6713098919

Committed 31 Oct 2023 10:21PM UTC coverage: 52.831% (-21.8%) from 74.636%

Build # 6713098919

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Commit Message

Merge d0a2a1ee9 into b185d4972

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0.0

/packages/linespacing/init.lua

local base = require("packages.base")

local package = pl.class(base)
package._name = "linespacing"

local metrics = require("fontmetrics")

local metricscache = {}

local getLineMetrics = function (l)
  local linemetrics = { ascender = 0, descender = 0, lineheight = SILE.length() }
  if not l or not l.nodes then return linemetrics end
  for i = 1, #(l.nodes) do
    local node = l.nodes[i]
    if node.is_nnode then
      local m = metricscache[SILE.font._key(node.options)]
      if not m then
        local face = SILE.font.cache(node.options, SILE.shaper.getFace)
        m = metrics.get_typographic_extents(face)
        m.ascender = m.ascender * node.options.size
        m.descender = m.descender * node.options.size
        metricscache[SILE.font._key(node.options)] = m
      end
      SILE.settings:temporarily(function ()
        SILE.call("font", node.options, {})
        m.lineheight = SU.cast("length", SILE.settings:get("linespacing.css.line-height")):absolute()
      end)
      if m.ascender > linemetrics.ascender then linemetrics.ascender = m.ascender end
      if m.descender > linemetrics.descender then linemetrics.descender = m.descender end
      if m.lineheight > linemetrics.lineheight then linemetrics.lineheight = m.lineheight end
    end
  end
  return linemetrics
end

local linespacingLeading = function (_, vbox, previous)
  local method = SILE.settings:get("linespacing.method")

  local firstline = SILE.settings:get("linespacing.minimumfirstlineposition"):absolute()
  if not previous then
    if firstline.length:tonumber() > 0 then
      local toAdd = SILE.length(firstline.length - vbox.height)
      return SILE.nodefactory.vkern(toAdd)
    else
      return nil
    end
  end

  if method == "tex" then
    return SILE.typesetters.base:leadingFor(vbox, previous)
  end

  if method == "fit-glyph" then
    local extra = SILE.settings:get("linespacing.fit-glyph.extra-space"):absolute()
    local toAdd = SILE.length(extra)
    return SILE.nodefactory.vglue(toAdd)
  end

  if method == "fixed" then
    local btob = SILE.settings:get("linespacing.fixed.baselinedistance"):absolute()
    local toAdd = SILE.length(btob.length - (vbox.height + previous.depth), btob.stretch, btob.shrink)
    return SILE.nodefactory.vglue(toAdd)
  end

  -- For these methods, we need to read the font metrics
  if not metrics then
    SU.error("'"..method.."' line spacing method requires font metrics module, which is not available.")
  end

  local thismetrics = getLineMetrics(vbox)
  local prevmetrics = getLineMetrics(previous)
  if method == "fit-font" then
    -- Distance to next baseline is max(descender) of fonts on previous +
    -- max(ascender) of fonts on next
    local extra = SILE.settings:get("linespacing.fit-font.extra-space"):absolute()
    local btob = prevmetrics.descender + thismetrics.ascender + extra
    local toAdd = btob - (vbox.height + (previous and previous.depth or 0))
    return SILE.nodefactory.vglue(toAdd)
  end

  if method == "css" then
    local lh = prevmetrics.lineheight
    local leading = (lh - (prevmetrics.ascender + prevmetrics.descender))
    if previous then
      previous.height = previous.height + leading / 2
      previous.depth = previous.depth + leading / 2
    end
    return SILE.nodefactory.vglue()

  end

  SU.error("Unknown line spacing method "..method)
end

function package:_init ()
  base._init(self)
  self.class:registerPostinit(function(_)
    SILE.typesetter.leadingFor = linespacingLeading
  end)
end

function package.declareSettings (_)

  SILE.settings:declare({
    parameter = "linespacing.method",
    default = "tex",
    type = "string",
    help = "How to set the line spacing (tex, fixed, fit-font, fit-glyph, css)"
  })

  SILE.settings:declare({
    parameter = "linespacing.fixed.baselinedistance",
    default = SILE.length("1.2em"),
    type = "length",
    help = "Distance from baseline to baseline in the case of fixed line spacing"
  })

  SILE.settings:declare({
    parameter = "linespacing.minimumfirstlineposition",
    default = SILE.length(0),
    type = "length"
  })

  SILE.settings:declare({
    parameter = "linespacing.fit-glyph.extra-space",
    default = SILE.length(0),
    type = "length"
  })

  SILE.settings:declare({
    parameter = "linespacing.fit-font.extra-space",
    default = SILE.length(0),
    type = "length"
  })

  SILE.settings:declare({
    parameter = "linespacing.css.line-height",
    default = SILE.length("1.2em"),
    type = "length"
  })

end

function package:registerCommands ()

  self:registerCommand("linespacing-on", function ()
    SILE.typesetter.leadingFor = linespacingLeading
  end)

  self:registerCommand("linespacing-off", function ()
    SILE.typesetter.leadingFor = SILE.typesetters.base.leadingFor
  end)

end

package.documentation = [[
\begin{document}
\linespacing-on
SILE’s default method of inserting leading between lines should be familiar to users of TeX, but it is not the most friendly system for book designers.
The \autodoc:package{linespacing} package provides a better choice of leading systems.

After loading the package, you are able to choose the linespacing mode by setting the \autodoc:setting{linespacing.method} parameter.
The following examples have funny sized words in them so that you can see how the different methods interact.

By default, this is set to \code{tex}. The other options available are:

\medskip
\set[parameter=linespacing.method,value=fixed]
\set[parameter=linespacing.fixed.baselinedistance,value=1.5em]
\begin{itemize}
\item{\code{fixed}. This set the lines at a fixed baseline-to-baseline distance, determined by the \autodoc:setting{linespacing.fixed.baselinedistance} parameter.
You can specify this parameter either relative to the type size (\code{1.2em}) or as a absolute distance (\code{15pt}).
This paragraph is set with a fixed 1.5em baseline-to-baseline distance.}
\end{itemize}

\medskip
\set[parameter=linespacing.method,value=fit-glyph]
\begin{itemize}
\item{\code{fit-glyph}. This sets the lines solid; that is, the lowest point on line 1 (either a descender like \font[size=20pt]{q} or, if there are no descenders, the baseline) will touch the \font[size=20pt]{highest} point of line 2, as in this paragraph.
You generally don’t want to use this as-is.}
\end{itemize}

\set[parameter=linespacing.fit-glyph.extra-space,value=5pt]

What you probably want to do is insert a constant (relative or absolute) s\font[size=20pt]{p}ace between the lines by setting the \autodoc:setting{linespacing.fit-glyph.extra-space} parameter.
\font[size=20pt]{T}his paragraph is set with 5 points of space between the descenders and the ascenders.

\medskip
\set[parameter=linespacing.method,value=fit-font]
\begin{itemize}
\item{\code{fit-font}. This inspects each \code{hbox} on the line, and asks the fonts it finds for their bounding boxes—the highest ascender and the lower descender.
It then sets the lines solid.
Essentially each character is treated as if it is the same height, rather like composing a slug of metal type.
If there are things other than text on your line, or the text is buried inside other boxes, this may not work well.}
\end{itemize}

\set[parameter=linespacing.fit-font.extra-space,value=5pt]

As with \code{fit-glyph}, you can insert extra space between the lines with the \autodoc:setting{linespacing.fit-font.extra-space} parameter.

\medskip
\set[parameter=linespacing.method,value=css]
\set[parameter=linespacing.css.line-height,value=2em]
\begin{itemize}
\item{\code{css}. This is similar to the method used in browsers; the baseline distance is set with the \autodoc:setting{linespacing.css.line-height} parameter, and the excess \font[size=20pt]{space} between this parameter and the actual height of the line is distributed between the top and bottom of the line.}
\end{itemize}
\medskip

\linespacing-off
\end{document}
]]

return package

1	local base = require("packages.base")	×
2
3	local package = pl.class(base)	×
4	package._name = "linespacing"	×
5
6	local metrics = require("fontmetrics")	×
7
8	local metricscache = {}	×
9
10	local getLineMetrics = function (l)
11	local linemetrics = { ascender = 0, descender = 0, lineheight = SILE.length() }	×
12	if not l or not l.nodes then return linemetrics end	×
13	for i = 1, #(l.nodes) do	×
14	local node = l.nodes[i]	×
15	if node.is_nnode then	×
16	local m = metricscache[SILE.font._key(node.options)]	×
17	if not m then	×
18	local face = SILE.font.cache(node.options, SILE.shaper.getFace)	×
19	m = metrics.get_typographic_extents(face)	×
20	m.ascender = m.ascender * node.options.size	×
21	m.descender = m.descender * node.options.size	×
22	metricscache[SILE.font._key(node.options)] = m	×
23	end
24	SILE.settings:temporarily(function ()	×
25	SILE.call("font", node.options, {})	×
26	m.lineheight = SU.cast("length", SILE.settings:get("linespacing.css.line-height")):absolute()	×
27	end)
28	if m.ascender > linemetrics.ascender then linemetrics.ascender = m.ascender end	×
29	if m.descender > linemetrics.descender then linemetrics.descender = m.descender end	×
30	if m.lineheight > linemetrics.lineheight then linemetrics.lineheight = m.lineheight end	×
31	end
32	end
33	return linemetrics	×
34	end
35
36	local linespacingLeading = function (_, vbox, previous)
37	local method = SILE.settings:get("linespacing.method")	×
38
39	local firstline = SILE.settings:get("linespacing.minimumfirstlineposition"):absolute()	×
40	if not previous then	×
41	if firstline.length:tonumber() > 0 then	×
42	local toAdd = SILE.length(firstline.length - vbox.height)	×
43	return SILE.nodefactory.vkern(toAdd)	×
44	else
45	return nil	×
46	end
47	end
48
49	if method == "tex" then	×
50	return SILE.typesetters.base:leadingFor(vbox, previous)	×
51	end
52
53	if method == "fit-glyph" then	×
54	local extra = SILE.settings:get("linespacing.fit-glyph.extra-space"):absolute()	×
55	local toAdd = SILE.length(extra)	×
56	return SILE.nodefactory.vglue(toAdd)	×
57	end
58
59	if method == "fixed" then	×
60	local btob = SILE.settings:get("linespacing.fixed.baselinedistance"):absolute()	×
61	local toAdd = SILE.length(btob.length - (vbox.height + previous.depth), btob.stretch, btob.shrink)	×
62	return SILE.nodefactory.vglue(toAdd)	×
63	end
64
65	-- For these methods, we need to read the font metrics
66	if not metrics then	×
67	SU.error("'"..method.."' line spacing method requires font metrics module, which is not available.")	×
68	end
69
70	local thismetrics = getLineMetrics(vbox)	×
71	local prevmetrics = getLineMetrics(previous)	×
72	if method == "fit-font" then	×
73	-- Distance to next baseline is max(descender) of fonts on previous +
74	-- max(ascender) of fonts on next
75	local extra = SILE.settings:get("linespacing.fit-font.extra-space"):absolute()	×
76	local btob = prevmetrics.descender + thismetrics.ascender + extra	×
77	local toAdd = btob - (vbox.height + (previous and previous.depth or 0))	×
78	return SILE.nodefactory.vglue(toAdd)	×
79	end
80
81	if method == "css" then	×
82	local lh = prevmetrics.lineheight	×
83	local leading = (lh - (prevmetrics.ascender + prevmetrics.descender))	×
84	if previous then	×
85	previous.height = previous.height + leading / 2	×
86	previous.depth = previous.depth + leading / 2	×
87	end
88	return SILE.nodefactory.vglue()	×
89
90	end
91
92	SU.error("Unknown line spacing method "..method)	×
93	end
94
95	function package:_init ()	×
96	base._init(self)	×
97	self.class:registerPostinit(function(_)	×
98	SILE.typesetter.leadingFor = linespacingLeading	×
99	end)
100	end
101
102	function package.declareSettings (_)	×
103
104	SILE.settings:declare({	×
105	parameter = "linespacing.method",
106	default = "tex",
107	type = "string",
108	help = "How to set the line spacing (tex, fixed, fit-font, fit-glyph, css)"	×
109	})
110
111	SILE.settings:declare({	×
112	parameter = "linespacing.fixed.baselinedistance",
113	default = SILE.length("1.2em"),
114	type = "length",
115	help = "Distance from baseline to baseline in the case of fixed line spacing"	×
116	})
117
118	SILE.settings:declare({	×
119	parameter = "linespacing.minimumfirstlineposition",
120	default = SILE.length(0),
121	type = "length"	×
122	})
123
124	SILE.settings:declare({	×
125	parameter = "linespacing.fit-glyph.extra-space",
126	default = SILE.length(0),
127	type = "length"	×
128	})
129
130	SILE.settings:declare({	×
131	parameter = "linespacing.fit-font.extra-space",
132	default = SILE.length(0),
133	type = "length"	×
134	})
135
136	SILE.settings:declare({	×
137	parameter = "linespacing.css.line-height",
138	default = SILE.length("1.2em"),
139	type = "length"	×
140	})
141
142	end
143
144	function package:registerCommands ()	×
145
146	self:registerCommand("linespacing-on", function ()	×
147	SILE.typesetter.leadingFor = linespacingLeading	×
148	end)
149
150	self:registerCommand("linespacing-off", function ()	×
151	SILE.typesetter.leadingFor = SILE.typesetters.base.leadingFor	×
152	end)
153
154	end
155
156	package.documentation = [[
157	\begin{document}
158	\linespacing-on
159	SILE’s default method of inserting leading between lines should be familiar to users of TeX, but it is not the most friendly system for book designers.
160	The \autodoc:package{linespacing} package provides a better choice of leading systems.
161
162	After loading the package, you are able to choose the linespacing mode by setting the \autodoc:setting{linespacing.method} parameter.
163	The following examples have funny sized words in them so that you can see how the different methods interact.
164
165	By default, this is set to \code{tex}. The other options available are:
166
167	\medskip
168	\set[parameter=linespacing.method,value=fixed]
169	\set[parameter=linespacing.fixed.baselinedistance,value=1.5em]
170	\begin{itemize}
171	\item{\code{fixed}. This set the lines at a fixed baseline-to-baseline distance, determined by the \autodoc:setting{linespacing.fixed.baselinedistance} parameter.
172	You can specify this parameter either relative to the type size (\code{1.2em}) or as a absolute distance (\code{15pt}).
173	This paragraph is set with a fixed 1.5em baseline-to-baseline distance.}
174	\end{itemize}
175
176	\medskip
177	\set[parameter=linespacing.method,value=fit-glyph]
178	\begin{itemize}
179	\item{\code{fit-glyph}. This sets the lines solid; that is, the lowest point on line 1 (either a descender like \font[size=20pt]{q} or, if there are no descenders, the baseline) will touch the \font[size=20pt]{highest} point of line 2, as in this paragraph.
180	You generally don’t want to use this as-is.}
181	\end{itemize}
182
183	\set[parameter=linespacing.fit-glyph.extra-space,value=5pt]
184
185	What you probably want to do is insert a constant (relative or absolute) s\font[size=20pt]{p}ace between the lines by setting the \autodoc:setting{linespacing.fit-glyph.extra-space} parameter.
186	\font[size=20pt]{T}his paragraph is set with 5 points of space between the descenders and the ascenders.
187
188	\medskip
189	\set[parameter=linespacing.method,value=fit-font]
190	\begin{itemize}
191	\item{\code{fit-font}. This inspects each \code{hbox} on the line, and asks the fonts it finds for their bounding boxes—the highest ascender and the lower descender.
192	It then sets the lines solid.
193	Essentially each character is treated as if it is the same height, rather like composing a slug of metal type.
194	If there are things other than text on your line, or the text is buried inside other boxes, this may not work well.}
195	\end{itemize}
196
197	\set[parameter=linespacing.fit-font.extra-space,value=5pt]
198
199	As with \code{fit-glyph}, you can insert extra space between the lines with the \autodoc:setting{linespacing.fit-font.extra-space} parameter.
200
201	\medskip
202	\set[parameter=linespacing.method,value=css]
203	\set[parameter=linespacing.css.line-height,value=2em]
204	\begin{itemize}
205	\item{\code{css}. This is similar to the method used in browsers; the baseline distance is set with the \autodoc:setting{linespacing.css.line-height} parameter, and the excess \font[size=20pt]{space} between this parameter and the actual height of the line is distributed between the top and bottom of the line.}
206	\end{itemize}
207	\medskip
208
209	\linespacing-off
210	\end{document}
211	]]	×
212
213	return package	×

sile-typesetter / sile / 6713098919

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