[pango/markup-sizes: 3/3] markup: Allow specifying size as percentage

[Matthias Clasen <matthiasc src gnome org>]

commit 59d38cde20425696543d262c5329b14056915614
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Aug 8 01:40:08 2021 -0400

    markup: Allow specifying size as percentage
    
    Accept values like 200%, in addition to other
    ways of specifying sizes in markup.
    
    Fixes: #23

 docs/pango_markup.md            |  6 ++++--
 pango/pango-markup.c            | 27 ++++++++++++++++++++++++++-
 tests/markups/valid-23.expected | 18 ++++++++++++++++++
 tests/markups/valid-23.markup   |  1 +
 4 files changed, 49 insertions(+), 3 deletions(-)
---
diff --git a/docs/pango_markup.md b/docs/pango_markup.md
index 408bead9..c82de9d5 100644
--- a/docs/pango_markup.md
+++ b/docs/pango_markup.md
@@ -79,11 +79,13 @@ 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 one of the relative sizes 'smaller' or 'larger'.
+  '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 was added in Pango 1.50.
+  Support for specifying font sizes in points or as percentages was added in
+  Pango 1.50.
 
 font_style
 style
diff --git a/pango/pango-markup.c b/pango/pango-markup.c
index a4bea3e5..5394c772 100644
--- a/pango/pango-markup.c
+++ b/pango/pango-markup.c
@@ -860,11 +860,29 @@ big_parse_func      (MarkupData            *md G_GNUC_UNUSED,
   return TRUE;
 }
 
+static gboolean
+parse_percentage (const char *input,
+                  double     *val)
+{
+  double v;
+  char *end;
+
+  v = g_ascii_strtod (input, &end);
+  if (errno == 0 && strcmp (end, "%") == 0 && v > 0)
+    {
+      *val = v;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
 static gboolean
 parse_absolute_size (OpenTag               *tag,
-                    const char            *size)
+                     const char            *size)
 {
   SizeLevel level = Medium;
+  double val;
   double factor;
 
   if (strcmp (size, "xx-small") == 0)
@@ -881,6 +899,11 @@ parse_absolute_size (OpenTag               *tag,
     level = XLarge;
   else if (strcmp (size, "xx-large") == 0)
     level = XXLarge;
+  else if (parse_percentage (size, &val))
+    {
+      factor = val / 100.0;
+      goto done;
+    }
   else
     return FALSE;
 
@@ -888,6 +911,8 @@ parse_absolute_size (OpenTag               *tag,
    * but not to sizes created by any other tags
    */
   factor = scale_factor (level, 1.0);
+
+done:
   add_attribute (tag, pango_attr_scale_new (factor));
   if (tag)
     open_tag_set_absolute_font_scale (tag, factor);
diff --git a/tests/markups/valid-23.expected b/tests/markups/valid-23.expected
new file mode 100644
index 00000000..43621301
--- /dev/null
+++ b/tests/markups/valid-23.expected
@@ -0,0 +1,18 @@
+test test
+
+
+---
+
+range 0 5
+[0,9]font-desc=Cantarell 11
+range 5 9
+[0,9]font-desc=Cantarell 11
+[5,9]scale=2.000000
+range 9 2147483647
+
+
+---
+
+[0:5] (null) Cantarell 11
+[5:9] (null) Cantarell 22
+[9:2147483647] (null) Cantarell 22
diff --git a/tests/markups/valid-23.markup b/tests/markups/valid-23.markup
new file mode 100644
index 00000000..601fa7ee
--- /dev/null
+++ b/tests/markups/valid-23.markup
@@ -0,0 +1 @@
+<span font="Cantarell 11">test <span size="200%">test</span></span>