74 lines
2.7 KiB
C++
74 lines
2.7 KiB
C++
/*
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Crafter®.Graphics
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Copyright (C) 2026 Catcrafts®
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Catcrafts.net
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 3.0 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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module;
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#ifndef CRAFTER_GRAPHICS_WINDOW_DOM
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#include "../lib/stb_truetype.h"
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#endif // !CRAFTER_GRAPHICS_WINDOW_DOM
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export module Crafter.Graphics:Font;
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#ifndef CRAFTER_GRAPHICS_WINDOW_DOM
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import std;
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namespace Crafter {
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// Decode the UTF-8 codepoint at `text[i]` and advance `i` past it.
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// Returns 0 once `i` reaches the end. Malformed sequences yield U+FFFD
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// and the index is moved past one byte to keep iteration finite.
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export inline std::uint32_t DecodeUtf8(std::string_view text, std::size_t& i) {
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if (i >= text.size()) return 0;
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std::uint8_t b0 = static_cast<std::uint8_t>(text[i]);
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// Single-byte ASCII is the common path.
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if (b0 < 0x80) { ++i; return b0; }
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int extra;
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std::uint32_t cp;
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if ((b0 & 0xE0) == 0xC0) { extra = 1; cp = b0 & 0x1F; }
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else if ((b0 & 0xF0) == 0xE0) { extra = 2; cp = b0 & 0x0F; }
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else if ((b0 & 0xF8) == 0xF0) { extra = 3; cp = b0 & 0x07; }
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else { ++i; return 0xFFFD; } // continuation byte at start, or 5+-byte leader
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++i;
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for (int k = 0; k < extra; ++k) {
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if (i >= text.size()) return 0xFFFD;
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std::uint8_t b = static_cast<std::uint8_t>(text[i]);
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if ((b & 0xC0) != 0x80) return 0xFFFD; // missing continuation
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cp = (cp << 6) | (b & 0x3Fu);
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++i;
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}
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return cp;
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}
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export class Font {
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public:
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std::vector<unsigned char> fontBuffer;
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std::int_fast32_t ascent;
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std::int_fast32_t descent;
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std::int_fast32_t lineGap;
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stbtt_fontinfo font;
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Font(const std::filesystem::path& font);
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std::uint32_t GetLineWidth(const std::string_view text, float size);
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float LineHeight(float size);
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float AscentPx(float size); // baseline offset from line-top
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float ScaleForSize(float size); // stb's pixel-units-per-em factor
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};
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}
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#endif // !CRAFTER_GRAPHICS_WINDOW_DOM
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