Merge pull request #10280 from The-OpenROAD-Project-staging/web-font-atlas

web: anti-aliased font atlas for tile text rendering

Author: maliberty

.github/workflows/github-actions-format-on-push.yml

@@ -23,7 +23,10 @@ jobs:
         run: |
           clang-format --version
           for file in ${{ steps.changed-files.outputs.all_changed_files }}; do
-            if [[ "${file##*.}" =~ ^(h|C|cc|cp|cpp|c++|CPP|cxx|hh)$ && "${file}" != "src/sta/"* && "${file}" != "src/odb/src/codeGenerator/"* ]]; then
+            if [[ "${file##*.}" =~ ^(h|C|cc|cp|cpp|c++|CPP|cxx|hh)$ \
+                  && "${file}" != "src/sta/"* \
+                  && "${file}" != "src/odb/src/codeGenerator/"* \
+                  && "${file}" != "third-party/"* ]]; then
               clang-format --dry-run --Werror $file
             fi
           done

src/web/BUILD

@@ -113,6 +113,11 @@ cc_library(
         "src/clock_tree_report.h",
         "src/color.cpp",
         "src/color.h",
+        "src/font_atlas.h",
+        "src/font_data.cpp",
+        "src/font_data.h",
+        "src/glyph_cache.cpp",
+        "src/glyph_cache.h",
         "src/hierarchy_report.cpp",
         "src/hierarchy_report.h",
         "src/json_builder.h",
@@ -155,6 +160,7 @@ cc_library(
         "//src/sta:opensta_lib",
         "//src/utl",
         "//third-party/lodepng",
+        "//third-party/stb_truetype",
         "@boost.asio",
         "@boost.beast",
         "@boost.geometry",

src/web/CMakeLists.txt

@@ -92,6 +92,8 @@ target_sources(web
     src/hierarchy_report.cpp
     src/request_handler.cpp
     src/search.cpp
+    src/font_data.cpp
+    src/glyph_cache.cpp
     src/tile_generator.cpp
     src/timing_report.cpp
     src/web.cpp
@@ -112,6 +114,7 @@ target_link_libraries(web
     gui_heatmap_core
     dbSta_lib
     lodepng
+    stb_truetype
     utl_lib
 )
 

src/web/fonts/DejaVuSans.ttf

@@ -0,0 +1,52 @@
+DejaVu Sans
+===========
+
+Source:    https://dejavu-fonts.github.io/
+Copyright (c) 2003 by Bitstream, Inc. All Rights Reserved.
+Bitstream Vera is a trademark of Bitstream, Inc.
+DejaVu changes are in public domain.
+
+Licensed under the Bitstream Vera Fonts License:
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of the fonts accompanying this license ("Fonts") and associated
+documentation files (the "Font Software"), to reproduce and distribute
+the Font Software, including without limitation the rights to use, copy,
+merge, publish, distribute, and/or sell copies of the Font Software, and
+to permit persons to whom the Font Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright and trademark notices and this permission notice
+shall be included in all copies of one or more of the Font Software
+typefaces.
+
+The Font Software may be modified, altered, or added to, and in
+particular the designs of glyphs or characters in the Fonts may be
+modified and additional glyphs or characters may be added to the Fonts,
+only if the fonts are renamed to names not containing either the words
+"Bitstream" or the word "Vera".
+
+This License becomes null and void to the extent applicable to Fonts or
+Font Software that has been modified and is distributed under the
+"Bitstream Vera" names.
+
+The Font Software may be sold as part of a larger software package but
+no copy of one or more of the Font Software typefaces may be sold by
+itself.
+
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF
+COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL
+BITSTREAM OR THE GNOME FOUNDATION BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL,
+OR CONSEQUENTIAL DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+OTHERWISE, ARISING FROM, OUT OF THE USE OR INABILITY TO USE THE FONT
+SOFTWARE OR FROM OTHER DEALINGS IN THE FONT SOFTWARE.
+
+Except as contained in this notice, the names of Gnome, the Gnome
+Foundation, and Bitstream Inc., shall not be used in advertising or
+otherwise to promote the sale, use or other dealings in this Font
+Software without prior written authorization from the Gnome Foundation
+or Bitstream Inc., respectively. For further information, contact:
+fonts at gnome dot org.

src/web/fonts/LICENSE

@@ -0,0 +1,42 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2025, The OpenROAD Authors
+#
+# Embed a binary font file as a C++ byte array.
+#
+# Usage:
+#   python3 embed_font.py --font fonts/LiberationMono-Regular.ttf -o font_data.cpp
+
+import argparse
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Embed a binary font file as a C++ byte array."
+    )
+    parser.add_argument("--font", required=True, help="Path to .ttf font file")
+    parser.add_argument("--output", "-o", required=True, help="Output .cpp file")
+    args = parser.parse_args()
+
+    with open(args.font, "rb") as f:
+        data = f.read()
+
+    with open(args.output, "w") as f:
+        f.write("// SPDX-License-Identifier: BSD-3-Clause\n")
+        f.write("// Copyright (c) 2026, The OpenROAD Authors\n")
+        f.write("//\n")
+        f.write("// Auto-generated by embed_font.py — do not edit.\n\n")
+        f.write('#include "font_data.h"\n\n')
+        f.write("namespace web {\n\n")
+        f.write(f"const unsigned int kEmbeddedFontSize = {len(data)};\n\n")
+        f.write("const unsigned char kEmbeddedFontData[] =\n")
+        for i in range(0, len(data), 16):
+            chunk = data[i : i + 16]
+            escaped = "".join(f"\\{b:03o}" for b in chunk)
+            f.write(f'    "{escaped}"\n')
+        f.write(";\n\n")
+        f.write("}  // namespace web\n")
+
+
+if __name__ == "__main__":
+    main()

src/web/src/embed_font.py

@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// Copyright (c) 2026, The OpenROAD Authors
+//
+// Thin shim over GlyphCache so tile_generator.cpp callers stay simple.
+
+#pragma once
+
+#include <string_view>
+
+#include "glyph_cache.h"
+
+namespace web {
+
+inline GlyphCache::FontSize fontAtlasGetFont(int height_px)
+{
+  return glyphCache().getFont(height_px);
+}
+
+inline int fontAtlasTextWidth(std::string_view text, int height_px)
+{
+  return glyphCache().textWidth(text, height_px);
+}
+
+inline int fontAtlasTextHeight(int height_px)
+{
+  return glyphCache().textHeight(height_px);
+}
+
+inline int fontAtlasCellHeight(int height_px)
+{
+  return glyphCache().cellHeight(height_px);
+}
+
+inline GlyphCache::GlyphInfo fontAtlasGlyph(int height_px, char ch)
+{
+  return glyphCache().glyph(height_px, ch);
+}
+
+inline int fontAtlasKern(int height_px, char ch1, char ch2)
+{
+  return glyphCache().kern(height_px, ch1, ch2);
+}
+
+}  // namespace web