Rust插件库fdsm的使用，fdsm提供高效的数据结构管理与操作功能

fdsm是一个纯Rust实现的多通道有符号距离场生成库，主要遵循Victor Chlumský的硕士论文实现。虽然它不是C++ msdfgen库的直接翻译，但在部分代码上参考了该库的实现。

特性

• visualize: 提供可视化辅助功能
• ttf-parser特性已移至单独的fdsm-ttf-parser crate

使用方法

以下是内容中提供的示例代码：

use fdsm::bezier::scanline::FillRule;
use fdsm::generate::generate_msdf;
use fdsm::render::{correct_sign_msdf, render_msdf};
use fdsm::shape::Shape;
# use fdsm::shape::Contour;
use fdsm::transform::Transform;
use image::{GrayImage, RgbImage};
use nalgebra::{Affine2, Similarity2, Vector2};

// 首先获取一个[`Shape`]。可以通过程序生成或从字体加载获得
# #[cfg(false)] {
use ttf_parser::Face;
let face = Face::parse(notosans::REGULAR_TTF, 0).unwrap();
let glyph_id = face.glyph_index('A').unwrap();
let mut shape = fdsm_ttf_parser::load_shape_from_face(&face, glyph_id);
let bbox = face.glyph_bounding_box(glyph_id).unwrap();
# manipulate_shape(shape, bbox);
# }

# fn manipulate_shape(mut shape: Shape<Contour>, bbox: ttf_parser::Rect) {
// 准备变换矩阵并计算生成的有符号距离场的尺寸
const RANGE: f64 = 4.0;
const SHRINKAGE: f64 = 16.0;
let transformation = nalgebra::convert::<_, Affine2<f64>>(Similarity2::new(
    Vector2::new(
        RANGE - bbox.x_min as f64 / SHRINKAGE,
        RANGE - bbox.y_min as f64 / SHRINKAGE,
    ),
    0.0,
    1.0 / SHRINKAGE,
));
let width =
    ((bbox.x_max as f64 - bbox.x_min as f64) / SHRINKAGE + 2.0 * RANGE).ceil() as u32;
let height =
    ((bbox.y_max as f64 - bbox.y_min as f64) / SHRINKAGE + 2.0 * RANGE).ceil() as u32;

// 预变换形状
shape.transform(&transformation);

// 为形状的边缘着色并准备计算
let colored_shape = Shape::edge_coloring_simple(shape, 0.03, 69441337420);
let prepared_colored_shape = colored_shape.prepare();

// 设置结果图像并生成距离场
let mut msdf = RgbImage::new(width, height);
generate_msdf(&prepared_colored_shape, RANGE, &mut msdf);
correct_sign_msdf(&mut msdf, &prepared_colored_shape, FillRule::Nonzero);

// 预览距离场作为测试
let mut preview = GrayImage::new(msdf.width() * 10, msdf.height() * 10);
render_msdf(&msdf, &mut preview, RANGE);
# }

完整示例代码

use fdsm::bezier::scanline::FillRule;
use fdsm::generate::generate_msdf;
use fdsm::render::{correct_sign_msdf, render_msdf};
use fdsm::shape::{Contour, Shape};
use fdsm::transform::Transform;
use image::{GrayImage, RgbImage};
use nalgebra::{Affine2, Similarity2, Vector2};

fn main() {
    // 创建一个简单的矩形形状
    let mut shape = Shape::new();
    let mut contour = Contour::new();
    
    // 添加矩形的四个顶点
    contour.add_point(0.0, 0.0);
    contour.add_point(100.0, 0.0);
    contour.add_point(100.0, 50.0);
    contour.add_point(0.0, 50.0);
    
    shape.add_contour(contour);
    
    // 设置参数
    const RANGE: f64 = 4.0;
    const SHRINKAGE: f64 = 1.0;
    
    // 创建变换矩阵
    let transformation = Affine2::identity();
    
    // 计算输出图像尺寸
    let width = (100.0 / SHRINKAGE + 2.0 * RANGE).ceil() as u32;
    let height = (50.0 / SHRINKAGE + 2.0 * RANGE).ceil() as u32;
    
    // 应用变换
    shape.transform(&transformation);
    
    // 边缘着色和准备
    let colored_shape = Shape::edge_coloring_simple(shape, 0.03, 12345);
    let prepared_colored_shape = colored_shape.prepare();
    
    // 生成MSDF
    let mut msdf = RgbImage::new(width, height);
    generate_msdf(&prepared_colored_shape, RANGE, &mut msdf);
    correct_sign_msdf(&mut msdf, &prepared_colored_shape, FillRule::Nonzero);
    
    // 渲染预览
    let mut preview = GrayImage::new(msdf.width() * 10, msdf.height * 10);
    render_msdf(&msdf, &mut preview, RANGE);
    
    // 保存结果
    msdf.save("output_msdf.png").unwrap();
    preview.save("output_preview.png").unwrap();
}

路线图

当前fdsm已具备生成MSDF的基本功能，并能在Noto Sans字体中正确生成A到Z字母的距离场。但仍缺少部分msdfgen的功能：

• [x] 错误校正
• [ ] 错误估计
• [x] 符号校正
• [ ] 形状简化
• [ ] 替代边缘着色算法
• [x] 与msdfgen的基准测试

安装

在项目目录中运行以下Cargo命令：

cargo add fdsm

或在Cargo.toml中添加：

fdsm = "0.7.0"