text-atlas.py

import os
import sys
from PIL import Image

from cairo import FontOptions, SVGSurface, ImageSurface, Context, Matrix
from cairo import FORMAT_ARGB32, FONT_SLANT_NORMAL, FONT_WEIGHT_BOLD, ANTIALIAS_SUBPIXEL, LINE_JOIN_ROUND

from gi.repository import Pango
from gi.repository import PangoCairo
 
class vector_atlas:
    data = None
    data_text = None
    width = 512
    height = 512
    texture_id = None
    text_texture_id = None

    surface = None
    draw = None
    pango_draw = None

    def __init__(self):
        self.data = None
        self.data_text = None
        self.width = 512
        self.height = 512
        self.texture_id = None
        self.text_texture_id = None
        self.surface = None
        self.draw = None
        self.pango_draw = None

    def setup(self, size=512):
        self.width = size
        self.height = size
        self.surface = ImageSurface(FORMAT_ARGB32, size, size)
        self.draw = Context(self.surface)
        self.draw.scale(1, 1)
        self.draw.set_source_rgb(0.0, 0.0, 0.0)

    def cairo_to_pil(self):
        return Image.frombuffer(
            'RGBA', (self.width, self.height),
            self.surface.get_data(), 'raw', 'BGRA', 0, 1
            ).tostring('raw', 'RGBA', 0, -1)

    def available_fonts(self):
        font_map = PangoCairo.cairo_font_map_get_default()
        families = font_map.list_families()
        print([f.get_name() for f in font_map.list_families()])

    def text_atlas(self, text, fontname='Monospace', font_size = 48, size=512):
        filename = './atlas' + str(size) + 'x' + str(size) + '.png'
        self.setup()

        layout = PangoCairo.create_layout(self.draw)

        font = Pango.FontDescription(fontname + " " + str(font_size))
        font_options = FontOptions()
        font_options.set_antialias(ANTIALIAS_SUBPIXEL)
        layout.set_font_description(font)

        width, height = layout.get_size()

        x_pos = 0
        y_pos = 0
        layout.set_height(64)
        self.draw.move_to(x_pos, y_pos)
        for letter in text:
            layout.set_text(letter, -1)

            self.draw.set_source_rgb(0, 0, 0)
            PangoCairo.update_layout(self.draw, layout)
            self.draw.move_to(x_pos, y_pos)
            PangoCairo.show_layout(self.draw, layout)
            x_pos += font_size
            if x_pos + font_size > size:
                x_pos = 0
                y_pos += font_size

        self.surface.write_to_png(filename)


v = vector_atlas()
v.text_atlas('y0123456789+-%xyz')