Asynchronous data loader¶

This is the Asynchronous Loader. You can use it to load an image and use it, even if data are not yet available. You must specify a default loading image when using the loader:

from kivy.loader import Loader
image = Loader.image('mysprite.png')

You can also load an image from a url:

image = Loader.image('http://mysite.com/test.png')

If you want to change the default loading image, you can do:

Loader.loading_image = Image('another_loading.png')

Tweaking the asynchronous loader¶

New in version 1.6.0.

You can tweak the loader to provide a better user experience or more performance, depending of the images you are going to load. Take a look at the parameters:

Loader.num_workers - define the number of threads to start for loading images.
Loader.max_upload_per_frame - define the maximum image uploads in GPU to do per frame.

class kivy.loader.LoaderBase¶

Bases: builtins.object

Common base for the Loader and specific implementations. By default, the Loader will be the best available loader implementation.

The _update() function is called every 1 / 25.s or each frame if we have less than 25 FPS.

image(filename, load_callback=None, post_callback=None, **kwargs)¶

Load a image using the Loader. A ProxyImage is returned with a loading image. You can use it as follows:

from kivy.app import App
from kivy.uix.image import Image
from kivy.loader import Loader

class TestApp(App):
    def _image_loaded(self, proxyImage):
        if proxyImage.image.texture:
            self.image.texture = proxyImage.image.texture

    def build(self):
        proxyImage = Loader.image("myPic.jpg")
        proxyImage.bind(on_load=self._image_loaded)
        self.image = Image()
        return self.image

TestApp().run()

In order to cancel all background loading, call Loader.stop().

pause()¶: Pause the loader, can be useful during interactions.

New in version 1.6.0.

resume()¶: Resume the loader, after a pause().

New in version 1.6.0.

run(*largs)¶: Main loop for the loader.

start()¶: Start the loader thread/process.

stop()¶: Stop the loader thread/process.

class kivy.loader.ProxyImage(arg, **kwargs)¶

Bases: kivy.core.image.Image

Image returned by the Loader.image() function.

Properties:

loaded: bool, defaults to False: This value may be True if the image is already cached.

Events:

on_load: Fired when the image is loaded or changed.
on_error: Fired when the image cannot be loaded. error: Exception data that occurred

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Asynchronous data loader¶

Tweaking the asynchronous loader¶