1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
|
---
Title: Text Attributes and Markup
---
# Text Attributes
Attributed text is used in a number of places in Pango. It is used as the
input to the itemization process and also when creating a [class@Pango.Layout].
Attributes can influence the various stages of the rendering pipeline. For example,
font or size attributes will influence the font selection that is happening during
itemization, font features and letterspacing attributes will influence shaping, and
color or underline attributes will be used for rendering.
Pango uses a simple structs for individual attributes, such as
[struct@Pango.AttrColor] or [struct@Pango.AttrFontDesc]. Each attribute has a type,
and a start and end index that determine the range of characters that the attribute
applies to. See the [enum@Pango.AttrType] enumeration for all the possible
attribute types.
Attributes rarely come alone. Pango uses the [struct@Pango.AttrList] structure
to hold all attributes that apply to a piece of text.
# Pango Markup
Frequently, you want to display some text to the user with attributes applied to
part of the text (for example, you might want bold or italicized words). With the
base Pango interfaces, you could create a [struct@Pango.AttrList] and apply it to
the text; the problem is that you'd need to apply attributes to some numeric range
of characters, for example "characters 12-17." This is broken from an
internationalization standpoint; once the text is translated, the word you wanted
to italicize could be in a different position.
The solution is to include the text attributes in the string to be translated.
Pango provides this feature with a small markup language. You can parse a marked-up
string into the string text plus a [struct@Pango.AttrList] using either of
[func@parse_markup] or [func@markup_parser_new].
A simple example of a marked-up string might be:
```
<span foreground="blue" size="x-large">Blue text</span> is <i>cool</i>!
```
A more elaborate example of using markup to color combining marks in
Arabic text:
```
<span foreground="purple">ا</span><span foreground="red">َ</span>ل<span foreground="blue">ْ</span>ع<span foreground="red">َ</span>ر<span foreground="red">َ</span>ب<span foreground="red">ِ</span>ي<span foreground="green">ّ</span><span foreground="red">َ</span>ة<span foreground="blue">ُ</span>
```
Pango uses GMarkup to parse this language, which means that XML features
such as numeric character entities such as `©` for © can be used too.
The root tag of a marked-up document is `<markup>`, but [func@Pango.parse_markup]
allows you to omit this tag, so you will most likely never need to use it.
The most general markup tag is `<span>`, then there are some convenience
tags.
## The `<span>` Attributes
font
font_desc
: A font description string, such as "Sans Italic 12". See
[func@Pango.FontDescription.from_string] for a description of the format of
the string representation. Note that any other span attributes will override
this description. So if you have "Sans Italic" and also a style="normal"
attribute, you will get Sans normal, not italic.
font_family
face
: A font family name.
font_size
size
: Font size in 1024ths of a point, or in points (e.g. '12.5pt'), or one of the
absolute sizes 'xx-small', 'x-small', 'small', 'medium', 'large', 'x-large',
'xx-large', or a percentage (e.g. '200%'), or one of the relative sizes 'smaller'
or 'larger'.
If you want to specify a absolute size, it's usually easier to take advantage
of the ability to specify a partial font description using 'font'; you can use
font='12.5' rather than size='12800' or size='12.5pt'.
Support for specifying font sizes in points or as percentages was added in
Pango 1.50.
font_style
style
: One of 'normal', 'oblique', 'italic'.
font_weight
weight
: One of 'ultralight', 'light', 'normal', 'bold', 'ultrabold', 'heavy', or a
numeric weight.
font_variant
variant
: One of 'normal' or 'smallcaps'.
font_stretch
stretch
: One of 'ultracondensed', 'extracondensed',
'condensed', 'semicondensed', 'normal', 'semiexpanded', 'expanded',
'extraexpanded', 'ultraexpanded'.
font_features
: A comma-separated list of OpenType font feature settings, in the same syntax as
accepted by CSS. E.g: `font_features='dlig=1, -kern, afrc on'`.
foreground
fgcolor
color
: An RGB color specification such as '#00FF00' or a color name such as 'red'.
Since 1.38, an RGBA color specification such as '#00FF007F' will be interpreted
as specifying both a foreground color and foreground alpha.
background
bgcolor
: An RGB color specification such as '#00FF00' or a color name such as 'red'.
Since 1.38, an RGBA color specification such as '#00FF007F' will be interpreted
as specifying both a background color and background alpha.
alpha
fgalpha
: An alpha value for the foreground color, either a plain integer between 1 and
65536 or a percentage value like '50%'.
background_alpha
bgalpha
: An alpha value for the background color, either a plain integer between 1 and
65536 or a percentage value like '50%'.
underline
: One of 'none', 'single', 'double', 'low', 'error'.
underline_color
: The color of underlines; an RGB color specification such as '#00FF00' or a color
name such as 'red'.
overline
: One of 'none' or 'single'. Overline support was added in Pango 1.46.
overline_color
: The color of overlines; an RGB color specification such as '#00FF00' or a color
name such as 'red'. Overline support was added in Pango 1.46.
rise
: Vertical displacement, in Pango units or in points (e.g. '5pt'). Can be
negative for subscript, positive for superscript.
Support for specifying rise in points was added in Pango 1.50.
strikethrough
: 'true' or 'false' whether to strike through the text.
strikethrough_color
: The color of strikethrough lines; an RGB color specification such as '#00FF00'
or a color name such as 'red'.
fallback
: 'true' or 'false' whether to enable fallback. If disabled, then characters will
only be used from the closest matching font on the system. No fallback will be
done to other fonts on the system that might contain the characters in the text.
Fallback is enabled by default. Most applications should not disable fallback.
lang
: A language code, indicating the text language.
letter_spacing
: Inter-letter spacing in 1024ths of a point.
gravity
: One of 'south', 'east', 'north', 'west', 'auto'.
gravity_hint
: One of 'natural', 'strong', 'line'.
show
: Specifies what special characters to show visibly. The value can be 'none'
or a combination of 'spaces', 'line-breaks' and 'ignorables', combined with '|'.
Support for showing special characters was added in Pango 1.44.
insert_hyphens
: 'true' or 'false' to indicate whether hyphens should be inserted when breaking
lines in the middle of words. Available since Pango 1.44.
allow_breaks
: 'true' or 'false' to indicate whether breaking lines is allowed. Available
since Pango 1.44.
line_height
: Overrides the line height. The value can be either a factor (< 1024) that is
used to scale up the logical extents of runs or an absolute value (in 1024th
of a point).
Available since Pango 1.50.
text_transform
: Specifies how characters are transformed during shaping. The values can be
'none', 'lowercase', 'uppercase' or 'capitalize'. Support for text transformation
was added in Pango 1.50.
## Convenience Tags
`<b>`
: Bold
`<big>`
: Makes font relatively larger, equivalent to `<span size="larger">`
`<i>`
: Italic
`<s>`
: Strikethrough
`<sub>`
: Subscript
`<sup>`
: Superscript
`<small>`
: Makes font relatively smaller, equivalent to `<span size="smaller">`
`<tt>`
: Monospace font
`<u>`
: Underline
|
