Add Text::get_chars() implementation and tests

The clutter_text_get_chars() function returns a section of the
contents of the Text actor, delimited by a start and an end position.

This commit adds the implementation for that function and a test
unit that guarantees the offset-to-bytes computations are correct.

clutter/clutter-text.c

@@ -2998,14 +2998,47 @@ clutter_text_delete_chars (ClutterText *self,
   g_object_notify (G_OBJECT (self), "text");
 }
 
+/**
+ * clutter_text_get_chars:
+ * @self: a #ClutterTex
+ * @start_pos: start of text, in characters
+ * @end_pos: end of text, in characters
+ *
+ * Retrieves the contents of the #ClutterText actor between
+ * @start_pos and @end_pos.
+ *
+ * The positions are specified in characters, not in bytes.
+ *
+ * Return value: a newly allocated string with the contents of
+ *   the text actor between the specified positions. Use g_free()
+ *   to free the resources when done
+ *
+ * Since: 1.0
+ */
 gchar *
 clutter_text_get_chars (ClutterText *self,
                         gssize       start_pos,
                         gssize       end_pos)
 {
+  ClutterTextPrivate *priv;
+  gint start_index, end_index;
+
   g_return_val_if_fail (CLUTTER_IS_TEXT (self), NULL);
 
-  return NULL;
+  priv = self->priv;
+
+  if (end_pos < 0)
+    end_pos = priv->n_chars;
+
+  start_pos = MIN (priv->n_chars, start_pos);
+  end_pos = MIN (priv->n_chars, end_pos);
+
+  start_index = g_utf8_offset_to_pointer (priv->text, start_pos)
+              - priv->text;
+  end_index   = g_utf8_offset_to_pointer (priv->text, end_pos)
+              - priv->text;
+
+  return g_strndup (priv->text + start_index, end_index - start_index);
 }
 
 void

tests/conform/test-clutter-text.c

@@ -238,6 +238,37 @@ test_text_delete_chars (TestConformSimpleFixture *fixture,
   clutter_actor_destroy (CLUTTER_ACTOR (text));
 }
 
+void
+test_text_get_chars (TestConformSimpleFixture *fixture,
+                     gconstpointer             data)
+{
+  ClutterText *text = CLUTTER_TEXT (clutter_text_new ());
+  gchar *chars;
+
+  clutter_text_set_text (text, "00abcdef11");
+  g_assert_cmpint (get_nchars (text), ==, 10);
+  g_assert_cmpint (get_nbytes (text), ==, 10);
+  g_assert_cmpstr (clutter_text_get_text (text), ==, "00abcdef11");
+
+  chars = clutter_text_get_chars (text, 2, -1);
+  g_assert_cmpstr (chars, ==, "abcdef11");
+  g_free (chars);
+
+  chars = clutter_text_get_chars (text, 0, 8);
+  g_assert_cmpstr (chars, ==, "00abcdef");
+  g_free (chars);
+
+  chars = clutter_text_get_chars (text, 2, 8);
+  g_assert_cmpstr (chars, ==, "abcdef");
+  g_free (chars);
+
+  chars = clutter_text_get_chars (text, 8, 12);
+  g_assert_cmpstr (chars, ==, "11");
+  g_free (chars);
+
+  clutter_actor_destroy (CLUTTER_ACTOR (text));
+}
+
 void
 test_text_delete_text (TestConformSimpleFixture *fixture,
 			gconstpointer data)

tests/conform/test-conform-main.c

@@ -75,14 +75,11 @@ main (int argc, char **argv)
   TEST_CONFORM_SIMPLE ("/entry", test_entry_empty);
   TEST_CONFORM_SIMPLE ("/entry", test_entry_set_empty);
   TEST_CONFORM_SIMPLE ("/entry", test_entry_set_text);
-
   TEST_CONFORM_SIMPLE ("/entry", test_entry_append_some);
   TEST_CONFORM_SIMPLE ("/entry", test_entry_prepend_some);
   TEST_CONFORM_SIMPLE ("/entry", test_entry_insert);
-
   TEST_CONFORM_SIMPLE ("/entry", test_entry_delete_chars);
   TEST_CONFORM_SIMPLE ("/entry", test_entry_delete_text);
-
   TEST_CONFORM_SIMPLE ("/entry", test_entry_cursor);
   TEST_CONFORM_SIMPLE ("/entry", test_entry_event);
 
@@ -91,16 +88,14 @@ main (int argc, char **argv)
   TEST_CONFORM_SIMPLE ("/text", test_text_empty);
   TEST_CONFORM_SIMPLE ("/text", test_text_set_empty);
   TEST_CONFORM_SIMPLE ("/text", test_text_set_text);
-
   TEST_CONFORM_SIMPLE ("/text", test_text_append_some);
   TEST_CONFORM_SIMPLE ("/text", test_text_prepend_some);
   TEST_CONFORM_SIMPLE ("/text", test_text_insert);
-
   TEST_CONFORM_SIMPLE ("/text", test_text_delete_chars);
   TEST_CONFORM_SIMPLE ("/text", test_text_delete_text);
-
   TEST_CONFORM_SIMPLE ("/text", test_text_cursor);
   TEST_CONFORM_SIMPLE ("/text", test_text_event);
+  TEST_CONFORM_SIMPLE ("/text", test_text_get_chars);
 
   TEST_CONFORM_SIMPLE ("/rectangle", test_rect_set_size);
   TEST_CONFORM_SIMPLE ("/rectangle", test_rect_set_color);