From ee883f30d47992e5ad87d0d70d2f97f79442e8ad Mon Sep 17 00:00:00 2001
From: Emmanuele Bassi <ebassi@linux.intel.com>
Date: Wed, 21 Jan 2009 17:35:47 +0000
Subject: [PATCH] Add units-from-em conversion
An em is a unit of measurement in typography, equal to the point
size of the current font.
It should be possible to convert a value expressed in em to
ClutterUnits by using the current font and the current DPI as
stored by the default backend.
---
clutter/clutter-units.c | 50 ++++++++++++++++++++++
clutter/clutter-units.h | 11 +++++
doc/reference/clutter/clutter-sections.txt | 4 ++
3 files changed, 65 insertions(+)
diff --git a/clutter/clutter-units.c b/clutter/clutter-units.c
index cdcb8390b..88b2e7fe6 100644
--- a/clutter/clutter-units.c
+++ b/clutter/clutter-units.c
@@ -153,6 +153,56 @@ clutter_units_pt (gdouble pt)
return pt * dpi / 72.0;
}
+/**
+ * clutter_units_em:
+ * @em: em to convert
+ *
+ * Converts a value in em to #ClutterUnit<!-- -->s at the
+ * current DPI.
+ *
+ * Return value: the value in units
+ *
+ * Since: 1.0
+ */
+ClutterUnit
+clutter_units_em (gdouble em)
+{
+ ClutterBackend *backend;
+ const gchar *font_name;
+ gdouble dpi;
+ ClutterUnit retval = 0;
+
+ backend = clutter_get_default_backend ();
+
+ dpi = clutter_backend_get_resolution (backend);
+ font_name = clutter_backend_get_font_name (backend);
+ if (G_LIKELY ((font_name && *font_name != '\0')))
+ {
+ PangoFontDescription *font_desc;
+ gdouble font_size = 0;
+
+ font_desc = pango_font_description_from_string (font_name);
+ if (G_LIKELY (font_desc != NULL))
+ {
+ gint pango_size;
+ gboolean is_absolute;
+
+ pango_size = pango_font_description_get_size (font_desc);
+ is_absolute =
+ pango_font_description_get_size_is_absolute (font_desc);
+ if (!is_absolute)
+ font_size = ((gdouble) font_size) / PANGO_SCALE;
+
+ pango_font_description_free (font_desc);
+ }
+
+ /* 10 points at 96 DPI is 12 pixels */
+ retval = 1.2 * font_size * dpi / 96.0;
+ }
+
+ return retval;
+}
+
static GTypeInfo _info = {
0,
NULL,
diff --git a/clutter/clutter-units.h b/clutter/clutter-units.h
index 8eb24d102..efc622e1b 100644
--- a/clutter/clutter-units.h
+++ b/clutter/clutter-units.h
@@ -131,8 +131,19 @@ typedef float ClutterUnit;
*/
#define CLUTTER_UNITS_FROM_POINTS(x) (clutter_units_pt (x))
+/**
+ * CLUTTER_UNITS_FROM_EM:
+ * @x: a value in em
+ *
+ * Converts a value in em into #ClutterUnit<!-- -->s
+ *
+ * Since: 1.0
+ */
+#define CLUTTER_UNITS_FROM_EM(x) (clutter_units_em (x))
+
ClutterUnit clutter_units_mm (gdouble mm);
ClutterUnit clutter_units_pt (gdouble pt);
+ClutterUnit clutter_units_em (gdouble em);
#define CLUTTER_TYPE_UNIT (clutter_unit_get_type ())
#define CLUTTER_TYPE_PARAM_UNIT (clutter_param_unit_get_type ())
diff --git a/doc/reference/clutter/clutter-sections.txt b/doc/reference/clutter/clutter-sections.txt
index abef50c16..748691144 100644
--- a/doc/reference/clutter/clutter-sections.txt
+++ b/doc/reference/clutter/clutter-sections.txt
@@ -33,6 +33,8 @@ CLUTTER_UNITS_FROM_FLOAT
CLUTTER_UNITS_TO_FLOAT
CLUTTER_UNITS_FROM_INT
CLUTTER_UNITS_TO_INT
+
+<SUBSECTION>
CLUTTER_UNITS_FROM_DEVICE
CLUTTER_UNITS_TO_DEVICE
CLUTTER_UNITS_FROM_FIXED
@@ -41,8 +43,10 @@ CLUTTER_UNITS_FROM_PANGO_UNIT
CLUTTER_UNITS_TO_PANGO_UNIT
CLUTTER_UNITS_FROM_MM
CLUTTER_UNITS_FROM_POINTS
+CLUTTER_UNITS_FROM_EM
clutter_units_mm
clutter_units_pt
+clutter_units_em
<SUBSECTION>
CLUTTER_MAXUNIT