XiuchengWu
7cb8cee70d
- Updated Cargo.toml to include freetype-rs for font rendering. - Modified message.rs to introduce a new Message variant for subtitles. - Enhanced HttpPlugin to send subtitle messages to the live2d plugin. - Implemented text rendering in the live2d plugin using FreeType for Chinese characters. - Added OpenGL shaders for rendering text overlays. - Created a new text.rs module for handling text rasterization and texture rendering. - Updated renderer.rs to integrate subtitle rendering logic.
240 lines
7.6 KiB
Rust
240 lines
7.6 KiB
Rust
//! 基于 FreeType 的中文文字光栅化 + OpenGL 纹理渲染（设备端 Live2D 字幕 overlay）。
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//!
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//! 设计：每个字符首次出现时用 FreeType 渲染为灰度位图（经 `render_glyph` 拿到位图），转成
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//! 白色字形（alpha=灰度）的 RGBA 纹理并缓存；绘制时按 pen 位置贴纹理即可。纹理创建需要
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//! `Gl` 函数指针（与渲染器共用同一 EGL 上下文）。
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use super::gl::gl as gl_const;
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use super::gl::Gl;
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use freetype::face::LoadFlag;
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use freetype::Face;
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use freetype::Library;
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use freetype::RenderMode;
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use std::collections::HashMap;
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use std::path::Path;
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use anyhow::Result;
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/// 单个字符的缓存字形
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#[derive(Clone)]
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pub struct CachedGlyph {
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/// 字形纹理（0 表示该字符无可见像素，仅用于步进）
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pub tex: gl_const::GLuint,
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pub w: i32,
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pub h: i32,
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/// 字形位图相对 pen 原点的偏移
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pub left: i32,
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pub top: i32,
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/// 26.6 定点像素步进（渲染端需 >> 6 转为像素）
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pub advance: i32,
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}
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pub struct TextRenderer {
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face: Face<'static>,
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font_px: u32,
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glyphs: HashMap<char, CachedGlyph>,
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white_tex: Option<gl_const::GLuint>,
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}
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// FreeType 的 Face 包裹裸指针，仅在本插件单一渲染线程使用。
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unsafe impl Send for TextRenderer {}
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/// FT_LOAD_RENDER 标志位（0x4）：加载字符的同时渲染为位图
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const FT_LOAD_RENDER: i32 = 0x4;
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impl TextRenderer {
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pub fn new(font_path: &Path, font_px: u32) -> Result<Self> {
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let library = Library::init()?;
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// 让 Library 成为 'static（程序级单例），从而 Face<'static> 可长期持有而不会悬垂
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let library: &'static Library = Box::leak(Box::new(library));
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let face = library.new_face(font_path, 0)?;
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let tr = Self {
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face,
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font_px,
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glyphs: HashMap::new(),
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white_tex: None,
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};
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tr.face.set_pixel_sizes(0, font_px)?;
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println!("[Live2D] 字幕字体就绪: {:?} ({}px)", font_path, font_px);
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Ok(tr)
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}
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/// 当前字号（像素）
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pub fn font_size(&self) -> u32 {
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self.font_px
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}
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/// 1x1 白色纹理（用于纯色背景框，alpha 恒为 1）。
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fn white_tex(&mut self, gl: &Gl) -> gl_const::GLuint {
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if let Some(t) = self.white_tex {
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return t;
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}
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let mut tex = 0u32;
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unsafe {
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(gl.gl_gen_textures)(1, &mut tex);
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(gl.gl_bind_texture)(gl_const::GL_TEXTURE_2D, tex);
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(gl.gl_tex_parameteri)(
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gl_const::GL_TEXTURE_2D,
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gl_const::GL_TEXTURE_MIN_FILTER,
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gl_const::GL_LINEAR as i32,
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);
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(gl.gl_tex_parameteri)(
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gl_const::GL_TEXTURE_2D,
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gl_const::GL_TEXTURE_MAG_FILTER,
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gl_const::GL_LINEAR as i32,
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);
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(gl.gl_tex_parameteri)(
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gl_const::GL_TEXTURE_2D,
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gl_const::GL_TEXTURE_WRAP_S,
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gl_const::GL_CLAMP_TO_EDGE as i32,
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);
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(gl.gl_tex_parameteri)(
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gl_const::GL_TEXTURE_2D,
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gl_const::GL_TEXTURE_WRAP_T,
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gl_const::GL_CLAMP_TO_EDGE as i32,
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);
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let px: [u8; 4] = [255, 255, 255, 255];
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(gl.gl_tex_image_2d)(
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gl_const::GL_TEXTURE_2D,
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0,
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gl_const::GL_RGBA as i32,
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1,
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1,
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0,
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gl_const::GL_RGBA,
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gl_const::GL_UNSIGNED_BYTE,
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px.as_ptr() as *const std::ffi::c_void,
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);
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}
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self.white_tex = Some(tex);
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tex
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}
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/// 取 1x1 白纹理（供外部画背景框）。
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pub fn white_texture(&mut self, gl: &Gl) -> gl_const::GLuint {
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self.white_tex(gl)
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}
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/// 估算字符像素宽度（用于换行布局，不创建纹理）。返回像素值。
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pub fn measure_advance(&mut self, ch: char) -> i32 {
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if self
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.face
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.load_char(ch as usize, LoadFlag::from_bits_truncate(FT_LOAD_RENDER))
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.is_ok()
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{
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(self.face.glyph().advance().x >> 6) as i32
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} else {
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(self.font_px as f32 * 0.5) as i32
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}
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}
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fn rasterize(&mut self, gl: &Gl, ch: char) -> Option<CachedGlyph> {
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let half_advance_26_6 = (self.font_px as i32) << 5; // 半字宽，26.6 定点
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if self
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.face
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.load_char(ch as usize, LoadFlag::from_bits_truncate(FT_LOAD_RENDER))
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.is_err()
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{
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return Some(CachedGlyph {
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tex: 0,
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w: 0,
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h: 0,
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left: 0,
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top: 0,
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advance: half_advance_26_6,
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});
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}
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let glyph = self.face.glyph();
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if glyph.render_glyph(RenderMode::Normal).is_err() {
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let adv = glyph.advance().x as i32; // 26.6 定点
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return Some(CachedGlyph {
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tex: 0,
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w: 0,
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h: 0,
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left: 0,
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top: 0,
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advance: adv,
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});
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}
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let bitmap = glyph.bitmap();
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let w = bitmap.width();
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let h = bitmap.rows();
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let left = glyph.bitmap_left();
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let top = glyph.bitmap_top();
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let advance = glyph.advance().x as i32; // 26.6 定点
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if w == 0 || h == 0 {
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return Some(CachedGlyph {
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tex: 0,
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w: 0,
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h: 0,
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left,
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top,
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advance,
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});
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}
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// 灰度 -> RGBA：白色字形，alpha=灰度
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let buf = bitmap.buffer();
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let mut rgba: Vec<u8> = Vec::with_capacity((w * h * 4) as usize);
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for &g in buf {
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rgba.push(255);
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rgba.push(255);
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rgba.push(255);
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rgba.push(g);
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}
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let mut tex = 0u32;
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unsafe {
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(gl.gl_gen_textures)(1, &mut tex);
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(gl.gl_bind_texture)(gl_const::GL_TEXTURE_2D, tex);
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(gl.gl_tex_parameteri)(
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gl_const::GL_TEXTURE_2D,
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gl_const::GL_TEXTURE_MIN_FILTER,
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gl_const::GL_LINEAR as i32,
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);
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(gl.gl_tex_parameteri)(
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gl_const::GL_TEXTURE_2D,
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gl_const::GL_TEXTURE_MAG_FILTER,
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gl_const::GL_LINEAR as i32,
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);
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(gl.gl_tex_parameteri)(
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gl_const::GL_TEXTURE_2D,
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gl_const::GL_TEXTURE_WRAP_S,
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gl_const::GL_CLAMP_TO_EDGE as i32,
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);
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(gl.gl_tex_parameteri)(
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gl_const::GL_TEXTURE_2D,
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gl_const::GL_TEXTURE_WRAP_T,
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gl_const::GL_CLAMP_TO_EDGE as i32,
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);
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(gl.gl_tex_image_2d)(
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gl_const::GL_TEXTURE_2D,
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0,
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gl_const::GL_RGBA as i32,
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w,
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h,
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0,
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gl_const::GL_RGBA,
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gl_const::GL_UNSIGNED_BYTE,
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rgba.as_ptr() as *const std::ffi::c_void,
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);
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}
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Some(CachedGlyph {
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tex,
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w,
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h,
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left,
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top,
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advance,
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})
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}
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/// 获取（必要时光栅化并缓存）字符字形。
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pub fn glyph(&mut self, gl: &Gl, ch: char) -> Option<CachedGlyph> {
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if !self.glyphs.contains_key(&ch) {
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if let Some(g) = self.rasterize(gl, ch) {
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self.glyphs.insert(ch, g);
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}
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}
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self.glyphs.get(&ch).cloned()
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}
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}
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