src/libANGLE/gen_overlay_fonts.py

#!/usr/bin/env vpython3
#
# [VPYTHON:BEGIN]
# wheel: <
#   name: "infra/python/wheels/freetype-py/${vpython_platform}"
#   version: "version:2.2.0.chromium.4"
# >
# [VPYTHON:END]

# Copyright 2019 The ANGLE Project Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#
# gen_vk_overlay_fonts.py:
#  Code generation for overlay fonts.  Should be run if the font file under overlay/ is changed,
#  or the font sizes declared in this file are modified.  The font is assumed to be monospace.
#  The output will contain ASCII characters in order from ' ' to '~'.  The output will be images
#  with 95 layers, with each smaller font size having half the size of the previous to form a mip
#  chain.
#  NOTE: don't run this script directly. Run scripts/run_code_generation.py.

import sys

# Conditional import enables getting inputs/outputs with python3 instead of vpython3
if len(sys.argv) < 2:
    from freetype import *

out_file_cpp = 'Overlay_font_autogen.cpp'
out_file_h = 'Overlay_font_autogen.h'
font_file = 'overlay/RobotoMono-Bold.ttf'
font_license = u"""// Font copyright Google:
//
//     Licensed under the Apache License, Version 2.0 (the "License");
//     you may not use this file except in compliance with the License.
//     You may obtain a copy of the License at
//
//         http://www.apache.org/licenses/LICENSE-2.0
//
//     Unless required by applicable law or agreed to in writing, software
//     distributed under the License is distributed on an "AS IS" BASIS,
//     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//     See the License for the specific language governing permissions and
//     limitations under the License."""

template_out_file_h = u"""// GENERATED FILE - DO NOT EDIT.
// Generated by {script_name} using {font_file}.
//
// Copyright 2022 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// {out_file_name}:
//   Autogenerated overlay font data.

#include "libANGLE/Overlay.h"

namespace gl
{{
namespace overlay
{{
constexpr uint32_t kFontMipCount = {font_count};
constexpr uint32_t kFontCharacters = {char_count};
constexpr uint32_t kFontGlyphWidth = {max_font_width};
constexpr uint32_t kFontGlyphHeight = {max_font_height};
constexpr uint32_t kFontMipDataSize[kFontMipCount] = {{{font_mip_data_sizes}}};
constexpr uint32_t kFontMipDataOffset[kFontMipCount] = {{{font_mip_data_offsets}}};
constexpr uint32_t kFontTotalDataSize = {total_font_data_size};
{font_mips}
}}  // namespace overlay
}}  // namespace gl

"""

template_out_file_cpp = u"""// GENERATED FILE - DO NOT EDIT.
// Generated by {script_name} using images from {font_file}.
//
// Copyright 2022 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
{font_license}
//
// {out_file_name}:
//   Autogenerated overlay font data.

#include "libANGLE/Overlay.h"
#include "libANGLE/Overlay_font_autogen.h"

#include <numeric>

namespace gl
{{
using namespace overlay;

// Save binary size if the font images are never to be used.
#if ANGLE_ENABLE_OVERLAY
namespace
{{
constexpr uint8_t kFontData[{total_font_data_size}] = {{
// clang-format off
{all_font_data}
// clang-format on
}};
}}  // anonymous namespace

const uint8_t *OverlayState::getFontData() const
{{
    return kFontData;
}}
#else
const uint8_t *OverlayState::getFontData() const
{{
    return nullptr;
}}
#endif
}}  // namespace gl
"""


def main():
    if len(sys.argv) == 2 and sys.argv[1] == 'inputs':
        # disabled because of issues on Windows. http://anglebug.com/3892
        # print(font_file)
        return
    if len(sys.argv) == 2 and sys.argv[1] == 'outputs':
        print(','.join([out_file_cpp, out_file_h]))
        return

    # Font sizes are chosen such that the sizes form a mip chain.
    font_defs = [('large', 29), ('small', 14)]
    chars = ' !"#$%&\'()*+,-./0123456789:;<=>?' + \
            '@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_' + \
            '`abcdefghijklmnopqrstuvwxyz{|}~'
    char_count = len(chars)

    font_glyph_widths = []
    font_glyph_heights = []
    font_data = ""
    font_mips = []
    current_font_mip = 0
    font_data_sizes = []
    font_data_offsets = []
    total_font_data_size = 0

    # Load the font file.
    face = Face(font_file)
    assert (face.is_fixed_width)

    for font_name, font_size in font_defs:

        # Since the font is fixed width, we can retrieve its size right away.
        face.set_char_size(font_size << 6)
        glyph_width = face.size.max_advance >> 6
        glyph_ascender = face.size.ascender >> 6
        glyph_descender = face.size.descender >> 6
        glyph_height = glyph_ascender - glyph_descender
        font_glyph_widths.append(glyph_width)
        font_glyph_heights.append(glyph_height)

        # Make sure the fonts form a mipchain
        if current_font_mip > 0:
            assert (glyph_width == font_glyph_widths[current_font_mip - 1] // 2)
            assert (glyph_height == font_glyph_heights[current_font_mip - 1] // 2)

        font_tag = font_name.capitalize()
        font_mip = str(current_font_mip)
        font_mip_symbol = 'kFontMip' + font_tag

        font_data += '// ' + font_tag + '\n'

        # Font pixels are packed in 32-bit values.
        font_data_size = char_count * glyph_width * glyph_height
        font_data_sizes.append(font_data_size)
        font_data_offsets.append(total_font_data_size)
        total_font_data_size += font_data_size

        for charIndex in range(char_count):
            char = chars[charIndex]
            font_data += "// '" + char + "'\n"

            # Render the character.
            face.load_char(char)
            bitmap = face.glyph.bitmap
            left = face.glyph.bitmap_left
            top = face.glyph.bitmap_top
            width = bitmap.width
            rows = bitmap.rows
            pitch = bitmap.pitch

            offset_x = left
            offset_y = glyph_height - (top - glyph_descender)

            # Some glyphs like '#', '&' etc generate a larger glyph than the "fixed" font width.
            if offset_x + width > glyph_width:
                offset_x = glyph_width - width
                if offset_x < 0:
                    width += offset_x
                    offset_x = 0

            assert (offset_x + width <= glyph_width)
            assert (offset_y + rows <= glyph_height)

            # Write the character bitmap in the font image.
            for y in range(glyph_height):
                for x in range(glyph_width):
                    if y < offset_y or y >= offset_y + rows or x < offset_x or x >= offset_x + width:
                        font_data += '   0,'
                    else:
                        pixel_value = bitmap.buffer[(y - offset_y) * pitch + (x - offset_x)]
                        if pixel_value == 0:
                            font_data += '   0,'
                        else:
                            font_data += '0x{:02X},'.format(pixel_value)
                font_data += '\n'

        font_mips.append('constexpr uint32_t ' + font_mip_symbol + ' = ' + font_mip + ';')
        current_font_mip += 1

    with open(out_file_h, 'w') as outfile:
        outfile.write(
            template_out_file_h.format(
                script_name=os.path.basename(__file__),
                font_file=font_file,
                out_file_name=out_file_h,
                font_count=len(font_defs),
                char_count=char_count,
                max_font_width=font_glyph_widths[0],
                max_font_height=font_glyph_heights[0],
                font_mip_data_sizes=','.join([str(s) for s in font_data_sizes]),
                font_mip_data_offsets=','.join([str(s) for s in font_data_offsets]),
                total_font_data_size=total_font_data_size,
                font_mips='\n'.join(font_mips)))
        outfile.close()

    with open(out_file_cpp, 'w') as outfile:
        outfile.write(
            template_out_file_cpp.format(
                script_name=os.path.basename(__file__),
                font_file=font_file,
                font_license=font_license,
                out_file_name=out_file_cpp,
                total_font_data_size=total_font_data_size,
                all_font_data=font_data))
        outfile.close()


if __name__ == '__main__':
    sys.exit(main())