How to improve speed of drawing? Very slow scene view.

[marcin_dybas]

I made a script using scene module. Basically it shows a different "image" depending on horizontal touch.location.

from scene import *
import ui

glyphsDict = {}  # My dictionary with paths to draw

class MyScene (Scene):
    def setup(self):

        self.myPath = ShapeNode(glyphsDict[1])  # first path to draw
        self.add_child(self.myPath)

        self.background_color = 'lightgrey'

    def touch_began(self, touch):
        x, y = touch.location
        z = int(x/(10.24/2)+1)
        self.myPath.path = glyphsDict[z]  # Setting a new path to draw

    def touch_moved(self, touch):
        x, y = touch.location
        z = int(x/(10.24/2)+1)
        self.myPath.path = glyphsDict[z]  # Setting a new path to draw

run(MyScene())

Before that i did the same using SpriteNode and swapping textures. I had 200 .gif images 7KB each (1.4MB summed up) and while the app crashed from time to time i got a rather smooth result if i "loaded" all the images by slowly moving my finger across the screen.

The version with SpriteNode and images looked like this: https://www.instagram.com/p/BSL9ea8g0dv/

I thought i'd move to drawing paths and the code above reflects that. My path information is 200KB so 7 times smaller that all the .gif's i was loading before. But now the animation is super slow and looks like 2fps or is not reacting at all if i move my finger very fast. On the bright side, I don't see the app crashing anymore.

How can i improve on this? Why drawing paths is slower than loading images that are bigger?

[JonB]

https://gist.github.com/8fe4aa269b15a7071633e256456786ca
Here is an improved method, using KeyFrame animations.
Basically, you set up 5 or whatever refernces, add to a PathAnimation, and then provide the interpolation value (0..len(glyphs)).

i have not tried installing your font yet. Might try UIFont.fontWithName_size_traits_(). or maybe need o set up fondDescriptor.

[ccc]

Can you please confirm if your iOS devices are 32 or 64 bit?

[JonB]

https://gist.github.com/c8b993ac42ede2574dc9f7cc26ebb1f4
and here is a version that uses your font file, and cleans things up a bit.

I am on 32 bit -- ccc, is this crashing for you? If so, on what line? I think I got typedefs correct but I may have missed a few

[ccc]

Unfortunately @JonB I confirm that it crashes on 64 bit.

[JonB]

Which line is crashing? Do you have the fault handler installed?

[JonB]

https://gist.github.com/7a73b8c3abab4dc502ef2314574c6744

For some reason I was missing a slew of definitions. Try this one on 64bit...

[marcin_dybas]

@JonB i get "No method found for mutableCopy" on line 80

[JonB]

https://gist.github.com/80660624600c28c8e7812b15e0652568
How about this one....

[marcin_dybas]

@JonB this one raises the exception from line 15

[JonB]

can you paste the full traceback? Also, did you place the Panvaria.ttf file in the same folder? I probably should have mentioned that!

[marcin_dybas]

@JonB yes, i have the file in the same folder.

Traceback (most recent call last):
  File "/private/var/mobile/Containers/Shared/AppGroup/2CB744A3-0F69-40E1-A5F1-95E464DBFC21/Pythonista3/Documents/PythonistaGit/VF/64bit.py", line 144, in <module>
    [glyphs_list, variation_values]=setupGlyphs(size=512,letter='e')
  File "/private/var/mobile/Containers/Shared/AppGroup/2CB744A3-0F69-40E1-A5F1-95E464DBFC21/Pythonista3/Documents/PythonistaGit/VF/64bit.py", line 78, in setupGlyphs
    basefont = c.CGFontCreateWithDataProvider(provider);
  File "/private/var/mobile/Containers/Shared/AppGroup/2CB744A3-0F69-40E1-A5F1-95E464DBFC21/Pythonista3/Documents/PythonistaGit/VF/64bit.py", line 15, in errcheck
    raise Exception('{} returned void pointer with args\n{}'.format(func.__name__,args))
Exception: CGFontCreateWithDataProvider returned void pointer with args
(6242820560,)```

[JonB]

added a little extra diagnostics, and tried passing provider as objcinstancee.
https://gist.github.com/b4c3e011e768320753e3c54405c56380

[marcin_dybas]

@JonB here's the traceback

Traceback (most recent call last):
  File "/private/var/mobile/Containers/Shared/AppGroup/2CB744A3-0F69-40E1-A5F1-95E464DBFC21/Pythonista3/Documents/PythonistaGit/VF/64bit.py", line 148, in <module>
    [glyphs_list, variation_values]=setupGlyphs(size=512,letter='e')
  File "/private/var/mobile/Containers/Shared/AppGroup/2CB744A3-0F69-40E1-A5F1-95E464DBFC21/Pythonista3/Documents/PythonistaGit/VF/64bit.py", line 82, in setupGlyphs
    basefont = c.CGFontCreateWithDataProvider(provider);
  File "/private/var/mobile/Containers/Shared/AppGroup/2CB744A3-0F69-40E1-A5F1-95E464DBFC21/Pythonista3/Documents/PythonistaGit/VF/64bit.py", line 15, in errcheck
    raise Exception('{} returned void pointer with args\n{}'.format(func.__name__,args))
Exception: CGFontCreateWithDataProvider returned void pointer with args
(<b'__NSCFType': <CGDataProvider 0x17418b530>>,)```

[JonB]

How did yoy get the ttf into the device? i think this is saying the font file is invalid.
This version downloads the font directly
https://gist.github.com/7a766eb282c71bf7d27bd13fb4926482

[marcin_dybas]

@JonB there was indeed something wrong with the file. this script just crashes the app. is there a method to catch errors on crash?

[JonB]

@dgelessus has a pythonista_startup repo that installs a fault handler and uncaught exception handler which write to a fault log, so you can see which line (for segfaults and the like) or an objc stack trace in the case of objc errors (which often include a helpful message)

https://github.com/dgelessus/pythonista_startup

See the readme, there are several scripts here, personally I just use the enable_faulthandler one.

You could also set a breakpoint by long pressing in the debugger, and just keep single stepping until the crash happens.

[JonB]

https://gist.github.com/38a5434b4ebd28775dab08d181a00771
Here is a version that logs all cdll calls to glyphlog.txt. if you can post that someplace, we can see exactly what is crashing.

[marcin_dybas]

@JonB thank you for hints on debugging, definetely helpful.

Here's the error log: https://gist.github.com/5bac67b24317b5e5b4badc06bee1b1c5

[JonB]

whoops, I missed one of the definitions.
https://gist.github.com/a30ddae506762c96e533f98668ad46dd
This should do it now....maybe

Thought for a future improvement....a CDLL which prevents calling a function unless restype and argtypes have specifically been defined.

[marcin_dybas]

@JonB unfortunatelly: https://gist.github.com/5f53f356c0c85fa9525efd13a1000198