scene updating every second

[jmv38]

hello
i am trying to animate a series of png images computed with pythonista. I would like to display 1 image every second, and record the film with the ipad record, so i try to customize the scene example of the doc. But nothing works, i keep getting stupid errors, probably my bad.
Can anyone help? Thanks.

[jmv38]

here is a code with no error, but the view_update is never called

# coding: utf-8
from scene import *
import ui
import photos
from PIL import Image
import io as io
def pil2ui(pil_img):
    with io.BytesIO() as buffer:
        pil_img.save(buffer, format='PNG')
        return ui.Image.from_data(buffer.getvalue())

def view_update():
      azim -= 10
      file = 'CieLuv_'+str(azim)+'.png'
      print(file)
      im = Image.open(file)
      ui_image = pil2ui(im)
          

class MyScene (Scene):
    global ui_image,t0,azim
    
    def setup(self):
        self.background_color = 'ligtgray'
        img = ui.Button(name='image')
        img.frame = (25, 50, 1476/1.5, 1024/1.5) #1476 1024
        img.background_image = ui_image
        img.enable = False
        img.hidden = False
        self.view.add_subview(img)

        # trying to update 1 per second
        self.view.update_interval = 1
        self.view.update = view_update
        
    def disp_photo(self,sender):
        img = sender.superview['image']
        img.hidden = not img.hidden
        
if __name__ == '__main__':
    global ui_image, azim
    im = Image.open("CieLuv_-10.png")
    ui_image = pil2ui(im)
    azim = 190
    
    run(MyScene())

[cvp]

@jmv38 the refresh method of a scene is update. You have mixed with view.update of an ui.View.
See animation sub-folder of examples

Perhaps it could be better that instead of a Scene, you use a ui.View.
In this cases, setup becomes the init, and the code of your view_update can be put in def update of the custom view class.

see here

[jmv38]

@cvp thanks, i’ll have a look.
The problem is that with Scene or ui.View some fair amount a background is needed to get it work smoothly. I wish i could just tweek a couple lines in an example and get what i need. The built in example are a bit too complex for that.
Thanks anyway. And happy new year!

[jmv38]

also searching in the forum with keywords really leads me nowhere. The search engine does not seem very smart, cause i am fairly sure i saw that kind of problems disucussed in the past, but i dont get any usefull link...

[jmv38]

with scene + update, how can i trigger something once per second? When i try to use globals to keep track of a global state t, i keep getting some ‘local variable t used before being assigned’ , although it is global and assigned in the main... I pbly dont get fully how python namespaces work or in which order things are called, so i am stuck.

[jmv38]

btw, for anyone interested, here is the kind of video i want to make
https://youtu.be/eXBGYHKKytI
this one i made by assembling the images manually with Splice, i am trying to make it more automatic.

[mikael]

@jmv38, if you use a View, you can set its update_interval to 1 (second), and its update method gets automatically called once per second.

Also, for better results, use Google to search instead of the forum search.

[JonB]

you want to avoid globals in Scenes -- make those variables methods of your scene. The way threads work in scene, I think as written you could have issues.

by the way, most scene examples use run(amyScene()), but you are allowed to do:

s=MyScene(someparams,that,your,init,accepts)
s.someattrib=value
run(s)

[JonB]

Also, take a look at the scene docs.
You need to implement either a draw method, which is called once per frame (and you would use scene_drawing.image method, using a set of images where you prefiously called load_pil_image to precache inages), or else you would use update to set spritenode texture. the scene.run method takes a frame_interval parameter to set fps.

you may define a custom init that sets scene attributes etc based on globals -- but setup might not have access to globals (not sure if this is still true -- but it does run in a separate thread). Use setup just to handle actual display stuff,

Depending in how many images you have, it might be worth creating all your SpriteNodes up front.

[jmv38]

thanks for your advices. I chose to go for the ui.view. It worked nicely https://youtu.be/Li5gV2tUj5M
(make sure to set 1080p when you watch the video, otherwise the quality is bad)

[jmv38]

here is the code

import ui
from console import clear
from PIL import Image
import io as io
def pil2ui(pil_img):
    with io.BytesIO() as buffer:
        pil_img.save(buffer, format='PNG')
        return ui.Image.from_data(buffer.getvalue())

class MyView (ui.View):
  def __init__(self):
    # global view settings
    self.name = 'Viewing where colors lie in the CIE L*u*v* color space'                                    
    self.background_color = 'gray'     
    # trying to update 1 per second
    self.update_interval = 1
    
    # image settings
    img = ui.Button(name='image')
    img.width = 1476/1.5
    img.height = 1024/1.5
    img.enable = False
    img.hidden = False
    self.add_subview(img)
    self.img = img
    
    # add a copyright
    txt = ui.Label()
    txt.text = 'copyright JMV38 2019'
    txt.text_color = (0.5, 0.5, 0.5, 0.2)
    txt.width = 600
    txt.height = 100
    txt.alignment = ui.ALIGN_CENTER
    fontName, fontSize = txt.font
    txt.font = (fontName,30)
    self.add_subview(txt)
    self.txt = txt
    
  def update(self):
    self.img.center = (self.width * 0.5, self.height * 0.5)
    self.txt.center = (self.width * 0.5, self.height * 0.5)
    try:
      self.azim -= 10
    except:
      self.azim = 180
    file = 'CieLuv_'+str(self.azim)+'.png'
    try:
      print(file)
      im = Image.open(file)
      ui_image = pil2ui(im)
      self.img.background_image = ui_image
    except:
      exit()
    
if __name__ == '__main__':
  clear()
  view = MyView()      
  view.present('full_screen')  
  

[mikael]

@jmv38, nice! Have you tried updating every 1/30 or even 1/60 sec and making it completely smooth?

[jmv38]

@mikael actually
1/ i have not computed enough intermediate frames (each take 30s on my ipad air)
2/ i use the video to view it frame by frame from the ipad photo roll, to turn around as i wish, so it is enough for my usage
3/ i have tried 0.5s once but it skipped 1 frame in the middle, so i thought i would remain at 1 Hz.
thanks.

[jmv38]

still in trouble.
I am trying to save my numpy structured array with np.save, here is the code for details

# differents tests avec Luv

from labColor import *
import numpy as np
from console import clear
# compute all colors

def getAllColors(step):
  dtype = [('L', float), ('u', float), ('v', float), ('c', tuple), ('d', float)]
  data = []
  for r in np.arange(0, 256, step):
    print(r)
    for g in np.arange(0, 256, step):
      for b in np.arange(0, 256, step):
        L, u, v = rgb_to_sLuv(r, g, b)
        data.append((L, u, v, (r/255,g/255,b/255), 0.0))
  ar = np.array(data,dtype=dtype)
  return ar

clear()
ar = getAllColors(50)
print(len(ar))
print(ar.dtype)
np.save('rgb.npy',ar)
a = np.load('rgb.npy')
print(len(a))
print(a.dtype)

but i get this error

Traceback (most recent call last):
  File "/private/var/mobile/Containers/Shared/AppGroup/..../Pythonista3/Documents/couleurs/labColor6.py", line 24, in <module>
    np.save('rgb.npy',ar)
  File "/var/containers/Bundle/Application/..../Pythonista3.app/Frameworks/Py3Kit.framework/pylib/site-packages/numpy/lib/npyio.py", line 451, in save
    format.write_array(fid, arr)
  File "/var/containers/Bundle/Application/.../Pythonista3.app/Frameworks/Py3Kit.framework/pylib/site-packages/numpy/lib/format.py", line 407, in write_array
    pickle.dump(array, fp, protocol=2)
_pickle.PicklingError: Can't pickle <built-in function _reconstruct>: import of module 'multiarray' failed

what am i doing wrong?
thanks

[jmv38]

ok i got it. numpy.save cannot decode tuples by itself...
surprising that there is no simple way to save a structured array, and that i must flatten the structure to save it. Extra work and risk of errors... Anyway...

[jmv38]

here is another video, technically more useful
https://youtu.be/6Qi0UBBXZVw