Code to render character cells

freetype/__init__.py

@@ -992,7 +992,7 @@ class Face( object ):
             FT_Done_Face( self._FT_Face )
 
     def __repr__(self):
-        return 'Face({})'.format(self.family_name)
+        return 'Face({}, {})'.format(self.family_name, self.style_name)
 
     def attach_file( self, filename ):
         '''

kitty/char_grid.py

@@ -5,7 +5,7 @@
 from threading import Lock
 
 from .config import build_ansi_color_tables, to_color
-from .fonts import load_font_family
+from .fonts import set_font_family
 
 from OpenGL.arrays import ArrayDatatype
 from OpenGL.GL import (
@@ -51,8 +51,7 @@ class CharGrid:
         self.opts = opts
         self.default_bg = self.original_bg = opts.background
         self.default_fg = self.original_fg = opts.foreground
-        self.base_font_family = load_font_family(opts.font_family)
-        self.font_size = int(opts.font_size * 64)
+        self.base_font_family = set_font_family(opts.font_family)
         self.apply_clear_color()
 
     def on_resize(self, window, w, h):

kitty/fonts.py

@@ -3,11 +3,17 @@
 # License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 
 import subprocess
+import unicodedata
 import re
 from collections import namedtuple
 from functools import lru_cache
 
-from freetype import Face
+from freetype import (
+    Face, FT_LOAD_RENDER, FT_LOAD_TARGET_NORMAL, FT_LOAD_TARGET_LIGHT,
+    FT_LOAD_NO_HINTING, FT_PIXEL_MODE_GRAY
+)
+
+from .utils import get_logical_dpi
 
 
 def escape_family_name(name):
@@ -23,8 +29,8 @@ def get_font_information(q, bold=False, italic=False):
         q += ':bold=200'
     if italic:
         q += ':slant=100'
-    raw = subprocess.check_output(['fc-match', q, '-f', '%{file}\x31%{hinting}\x31%{hintstyle}']).decode('utf-8')
-    parts = raw.split('\x31')
+    raw = subprocess.check_output(['fc-match', q, '-f', '%{file}\x1e%{hinting}\x1e%{hintstyle}']).decode('utf-8')
+    parts = raw.split('\x1e')
     hintstyle, hinting = 1, 'True'
     if len(parts) == 3:
         path, hinting, hintstyle = parts
@@ -48,6 +54,58 @@ def get_font_files(family):
     return ans
 
 
-@lru_cache()
-def load_font_family(r):
-    return get_font_files(r)
+current_font_family = current_font_family_name = None
+
+
+def set_font_family(family):
+    global current_font_family, current_font_family_name
+    if current_font_family_name != family:
+        current_font_family = get_font_files(family)
+        current_font_family_name = family
+    return current_font_family['regular'].face
+
+CharData = namedtuple('CharData', 'left width ascender descender')
+
+
+def render_char(text, size_in_pts, bold=False, italic=False):
+    # TODO: Handle non-normalizable combining chars. Probably need to use
+    # harfbuzz for that
+    text = unicodedata.normalize('NFC', text)[0]
+    key = 'regular'
+    if bold:
+        key = 'bi' if italic else 'bold'
+    elif italic:
+        key = 'italic'
+    font = current_font_family.get(key) or current_font_family['regular']
+    dpi = get_logical_dpi()
+    sz = int(64 * size_in_pts)
+    face = font.face
+    face.set_char_size(width=sz, height=sz, hres=dpi[0], vres=dpi[1])
+    flags = FT_LOAD_RENDER
+    if font.hinting:
+        if font.hintstyle >= 3:
+            flags |= FT_LOAD_TARGET_NORMAL
+        elif 0 < font.hintstyle < 3:
+            flags |= FT_LOAD_TARGET_LIGHT
+    else:
+        flags |= FT_LOAD_NO_HINTING
+    face.load_char(text, flags)
+    bitmap = face.glyph.bitmap
+    if bitmap.pixel_mode != FT_PIXEL_MODE_GRAY:
+        raise ValueError('FreeType rendered the glyph with an unsupported pixel mode: {}'.format(bitmap.pixel_mode))
+    width = bitmap.width
+    ascender = face.glyph.bitmap_top
+    descender = bitmap.rows - ascender
+    left = face.glyph.bitmap_left
+
+    return bitmap.buffer, CharData(left, width, ascender, descender)
+
+
+def test_rendering(text='M', sz=144, family='monospace'):
+    set_font_family(family)
+    buf, char_data = render_char(text, sz)
+    print(char_data)
+    from PIL import Image
+    img = Image.new('L', (char_data.width, char_data.ascender + char_data.descender))
+    img.putdata(buf)
+    img.show()

kitty/utils.py

@@ -108,6 +108,14 @@ def sanitize_title(x):
     return re.sub(r'\s+', ' ', re.sub(r'[\0-\x19]', '', x))
 
 
+def get_logical_dpi():
+    if not hasattr(get_logical_dpi, 'ans'):
+        raw = subprocess.check_output(['xdpyinfo']).decode('utf-8')
+        m = re.search(r'^\s*resolution:\s*(\d+)+x(\d+)', raw, flags=re.MULTILINE)
+        get_logical_dpi.ans = int(m.group(1)), int(m.group(2))
+    return get_logical_dpi.ans
+
+
 def get_dpi():
     if not hasattr(get_dpi, 'ans'):
         m = glfw.glfwGetPrimaryMonitor()
@@ -115,8 +123,5 @@ def get_dpi():
         vmode = glfw.glfwGetVideoMode(m)
         dpix = vmode.width / (width / 25.4)
         dpiy = vmode.height / (height / 25.4)
-        get_dpi.ans = {'physical': (dpix, dpiy)}
-        raw = subprocess.check_output(['xdpyinfo']).decode('utf-8')
-        m = re.search(r'^\s*resolution:\s*(\d+)+x(\d+)', raw, flags=re.MULTILINE)
-        get_dpi.ans['logical'] = (int(m.group(1)), int(m.group(2)))
+        get_dpi.ans = {'physical': (dpix, dpiy), 'logical': get_logical_dpi()}
     return get_dpi.ans