Bug 323173 – Add layout of mixed direction text for vertical layout

2007-01-15  Behdad Esfahbod  <behdad@gnome.org>

        Bug 323173 – Add layout of mixed direction text for vertical layout

        * pango/pango-gravity.h:
        * pango/pango-gravity.c:
        Moved gravity stuff here.  New public API:

                PangoGravityHint
                pango_gravity_get_for_matrix()
                pango_gravity_get_for_script()

        * pango/pango-context.h:
        * pango/pango-context.c (pango_context_init),
        (update_resolved_gravity), (itemize_state_update_for_new_run):
        Support gravity hint.  New public API:

                pango_context_set_gravity_hint()
                pango_context_get_gravity_hint()

        * pango/pango-utils.c:
        * pango/pango-matrix.c:
        * pango/pango-matrix.h:
        * pango/pango-types.h:
        Moved gravity and matrix stuff into its own header.  pango-types.h
        includes both pango-matrix.h and pango-gravity.h

        * pango/pango.h:
        Include new headers.

        * pango/pango.def:
        * pango/Makefile.am:
        Update.

        * docs/pango-docs.sgml:
        * docs/pango-sections.txt:
        * docs/tmpl/glyphs.sgml:
        * docs/tmpl/main.sgml:
        * docs/tmpl/vertical.sgml:
        Add a section for Vertical Text.

        * examples/renderdemo.c (do_output), (parse_gravity_hint),
        (parse_options):
        Support gravity hint.

        * examples/test-mixed.txt:
        New test, mixed Latin, Arabic, Chinese text.


svn path=/trunk/; revision=2144

1 files changed, 294 insertions, 0 deletions

diff --git a/pango/pango-gravity.c b/pango/pango-gravity.c
new file mode 100644
index 00000000..73103134
--- /dev/null
+++ b/pango/pango-gravity.c
@@ -0,0 +1,294 @@
+/* Pango
+ * pango-gravity.c: Gravity routines
+ *
+ * Copyright (C) 2006, 2007 Red Hat Software
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <config.h>
+
+#include "pango-gravity.h"
+
+#include <math.h>
+
+/**
+ * pango_gravity_to_rotation:
+ * @gravity: gravity to query
+ *
+ * Converts a #PangoGravity value to its rotation value.
+ * @gravity should not be %PANGO_GRAVITY_AUTO.
+ *
+ * Return value: the rotation value corresponding to @gravity.
+ *
+ * Since: 1.16
+ */
+double
+pango_gravity_to_rotation (PangoGravity gravity)
+{
+  double rotation;
+
+  g_return_val_if_fail (gravity != PANGO_GRAVITY_AUTO, 0);
+
+  switch (gravity)
+    {
+      default:
+      case PANGO_GRAVITY_AUTO: /* shut gcc up */
+      case PANGO_GRAVITY_SOUTH:	rotation =  0;		break;
+      case PANGO_GRAVITY_NORTH:	rotation =  G_PI;	break;
+      case PANGO_GRAVITY_EAST:	rotation = -G_PI_2;	break;
+      case PANGO_GRAVITY_WEST:	rotation = +G_PI_2;	break;
+    }
+
+  return rotation;
+}
+
+/**
+ * pango_gravity_get_for_matrix:
+ * @matrix: a #PangoMatrix
+ *
+ * Finds the gravity that best matches the rotation component
+ * in a #PangoMatrix.
+ *
+ * Return value: the gravity of @matrix, which will never be
+ * %PANGO_GRAVITY_AUTO, or %PANGO_GRAVITY_SOUTH if @matrix is %NULL
+ *
+ * Since: 1.16
+ */
+PangoGravity
+pango_gravity_get_for_matrix (const PangoMatrix *matrix)
+{
+  PangoGravity gravity;
+  double x;
+  double y;
+
+  if (!matrix)
+    return PANGO_GRAVITY_SOUTH;
+
+  x = matrix->xy;
+  y = matrix->yy;
+
+  if (fabs (x) > fabs (y))
+    gravity = x > 0 ? PANGO_GRAVITY_WEST : PANGO_GRAVITY_EAST;
+  else
+    gravity = y < 0 ? PANGO_GRAVITY_NORTH : PANGO_GRAVITY_SOUTH;
+
+  return gravity;
+}
+
+
+
+typedef enum
+{
+  PANGO_VERTICAL_DIRECTION_NONE,
+  PANGO_VERTICAL_DIRECTION_TTB,
+  PANGO_VERTICAL_DIRECTION_BTT
+} PangoVerticalDirection;
+
+typedef struct {
+  /* PangoDirection */
+  guint8 horiz_dir;		/* Orientation in horizontal context */
+
+  /* PangoVerticalDirection */
+  guint8 vert_dir;		/* Orientation in vertical context */
+
+  /* PangoGravity */
+  guint8 preferred_gravity;	/* Preferred context gravity */
+
+  /* gboolean */
+  guint8 upright;		/* Whether glyphs are upright or
+				 * rotated in foreign context */
+} PangoScriptProperties;
+
+#define NONE PANGO_VERTICAL_DIRECTION_NONE
+#define TTB  PANGO_VERTICAL_DIRECTION_TTB
+#define BTT  PANGO_VERTICAL_DIRECTION_BTT
+
+#define LTR  PANGO_DIRECTION_LTR
+#define RTL  PANGO_DIRECTION_RTL
+#define WEAK PANGO_DIRECTION_WEAK_LTR
+
+#define S PANGO_GRAVITY_SOUTH
+#define E PANGO_GRAVITY_EAST
+#define N PANGO_GRAVITY_NORTH
+#define W PANGO_GRAVITY_WEST
+
+const PangoScriptProperties script_properties[] =
+  {				/* ISO 15924 code */
+      {LTR, NONE, S, FALSE},	/* Zyyy */
+      {LTR, NONE, S, FALSE},	/* Qaai */
+      {RTL, NONE, S, FALSE},	/* Arab */
+      {LTR, NONE, S, FALSE},	/* Armn */
+      {LTR, NONE, S, FALSE},	/* Beng */
+      {LTR, TTB,  E, TRUE },	/* Bopo */
+      {LTR, NONE, S, FALSE},	/* Cher */
+      {LTR, NONE, S, FALSE},	/* Qaac */
+      {LTR, NONE, S, FALSE},	/* Cyrl (Cyrs) */
+      {LTR, NONE, S, FALSE},	/* Dsrt */
+      {LTR, NONE, S, FALSE},	/* Deva */
+      {LTR, NONE, S, FALSE},	/* Ethi */
+      {LTR, NONE, S, FALSE},	/* Geor (Geon, Geoa) */
+      {LTR, NONE, S, FALSE},	/* Goth */
+      {LTR, NONE, S, FALSE},	/* Grek */
+      {LTR, NONE, S, FALSE},	/* Gujr */
+      {LTR, NONE, S, FALSE},	/* Guru */
+      {LTR, TTB,  E, TRUE },	/* Hani */
+      {LTR, TTB,  E, TRUE },	/* Hang */
+      {RTL, NONE, S, FALSE},	/* Hebr */
+      {LTR, TTB,  E, TRUE },	/* Hira */
+      {LTR, NONE, S, FALSE},	/* Knda */
+      {LTR, TTB,  E, TRUE },	/* Kana */
+      {LTR, NONE, S, FALSE},	/* Khmr */
+      {LTR, NONE, S, FALSE},	/* Laoo */
+      {LTR, NONE, S, FALSE},	/* Latn (Latf, Latg) */
+      {LTR, NONE, S, FALSE},	/* Mlym */
+      {WEAK,TTB,  W, FALSE},	/* Mong */
+      {LTR, NONE, S, FALSE},	/* Mymr */
+      {LTR, BTT,  W, FALSE},	/* Ogam */
+      {LTR, NONE, S, FALSE},	/* Ital */
+      {LTR, NONE, S, FALSE},	/* Orya */
+      {LTR, NONE, S, FALSE},	/* Runr */
+      {LTR, NONE, S, FALSE},	/* Sinh */
+      {RTL, NONE, S, FALSE},	/* Syrc (Syrj, Syrn, Syre) */
+      {LTR, NONE, S, FALSE},	/* Taml */
+      {LTR, NONE, S, FALSE},	/* Telu */
+      {RTL, NONE, S, FALSE},	/* Thaa */
+      {LTR, NONE, S, FALSE},	/* Thai */
+      {LTR, NONE, S, FALSE},	/* Tibt */
+      {LTR, NONE, S, FALSE},	/* Cans */
+      {LTR, TTB,  S, TRUE },	/* Yiii */
+      {LTR, NONE, S, FALSE},	/* Tglg */
+      {LTR, NONE, S, FALSE},	/* Hano */
+      {LTR, NONE, S, FALSE},	/* Buhd */
+      {LTR, NONE, S, FALSE},	/* Tagb */
+
+      /* Unicode-4.0 additions */
+      {LTR, NONE, S, FALSE},	/* Brai */
+      {LTR, NONE, S, FALSE},	/* Cprt */
+      {LTR, NONE, S, FALSE},	/* Limb */
+      {LTR, NONE, S, FALSE},	/* Osma */
+      {LTR, NONE, S, FALSE},	/* Shaw */
+      {LTR, NONE, S, FALSE},	/* Linb */
+      {LTR, NONE, S, FALSE},	/* Tale */
+      {LTR, NONE, S, FALSE},	/* Ugar */
+
+      /* Unicode-4.1 additions */
+      {LTR, NONE, S, FALSE},	/* Talu */
+      {LTR, NONE, S, FALSE},	/* Bugi */
+      {LTR, NONE, S, FALSE},	/* Glag */
+      {LTR, NONE, S, FALSE},	/* Tfng */
+      {LTR, NONE, S, FALSE},	/* Sylo */
+      {LTR, NONE, S, FALSE},	/* Xpeo */
+      {LTR, NONE, S, FALSE},	/* Khar */
+
+      /* Unicode-5.0 additions */
+      {LTR, NONE, S, FALSE},	/* Zzzz */
+      {LTR, NONE, S, FALSE},	/* Bali */
+      {LTR, NONE, S, FALSE},	/* Xsux */
+      {RTL, NONE, S, FALSE},	/* Phnx */
+      {LTR, NONE, S, FALSE},	/* Phag */
+      {RTL, NONE, S, FALSE}	/* Nkoo */
+};
+
+#undef NONE
+#undef TTB
+#undef BTT
+
+#undef LTR
+#undef RTL
+#undef WEAK
+
+#undef S
+#undef E
+#undef N
+#undef W
+
+static PangoScriptProperties
+get_script_properties (PangoScript script)
+{
+  if ((guint)script >= G_N_ELEMENTS (script_properties))
+    script = 0;
+
+  return script_properties[script];
+}
+
+/**
+ * pango_gravity_get_for_script:
+ * @script: #PangoScript to query
+ * @base_gravity: base gravity of the paragraph
+ * @hint: orientation hint
+ *
+ * Based on the script, base gravity, and hint, returns actual gravity
+ * to use in laying out a single #PangoItem.
+ *
+ * If @base_gravity is %PANGO_GRAVITY_AUTO, it is first replaced with the
+ * preferred gravity of @script.  To get the preferred gravity of a script,
+ * pass %PANGO_GRAVITY_AUTO and %PANGO_GRAVITY_HINT_STRONG in.
+ *
+ * Return value: resolved gravity suitable to use for a run of text
+ *
+ * Since: 1.16
+ */
+PangoGravity
+pango_gravity_get_for_script (PangoScript      script,
+			      PangoGravity     base_gravity,
+			      PangoGravityHint hint)
+{
+  PangoScriptProperties props = get_script_properties (script);
+  gboolean vertical;
+  
+
+  if (G_UNLIKELY (base_gravity == PANGO_GRAVITY_AUTO))
+    base_gravity = props.preferred_gravity;
+  
+  vertical = PANGO_GRAVITY_IS_VERTICAL (base_gravity);
+
+  /* Everything is designed such that a system with no vertical support
+   * renders everything correctly horizontally.  So, if not in a vertical
+   * gravity, base and resolved gravities are always the same.
+   *
+   * If the script should be upright all the time, like Chinese and Japenese,
+   * any base gravity should resolve to itself.
+   */
+  if (G_LIKELY (!vertical || props.upright))
+    return base_gravity;
+
+  /* If here, we have a non-upright script in a vertical gravity setting.
+   * Resolve depending on the hint.
+   */
+  switch (hint)
+    {
+    default:
+    case PANGO_GRAVITY_HINT_NATURAL:
+      if (props.vert_dir == PANGO_VERTICAL_DIRECTION_NONE)
+        return PANGO_GRAVITY_SOUTH;
+      if ((base_gravity   == PANGO_GRAVITY_EAST) ^
+	  (props.vert_dir == PANGO_VERTICAL_DIRECTION_BTT))
+        return PANGO_GRAVITY_SOUTH;
+      else
+        return PANGO_GRAVITY_NORTH;
+
+    case PANGO_GRAVITY_HINT_STRONG:
+      return base_gravity;
+
+    case PANGO_GRAVITY_HINT_LINE:
+      if ((base_gravity    == PANGO_GRAVITY_EAST) ^
+	  (props.horiz_dir == PANGO_DIRECTION_RTL))
+        return PANGO_GRAVITY_SOUTH;
+      else
+        return PANGO_GRAVITY_NORTH;
+    }
+}