munmap_chunk(): invalid pointer; Aborted (core dumped) - when Label text rendering (sdl2 provider)

[me2beats]

the error appears when you start the application using this font:
https://www.dafont.com/bleeding-cowboys.font

from kivy.lang import Builder
from kivy.core.text import LabelBase

LabelBase.register(
    name='Bleeding_Cowboys',
    fn_regular='Bleeding_Cowboys.ttf',
    fn_bold='Bleeding_Cowboys.ttf')

KV = """
Label
    font_name: 'Bleeding_Cowboys'

    text: 'AR' # <-- 'munmap_chunk(): invalid pointer; Aborted (core dumped)'

#    text: 'aR' # <-- same error
#    text: 'bR' # <-- same error
#    text: '.R' # <-- same error

#    text: 'R' # <-- this works
#    text: 'Ar' # <-- this works
#    text: 'ar' # <-- this works

"""

class MyApp(App):
    def build(self):
        self.root = Builder.load_string(KV)

MyApp().run()

Result:

1. sdl2 provider:

munmap_chunk(): invalid pointer
Aborted (core dumped)

2. pil provider:
   error doesn't appear but the render is incorrect (for example, the letter R is not fully rendered)

[tito]

It might be better that you try opening issue on the underlaying library rather than us no?
Aka either SDL2/pygame, but they all uses freetype. If you find a segfault, nothing we could do here again. Report it to freetype!

[me2beats]

Ok I'll try to report it to freetype.

some more info:

1. Pygame has about the same problem with core dumped (I created an issue):
   Some fonts cause 'core dumped' error pygame/pygame#817

2. this font
   https://www.dafontfree.net/freefonts-bickham-script-alt-one-f115107.htm
   behaves about the same:

from kivy.lang import Builder
from kivy.core.text import LabelBase

font = 'BickhamScriptAltOne.ttf'
LabelBase.register(name=font, fn_regular=font,  fn_bold=font)

KV = """
Label
    font_size: 100
    font_name: 'BickhamScriptAltOne.ttf'

    text: 'rg' #sdl2 = app crash, pil = not fully rendered
#    text: 'r' # ok
#    text: 'g' # ok

"""

class MyApp(App):
    def build(self):
        self.root = Builder.load_string(KV)

MyApp().run()

• sdl2: core dumped, crash

• pil: rendered, but not fully displayed

• Pygame app (not backend): works fine

You may also notice that in pygame this text rendered a little more smoothly then in kivy pil. (?)

Pygame code:

import pygame, sys
from pygame.locals import *

pygame.init()

windowSurface = pygame.display.set_mode((500, 400), 0, 32)
pygame.display.set_caption('Hello world!')

WHITE = (255, 255, 255)

basicFont = pygame.font.Font('BickhamScriptAltOne.ttf', 100)

text = basicFont.render('rg', True, WHITE)
textRect = text.get_rect()
textRect.centerx = windowSurface.get_rect().centerx
textRect.centery = windowSurface.get_rect().centery

windowSurface.blit(text, textRect)

pygame.display.update()

while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

[tito]

Yep. So i'll close this issue as it's actually not something we can fix in Kivy itself, but require the fix to be done in the upstream libraries.