core/modtrezorui: add display_text_split

core/embed/extmod/modtrezorui/display.c

@@ -692,6 +692,37 @@ int display_text_width(const char *text, int textlen, int font) {
   return width;
 }
 
+// Returns how many characters of the string can be used before exceeding
+// the requested width. Tries to avoid breaking words if possible.
+int display_text_split(const char *text, int textlen, int font,
+                       int requested_width) {
+  int width = 0;
+  int lastspace = 0;
+#if TREZOR_MODEL == T
+  // determine text length if not provided
+  if (textlen < 0) {
+    textlen = strlen(text);
+  }
+  for (int i = 0; i < textlen; i++) {
+    if (text[i] == ' ') {
+      lastspace = i;
+    }
+    const uint8_t *g = get_glyph(font, (uint8_t)text[i]);
+    if (!g) continue;
+    const uint8_t adv = g[2];  // advance
+    width += adv;
+    if (width > requested_width) {
+      if (lastspace > 0) {
+        return lastspace;
+      } else {
+        return i;
+      }
+    }
+  }
+#endif
+  return textlen;
+}
+
 #define QR_MAX_VERSION 9
 
 void display_qrcode(int x, int y, const char *data, uint32_t datalen,

core/embed/extmod/modtrezorui/display.h

@@ -103,6 +103,8 @@ void display_text_center(int x, int y, const char *text, int textlen, int font,
 void display_text_right(int x, int y, const char *text, int textlen, int font,
                         uint16_t fgcolor, uint16_t bgcolor);
 int display_text_width(const char *text, int textlen, int font);
+int display_text_split(const char *text, int textlen, int font,
+                       int requested_width);
 
 void display_qrcode(int x, int y, const char *data, uint32_t datalen,
                     uint8_t scale);

core/embed/extmod/modtrezorui/modtrezorui-display.h

@@ -414,6 +414,25 @@ STATIC mp_obj_t mod_trezorui_Display_text_width(mp_obj_t self, mp_obj_t text,
 STATIC MP_DEFINE_CONST_FUN_OBJ_3(mod_trezorui_Display_text_width_obj,
                                  mod_trezorui_Display_text_width);
 
+/// def text_split(self, text: str, font: int, requested_width: int) -> int:
+///     """
+///     Returns how many characters of the string can be used before exceeding
+///     the requested width. Tries to avoid breaking words if possible. Font
+///     font is used for rendering.
+///     """
+STATIC mp_obj_t mod_trezorui_Display_text_split(size_t n_args,
+                                                const mp_obj_t *args) {
+  mp_buffer_info_t text;
+  mp_get_buffer_raise(args[1], &text, MP_BUFFER_READ);
+  mp_int_t font = mp_obj_get_int(args[2]);
+  mp_int_t requested_width = mp_obj_get_int(args[3]);
+  int chars = display_text_split(text.buf, text.len, font, requested_width);
+  return mp_obj_new_int(chars);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorui_Display_text_split_obj,
+                                           4, 4,
+                                           mod_trezorui_Display_text_split);
+
 /// def qrcode(self, x: int, y: int, data: bytes, scale: int) -> None:
 ///     """
 ///     Renders data encoded as a QR code centered at position (x,y).
@@ -563,6 +582,8 @@ STATIC const mp_rom_map_elem_t mod_trezorui_Display_locals_dict_table[] = {
      MP_ROM_PTR(&mod_trezorui_Display_text_right_obj)},
     {MP_ROM_QSTR(MP_QSTR_text_width),
      MP_ROM_PTR(&mod_trezorui_Display_text_width_obj)},
+    {MP_ROM_QSTR(MP_QSTR_text_split),
+     MP_ROM_PTR(&mod_trezorui_Display_text_split_obj)},
     {MP_ROM_QSTR(MP_QSTR_qrcode), MP_ROM_PTR(&mod_trezorui_Display_qrcode_obj)},
     {MP_ROM_QSTR(MP_QSTR_orientation),
      MP_ROM_PTR(&mod_trezorui_Display_orientation_obj)},

core/mocks/generated/trezorui.pyi

@@ -157,6 +157,13 @@ class Display:
         Returns a width of text in pixels. Font font is used for rendering.
         """
 
+    def text_split(self, text: str, font: int, requested_width: int) -> int:
+        """
+        Returns how many characters of the string can be used before exceeding
+        the requested width. Tries to avoid breaking words if possible. Font
+        font is used for rendering.
+        """
+
     def qrcode(self, x: int, y: int, data: bytes, scale: int) -> None:
         """
         Renders data encoded as a QR code centered at position (x,y).