diff options
Diffstat (limited to 'ui/font.cpp')
| -rw-r--r-- | ui/font.cpp | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/ui/font.cpp b/ui/font.cpp new file mode 100644 index 0000000..5596f20 --- /dev/null +++ b/ui/font.cpp @@ -0,0 +1,182 @@ +#include "font.h" +#include <algorithm> +#include <cctype> +#include <ft2build.h> +#include FT_FREETYPE_H +#include <glRef.hpp> +#include <maths.h> +#include <memory> +#include <optional> +#include <stdexcept> +#include <unicode.h> +#include <utility> +// IWYU pragma: no_forward_declare FT_LibraryRec_ + +std::string +FT_Error_StringSafe(FT_Error err) +{ + if (const auto errstr = FT_Error_String(err)) { + return {errstr}; + } + return std::to_string(err); +} + +template<auto Func, typename... Args> +void +FT_Check(Args &&... args) +{ + if (const auto err = Func(std::forward<Args>(args)...)) { + throw std::runtime_error {std::string {"FreeType error: "} + FT_Error_StringSafe(err)}; + } +} + +const std::string BASIC_CHARS = []() { + std::string chars; + for (char c {}; c >= 0; c++) { + if (isgraph(c)) { + chars += c; + } + } + return chars + "£€²³"; +}(); + +using FT = glRef<FT_Library, + []() { + FT_Library ft {}; + FT_Check<FT_Init_FreeType>(&ft); + return ft; + }, + FT_Done_FreeType>; + +using Face = glRef<FT_Face, + [](FT_Library ft, const char * const name) { + FT_Face face {}; + FT_Check<FT_New_Face>(ft, name, 0, &face); + return face; + }, + FT_Done_Face>; + +Font::Font(const char * const p, unsigned s) : path {p}, size {getTextureSize(s)} +{ + generateChars(BASIC_CHARS); +} + +void +Font::generateChars(const std::string_view chars) const +{ + std::optional<FT> ft; + std::optional<Face> face; + + for (auto c = chars.data(); c <= &chars.back(); c = next_char(c)) { + const auto codepoint = get_codepoint(c); + if (charsData.find(codepoint) == charsData.end()) { + if (!ft) { + ft.emplace(); + } + if (!face) { + face.emplace(*ft, path.c_str()); + FT_Set_Pixel_Sizes(*face, 0, size.z); + } + FT_UInt glyph_index = FT_Get_Char_Index(*face, codepoint); + if (FT_Load_Glyph(*face, glyph_index, FT_LOAD_RENDER)) { + charsData.emplace(codepoint, CharData {}); + continue; + } + + const auto & glyph = (*face)->glyph; + const auto textureIdx = getTextureWithSpace(glyph->bitmap.width); + auto & texture = fontTextures[textureIdx]; + + glTexSubImage2D(GL_TEXTURE_2D, 0, static_cast<GLint>(texture.used), 0, + static_cast<GLsizei>(glyph->bitmap.width), static_cast<GLsizei>(glyph->bitmap.rows), GL_RED, + GL_UNSIGNED_BYTE, glyph->bitmap.buffer); + + const auto & cd = charsData + .emplace(codepoint, + CharData {textureIdx, {glyph->bitmap.width, glyph->bitmap.rows}, + {texture.used, 0}, {glyph->bitmap_left, glyph->bitmap_top}, + glyph->advance.x >> 6}) + .first->second; + texture.used += cd.size.x; + } + } +} + +std::size_t +Font::getTextureWithSpace(unsigned int adv) const +{ + if (auto itr = std::find_if(fontTextures.begin(), fontTextures.end(), + [adv, this](const FontTexture & ft) { + return (ft.used + adv) < size.x; + }); + itr != fontTextures.end()) { + glBindTexture(GL_TEXTURE_2D, itr->texture); + return static_cast<std::size_t>(itr - fontTextures.begin()); + } + + auto & texture = fontTextures.emplace_back(); + glGenTextures(1, &texture.texture); + glBindTexture(GL_TEXTURE_2D, texture.texture); + glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, static_cast<GLsizei>(size.x), static_cast<GLsizei>(size.y), 0, GL_RED, + GL_UNSIGNED_BYTE, nullptr); + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); + + return fontTextures.size() - 1; +} + +glm::uvec3 +Font::getTextureSize(unsigned int height) +{ + auto pow2 = [](unsigned int target) { + unsigned int v {8}; + do { + v <<= 1; + } while (v << 1 < GL_MAX_TEXTURE_SIZE && v < target); + return v; + }; + + constexpr const unsigned int WIDTH_PER_HEIGHT {64}; + return {pow2(height * WIDTH_PER_HEIGHT), pow2(height), height}; +} + +Font::TextureQuads +Font::render(const std::string_view chars) const +{ + constexpr static const std::array<std::pair<glm::vec2, glm::vec2>, 4> C {{ + {{0, 0}, {0, 1}}, + {{1, 0}, {1, 1}}, + {{1, 1}, {1, 0}}, + {{0, 1}, {0, 0}}, + }}; + + generateChars(chars); + + glm::vec2 pos {}; + TextureQuads out; + for (auto c = chars.data(); c <= &chars.back(); c = next_char(c)) { + if (isspace(*c)) { + pos.x += static_cast<float>(size.y) / 4.F; + continue; + } + const auto & ch = charsData.at(get_codepoint(c)); + if (!ch.advance) { + continue; + } + + const auto charPos = pos + glm::vec2 {ch.bearing.x, ch.bearing.y - static_cast<int>(ch.size.y)}; + const auto size = glm::vec2 {ch.size}; + + Quad q; + std::transform(C.begin(), C.end(), q.begin(), [&size, &charPos, &ch, this](const auto & c) { + return (charPos + (size * c.first)) + || ((glm::vec2 {ch.position} + (glm::vec2 {ch.size} * c.second)) / glm::vec2 {this->size}); + }); + out[fontTextures[ch.textureIdx].texture].emplace_back(q); + + pos.x += static_cast<float>(ch.advance); + } + return out; +} |