    {-# LINE 2 "./Graphics/Rendering/Pango/Markup.chs" #-}
    -- -*-haskell-*-
    -- GIMP Toolkit (GTK) Markup
    --
    -- Author : Axel Simon
    --
    -- Created: 5 June 2001
    --
    -- Copyright (C) 1999-2005 Axel Simon
    --
    -- This library is free software; you can redistribute it and/or
    -- modify it under the terms of the GNU Lesser General Public
    -- License as published by the Free Software Foundation; either
    -- version 2.1 of the License, or (at your option) any later version.
    --
    -- This library is distributed in the hope that it will be useful,
    -- but WITHOUT ANY WARRANTY; without even the implied warranty of
    -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    -- Lesser General Public License for more details.
    --
    -- |
    -- Maintainer : gtk2hs-users@lists.sourceforge.net
    -- Stability : provisional
    -- Portability : portable (depends on GHC)
    --
    -- This module defines some helper functions for generating texts with
    -- embedded attributes. Note that there is no need to use these functions.
    -- In particular, if you set markup in labels that are subject to
    -- internationalization, it can be of advantage to write out the markup
    -- instead of using the functions in this module.
    --
    -- In order to display a string that may contain markup characters, use
    -- 'Graphics.UI.Gtk.Pango.Layout.escapeMarkup'.
    --
    -- When you write markup directly, you can make use of the following
    -- convenience tags:
    --
    -- [@b@] Bold
    --
    -- [@big@] Makes font relatively larger
    --
    -- [@i@] Italic
    --
    -- [@s@] Strikethrough
    --
    -- [@sub@] Subscript
    --
    -- [@sup@] Superscript
    --
    -- [@small@] Makes font relatively smaller
    --
    -- [@tt@] Monospace font
    --
    -- [@u@] Underline
    --
    module Graphics.Rendering.Pango.Markup (
      Pango.Markup,
      SpanAttribute(..),
      markSpan,
      parseMarkup
      ) where

    import qualified Graphics.Rendering.Pango.Enums as Pango
    import Graphics.Rendering.Pango.Attributes ( parseMarkup )

    -- | These are all the attributes the 'markSpan' function can express.
    --
    data SpanAttribute
      -- | Choose a font by textual description.
      --
      -- * Takes a string to completely describe the font, example:
      -- @FontDescr@ \"Sans Italic 12\"
      = FontDescr String

      -- | Specify the family of font to use.
      --
      -- * Example: @FontFamily@ \"Sans\"
      | FontFamily String

      -- | Change the size of the current font.
      --
      -- * The constuctor takes the size in points (pt) or a predefined
      -- sizes. Setting the absolute size 12.5pt can be achieved by passing
      -- 'FontSize' ('SizePoint' 12.5) to 'markSpan'. Next to predefined
      -- absolute sizes such as 'Pango.SizeSmall' the size can be changed by
      -- asking for the next larger or smaller front with
      -- 'Pango.SizeLarger' and 'Pango.SizeSmaller', respectively.
      | FontSize Pango.Size

      -- | Change the slant of the current font.
      --
      | FontStyle Pango.FontStyle

      -- | Change the thickness of the current font.
      --
      -- * The constructor takes one of the six predefined weights. Most likely to
      -- be supported: 'Pango.WeightBold'.
      --
      | FontWeight Pango.Weight

      -- | Choosing an alternative rendering for lower case letters.
      --
      -- * The argument 'Pango.VariantSmallCaps' will display lower case letters
      -- as smaller upper case letters, if this option is available.
      | FontVariant Pango.Variant

      -- | Choose a different width.
      --
      -- * Takes one of nine font widths, e.g. 'Pango.WidthExpanded'.
      --
      | FontStretch Pango.Stretch

      -- | Foreground color.
      --
      -- * This constructor and 'FontBackground' take both a description
      -- of the color to be used for rendering. The name is either a
      -- hex code of the form \"#RRGGBB\" or an X11 color name like
      -- \"dark olive green\".
      --
      | FontForeground String -- FIXME: should be ColorName from GDK or so

      -- | Background color.
      | FontBackground String

      -- | Specify underlining of text.
      --
      | FontUnderline Pango.Underline

      -- | Specify a vertical displacement.
      --
      -- * Takes the vertical displacement in em (the width of the \'m\' character
      -- in the current font).
      | FontRise Double

      -- | Give a hint about the language to be displayed.
      --
      -- * This hint might help the system rendering a particular piece of text
      -- with different fonts that are more suitable for the given language.
      --
      | FontLang Pango.Language

      -- | Gravity of text, use for ratation.
      | FontGravity Pango.PangoGravity

      -- | Intensity of gravity.
      | FontGravityHint Pango.PangoGravityHint

    instance Show SpanAttribute where
      showsPrec _ (FontDescr str) = showString " font_desc=".shows str
      showsPrec _ (FontFamily str) = showString " font_family=".shows str
      showsPrec _ (FontSize size) = showString " size=".shows size
      showsPrec _ (FontStyle style) = showString " style=".shows style
      showsPrec _ (FontWeight w) = showString " weight=".shows w
      showsPrec _ (FontVariant v) = showString " variant=".shows v
      showsPrec _ (FontStretch s) = showString " stretch=".shows s
      showsPrec _ (FontForeground c) = showString " foreground=".shows c
      showsPrec _ (FontBackground c) = showString " background=".shows c
      showsPrec _ (FontUnderline u) = showString " underline=".shows u
      showsPrec _ (FontRise r) = showString " rise=".shows
           (show (round (r*10000)))
      showsPrec _ (FontLang l) = showString " lang=".shows l

      showsPrec _ (FontGravity g) = showString " gravity=".shows g
      showsPrec _ (FontGravityHint h) = showString " gravity_hint".shows h

    -- | Create the most generic span attribute.
    --
    markSpan :: [SpanAttribute] -> String -> String
    markSpan attrs text = showString "<span".
            foldr (.) (showChar '>') (map shows attrs).
            showString text.
            showString "</span>" $ ""