Add a ligature shaping test

kitty/fonts.c

@@ -499,15 +499,27 @@ shape_run(Cell *first_cell, index_type num_cells, Font *font) {
 }
 
 static PyObject*
-test_shape(PyObject UNUSED *self, Line *line) {
+test_shape(PyObject UNUSED *self, PyObject *args) {
+    Line *line;
+    char *path = NULL;
+    int index = 0;
+    if(!PyArg_ParseTuple(args, "O!|zi", &Line_Type, &line, &path, &index)) return NULL;
     index_type num = 0;
     while(num < line->xnum && line->cells[num].ch) num++;
     load_hb_buffer(line->cells, num);
+    PyObject *face = NULL;
+    hb_font_t *hb_font; 
     Font *font = &medium_font;
-    hb_shape_full(font->hb_font, harfbuzz_buffer, NULL, 0, SHAPERS);
+    if (path) {
+        face = face_from_path(path, index);
+        if (face == NULL) return NULL;
+        hb_font = harfbuzz_font_for_face(face);
+    } else hb_font = font->hb_font;
+    hb_shape_full(hb_font, harfbuzz_buffer, NULL, 0, SHAPERS);
     unsigned int num_glyphs;
     hb_buffer_get_glyph_infos(harfbuzz_buffer, &num_glyphs);
-    hb_buffer_serialize_glyphs(harfbuzz_buffer, 0, num_glyphs, (char*)canvas, CELLS_IN_CANVAS * cell_width * cell_height, NULL, font->hb_font, HB_BUFFER_SERIALIZE_FORMAT_JSON, HB_BUFFER_SERIALIZE_FLAG_DEFAULT | HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS | HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS);
+    hb_buffer_serialize_glyphs(harfbuzz_buffer, 0, num_glyphs, (char*)canvas, CELLS_IN_CANVAS * cell_width * cell_height, NULL, hb_font, HB_BUFFER_SERIALIZE_FORMAT_JSON, HB_BUFFER_SERIALIZE_FLAG_DEFAULT | HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS | HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS);
+    Py_CLEAR(face);
     return Py_BuildValue("s", canvas);
 }
 
@@ -739,7 +751,7 @@ static PyMethodDef module_methods[] = {
     METHODB(test_sprite_position_for, METH_VARARGS),
     METHODB(concat_cells, METH_VARARGS),
     METHODB(set_send_sprite_to_gpu, METH_O),
-    METHODB(test_shape, METH_O),
+    METHODB(test_shape, METH_VARARGS),
     METHODB(current_fonts, METH_NOARGS),
     METHODB(test_render_line, METH_VARARGS),
     METHODB(get_fallback_font, METH_VARARGS),

kitty/fonts.h

@@ -29,3 +29,4 @@ PyObject* ft_face_from_path_and_psname(PyObject* path, const char* psname, void
 PyObject* specialize_font_descriptor(PyObject *base_descriptor);
 PyObject* create_fallback_face(PyObject *base_face, Cell* cell, bool bold, bool italic);
 PyObject* face_from_descriptor(PyObject*);
+PyObject* face_from_path(const char *path, int index);

kitty/fonts/render.py

@@ -187,14 +187,14 @@ def render_string(text, family='monospace', size=11.0, dpi=96.0):
     return cell_width, cell_height, cells
 
 
-def shape_string(text="abcd", family='monospace', size=11.0, dpi=96.0):
+def shape_string(text="abcd", family='monospace', size=11.0, dpi=96.0, path=None):
     import json
     try:
         sprites, cell_width, cell_height = setup_for_testing(family, size, dpi)
         s = Screen(None, 1, len(text)*2)
         line = s.line(0)
         s.draw(text)
-        data = test_shape(line)
+        data = test_shape(line, path)
         return json.loads('[' + data + ']')
     finally:
         set_send_sprite_to_gpu(None)

kitty/freetype.c

@@ -221,6 +221,17 @@ face_from_descriptor(PyObject *descriptor) {
 }
 #endif
  
+PyObject*
+face_from_path(const char *path, int index) {
+    Face *ans = (Face*)Face_Type.tp_alloc(&Face_Type, 0);
+    if (ans == NULL) return NULL;
+    int error;
+    error = FT_New_Face(library, path, index, &ans->face);
+    if (error) { set_freetype_error("Failed to load face, with error:", error); ans->face = NULL; return NULL; }
+    if (!init_ft_face(ans, Py_None, true, 3)) { Py_CLEAR(ans); return NULL; }
+    return (PyObject*)ans;
+}
+
 static void
 dealloc(Face* self) {
     if (self->harfbuzz_font) hb_font_destroy(self->harfbuzz_font);

kitty_tests/fonts.py

@@ -70,6 +70,9 @@ class Rendering(BaseTest):
         self.ae(len(cells), sz)
 
     def test_shaping(self):
-        self.assertEqual(len(shape_string('abcd')), 4)
+        flags = [x.get('fl', 0) for x in shape_string('abcd')]
+        self.ae(flags, [0, 0, 0, 0])
         flags = [x.get('fl', 0) for x in shape_string('e\u0347\u0305')]
         self.assertEqual(flags, [0, 1, 1])
+        flags = [x.get('fl', 0) for x in shape_string('===', path='kitty_tests/FiraCode-Medium.otf')]
+        self.assertEqual(flags, [0, 1, 1])