Crafter.Graphics/implementations/Crafter.Graphics-TextElement.cpp

/*
Crafter®.Graphics
Copyright (C) 2025 Catcrafts®
Catcrafts.net

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3.0 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
*/

module;
#include "../lib/stb_truetype.h"
module Crafter.Graphics:TextElement_impl;
import :TextElement;
import :RenderingElement;
import :Window;
import :Types;
import :Font;
import std;

using namespace Crafter;

TextElement::TextElement() : RenderingElement() {

}

TextElement::TextElement(const std::string_view text, float size, Pixel_BU8_GU8_RU8_AU8 pixel, Font& font, std::int_fast32_t anchorX, std::int_fast32_t anchorY, std::uint_fast32_t relativeWidth, std::uint_fast32_t relativeHeight, std::int_fast32_t anchorOffsetX, std::int_fast32_t anchorOffsetY, std::int_fast32_t z, bool ignoreScaling) : RenderingElement(false, anchorX, anchorY, relativeWidth, relativeHeight, anchorOffsetX, anchorOffsetY, z, ignoreScaling) {
    RenderText(text, size, pixel, font);
}

void TextElement::RenderText(const std::string_view text, float size, Pixel_BU8_GU8_RU8_AU8 color, Font& font) {
    buffer.clear();

    float scale = stbtt_ScaleForPixelHeight(&font.font, size);

    int baseline = (int)(font.ascent * scale);

    std::uint_fast32_t bufferWidth = 0;
    for (const char c : text) {
        int advance, lsb;
        stbtt_GetCodepointHMetrics(&font.font, c, &advance, &lsb);
        bufferWidth += (int)(advance * scale);
    }

    ResizeBuffer(bufferWidth, (font.ascent - font.descent) * scale);

    int x = 0;
    for (std::uint_fast32_t i = 0; i < text.size(); i++) {
        int codepoint = text[i];

        int ax;
        int lsb;
        stbtt_GetCodepointHMetrics(&font.font, codepoint, &ax, &lsb);

        int c_x1, c_y1, c_x2, c_y2;
        stbtt_GetCodepointBitmapBox(&font.font, codepoint, scale, scale, &c_x1, &c_y1, &c_x2, &c_y2);

        int w = c_x2 - c_x1;
        int h = c_y2 - c_y1;

        std::vector<unsigned char> bitmap(w * h);
        stbtt_MakeCodepointBitmap(&font.font, bitmap.data(), w, h, w, scale, scale, codepoint);

        for (int j = 0; j < h; j++) {
            for (int i = 0; i < w; i++) {
                buffer[(baseline + j + c_y1) * bufferWidth + (x + i + c_x1)] = {color.r, color.g, color.b, bitmap[j * w + i]};
            }
        }

        x += (int)(ax * scale);

        if (i + 1 < text.size()) {
            x += (int)stbtt_GetCodepointKernAdvance(&font.font, codepoint, text[i+1] * scale);
        }
    }
}