import gi
gi.require_version("Gtk", "3.0")
from gi.repository import Gtk, HarfBuzz as hb
POOL = {}
def move_to_f(funcs, draw_data, st, to_x, to_y, user_data):
context = POOL[draw_data]
context.move_to(to_x, to_y)
def line_to_f(funcs, draw_data, st, to_x, to_y, user_data):
context = POOL[draw_data]
context.line_to(to_x, to_y)
def cubic_to_f(
funcs,
draw_data,
st,
control1_x,
control1_y,
control2_x,
control2_y,
to_x,
to_y,
user_data,
):
context = POOL[draw_data]
context.curve_to(control1_x, control1_y, control2_x, control2_y, to_x, to_y)
def close_path_f(funcs, draw_data, st, user_data):
context = POOL[draw_data]
context.close_path()
DFUNCS = hb.draw_funcs_create()
hb.draw_funcs_set_move_to_func(DFUNCS, move_to_f, None)
hb.draw_funcs_set_line_to_func(DFUNCS, line_to_f, None)
hb.draw_funcs_set_cubic_to_func(DFUNCS, cubic_to_f, None)
hb.draw_funcs_set_close_path_func(DFUNCS, close_path_f, None)
def push_transform_f(funcs, paint_data, xx, yx, xy, yy, dx, dy, user_data):
raise NotImplementedError
def pop_transform_f(funcs, paint_data, user_data):
raise NotImplementedError
def color_f(funcs, paint_data, is_foreground, color, user_data):
context = POOL[paint_data]
r = hb.color_get_red(color) / 255
g = hb.color_get_green(color) / 255
b = hb.color_get_blue(color) / 255
a = hb.color_get_alpha(color) / 255
context.set_source_rgba(r, g, b, a)
context.paint()
def push_clip_rectangle_f(funcs, paint_data, xmin, ymin, xmax, ymax, user_data):
context = POOL[paint_data]
context.save()
context.rectangle(xmin, ymin, xmax, ymax)
context.clip()
def push_clip_glyph_f(funcs, paint_data, glyph, font, user_data):
context = POOL[paint_data]
context.save()
context.new_path()
hb.font_draw_glyph(font, glyph, DFUNCS, paint_data)
context.close_path()
context.clip()
def pop_clip_f(funcs, paint_data, user_data):
context = POOL[paint_data]
context.restore()
def push_group_f(funcs, paint_data, user_data):
raise NotImplementedError
def pop_group_f(funcs, paint_data, mode, user_data):
raise NotImplementedError
PFUNCS = hb.paint_funcs_create()
hb.paint_funcs_set_push_transform_func(PFUNCS, push_transform_f, None)
hb.paint_funcs_set_pop_transform_func(PFUNCS, pop_transform_f, None)
hb.paint_funcs_set_color_func(PFUNCS, color_f, None)
hb.paint_funcs_set_push_clip_glyph_func(PFUNCS, push_clip_glyph_f, None)
hb.paint_funcs_set_push_clip_rectangle_func(PFUNCS, push_clip_rectangle_f, None)
hb.paint_funcs_set_pop_clip_func(PFUNCS, pop_clip_f, None)
hb.paint_funcs_set_push_group_func(PFUNCS, push_group_f, None)
hb.paint_funcs_set_pop_group_func(PFUNCS, pop_group_f, None)
def makebuffer(words):
buf = hb.buffer_create()
text = " ".join(words)
hb.buffer_add_codepoints(buf, [ord(c) for c in text], 0, len(text))
hb.buffer_guess_segment_properties(buf)
return buf
def justify(face, words, advance, target_advance):
font = hb.font_create(face)
buf = makebuffer(words)
wiggle = 5
shrink = target_advance - wiggle < advance
expand = target_advance + wiggle > advance
ret, advance, tag, value = hb.shape_justify(
font,
buf,
None,
None,
target_advance,
target_advance,
advance,
)
if not ret:
return False, buf, None
if tag:
variation = hb.variation_t()
variation.tag = tag
variation.value = value
else:
variation = None
if shrink and advance > target_advance + wiggle:
return False, buf, variation
if expand and advance < target_advance - wiggle:
return False, buf, variation
return True, buf, variation
def shape(face, words):
font = hb.font_create(face)
buf = makebuffer(words)
hb.shape(font, buf)
positions = hb.buffer_get_glyph_positions(buf)
advance = sum(p.x_advance for p in positions)
return buf, advance
def typeset(face, text, target_advance):
lines = []
words = []
for word in text.split():
words.append(word)
buf, advance = shape(face, words)
if advance > target_advance:
# Shrink
ret, buf, variation = justify(face, words, advance, target_advance)
if ret:
lines.append((buf, variation))
words = []
# If if fails, pop the last word and shrink, and hope for the best.
# A too short line is better than too long.
elif len(words) > 1:
words.pop()
_, buf, variation = justify(face, words, advance, target_advance)
lines.append((buf, variation))
words = [word]
# But if it is one word, meh.
else:
lines.append((buf, variation))
words = []
# Justify last line
if words:
_, buf, variation = justify(face, words, advance, target_advance)
lines.append((buf, variation))
return lines
def render(face, text, context, width, height, fontsize):
font = hb.font_create(face)
margin = fontsize * 2
scale = fontsize / hb.face_get_upem(face)
target_advance = (width - (margin * 2)) / scale
lines = typeset(face, text, target_advance)
_, extents = hb.font_get_h_extents(font)
lineheight = extents.ascender - extents.descender + extents.line_gap
lineheight *= scale
context.save()
context.translate(0, margin)
context.set_font_size(12)
context.set_source_rgb(1, 0, 0)
for buf, variation in lines:
rtl = hb.buffer_get_direction(buf) == hb.direction_t.RTL
if rtl:
hb.buffer_reverse(buf)
infos = hb.buffer_get_glyph_infos(buf)
positions = hb.buffer_get_glyph_positions(buf)
advance = sum(p.x_advance for p in positions)
context.translate(0, lineheight)
context.save()
context.save()
context.move_to(0, -20)
if variation:
tag = hb.tag_to_string(variation.tag).decode("ascii")
context.show_text(f" {tag}={variation.value:g}")
context.move_to(0, 0)
context.show_text(f" {advance:g}/{target_advance:g}")
context.restore()
if variation:
hb.font_set_variations(font, [variation])
context.translate(margin, 0)
context.scale(scale, -scale)
if rtl:
context.translate(target_advance, 0)
for info, pos in zip(infos, positions):
if rtl:
context.translate(-pos.x_advance, pos.y_advance)
context.save()
context.translate(pos.x_offset, pos.y_offset)
hb.font_paint_glyph(font, info.codepoint, PFUNCS, id(context), 0, 0x0000FF)
context.restore()
if not rtl:
context.translate(+pos.x_advance, pos.y_advance)
context.restore()
context.restore()
def main(fontpath, textpath):
fontsize = 70
blob = hb.blob_create_from_file(fontpath)
face = hb.face_create(blob, 0)
with open(textpath) as f:
text = f.read()
def on_draw(da, context):
alloc = da.get_allocation()
POOL[id(context)] = context
render(face, text, context, alloc.width, alloc.height, fontsize)
del POOL[id(context)]
drawingarea = Gtk.DrawingArea()
drawingarea.connect("draw", on_draw)
win = Gtk.Window()
win.connect("destroy", Gtk.main_quit)
win.set_default_size(1000, 700)
win.add(drawingarea)
win.show_all()
Gtk.main()
if __name__ == "__main__":
import argparse
parser = argparse.ArgumentParser(description="HarfBuzz justification demo.")
parser.add_argument("fontfile", help="font file")
parser.add_argument("textfile", help="text")
args = parser.parse_args()
main(args.fontfile, args.textfile)
