Infra to display rendered strings as images for testing

kitty/fonts.c

@@ -369,6 +369,7 @@ render_run(Cell *first_cell, index_type num_cells, Font UNUSED *font, FontType f
 
 void
 render_line(Line *line) {
+#define RENDER if ((run_font != NULL || run_font_type != FONT) && i > first_cell_in_run) render_run(line->cells + first_cell_in_run, i - first_cell_in_run, run_font, run_font_type);
     Font *run_font = NULL;
     FontType run_font_type = MISSING_FONT;
     index_type first_cell_in_run, i;
@@ -380,11 +381,12 @@ render_line(Line *line) {
         FontType cell_font_type = font_for_cell(cell, &cell_font);
         prev_width = cell->attrs & WIDTH_MASK;
         if (cell_font_type == run_font_type && cell_font == run_font) continue;
-        if ((run_font != NULL || run_font_type != FONT) && i > first_cell_in_run) render_run(cell, i - first_cell_in_run, run_font, run_font_type);
+        RENDER;
         run_font = cell_font; run_font_type = cell_font_type;
         first_cell_in_run = i;
     }
-    if ((run_font != NULL || run_font_type != FONT) && i > first_cell_in_run) render_run(line->cells + first_cell_in_run, i - first_cell_in_run, run_font, run_font_type);
+    RENDER;
+#undef RENDER
 }
 
 static PyObject*
@@ -503,6 +505,27 @@ test_render_line(PyObject UNUSED *self, PyObject *args) {
     Py_RETURN_NONE;
 }
 
+static PyObject*
+concat_cells(PyObject UNUSED *self, PyObject *args) {
+    unsigned int cell_width, cell_height;
+    PyObject *cells;
+    if (!PyArg_ParseTuple(args, "IIO!", &cell_width, &cell_height, &PyTuple_Type, &cells)) return NULL;
+    size_t num_cells = PyTuple_GET_SIZE(cells), r, c, i;
+    PyObject *ans = PyBytes_FromStringAndSize(NULL, 3 * cell_width * cell_height * num_cells);
+    if (ans == NULL) return PyErr_NoMemory();
+    uint8_t *dest = (uint8_t*)PyBytes_AS_STRING(ans), *src;
+    for (r = 0; r < cell_height; r++) {
+        for (c = 0; c < num_cells; c++) {
+            src = ((uint8_t*)PyBytes_AS_STRING(PyTuple_GET_ITEM(cells, c))) + cell_width * r;
+            for (i = 0; i < cell_width; i++, dest += 3) {
+                dest[0] = src[i]; dest[1] = src[i]; dest[2] = src[i];
+            }
+
+        }
+    }
+    return ans;
+}
+
 static PyMethodDef module_methods[] = {
     METHODB(set_font_size, METH_VARARGS),
     METHODB(set_font, METH_VARARGS),
@@ -510,6 +533,7 @@ static PyMethodDef module_methods[] = {
     METHODB(sprite_map_set_layout, METH_VARARGS),
     METHODB(send_prerendered_sprites, METH_VARARGS),
     METHODB(test_sprite_position_for, METH_VARARGS),
+    METHODB(concat_cells, METH_VARARGS),
     METHODB(set_send_sprite_to_gpu, METH_O),
     METHODB(test_render_line, METH_VARARGS),
     {NULL, NULL, 0, NULL}        /* Sentinel */

kitty/fonts/render.py

@@ -175,3 +175,37 @@ def render_box_drawing(codepoint):
         chr(codepoint), CharTexture(), cell_width, cell_height
     )
     return ctypes.addressof(buf), buf
+
+
+def test_render_string(text='\'Qing👁a⧽', size=200.0, dpi=96.0):
+    from tempfile import NamedTemporaryFile
+    from kitty.fast_data_types import concat_cells, set_send_sprite_to_gpu, Screen, sprite_map_set_limits, test_render_line
+    from kitty.icat import detect_support, show
+    if not detect_support():
+        raise SystemExit('Your terminal does not support the graphics protocol')
+    sprites = {}
+
+    def send_to_gpu(x, y, z, data):
+        sprites[(x, y, z)] = data
+
+    sprite_map_set_limits(100000, 100)
+    set_send_sprite_to_gpu(send_to_gpu)
+    try:
+        cell_width, cell_height = set_font_family(override_dpi=(dpi, dpi), override_font_size=size)
+        s = Screen(None, 1, len(text)*2)
+        line = s.line(0)
+        s.draw(text)
+        test_render_line(line)
+    finally:
+        set_send_sprite_to_gpu(None)
+    cells = []
+    for i in range(s.columns):
+        sp = line.sprite_at(i)
+        if sp != (0, 0, 0):
+            cells.append(sprites[sp])
+    rgb_data = concat_cells(cell_width, cell_height, tuple(cells))
+    with NamedTemporaryFile(delete=False) as f:
+        f.write(rgb_data)
+    print('Rendered string below: ({}x{})'.format(cell_width, cell_height))
+    show(f.name, cell_width * len(cells), cell_height, 24)
+    print()

kitty/icat.py

@@ -124,7 +124,7 @@ def write_chunked(cmd, data):
         cmd.clear()
 
 
-def show(outfile, width, height, fmt, transmit_mode):
+def show(outfile, width, height, fmt, transmit_mode='t'):
     cmd = {'a': 'T', 'f': fmt, 's': width, 'v': height}
     set_cursor(cmd, width, height)
     if detect_support.has_files:

kitty/line.c

@@ -203,6 +203,16 @@ as_unicode(Line* self) {
     return unicode_in_range(self, 0, xlimit_for_line(self), true, 0);
 }
 
+static PyObject*
+sprite_at(Line* self, PyObject *x) {
+#define sprite_at_doc "[x] -> Return the sprite in the specified cell"
+    unsigned long xval = PyLong_AsUnsignedLong(x);
+    if (xval >= self->xnum) { PyErr_SetString(PyExc_IndexError, "Column number out of bounds"); return NULL; }
+    Cell *c = self->cells + xval;
+    return Py_BuildValue("HHH", c->sprite_x, c->sprite_y, c->sprite_z);
+}
+
+
 static inline bool
 write_sgr(unsigned int val, Py_UCS4 *buf, index_type buflen, index_type *i) {
     static char s[20] = {0};
@@ -584,6 +594,7 @@ static PyMethodDef methods[] = {
     METHOD(width, METH_O)
     METHOD(url_start_at, METH_O)
     METHOD(url_end_at, METH_O)
+    METHOD(sprite_at, METH_O)
         
     {NULL}  /* Sentinel */
 };