Added transform functions between double and fraction.

Original commit message from CVS:
* gst/gstvalue.c: (gst_value_transform_double_fraction),
(gst_value_transform_fraction_double), (_gst_value_initialize):
* testsuite/caps/Makefile.am:
* testsuite/caps/fraction-convert.c: (check_from_double_convert),
(check_from_fraction_convert), (transform_test), (main):
Added transform functions between double and fraction.
Added testcase to verify transforms

6 files changed, 336 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index f738cb98d..2f61831ef 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2004-07-27  Wim Taymans  <wim@fluendo.com>
+
+	* gst/gstvalue.c: (gst_value_transform_double_fraction),
+	(gst_value_transform_fraction_double), (_gst_value_initialize):
+	* testsuite/caps/Makefile.am:
+	* testsuite/caps/fraction-convert.c: (check_from_double_convert),
+	(check_from_fraction_convert), (transform_test), (main):
+	Added transform functions between double and fraction.
+	Added testcase to verify transforms
+
 2004-07-26  Steve Lhomme  <steve.lhomme@free.fr>
 
 	* win32/GStreamer.vcproj:
diff --git a/gst/gstvalue.c b/gst/gstvalue.c
index 59a04b874..37612921f 100644
--- a/gst/gstvalue.c
+++ b/gst/gstvalue.c
@@ -20,6 +20,7 @@
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
+#include <math.h>
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
@@ -2544,6 +2545,95 @@ gst_value_transform_string_fraction (const GValue * src_value,
   gst_value_deserialize_fraction (dest_value, src_value->data[0].v_pointer);
 }
 
+#define MAX_TERMS       30
+#define MIN_DIVISOR     1.0e-10
+#define MAX_ERROR       1.0e-20
+
+/* use continued fractions to transform a double into a fraction,
+ * see http://mathforum.org/dr.math/faq/faq.fractions.html#decfrac.
+ * This algorithm takes care of overflows.
+ */
+static void
+gst_value_transform_double_fraction (const GValue * src_value,
+    GValue * dest_value)
+{
+  gdouble V, F;                 /* double being converted */
+  gint N, D;                    /* will contain the result */
+  gint A;                       /* current term in continued fraction */
+  gint64 N1, D1;                /* numerator, denominator of last approx */
+  gint64 N2, D2;                /* numerator, denominator of previous approx */
+  gint i;
+  gboolean negative = FALSE;
+
+  /* initialize fraction being converted */
+  F = src_value->data[0].v_double;
+  if (F < 0.0) {
+    F = -F;
+    negative = TRUE;
+  }
+
+  V = F;
+  /* initialize fractions with 1/0, 0/1 */
+  N1 = 1;
+  D1 = 0;
+  N2 = 0;
+  D2 = 1;
+  N = 1;
+  D = 1;
+
+  for (i = 0; i < MAX_TERMS; i++) {
+    /* get next term */
+    A = floor (F);
+    /* get new divisor */
+    F = F - A;
+
+    /* calculate new fraction in temp */
+    N2 = N1 * A + N2;
+    D2 = D1 * A + D2;
+
+    /* guard against overflow */
+    if (N2 > G_MAXINT || D2 > G_MAXINT) {
+      break;
+    }
+
+    N = N2;
+    D = D2;
+
+    /* save last two fractions */
+    N2 = N1;
+    D2 = D1;
+    N1 = N;
+    D1 = D;
+
+    /* quit if dividing by zero or close enough to target */
+    if (F < MIN_DIVISOR || fabs (V - ((gdouble) N) / D) < MAX_ERROR) {
+      break;
+    }
+
+    /* Take reciprocal */
+    F = 1 / F;
+  }
+  /* fix for overflow */
+  if (D == 0) {
+    N = G_MAXINT;
+    D = 1;
+  }
+  /* fix for negative */
+  if (negative)
+    N = -N;
+
+  /* will also simplify */
+  gst_value_set_fraction (dest_value, N, D);
+}
+
+static void
+gst_value_transform_fraction_double (const GValue * src_value,
+    GValue * dest_value)
+{
+  dest_value->data[0].v_double = ((double) src_value->data[0].v_int) /
+      ((double) src_value->data[1].v_int);
+}
+
 static int
 gst_value_compare_fraction (const GValue * value1, const GValue * value2)
 {
@@ -2817,6 +2907,10 @@ _gst_value_initialize (void)
       gst_value_transform_fraction_string);
   g_value_register_transform_func (G_TYPE_STRING, GST_TYPE_FRACTION,
       gst_value_transform_string_fraction);
+  g_value_register_transform_func (GST_TYPE_FRACTION, G_TYPE_DOUBLE,
+      gst_value_transform_fraction_double);
+  g_value_register_transform_func (G_TYPE_DOUBLE, GST_TYPE_FRACTION,
+      gst_value_transform_double_fraction);
 
   gst_value_register_intersect_func (G_TYPE_INT, GST_TYPE_INT_RANGE,
       gst_value_intersect_int_int_range);
diff --git a/tests/old/testsuite/caps/Makefile.am b/tests/old/testsuite/caps/Makefile.am
index 42efbd4b2..8d961d626 100644
--- a/tests/old/testsuite/caps/Makefile.am
+++ b/tests/old/testsuite/caps/Makefile.am
@@ -10,6 +10,7 @@ tests_pass = \
 	union \
 	string-conversions \
 	fixed \
+	fraction-convert \
 	fraction-multiply-and-zero \
 	intersect2 \
 	caps \
diff --git a/tests/old/testsuite/caps/fraction-convert.c b/tests/old/testsuite/caps/fraction-convert.c
new file mode 100644
index 000000000..41aae4047
--- /dev/null
+++ b/tests/old/testsuite/caps/fraction-convert.c
@@ -0,0 +1,115 @@
+/* GStreamer
+ *
+ * fraction-convert.c: test for GstFraction transform
+ *
+ * Copyright (C) <2004> Thomas Vander Stichele <thomas at apestaart dot org>
+ *
+ * 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 <math.h>
+#include <gst/gst.h>
+#include <glib.h>
+
+static void
+check_from_double_convert (gdouble value, gint nom, gint denom, gdouble prec)
+{
+  GValue value1 = { 0 };
+  GValue value2 = { 0 };
+  gdouble check;
+
+  g_value_init (&value1, G_TYPE_DOUBLE);
+  g_value_init (&value2, GST_TYPE_FRACTION);
+
+  g_value_set_double (&value1, value);
+  g_value_transform (&value1, &value2);
+  g_print ("%s = %s\n",
+      gst_value_serialize (&value1), gst_value_serialize (&value2));
+  g_assert (gst_value_get_fraction_numerator (&value2) == nom);
+  g_assert (gst_value_get_fraction_denominator (&value2) == denom);
+  g_value_transform (&value2, &value1);
+  g_print ("%s = %s\n",
+      gst_value_serialize (&value2), gst_value_serialize (&value1));
+  check = g_value_get_double (&value1);
+  g_assert (fabs (value - check) <= prec);
+}
+
+static void
+check_from_fraction_convert (gint nom, gint denom, gdouble prec)
+{
+  GValue value1 = { 0 };
+  GValue value2 = { 0 };
+  gdouble value;
+
+  g_value_init (&value1, GST_TYPE_FRACTION);
+  g_value_init (&value2, G_TYPE_DOUBLE);
+
+  gst_value_set_fraction (&value1, nom, denom);
+  g_value_transform (&value1, &value2);
+
+  value = g_value_get_double (&value2);
+  g_assert (fabs (value - ((gdouble) nom) / denom) < prec);
+
+  g_print ("%s = %s, %2.50lf as double\n",
+      gst_value_serialize (&value1), gst_value_serialize (&value2), value);
+
+  g_value_transform (&value2, &value1);
+  g_print ("%s = %s\n",
+      gst_value_serialize (&value2), gst_value_serialize (&value1));
+  value = g_value_get_double (&value2);
+  g_assert (gst_value_get_fraction_numerator (&value1) == nom);
+  g_assert (gst_value_get_fraction_denominator (&value1) == denom);
+
+  g_value_unset (&value2);
+  g_value_unset (&value1);
+}
+
+static void
+transform_test (void)
+{
+  check_from_fraction_convert (30000, 1001, 1.0e-12);
+  check_from_fraction_convert (1, G_MAXINT, 1.0e-12);
+  check_from_fraction_convert (G_MAXINT, 1, 1.0e-12);
+
+  check_from_double_convert (0.0, 0, 1, 1.0e-12);
+  check_from_double_convert (1.0, 1, 1, 1.0e-12);
+  check_from_double_convert (-1.0, -1, 1, 1.0e-12);
+  check_from_double_convert (M_PI, 1881244168, 598818617, 1.0e-12);
+  check_from_double_convert (-M_PI, -1881244168, 598818617, 1.0e-12);
+
+  check_from_double_convert (G_MAXDOUBLE, G_MAXINT, 1, G_MAXDOUBLE);
+  check_from_double_convert (G_MINDOUBLE, 0, 1, G_MAXDOUBLE);
+  check_from_double_convert (-G_MAXDOUBLE, -G_MAXINT, 1, G_MAXDOUBLE);
+  check_from_double_convert (-G_MINDOUBLE, 0, 1, G_MAXDOUBLE);
+
+  check_from_double_convert (((gdouble) G_MAXINT) + 1, G_MAXINT, 1,
+      G_MAXDOUBLE);
+  check_from_double_convert (((gdouble) G_MININT) - 1, G_MININT + 1, 1,
+      G_MAXDOUBLE);
+
+  check_from_double_convert (G_MAXINT - 1, G_MAXINT - 1, 1, 0);
+  check_from_double_convert (G_MININT + 1, G_MININT + 1, 1, 0);
+}
+
+int
+main (int argc, char *argv[])
+{
+  gst_init (&argc, &argv);
+
+  transform_test ();
+
+  return 0;
+}
diff --git a/testsuite/caps/Makefile.am b/testsuite/caps/Makefile.am
index 42efbd4b2..8d961d626 100644
--- a/testsuite/caps/Makefile.am
+++ b/testsuite/caps/Makefile.am
@@ -10,6 +10,7 @@ tests_pass = \
 	union \
 	string-conversions \
 	fixed \
+	fraction-convert \
 	fraction-multiply-and-zero \
 	intersect2 \
 	caps \
diff --git a/testsuite/caps/fraction-convert.c b/testsuite/caps/fraction-convert.c
new file mode 100644
index 000000000..41aae4047
--- /dev/null
+++ b/testsuite/caps/fraction-convert.c
@@ -0,0 +1,115 @@
+/* GStreamer
+ *
+ * fraction-convert.c: test for GstFraction transform
+ *
+ * Copyright (C) <2004> Thomas Vander Stichele <thomas at apestaart dot org>
+ *
+ * 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 <math.h>
+#include <gst/gst.h>
+#include <glib.h>
+
+static void
+check_from_double_convert (gdouble value, gint nom, gint denom, gdouble prec)
+{
+  GValue value1 = { 0 };
+  GValue value2 = { 0 };
+  gdouble check;
+
+  g_value_init (&value1, G_TYPE_DOUBLE);
+  g_value_init (&value2, GST_TYPE_FRACTION);
+
+  g_value_set_double (&value1, value);
+  g_value_transform (&value1, &value2);
+  g_print ("%s = %s\n",
+      gst_value_serialize (&value1), gst_value_serialize (&value2));
+  g_assert (gst_value_get_fraction_numerator (&value2) == nom);
+  g_assert (gst_value_get_fraction_denominator (&value2) == denom);
+  g_value_transform (&value2, &value1);
+  g_print ("%s = %s\n",
+      gst_value_serialize (&value2), gst_value_serialize (&value1));
+  check = g_value_get_double (&value1);
+  g_assert (fabs (value - check) <= prec);
+}
+
+static void
+check_from_fraction_convert (gint nom, gint denom, gdouble prec)
+{
+  GValue value1 = { 0 };
+  GValue value2 = { 0 };
+  gdouble value;
+
+  g_value_init (&value1, GST_TYPE_FRACTION);
+  g_value_init (&value2, G_TYPE_DOUBLE);
+
+  gst_value_set_fraction (&value1, nom, denom);
+  g_value_transform (&value1, &value2);
+
+  value = g_value_get_double (&value2);
+  g_assert (fabs (value - ((gdouble) nom) / denom) < prec);
+
+  g_print ("%s = %s, %2.50lf as double\n",
+      gst_value_serialize (&value1), gst_value_serialize (&value2), value);
+
+  g_value_transform (&value2, &value1);
+  g_print ("%s = %s\n",
+      gst_value_serialize (&value2), gst_value_serialize (&value1));
+  value = g_value_get_double (&value2);
+  g_assert (gst_value_get_fraction_numerator (&value1) == nom);
+  g_assert (gst_value_get_fraction_denominator (&value1) == denom);
+
+  g_value_unset (&value2);
+  g_value_unset (&value1);
+}
+
+static void
+transform_test (void)
+{
+  check_from_fraction_convert (30000, 1001, 1.0e-12);
+  check_from_fraction_convert (1, G_MAXINT, 1.0e-12);
+  check_from_fraction_convert (G_MAXINT, 1, 1.0e-12);
+
+  check_from_double_convert (0.0, 0, 1, 1.0e-12);
+  check_from_double_convert (1.0, 1, 1, 1.0e-12);
+  check_from_double_convert (-1.0, -1, 1, 1.0e-12);
+  check_from_double_convert (M_PI, 1881244168, 598818617, 1.0e-12);
+  check_from_double_convert (-M_PI, -1881244168, 598818617, 1.0e-12);
+
+  check_from_double_convert (G_MAXDOUBLE, G_MAXINT, 1, G_MAXDOUBLE);
+  check_from_double_convert (G_MINDOUBLE, 0, 1, G_MAXDOUBLE);
+  check_from_double_convert (-G_MAXDOUBLE, -G_MAXINT, 1, G_MAXDOUBLE);
+  check_from_double_convert (-G_MINDOUBLE, 0, 1, G_MAXDOUBLE);
+
+  check_from_double_convert (((gdouble) G_MAXINT) + 1, G_MAXINT, 1,
+      G_MAXDOUBLE);
+  check_from_double_convert (((gdouble) G_MININT) - 1, G_MININT + 1, 1,
+      G_MAXDOUBLE);
+
+  check_from_double_convert (G_MAXINT - 1, G_MAXINT - 1, 1, 0);
+  check_from_double_convert (G_MININT + 1, G_MININT + 1, 1, 0);
+}
+
+int
+main (int argc, char *argv[])
+{
+  gst_init (&argc, &argv);
+
+  transform_test ();
+
+  return 0;
+}