Using Kivy in Buildroot on RPi4

[Jimmy]

Good evening all,

I'm trying to get Kivy running inside of a Buildroot based system on the Raspberry Pi 4 (Python 3.7). I've gotten the package to compile/install, but it doesn't look like its able to spin up a window using either the sdl2 or rpi_egl backends. I've installed the rpi_userland and rpi_firmware packages which provide the native Broadcom blobs and OpenGL backend.  I can see where the application enters the main loop, but I never see any graphics on screen. The console just logs the following text and the cursor continues to blink. I can even ctrl+C out of the program, so its not like its freezing. (This is with KIVY_GL_BACKEND=gl set)

[INFO   ] Logger: Record log in /root/.kivy/logs/kivy_20-05-13_1.txt

[INFO   ] Kivy: v1.11.0

[INFO   ] Kivy: Installed at "/usr/lib/python3.7/site-packages/kivy/__init__.pyc"

[INFO   ] Python: v3.7.4 (default, May 12 2020, 15:19:35)

[GCC 7.5.0]

[INFO   ] Python: Interpreter at "/usr/bin/python"

[INFO   ] Factory: 184 symbols loaded

[DEBUG  ] Cache: register <kv.lang> with limit=None, timeout=None

[DEBUG  ] Cache: register <kv.image> with limit=None, timeout=60

[DEBUG  ] Cache: register <kv.atlas> with limit=None, timeout=None

[INFO   ] ImageLoaderFFPy: Using ffpyplayer 4.3.1

[INFO   ] Image: Providers: img_tex, img_dds, img_sdl2, img_pil, img_ffpyplayer, img_gif

[DEBUG  ] Cache: register <kv.texture> with limit=1000, timeout=60

[DEBUG  ] Cache: register <kv.shader> with limit=1000, timeout=3600

[INFO   ] Text: Provider: sdl2

[DEBUG  ] App: Loading kv <./my.kv>

[DEBUG  ] App: kv <./my.kv> not found

[INFO   ] Window: Provider: egl_rpi

[DEBUG  ] Window: Actual display size: 1920x1080

[INFO   ] GL: Using the "OpenGL ES 2" graphics system

[DEBUG  ] GL: glShaderBinary is not available

[INFO   ] GL: Backend used <gl>

[INFO   ] GL: OpenGL version <b'OpenGL ES 2.0'>

[INFO   ] GL: OpenGL vendor <b'Broadcom'>

[INFO   ] GL: OpenGL renderer <b'VideoCore IV HW'>

[INFO   ] GL: OpenGL parsed version: 2, 0

[INFO   ] GL: Shading version <b'OpenGL ES GLSL ES 1.00'>

[INFO   ] GL: Texture max size <2048>

[INFO   ] GL: Texture max units <8>

[DEBUG  ] Shader: Fragment compiled successfully

[DEBUG  ] Shader: Vertex compiled successfully

[DEBUG  ] ImageSDL2: Load </usr/lib/python3.7/site-packages/kivy/data/glsl/default.png>

[INFO   ] Window: virtual keyboard not allowed, single mode, not docked

[DEBUG  ] Resource: add </usr/lib/python3.7/site-packages/kivy/data/fonts> in path list

[DEBUG  ] Base: Create provider from mouse

[DEBUG  ] Base: Create provider from probesysfs

[DEBUG  ] ProbeSysfs: using probesysfs!

[INFO   ] Base: Start application main loop

[INFO   ] GL: NPOT texture support is available

My package build file is based on James Moore's. I've tried with both Kivy 1.11.0 and 2.0.0rc2.

PYTHON_KIVY_VERSION = 2.0.0rc2

PYTHON_KIVY_SITE = $(call github,kivy,kivy,$(PYTHON_KIVY_VERSION))

PYTHON_KIVY_SETUP_TYPE = distutils

PYTHON_KIVY_LICENSE = MIT

PYTHON_KIVY_LICENSE_FILES = LICENSE

PYTHON_KIVY_DEPENDENCIES = host-python-cython libgl

PYTHON_KIVY_ENV += KIVY_CROSS_PLATFORM=rpi

ifeq ($(BR2_PACKAGE_GSTREAMER),y)

PYTHON_KIVY_DEPENDENCIES += gstreamer

PYTHON_KIVY_ENV += USE_GSTREAMER=1

else

PYTHON_KIVY_ENV += USE_GSTREAMER=0

endif

ifeq ($(BR2_PACKAGE_HAS_LIBEGL),y)

PYTHON_KIVY_DEPENDENCIES += libegl

PYTHON_KIVY_ENV += USE_EGL=1

else

PYTHON_KIVY_ENV += USE_EGL=0

endif

ifeq ($(BR2_PACKAGE_SDL2)$(BR2_PACKAGE_SDL2_IMAGE)$(BR2_PACKAGE_SDL2_MIXER)$(BR2_PACKAGE_SDL2_TTF),yyyy)

PYTHON_KIVY_DEPENDENCIES += sdl2 sdl2_image sdl2_mixer sdl2_ttf

PYTHON_KIVY_ENV += USE_SDL2=1

PYTHON_KIVY_ENV += KIVY_SDL2_PATH=$(STAGING_DIR)/usr/include/SDL2

else

PYTHON_KIVY_ENV += USE_SDL2=0

endif

ifeq ($(BR2_PACKAGE_WAYLAND),y)

PYTHON_KIVY_DEPENDENCIES += wayland

PYTHON_KIVY_ENV += USE_WAYLAND=1

else

PYTHON_KIVY_ENV += USE_WAYLAND=0

endif

ifeq ($(BR2_PACKAGE_XLIB_LIBX11)$(BR2_PACKAGE_XLIB_LIBXRENDER),yy)

PYTHON_KIVY_DEPENDENCIES += xlib_libX11 xlib_libXrender

PYTHON_KIVY_ENV += USE_X11=1

else

PYTHON_KIVY_ENV += USE_X11=0

endif

define PYTHON_KIVY_REMOVE_EXAMPLES

rm -rf $(TARGET_DIR)/usr/share/kivy-examples

endef

PYTHON_KIVY_POST_INSTALL_TARGET_HOOKS += PYTHON_KIVY_REMOVE_EXAMPLES

$(eval $(python-package))

I've also got SDL/SDL2 (TTF/Image/Mixer) installed on the cross build system prior to Kivy, and it looks like its being detected in the compilation:

Build configuration is:

 * use_rpi = 1

 * use_egl = 1

 * use_opengl_es2 = 1

 * use_opengl_mock = 0

 * use_sdl2 = 1

 * use_pangoft2 = 0

 * use_ios = 0

 * use_android = 0

 * use_mesagl = 0

 * use_x11 = 0

 * use_wayland = 0

 * use_gstreamer = 0

 * use_avfoundation = 0

 * use_osx_frameworks = 0

 * debug_gl = 0

 * kivy_sdl_gl_alpha_size = 8

 * debug = False

Has anyone run into this before? I imagine getting a good buildroot based package on something as low-cost as a RPi would be good for embedded touch systems.

The test code is a simple Kivy example:

import kivy

kivy.require('1.10.0')

from kivy.app import App

from kivy.uix.label import Label

class MyApp(App):

    def build(self):

        return Label(text='Hello World')

if __name__ == '__main__':

    MyApp().run()

Thanks in advance! I feel like I'm so close to solving this!

-- Jimmy

[Jimmy]

Still trying to troubleshoot this. Any help would be appreciated.

I've gotten to the point where I'm forcing the KIVY_CROSS_PLATFORM variable to be 'vc' as I understand that the rpi4 doesn't actually use the 'rpi' platform configuration.

Unfortunately for some reason with the way the setup.py is constructed it forces a requirement for X11?