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Diffstat (limited to 'src/helper/units.h')
| -rw-r--r-- | src/helper/units.h | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/src/helper/units.h b/src/helper/units.h new file mode 100644 index 000000000..3acb65828 --- /dev/null +++ b/src/helper/units.h @@ -0,0 +1,146 @@ +#ifndef __SP_UNIT_H__ +#define __SP_UNIT_H__ + +/* + * SPUnit + * + * Ported from libgnomeprint + * + * Authors: + * Dirk Luetjens <dirk@luedi.oche.de> + * Yves Arrouye <Yves.Arrouye@marin.fdn.fr> + * Lauris Kaplinski <lauris@ximian.com> + * + * Copyright 1999-2001 Ximian, Inc. and authors + * + */ + +#include <glib/gmessages.h> +#include <glib/gslist.h> +#include <glib/gtypes.h> +#include "sp-metric.h" + + +/* + * Units and conversion methods used by libgnomeprint. + * + * You need those for certain config keys (like paper size), if you are + * interested in using these (look at gnome-print-config.h for discussion, + * why you may NOT be interested in paper size). + * + * Unit bases define set of mutually unrelated measuring systems (numbers, + * paper, screen and dimesionless user coordinates). Still, you can convert + * between those, specifying scaling factors explicitly. + * + * Paper (i.e. output) coordinates are taken as absolute real world units. + * It has some justification, because screen unit (pixel) size changes, + * if you change screen resolution, while you cannot change output on paper + * as easily (unless you have thermally contracting paper, of course). + * + */ + +struct SPUnit; +struct SPDistance; + +/* + * The base linear ("absolute") unit is 1/72th of an inch, i.e. the base unit of postscript. + */ + +/* + * Unit bases + */ +enum SPUnitBase { + SP_UNIT_DIMENSIONLESS = (1 << 0), /* For percentages and like */ + SP_UNIT_ABSOLUTE = (1 << 1), /* Real world distances - i.e. mm, cm... */ + SP_UNIT_DEVICE = (1 << 2), /* Pixels in the SVG/CSS sense. */ + SP_UNIT_VOLATILE = (1 << 3) /* em and ex */ +}; + +/* + * Units: indexes into sp_units. + */ +enum SPUnitId { + SP_UNIT_SCALE, // 1.0 == 100% + SP_UNIT_PT, // Postscript points: exactly 72 per inch + SP_UNIT_PX, // "Pixels" in the CSS sense; though Inkscape assumes a constant 90 per inch. + SP_UNIT_PERCENT, /* Note: In Inkscape this often means "relative to current value" (for + users to edit a value), rather than the SVG/CSS use of percentages. */ + SP_UNIT_MM, // millimetres + SP_UNIT_CM, // centimetres + SP_UNIT_M, // metres + SP_UNIT_IN, // inches + SP_UNIT_EM, // font-size of relevant font + SP_UNIT_EX, // x-height of relevant font + sp_max_unit_id = SP_UNIT_EX // For bounds-checking in sp_unit_get_by_id. +}; + +/* + * Notice, that for correct menus etc. you have to use + * ngettext method family yourself. For that reason we + * do not provide translations in unit names. + * I also do not know, whether to allow user-created units, + * because this would certainly confuse textdomain. + */ + +struct SPUnit { + SPUnitId unit_id; /* used as sanity check */ + SPUnitBase base; + gdouble unittobase; /* how many base units in this unit */ + SPMetric metric; // the corresponding SPMetric from sp-metrics.h + guint svg_unit; // the corresponding SVGLengthUnit + + /* When using, you must call "gettext" on them so they're translated */ + gchar const *name; + gchar const *abbr; + gchar const *plural; + gchar const *abbr_plural; +}; + +const SPUnit *sp_unit_get_by_abbreviation (const gchar *abbreviation); +/* When using, you must call "gettext" on them so they're translated */ +const gchar *sp_unit_get_abbreviation (const SPUnit *unit); +gchar const *sp_unit_get_plural (SPUnit const *unit); + +SPMetric sp_unit_get_metric(SPUnit const *unit); +guint sp_unit_get_svg_unit(SPUnit const *unit); + +extern SPUnit const sp_units[]; + +inline SPUnit const & +sp_unit_get_by_id(SPUnitId const id) +{ + /* inline because the compiler should optimize away the g_return_val_if_fail test in the + usual case that the argument value is known at compile-time, leaving just + "return sp_units[constant]". */ + unsigned const ix = unsigned(id); + g_return_val_if_fail(ix <= sp_max_unit_id, sp_units[SP_UNIT_PX]); + return sp_units[ix]; +} + +#define SP_PS_UNIT (&sp_unit_get_by_id(SP_UNIT_PT)) + + +/** Used solely by units-test.cpp. */ +bool sp_units_table_sane(); + +#define SP_UNITS_ALL (SP_UNIT_DIMENSIONLESS | SP_UNIT_ABSOLUTE | SP_UNIT_DEVICE | SP_UNIT_VOLATILE) + +GSList *sp_unit_get_list (guint bases); +void sp_unit_free_list (GSList *units); + +/* These are pure utility */ +/* Return TRUE if conversion is possible, FALSE if unit bases differ */ +gboolean sp_convert_distance (gdouble *distance, const SPUnit *from, const SPUnit *to); + +/* If either one is NULL, transconverting to/from that base fails */ +/* Generic conversion between volatile units would be useless anyways */ +gdouble sp_convert_distance_full(gdouble const from_dist, SPUnit const &from, SPUnit const &to); + +/* Some more convenience */ +gdouble sp_units_get_pixels(gdouble const units, SPUnit const &unit); +gdouble sp_pixels_get_units(gdouble const pixels, SPUnit const &unit); + +double angle_to_compass(double angle); +double angle_from_compass(double angle); + +#endif |