<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <!-- Generated by HsColour, http://www.cs.york.ac.uk/fp/darcs/hscolour/ --> <title>dist/build/Graphics/UI/Gtk/Cairo.hs</title> <link type='text/css' rel='stylesheet' href='hscolour.css' /> </head> <body> <pre><a name="line-1"></a> <a name="line-2"></a><span class='hs-comment'>{-# LINE 2 "./Graphics/UI/Gtk/Cairo.chs" #-}</span> <a name="line-3"></a><span class='hs-comment'>-- -*-haskell-*-</span> <a name="line-4"></a><span class='hs-comment'>-- GIMP Toolkit (GTK) Cairo GDK integration</span> <a name="line-5"></a><span class='hs-comment'>--</span> <a name="line-6"></a><span class='hs-comment'>-- Author : Duncan Coutts</span> <a name="line-7"></a><span class='hs-comment'>--</span> <a name="line-8"></a><span class='hs-comment'>-- Created: 17 August 2005</span> <a name="line-9"></a><span class='hs-comment'>--</span> <a name="line-10"></a><span class='hs-comment'>-- Copyright (C) 2005 Duncan Coutts</span> <a name="line-11"></a><span class='hs-comment'>--</span> <a name="line-12"></a><span class='hs-comment'>-- This library is free software; you can redistribute it and/or</span> <a name="line-13"></a><span class='hs-comment'>-- modify it under the terms of the GNU Lesser General Public</span> <a name="line-14"></a><span class='hs-comment'>-- License as published by the Free Software Foundation; either</span> <a name="line-15"></a><span class='hs-comment'>-- version 2.1 of the License, or (at your option) any later version.</span> <a name="line-16"></a><span class='hs-comment'>--</span> <a name="line-17"></a><span class='hs-comment'>-- This library is distributed in the hope that it will be useful,</span> <a name="line-18"></a><span class='hs-comment'>-- but WITHOUT ANY WARRANTY; without even the implied warranty of</span> <a name="line-19"></a><span class='hs-comment'>-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU</span> <a name="line-20"></a><span class='hs-comment'>-- Lesser General Public License for more details.</span> <a name="line-21"></a><span class='hs-comment'>--</span> <a name="line-22"></a><span class='hs-comment'>-- #hide</span> <a name="line-23"></a> <a name="line-24"></a><span class='hs-comment'>-- |</span> <a name="line-25"></a><span class='hs-comment'>-- Maintainer : gtk2hs-users@lists.sourceforge.net</span> <a name="line-26"></a><span class='hs-comment'>-- Stability : provisional</span> <a name="line-27"></a><span class='hs-comment'>-- Portability : portable (depends on GHC)</span> <a name="line-28"></a><span class='hs-comment'>--</span> <a name="line-29"></a><span class='hs-comment'>--</span> <a name="line-30"></a><span class='hs-comment'>-- Gtk specific functions to for redering with Cairo.</span> <a name="line-31"></a><span class='hs-comment'>--</span> <a name="line-32"></a><span class='hs-comment'>-- Cairo is a graphics library that supports vector graphics and image</span> <a name="line-33"></a><span class='hs-comment'>-- compositing that can be used with Gdk.</span> <a name="line-34"></a><span class='hs-comment'>-- The Cairo API is an addition to Gdk\/Gtk (rather than a replacement).</span> <a name="line-35"></a><span class='hs-comment'>-- Cairo rendering can be performed on any 'Graphics.UI.Gtk.Gdk.Drawable'</span> <a name="line-36"></a><span class='hs-comment'>-- by calling 'renderWithDrawable'. The functions in this module provide</span> <a name="line-37"></a><span class='hs-comment'>-- ways of drawing Gtk specific elements, such as 'Pixbuf's or text</span> <a name="line-38"></a><span class='hs-comment'>-- laid out with Pango.</span> <a name="line-39"></a><span class='hs-comment'>--</span> <a name="line-40"></a><span class='hs-comment'>-- All functions in this module are only available in Gtk 2.8 or higher.</span> <a name="line-41"></a><span class='hs-comment'>--</span> <a name="line-42"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>UI</span><span class='hs-varop'>.</span><span class='hs-conid'>Gtk</span><span class='hs-varop'>.</span><span class='hs-conid'>Cairo</span> <span class='hs-layout'>(</span> <a name="line-43"></a> <a name="line-44"></a> <span class='hs-comment'>-- * Global Cairo settings.</span> <a name="line-45"></a> <span class='hs-varid'>cairoFontMapGetDefault</span><span class='hs-layout'>,</span> <a name="line-46"></a> <span class='hs-varid'>cairoFontMapSetResolution</span><span class='hs-layout'>,</span> <a name="line-47"></a> <span class='hs-varid'>cairoFontMapGetResolution</span><span class='hs-layout'>,</span> <a name="line-48"></a> <span class='hs-varid'>cairoCreateContext</span><span class='hs-layout'>,</span> <a name="line-49"></a> <span class='hs-varid'>cairoContextSetResolution</span><span class='hs-layout'>,</span> <a name="line-50"></a> <span class='hs-varid'>cairoContextGetResolution</span><span class='hs-layout'>,</span> <a name="line-51"></a> <span class='hs-varid'>cairoContextSetFontOptions</span><span class='hs-layout'>,</span> <a name="line-52"></a> <span class='hs-varid'>cairoContextGetFontOptions</span><span class='hs-layout'>,</span> <a name="line-53"></a> <span class='hs-comment'>-- * Functions for the 'Render' monad.</span> <a name="line-54"></a> <span class='hs-varid'>renderWithDrawable</span><span class='hs-layout'>,</span> <a name="line-55"></a> <span class='hs-varid'>setSourceColor</span><span class='hs-layout'>,</span> <a name="line-56"></a> <span class='hs-varid'>setSourcePixbuf</span><span class='hs-layout'>,</span> <a name="line-57"></a> <span class='hs-varid'>region</span><span class='hs-layout'>,</span> <a name="line-58"></a> <span class='hs-varid'>updateContext</span><span class='hs-layout'>,</span> <a name="line-59"></a> <span class='hs-varid'>createLayout</span><span class='hs-layout'>,</span> <a name="line-60"></a> <span class='hs-varid'>updateLayout</span><span class='hs-layout'>,</span> <a name="line-61"></a> <span class='hs-varid'>showGlyphString</span><span class='hs-layout'>,</span> <a name="line-62"></a> <span class='hs-varid'>showLayoutLine</span><span class='hs-layout'>,</span> <a name="line-63"></a> <span class='hs-varid'>showLayout</span><span class='hs-layout'>,</span> <a name="line-64"></a> <span class='hs-varid'>glyphStringPath</span><span class='hs-layout'>,</span> <a name="line-65"></a> <span class='hs-varid'>layoutLinePath</span><span class='hs-layout'>,</span> <a name="line-66"></a> <span class='hs-varid'>layoutPath</span> <a name="line-67"></a> <a name="line-68"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span> <a name="line-69"></a> <a name="line-70"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span> <span class='hs-layout'>(</span><span class='hs-varid'>bracket</span><span class='hs-layout'>)</span> <a name="line-71"></a> <a name="line-72"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Glib</span><span class='hs-varop'>.</span><span class='hs-conid'>FFI</span> <a name="line-73"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>UI</span><span class='hs-varop'>.</span><span class='hs-conid'>Gtk</span><span class='hs-varop'>.</span><span class='hs-conid'>Types</span> <a name="line-74"></a><span class='hs-comment'>{-# LINE 73 "./Graphics/UI/Gtk/Cairo.chs" #-}</span> <a name="line-75"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>UI</span><span class='hs-varop'>.</span><span class='hs-conid'>Gtk</span><span class='hs-varop'>.</span><span class='hs-conid'>Gdk</span><span class='hs-varop'>.</span><span class='hs-conid'>Region</span> <span class='hs-layout'>(</span><span class='hs-conid'>Region</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <a name="line-76"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Rendering</span><span class='hs-varop'>.</span><span class='hs-conid'>Pango</span><span class='hs-varop'>.</span><span class='hs-conid'>Cairo</span> <a name="line-77"></a><span class='hs-comment'>{-# LINE 75 "./Graphics/UI/Gtk/Cairo.chs" #-}</span> <a name="line-78"></a> <a name="line-79"></a> <a name="line-80"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Rendering</span><span class='hs-varop'>.</span><span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Types</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Cairo</span> <a name="line-81"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Rendering</span><span class='hs-varop'>.</span><span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span> <a name="line-82"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Rendering</span><span class='hs-varop'>.</span><span class='hs-conid'>Cairo</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Cairo</span> <a name="line-83"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Graphics</span><span class='hs-varop'>.</span><span class='hs-conid'>Rendering</span><span class='hs-varop'>.</span><span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span> <span class='hs-layout'>(</span><span class='hs-conid'>Render</span><span class='hs-layout'>(</span><span class='hs-conid'>Render</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <a name="line-84"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Reader</span> <a name="line-85"></a> <a name="line-86"></a> <a name="line-87"></a> <a name="line-88"></a><span class='hs-comment'>{-# LINE 85 "./Graphics/UI/Gtk/Cairo.chs" #-}</span> <a name="line-89"></a> <a name="line-90"></a><span class='hs-comment'>--------------------</span> <a name="line-91"></a><span class='hs-comment'>-- Methods</span> <a name="line-92"></a> <a name="line-93"></a> <a name="line-94"></a><a name="renderWithDrawable"></a><span class='hs-comment'>-- | Creates a Cairo context for drawing to a 'Drawable'.</span> <a name="line-95"></a><span class='hs-comment'>--</span> <a name="line-96"></a><span class='hs-definition'>renderWithDrawable</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>DrawableClass</span> <span class='hs-varid'>drawable</span> <span class='hs-keyglyph'>=></span> <a name="line-97"></a> <span class='hs-varid'>drawable</span> <span class='hs-comment'>-- ^ @drawable@ - a 'Drawable'</span> <a name="line-98"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Render</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ A newly created Cairo context.</span> <a name="line-99"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span> <a name="line-100"></a><span class='hs-definition'>renderWithDrawable</span> <span class='hs-varid'>drawable</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <a name="line-101"></a> <span class='hs-varid'>bracket</span> <span class='hs-layout'>(</span><span class='hs-varid'>liftM</span> <span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Cairo</span> <span class='hs-varop'>$</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Drawable</span> <span class='hs-varid'>arg1</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>withForeignPtr</span> <span class='hs-varid'>arg1</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>argPtr1</span> <span class='hs-keyglyph'>-></span><span class='hs-varid'>gdk_cairo_create</span> <span class='hs-varid'>argPtr1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>toDrawable</span> <span class='hs-varid'>drawable</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <a name="line-102"></a> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>context</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-varid'>status</span> <span class='hs-keyglyph'><-</span> <span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span><span class='hs-varop'>.</span><span class='hs-varid'>status</span> <span class='hs-varid'>context</span> <a name="line-103"></a> <span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span><span class='hs-varop'>.</span><span class='hs-varid'>destroy</span> <span class='hs-varid'>context</span> <a name="line-104"></a> <span class='hs-varid'>unless</span> <span class='hs-layout'>(</span><span class='hs-varid'>status</span> <span class='hs-varop'>==</span> <span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>StatusSuccess</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <a name="line-105"></a> <span class='hs-varid'>fail</span> <span class='hs-varop'>=<<</span> <span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span><span class='hs-varop'>.</span><span class='hs-varid'>statusToString</span> <span class='hs-varid'>status</span><span class='hs-layout'>)</span> <a name="line-106"></a> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>context</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runReaderT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Cairo</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span><span class='hs-varop'>.</span><span class='hs-varid'>runRender</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>context</span><span class='hs-layout'>)</span> <a name="line-107"></a> <a name="line-108"></a><a name="setSourcePixbuf"></a><span class='hs-comment'>-- | Sets the given pixbuf as the source pattern for the Cairo context. The</span> <a name="line-109"></a><span class='hs-comment'>-- pattern has an extend mode of 'ExtendNone' and is aligned so that the</span> <a name="line-110"></a><span class='hs-comment'>-- origin of pixbuf is @(x, y)@.</span> <a name="line-111"></a><span class='hs-comment'>--</span> <a name="line-112"></a><span class='hs-definition'>setSourcePixbuf</span> <span class='hs-keyglyph'>::</span> <a name="line-113"></a> <span class='hs-conid'>Pixbuf</span> <a name="line-114"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Double</span> <span class='hs-comment'>-- ^ x</span> <a name="line-115"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Double</span> <span class='hs-comment'>-- ^ y</span> <a name="line-116"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Render</span> <span class='hs-conid'>()</span> <a name="line-117"></a><span class='hs-definition'>setSourcePixbuf</span> <span class='hs-varid'>pixbuf</span> <span class='hs-varid'>pixbufX</span> <span class='hs-varid'>pixbufY</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Render</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span> <a name="line-118"></a> <span class='hs-varid'>cr</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>ask</span> <a name="line-119"></a> <span class='hs-varid'>liftIO</span> <span class='hs-varop'>$</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Cairo</span> <span class='hs-varid'>arg1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Pixbuf</span> <span class='hs-varid'>arg2</span><span class='hs-layout'>)</span> <span class='hs-varid'>arg3</span> <span class='hs-varid'>arg4</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>withForeignPtr</span> <span class='hs-varid'>arg2</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>argPtr2</span> <span class='hs-keyglyph'>-></span><span class='hs-varid'>gdk_cairo_set_source_pixbuf</span> <span class='hs-varid'>arg1</span> <span class='hs-varid'>argPtr2</span> <span class='hs-varid'>arg3</span> <span class='hs-varid'>arg4</span><span class='hs-layout'>)</span> <a name="line-120"></a><span class='hs-comment'>{-# LINE 116 "./Graphics/UI/Gtk/Cairo.chs" #-}</span> <a name="line-121"></a> <span class='hs-varid'>cr</span> <a name="line-122"></a> <span class='hs-varid'>pixbuf</span> <a name="line-123"></a> <span class='hs-layout'>(</span><span class='hs-varid'>realToFrac</span> <span class='hs-varid'>pixbufX</span><span class='hs-layout'>)</span> <a name="line-124"></a> <span class='hs-layout'>(</span><span class='hs-varid'>realToFrac</span> <span class='hs-varid'>pixbufY</span><span class='hs-layout'>)</span> <a name="line-125"></a> <a name="line-126"></a><a name="region"></a><span class='hs-comment'>-- | Adds the given region to the current path of the 'Render' context.</span> <a name="line-127"></a><span class='hs-comment'>--</span> <a name="line-128"></a><span class='hs-definition'>region</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Region</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Render</span> <span class='hs-conid'>()</span> <a name="line-129"></a><span class='hs-definition'>region</span> <span class='hs-varid'>region</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Render</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span> <a name="line-130"></a> <span class='hs-varid'>cr</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>ask</span> <a name="line-131"></a> <span class='hs-varid'>liftIO</span> <span class='hs-varop'>$</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Cairo</span> <span class='hs-varid'>arg1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Region</span> <span class='hs-varid'>arg2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>withForeignPtr</span> <span class='hs-varid'>arg2</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>argPtr2</span> <span class='hs-keyglyph'>-></span><span class='hs-varid'>gdk_cairo_region</span> <span class='hs-varid'>arg1</span> <span class='hs-varid'>argPtr2</span><span class='hs-layout'>)</span> <a name="line-132"></a><span class='hs-comment'>{-# LINE 127 "./Graphics/UI/Gtk/Cairo.chs" #-}</span> <a name="line-133"></a> <span class='hs-varid'>cr</span> <a name="line-134"></a> <span class='hs-varid'>region</span> <a name="line-135"></a> <a name="line-136"></a><span class='hs-keyword'>foreign</span> <span class='hs-keyword'>import</span> <span class='hs-keyword'>ccall</span> <span class='hs-keyword'>unsafe</span> <span class='hs-str'>"gdk_cairo_create"</span> <a name="line-137"></a> <span class='hs-varid'>gdk_cairo_create</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>Ptr</span> <span class='hs-conid'>Drawable</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Ptr</span> <span class='hs-conid'>Cairo</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <a name="line-138"></a> <a name="line-139"></a><span class='hs-keyword'>foreign</span> <span class='hs-keyword'>import</span> <span class='hs-keyword'>ccall</span> <span class='hs-keyword'>unsafe</span> <span class='hs-str'>"gdk_cairo_set_source_pixbuf"</span> <a name="line-140"></a> <span class='hs-varid'>gdk_cairo_set_source_pixbuf</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>Ptr</span> <span class='hs-conid'>Cairo</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>Ptr</span> <span class='hs-conid'>Pixbuf</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>CDouble</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>CDouble</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>IO</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <a name="line-141"></a> <a name="line-142"></a><span class='hs-keyword'>foreign</span> <span class='hs-keyword'>import</span> <span class='hs-keyword'>ccall</span> <span class='hs-keyword'>unsafe</span> <span class='hs-str'>"gdk_cairo_region"</span> <a name="line-143"></a> <span class='hs-varid'>gdk_cairo_region</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>Ptr</span> <span class='hs-conid'>Cairo</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>Ptr</span> <span class='hs-conid'>Region</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>IO</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> </pre></body> </html>