegHorzSeg</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-varid'>n</span> <span class='hs-varid'>w</span> <span class='hs-varid'>e</span>
<a name="line-166"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>pos</span>
<a name="line-167"></a>
<a name="line-168"></a> <span class='hs-comment'>-- starts left of extent</span>
<a name="line-169"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x1</span> <span class='hs-varop'><</span> <span class='hs-varid'>w</span>
<a name="line-170"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>pos</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>intersectSegVertSeg</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-varid'>w</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n</span>
<a name="line-171"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>pos</span>
<a name="line-172"></a>
<a name="line-173"></a> <span class='hs-comment'>-- starts right of extent</span>
<a name="line-174"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x1</span> <span class='hs-varop'>></span> <span class='hs-varid'>e</span>
<a name="line-175"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>pos</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>intersectSegVertSeg</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-varid'>e</span> <span class='hs-varid'>s</span> <span class='hs-varid'>n</span>
<a name="line-176"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>pos</span>
<a name="line-177"></a>
<a name="line-178"></a> <span class='hs-comment'>-- must be starting inside extent.</span>
<a name="line-179"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span>
<a name="line-180"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-181"></a>
<a name="line-182"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>n'</span>
<a name="line-183"></a> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>s'</span>
<a name="line-184"></a> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>e'</span>
<a name="line-185"></a> <span class='hs-varid'>w</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>w'</span>
<a name="line-186"></a>
<a name="line-187"></a>
<a name="line-188"></a><a name="touchesSegExtent"></a><span class='hs-comment'>-- | Check whether a line segment's endpoints are inside an extent, or if it</span>
<a name="line-189"></a><span class='hs-comment'>-- intersects with the boundary.</span>
<a name="line-190"></a><span class='hs-definition'>touchesSegExtent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Point</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Point</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Extent</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-191"></a><span class='hs-definition'>touchesSegExtent</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-varid'>extent</span>
<a name="line-192"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pointInExtent</span> <span class='hs-varid'>extent</span> <span class='hs-varid'>p1</span>
<a name="line-193"></a> <span class='hs-varop'>||</span> <span class='hs-varid'>pointInExtent</span> <span class='hs-varid'>extent</span> <span class='hs-varid'>p2</span>
<a name="line-194"></a> <span class='hs-varop'>||</span> <span class='hs-varid'>isJust</span> <span class='hs-layout'>(</span><span class='hs-varid'>intersectSegExtent</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-varid'>extent</span><span class='hs-layout'>)</span>
<a name="line-195"></a>
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