[pango/bidi-adventures] Add tests for pango_layout_move_cursor_visually

[Matthias Clasen <matthiasc src gnome org>]

commit 045026f4ff893f02cf28e4b151b9c228cf29ec06
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Aug 5 14:43:34 2021 -0400

    Add tests for pango_layout_move_cursor_visually
    
    Some of these currently fail.

 tests/meson.build |   2 +-
 tests/test-bidi.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 122 insertions(+), 1 deletion(-)
---
diff --git a/tests/meson.build b/tests/meson.build
index 841a78eb..e8b52ce8 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -19,7 +19,6 @@ test_env.set('G_TEST_BUILDDIR', meson.current_build_dir())
 test_env.set('LC_ALL', 'en_US.UTF-8')
 
 tests = [
-  [ 'test-bidi' ],
   [ 'test-coverage' ],
   [ 'testboundaries' ],
   [ 'testboundaries_ucd' ],
@@ -40,6 +39,7 @@ endif
 if cairo_dep.found()
   test_cflags += '-DHAVE_CAIRO'
   tests += [
+    [ 'test-bidi', [ 'test-bidi.c' ], [ libpangocairo_dep ] ],
     [ 'testcontext', [ 'testcontext.c' ], [ libpangocairo_dep ] ],
     [ 'testiter', [ 'testiter.c' ], [ libpangocairo_dep ] ],
     [ 'test-ellipsize', [ 'test-ellipsize.c' ], [ libpangocairo_dep ] ],
diff --git a/tests/test-bidi.c b/tests/test-bidi.c
index fbdcc8cb..1108d443 100644
--- a/tests/test-bidi.c
+++ b/tests/test-bidi.c
@@ -19,7 +19,11 @@
  * Boston, MA 02111-1307, USA.
  */
 
+#include <locale.h>
 #include <pango/pango.h>
+#include <pango/pangocairo.h>
+
+static PangoContext *context;
 
 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
 
@@ -154,15 +158,132 @@ test_bidi_embedding_levels (void)
     }
 }
 
+/* Some basic tests for pango_layout_move_cursor_visually:
+ * - check that we actually move the cursor in the right direction
+ * - check that we get through the line with at most n steps
+ */
+static void
+test_move_cursor_visually (void)
+{
+  const char *tests[] = {
+    "abc😂️def",
+    "abcאבגdef",
+    "אבabcב",
+    "aאב12b",
+  };
+  PangoLayout *layout;
+  gboolean fail = FALSE;
+
+  layout = pango_layout_new (context);
+
+  for (int i = 0; i < G_N_ELEMENTS (tests); i++)
+    {
+      const char *text;
+      gsize n_chars;
+      int index;
+      int start_index;
+      gboolean trailing;
+      PangoRectangle s_pos, old_s_pos;
+      PangoRectangle w_pos, old_w_pos;
+      PangoLayoutLine *line;
+      struct {
+        int direction;
+        gboolean strong;
+      } params[] = {
+        { 1, TRUE },
+        { 1, FALSE },
+        { -1, TRUE },
+        { -1, FALSE },
+      };
+
+      pango_layout_set_text (layout, tests[i], -1);
+      text = pango_layout_get_text (layout);
+      line = pango_layout_get_line_readonly (layout, 0);
+
+      n_chars = g_utf8_strlen (text, -1);
+
+      for (int j = 0; j < G_N_ELEMENTS (params); j++)
+        {
+          gboolean ok;
+
+          if (g_test_verbose ())
+            g_print ("'%s' %s %s :\t",
+                     text,
+                     params[j].direction > 0 ? "->" : "<-",
+                     params[j].strong ? "strong" : "weak");
+
+      if ((pango_layout_line_get_resolved_direction (line) == PANGO_DIRECTION_LTR) == (params[j].direction > 
0))
+        start_index = 0;
+      else
+        start_index = strlen (text);
+
+          index = start_index;
+
+          pango_layout_get_cursor_pos (layout, index, &s_pos, &w_pos);
+
+          ok = TRUE;
+
+          for (int k = 0; k < n_chars; k++)
+            {
+              old_s_pos = s_pos;
+              old_w_pos = w_pos;
+              pango_layout_move_cursor_visually (layout, params[j].strong,
+                                                 index, 0,
+                                                 params[j].direction,
+                                                 &index, &trailing);
+
+              while (trailing--)
+                index = g_utf8_next_char (text + index) - text;
+
+              if (index < 0 || index >= strlen (text))
+                break;
+
+              pango_layout_get_cursor_pos (layout, index, &s_pos, &w_pos);
+
+              if ((params[j].direction > 0 && params[j].strong && old_s_pos.x > s_pos.x) ||
+                  (params[j].direction < 0 && params[j].strong && old_s_pos.x < s_pos.x) ||
+                  (params[j].direction > 0 && !params[j].strong && old_w_pos.x > w_pos.x) ||
+                  (params[j].direction < 0 && !params[j].strong && old_w_pos.x < w_pos.x))
+                {
+                  ok = FALSE;
+                  break;
+                }
+            }
+
+          if (!(index >= strlen (text) || index <= 0))
+            ok = FALSE;
+
+          if (g_test_verbose ())
+            g_print ("%s\n", ok ? "ok": "not ok");
+
+          fail = fail || !ok;
+        }
+    }
+
+  g_object_unref (layout);
+
+  if (fail)
+    g_test_skip ("known to fail");
+}
+
+
 int
 main (int argc, char *argv[])
 {
+  PangoFontMap *fontmap;
+
+  setlocale (LC_ALL, "");
+
+  fontmap = pango_cairo_font_map_get_default ();
+  context = pango_font_map_create_context (fontmap);
+
   g_test_init (&argc, &argv, NULL);
 
   g_test_add_func ("/bidi/mirror-char", test_mirror_char);
   g_test_add_func ("/bidi/type-for-unichar", test_bidi_type_for_unichar);
   g_test_add_func ("/bidi/unichar-direction", test_unichar_direction);
   g_test_add_func ("/bidi/embedding-levels", test_bidi_embedding_levels);
+  g_test_add_func ("/bidi/move-cursor-visually", test_move_cursor_visually);
 
   return g_test_run ();
 }