[lvgl] Migrate lv_font creation into Font class and optimise (#11915)

esphome/components/font/font.cpp

@@ -6,42 +6,147 @@
 
 namespace esphome {
 namespace font {
-
 static const char *const TAG = "font";
 
-// Compare the char at the string position with this char.
-// Return true if this char is less than or equal the other.
-bool Glyph::compare_to(const uint8_t *str) const {
-  // 1 -> this->char_
-  // 2 -> str
-  for (uint32_t i = 0;; i++) {
-    if (this->a_char[i] == '\0')
-      return true;
-    if (str[i] == '\0')
-      return false;
-    if (this->a_char[i] > str[i])
-      return false;
-    if (this->a_char[i] < str[i])
-      return true;
+#ifdef USE_LVGL_FONT
+const uint8_t *Font::get_glyph_bitmap(const lv_font_t *font, uint32_t unicode_letter) {
+  auto *fe = (Font *) font->dsc;
+  const auto *gd = fe->get_glyph_data_(unicode_letter);
+  if (gd == nullptr) {
+    return nullptr;
   }
-  // this should not happen
-  return false;
+  return gd->data;
 }
-int Glyph::match_length(const uint8_t *str) const {
-  for (uint32_t i = 0;; i++) {
-    if (this->a_char[i] == '\0')
-      return i;
-    if (str[i] != this->a_char[i])
+
+bool Font::get_glyph_dsc_cb(const lv_font_t *font, lv_font_glyph_dsc_t *dsc, uint32_t unicode_letter, uint32_t next) {
+  auto *fe = (Font *) font->dsc;
+  const auto *gd = fe->get_glyph_data_(unicode_letter);
+  if (gd == nullptr) {
+    return false;
+  }
+  dsc->adv_w = gd->advance;
+  dsc->ofs_x = gd->offset_x;
+  dsc->ofs_y = fe->height_ - gd->height - gd->offset_y - fe->lv_font_.base_line;
+  dsc->box_w = gd->width;
+  dsc->box_h = gd->height;
+  dsc->is_placeholder = 0;
+  dsc->bpp = fe->get_bpp();
+  return true;
+}
+
+const Glyph *Font::get_glyph_data_(uint32_t unicode_letter) {
+  if (unicode_letter == this->last_letter_ && this->last_letter_ != 0)
+    return this->last_data_;
+  auto *glyph = this->find_glyph(unicode_letter);
+  if (glyph == nullptr) {
+    return nullptr;
+  }
+  this->last_data_ = glyph;
+  this->last_letter_ = unicode_letter;
+  return glyph;
+}
+#endif
+
+/**
+ *  Attempt to extract a 32 bit Unicode codepoint from a UTF-8 string.
+ *  If successful, return the codepoint and set the length to the number of bytes read.
+ *  If the end of the string has been reached and a valid codepoint has not been found, return 0 and set the length to
+ * 0.
+ *
+ * @param utf8_str The input string
+ * @param length Pointer to length storage
+ * @return The extracted code point
+ */
+static uint32_t extract_unicode_codepoint(const char *utf8_str, size_t *length) {
+  // Safely cast to uint8_t* for correct bitwise operations on bytes
+  const uint8_t *current = reinterpret_cast<const uint8_t *>(utf8_str);
+  uint32_t code_point = 0;
+  uint8_t c1 = *current++;
+
+  // check for end of string
+  if (c1 == 0) {
+    *length = 0;
+    return 0;
+  }
+
+  // --- 1-Byte Sequence: 0xxxxxxx (ASCII) ---
+  if (c1 < 0x80) {
+    // Valid ASCII byte.
+    code_point = c1;
+    // Optimization: No need to check for continuation bytes.
+  }
+  // --- 2-Byte Sequence: 110xxxxx 10xxxxxx ---
+  else if ((c1 & 0xE0) == 0xC0) {
+    uint8_t c2 = *current++;
+
+    // Error Check 1: Check if c2 is a valid continuation byte (10xxxxxx)
+    if ((c2 & 0xC0) != 0x80) {
+      *length = 0;
       return 0;
+    }
+
+    code_point = (c1 & 0x1F) << 6;
+    code_point |= (c2 & 0x3F);
+
+    // Error Check 2: Overlong check (2-byte must be > 0x7F)
+    if (code_point <= 0x7F) {
+      *length = 0;
+      return 0;
+    }
   }
-  // this should not happen
-  return 0;
-}
-void Glyph::scan_area(int *x1, int *y1, int *width, int *height) const {
-  *x1 = this->offset_x;
-  *y1 = this->offset_y;
-  *width = this->width;
-  *height = this->height;
+  // --- 3-Byte Sequence: 1110xxxx 10xxxxxx 10xxxxxx ---
+  else if ((c1 & 0xF0) == 0xE0) {
+    uint8_t c2 = *current++;
+    uint8_t c3 = *current++;
+
+    // Error Check 1: Check continuation bytes
+    if (((c2 & 0xC0) != 0x80) || ((c3 & 0xC0) != 0x80)) {
+      *length = 0;
+      return 0;
+    }
+
+    code_point = (c1 & 0x0F) << 12;
+    code_point |= (c2 & 0x3F) << 6;
+    code_point |= (c3 & 0x3F);
+
+    // Error Check 2: Overlong check (3-byte must be > 0x7FF)
+    // Also check for surrogates (0xD800-0xDFFF)
+    if (code_point <= 0x7FF || (code_point >= 0xD800 && code_point <= 0xDFFF)) {
+      *length = 0;
+      return 0;
+    }
+  }
+  // --- 4-Byte Sequence: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx ---
+  else if ((c1 & 0xF8) == 0xF0) {
+    uint8_t c2 = *current++;
+    uint8_t c3 = *current++;
+    uint8_t c4 = *current++;
+
+    // Error Check 1: Check continuation bytes
+    if (((c2 & 0xC0) != 0x80) || ((c3 & 0xC0) != 0x80) || ((c4 & 0xC0) != 0x80)) {
+      *length = 0;
+      return 0;
+    }
+
+    code_point = (c1 & 0x07) << 18;
+    code_point |= (c2 & 0x3F) << 12;
+    code_point |= (c3 & 0x3F) << 6;
+    code_point |= (c4 & 0x3F);
+
+    // Error Check 2: Overlong check (4-byte must be > 0xFFFF)
+    // Also check for valid Unicode range (must be <= 0x10FFFF)
+    if (code_point <= 0xFFFF || code_point > 0x10FFFF) {
+      *length = 0;
+      return 0;
+    }
+  }
+  // --- Invalid leading byte (e.g., 10xxxxxx or 11111xxx) ---
+  else {
+    *length = 0;
+    return 0;
+  }
+  *length = current - reinterpret_cast<const uint8_t *>(utf8_str);
+  return code_point;
 }
 
 Font::Font(const Glyph *data, int data_nr, int baseline, int height, int descender, int xheight, int capheight,
@@ -53,82 +158,93 @@ Font::Font(const Glyph *data, int data_nr, int baseline, int height, int descend
       linegap_(height - baseline - descender),
       xheight_(xheight),
       capheight_(capheight),
-      bpp_(bpp) {}
-int Font::match_next_glyph(const uint8_t *str, int *match_length) const {
+      bpp_(bpp) {
+#ifdef USE_LVGL_FONT
+  this->lv_font_.dsc = this;
+  this->lv_font_.line_height = this->get_height();
+  this->lv_font_.base_line = this->lv_font_.line_height - this->get_baseline();
+  this->lv_font_.get_glyph_dsc = get_glyph_dsc_cb;
+  this->lv_font_.get_glyph_bitmap = get_glyph_bitmap;
+  this->lv_font_.subpx = LV_FONT_SUBPX_NONE;
+  this->lv_font_.underline_position = -1;
+  this->lv_font_.underline_thickness = 1;
+#endif
+}
+
+const Glyph *Font::find_glyph(uint32_t codepoint) const {
   int lo = 0;
   int hi = this->glyphs_.size() - 1;
   while (lo != hi) {
     int mid = (lo + hi + 1) / 2;
-    if (this->glyphs_[mid].compare_to(str)) {
+    if (this->glyphs_[mid].is_less_or_equal(codepoint)) {
       lo = mid;
     } else {
       hi = mid - 1;
     }
   }
-  *match_length = this->glyphs_[lo].match_length(str);
-  if (*match_length <= 0)
-    return -1;
-  return lo;
+  auto *result = &this->glyphs_[lo];
+  if (result->code_point == codepoint)
+    return result;
+  return nullptr;
 }
+
 #ifdef USE_DISPLAY
 void Font::measure(const char *str, int *width, int *x_offset, int *baseline, int *height) {
   *baseline = this->baseline_;
   *height = this->height_;
-  int i = 0;
   int min_x = 0;
   bool has_char = false;
   int x = 0;
-  while (str[i] != '\0') {
-    int match_length;
-    int glyph_n = this->match_next_glyph((const uint8_t *) str + i, &match_length);
-    if (glyph_n < 0) {
+  for (;;) {
+    size_t length;
+    auto code_point = extract_unicode_codepoint(str, &length);
+    if (length == 0)
+      break;
+    str += length;
+    auto *glyph = this->find_glyph(code_point);
+    if (glyph == nullptr) {
       // Unknown char, skip
-      if (!this->get_glyphs().empty())
-        x += this->get_glyphs()[0].advance;
-      i++;
+      if (!this->glyphs_.empty())
+        x += this->glyphs_[0].advance;
       continue;
     }
 
-    const Glyph &glyph = this->glyphs_[glyph_n];
     if (!has_char) {
-      min_x = glyph.offset_x;
+      min_x = glyph->offset_x;
     } else {
-      min_x = std::min(min_x, x + glyph.offset_x);
+      min_x = std::min(min_x, x + glyph->offset_x);
     }
-    x += glyph.advance;
+    x += glyph->advance;
 
-    i += match_length;
     has_char = true;
   }
   *x_offset = min_x;
   *width = x - min_x;
 }
+
 void Font::print(int x_start, int y_start, display::Display *display, Color color, const char *text, Color background) {
-  int i = 0;
   int x_at = x_start;
-  int scan_x1, scan_y1, scan_width, scan_height;
-  while (text[i] != '\0') {
-    int match_length;
-    int glyph_n = this->match_next_glyph((const uint8_t *) text + i, &match_length);
-    if (glyph_n < 0) {
+  for (;;) {
+    size_t length;
+    auto code_point = extract_unicode_codepoint(text, &length);
+    if (length == 0)
+      break;
+    text += length;
+    auto *glyph = this->find_glyph(code_point);
+    if (glyph == nullptr) {
       // Unknown char, skip
-      ESP_LOGW(TAG, "Encountered character without representation in font: '%c'", text[i]);
-      if (!this->get_glyphs().empty()) {
-        uint8_t glyph_width = this->get_glyphs()[0].advance;
-        display->filled_rectangle(x_at, y_start, glyph_width, this->height_, color);
+      ESP_LOGW(TAG, "Codepoint 0x%08" PRIx32 " not found in font", code_point);
+      if (!this->glyphs_.empty()) {
+        uint8_t glyph_width = this->glyphs_[0].advance;
+        display->rectangle(x_at, y_start, glyph_width, this->height_, color);
         x_at += glyph_width;
       }
-
-      i++;
       continue;
     }
 
-    const Glyph &glyph = this->get_glyphs()[glyph_n];
-    glyph.scan_area(&scan_x1, &scan_y1, &scan_width, &scan_height);
-
-    const uint8_t *data = glyph.data;
-    const int max_x = x_at + scan_x1 + scan_width;
-    const int max_y = y_start + scan_y1 + scan_height;
+    const uint8_t *data = glyph->data;
+    const int max_x = x_at + glyph->offset_x + glyph->width;
+    const int max_y = y_start + glyph->offset_y + glyph->height;
 
     uint8_t bitmask = 0;
     uint8_t pixel_data = 0;
@@ -141,10 +257,10 @@ void Font::print(int x_start, int y_start, display::Display *display, Color colo
     auto b_g = (float) background.g;
     auto b_b = (float) background.b;
     auto b_w = (float) background.w;
-    for (int glyph_y = y_start + scan_y1; glyph_y != max_y; glyph_y++) {
-      for (int glyph_x = x_at + scan_x1; glyph_x != max_x; glyph_x++) {
+    for (int glyph_y = y_start + glyph->offset_y; glyph_y != max_y; glyph_y++) {
+      for (int glyph_x = x_at + glyph->offset_x; glyph_x != max_x; glyph_x++) {
         uint8_t pixel = 0;
-        for (int bit_num = 0; bit_num != this->bpp_; bit_num++) {
+        for (uint8_t bit_num = 0; bit_num != this->bpp_; bit_num++) {
           if (bitmask == 0) {
             pixel_data = progmem_read_byte(data++);
             bitmask = 0x80;
@@ -164,12 +280,9 @@ void Font::print(int x_start, int y_start, display::Display *display, Color colo
         }
       }
     }
-    x_at += glyph.advance;
-
-    i += match_length;
+    x_at += glyph->advance;
   }
 }
 #endif
-
 }  // namespace font
 }  // namespace esphome