panel/src/ui/font.rs

use config::Config;
use freetype as ft;
use fontconfig_sys::*;
use ui::ext;
use ui::ext::ConnectionExt;
use ui::util;
use ui::x11;
use xcb;

use std::cell::RefCell;
use std::collections::HashMap;
use std::ffi::{CString, CStr};
use std::mem;
use std::ptr;
use std::sync::{Once, ONCE_INIT};

static FC_INIT: Once = ONCE_INIT;

struct Font {
    pub id: xcb::render::Glyphset,
    face: ft::Face<'static>,
    char_widths: RefCell<HashMap<char, u16>>
}

impl Font {
    pub fn new(conn: &xcb::Connection, face: ft::Face<'static>) -> Font {
        let format = conn.get_pict_format(ext::PictFormat::ARGB32);
        let id = conn.generate_id();
        xcb::render::create_glyph_set(conn, id, format);

        Font {
            id: id,
            face: face,
            char_widths: RefCell::new(HashMap::new())
        }
    }

    pub fn load_glyph(&self, conn: &xcb::Connection, charcode: char) -> Option<u16> {
        if self.char_widths.borrow().contains_key(&charcode) {
            return self.char_widths.borrow().get(&charcode).map(|r| *r)
        }
        if self.face.get_char_index(charcode as usize) == 0 {
            return None
        }
        match self.face.load_char(charcode as usize, ft::face::RENDER | ft::face::TARGET_LCD) {
            Ok(_) => {
                let glyph = self.face.glyph();
                let bitmap = glyph.bitmap();

                let pixel_width = (bitmap.width() / 3) as usize;
                let pixel_height = bitmap.rows() as usize;

                let info = xcb::render::Glyphinfo::new(
                    pixel_width as u16,
                    pixel_height as u16,
                    -glyph.bitmap_left() as i16,
                    glyph.bitmap_top() as i16,
                    (glyph.advance().x / 64) as i16,
                    (glyph.advance().y / 64) as i16
                );

                let stride = bitmap.width() as usize + (pixel_width & 3); // round up to 4 somehow
                let source = bitmap.buffer();
                let pixels = pixel_height * pixel_width;

                let mut buf = Vec::with_capacity(pixels * 4);
                for i in 0..pixel_height {
                    let offset = i * stride;
                    for j in 0..pixel_width {
                        let offset = offset + j * 3;
                        buf.push(source[offset+2]);
                        buf.push(source[offset+1]);
                        buf.push(source[offset]);
                        buf.push(0);
                    }
                }
                let width = (glyph.advance().x / 64) as u16;
                xcb::render::add_glyphs(conn, self.id, &[charcode as u32], &[info], buf.as_slice());
                self.char_widths.borrow_mut().insert(charcode, width);
                Some(width)
            },
            _ => None
        }
    }

    pub fn baseline_offset(&self, height: u16) -> i16 {
        self.face.load_char('X' as usize, ft::face::LoadFlag::empty()).unwrap();
        let ascender = self.face.glyph().metrics().horiBearingY / 64;
        (height as i16 - ascender as i16) / 2
    }
}

pub struct TextGroup<'a> {
    pub text: &'a str,
    pub glyphset: xcb::render::Glyphset
}

pub struct RenderableText<'a> {
    pub width: u16,
    groups: Vec<TextGroup<'a>>
}

impl<'a> RenderableText<'a> {
    pub fn render(&self, conn: &xcb::Connection, pen: xcb::render::Picture, pic: xcb::render::Picture, x: u16, y: u16) {
        let mut cmds = util::GlyphCmd::new();
        let mut default_glyphset = 0;
        cmds.set_position(x, y);
        for group in self.groups.iter() {
            default_glyphset = group.glyphset;
            cmds.set_glyphset(group.glyphset);
            cmds.add_text(group.text);
        }
        xcb::render::composite_glyphs_32(
            conn,
            xcb::render::PICT_OP_OVER as u8,
            pen,
            pic,
            0,
            default_glyphset,
            0, 0,
            cmds.as_ref()
        );
    }
}

pub struct FontLoader {
    conn: x11::Connection,
    library: ft::Library,
    fonts: Vec<Font>
}

impl FontLoader {
    pub fn new(conn: x11::Connection) -> Self {
        FC_INIT.call_once(|| unsafe {
            assert_eq!(FcInit(), 1);
        });

        let library = ft::Library::init().unwrap();
        unsafe {
            ft::ffi::FT_Library_SetLcdFilter(library.raw(), ft::ffi::FT_LCD_FILTER_DEFAULT);
        };
        FontLoader {
            conn: conn,
            library: library,
            fonts: vec![]
        }
    }

    pub fn from_config(conn: x11::Connection, cfg: &Config) -> Self {
        let val = cfg.lookup("bar.fonts").unwrap();
        let fonts = val.as_slice().unwrap();
        let fonts = fonts.iter().flat_map(|elem| elem.as_str());
        let mut font_loader = Self::new(conn);
        for font in fonts {
            font_loader.load(font);
        }
        font_loader
    }

    fn find_face(&self, name: &str) -> Option<ft::Face<'static>> {
        unsafe {
            let slice = CString::new(name.to_string()).unwrap();
            let pattern = FcNameParse(slice.as_ptr() as *const u8);
            FcConfigSubstitute(ptr::null_mut(), pattern, FcMatchPattern);
            FcDefaultSubstitute(pattern);

            let mut result: FcResult = mem::uninitialized();
            let font = FcFontMatch(ptr::null_mut(), pattern, &mut result);
            if !font.is_null() {
                let field = CString::new("file").unwrap();
                let mut ret: *mut FcChar8 = mem::uninitialized();
                if FcPatternGetString(font, field.as_ptr(), 0, &mut ret) == FcResultMatch {
                    let file = CStr::from_ptr(ret as *const i8);
                    let path = file.to_string_lossy().to_string();
                    let face = self.library.new_face(&path, 0).unwrap();

                    let field = CString::new("dpi").unwrap();
                    let mut dpi = 0.0;
                    if FcPatternGetDouble(font, field.as_ptr(), 0, &mut dpi) != FcResultMatch {
                        dpi = 75.0;
                    }

                    let field = CString::new("pixelsize").unwrap();
                    let mut pixel_size = 0.0;
                    if FcPatternGetDouble(font, field.as_ptr(), 0, &mut pixel_size) == FcResultMatch {
                        face.set_pixel_sizes((96.0 / dpi * pixel_size) as u32, 0).unwrap();
                    }
                    return Some(face)
                }
            }
            None
        }
    }

    pub fn load(&mut self, name: &str) {
        if let Some(face) = self.find_face(name) {
            let font = Font::new(&self.conn, face);
            self.fonts.push(font);
        }
        else {
            panic!("Could not load font {}", name);
        }
    }

    pub fn default_offset(&self, height: u16) -> i16 {
        self.fonts[0].baseline_offset(height)
    }

    fn glyphset_and_width_for_char(&self, charcode: char) -> Option<(xcb::render::Glyphset, u16)> {
        for font in self.fonts.iter() {
            if let Some(width) = font.load_glyph(&self.conn, charcode) {
                return Some((font.id, width))
            }
        }
        None
    }

    pub fn create_renderable_text<'a>(&self, string: &'a str) -> RenderableText<'a> {
        let mut ret = vec![];
        let mut prev = 0;
        let mut id = 0;
        let mut width = 0;
        for (i, charcode) in string.char_indices() {
            if let Some((this_id, char_width)) = self.glyphset_and_width_for_char(charcode) {
                width += char_width;
                if i == 0 {
                    id = this_id;
                }
                else if id != this_id {
                    ret.push(TextGroup {
                        text: &string[prev..i],
                        glyphset: id
                    });
                    id = this_id;
                    prev = i;
                }
            }
        }
        ret.push(TextGroup {
            text: &string[prev..string.len()],
            glyphset: id
        });

        RenderableText {
            width: width,
            groups: ret
        }
    }
}