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Those of you who use Workflow know it can handle images.

Any idea how a Pythonista "stage" in the pipeline might pass an image back?

I also use Workflow to get any file from it or from iCloud Drive.
In Workflow, I save the file on a Dropbox folder and my Pythonista script reads the file from Dropbox, and deletes the file from Dropbox.

@MartinPacker I haven't really tried this yet, but an easy way might be to use the clipboard.

I tried the following workflow and it seems to work fine.

1. Select photos
2. share (run pythonista appex script "convert_to_gray_image.py" given below)
3. Get Clipboard
4. Save to photo album

The script "convert_to_gray_image.py" is given below.

from PIL import Image, ImageOps
import appex
import ui, clipboard

def main():
    if not appex.is_running_extension():
        print('This script is intended to be run from the sharing extension.')
        return
    img = appex.get_image()
    if not img:
        print('No input image')
        return
    if not img.mode.startswith('RGB'):
        img = img.convert('RGB')
    gray_img = ImageOps.grayscale(img)
    clipboard.set_image(gray_img)

if __name__ == '__main__':
    main()

You should be able to add actions in your workflow to:
- action: select photo, to avoid Photos app
- action: copy your photo to the clipboard
- action: run your Pythonista script, to avoid manually sharing the photo to your script!
+ get clipboard
+ convert in gray
+ copy to clipboard
+ start Workflow
- action: get clipboard
- action: save

Thanks to all.

Workflow can have an image passed in to a "stage" in its pipeline. And I think it can have a stage output one.

While OK on the clipboard or persistent file front I wondered if the Pythonista stage could ingest and emit images directly.

Here is the modified script that uses action script instead of share script. ( @cvp What is "start workflow" step in "pythonista script"?
Do I have to add " webbrowser.open("workflow://") at the end?)

from PIL import Image, ImageOps
import ui, clipboard
import webbrowser

def main():
    img = clipboard.get_image()
    if not img:
        print('No input image')
        return
    if not img.mode.startswith('RGB'):
        img = img.convert('RGB')
    gray_img = ImageOps.grayscale(img)
    clipboard.set_image(gray_img)

main()
webbrowser.open('workflow://')

url_scheme = 'workflow://x-callback-url/run-workflow?name=your_file&input=clipboard&x-success=pythonista://'
if appex.is_running_extension():    
    app = UIApplication.sharedApplication()
    app.openURL_(nsurl(url_scheme))
else:
    webbrowser.open(url_scheme) 
# assume your Workflow writes xxx in the clipboard to warn it is finished
text = clipboard.get()
while text != 'xxx':
    text = clipboard.get()
    time.sleep(0.3)

@cvp Thanks. I do not use (or the need to create) any complicated workflows and I feel that "webbrowser.open('workflow://')" is good enough to return back to workflow app.

@MartinPacker editorial could do that (i.e. ingest and emit images directly). Workflow app may not add this facility in future but omz can make editorial workflow as easy as workflow app.

If I correctly understood your request, you don't need Workflow because your Pythonista script could perform it-self all your "actions", like
- select photos
- convert them
- save them to an album

1. My example is for illustration purpose only and I do not require that workflow. My sentiments are similar to the ones expressed in the following blog.
   https://spin.atomicobject.com/2016/01/16/ios-workflow-frustrations/

2. But the template could be useful in doing something very fast with little code, may be at some time later. Your comments are very helpful in building the template.I have also looked at the workflow site
   https://workflow.is/developer and the reddit site https://www.reddit.com/r/workflow
   I do not want to investigate much into this now and I am ok with current action script template.

Once again I would like to thank you for your helpful comments and I will look at your"x-callback-url" some time later.

Before I know Pythonista, I wrote a lot of Workflows, but since I use Pythonista, I've rewritten all in Python, with only one exception for Workflows saving or getting a file to/from ICloud Drive because Pythonista does not provide this functionality.

Would it be possible to interop with iCloud Drive using objc_utils? Or with something like https://pypi.python.org/pypi/pyicloud

I don't think so, I had already seen this import but it does not cover the iCloud Drive storage, only ICloud services.

To reveal a little more of the picture...

... My idea was to create a graphing Pythonista capability so Workflow might pass a CSV (file) into Pythonista and then do something with the graph (image) returned.

In essence I wanted to add graphing to Workflow. I would expect Pythonista would be a good way to do it.

Would Editorial do this better than Pythonista?

@cvp Please check the File Storage (Ubiquity) section of the page:

You can access documents stored in your iCloud account by using the files property’s dir method

@MartinPacker , I am not really sure about Editorial vrs Pythonista for the graphing, they could be equivalent. But my guess would be that Pythonista would be the superset of functionality.
But just really wanted to mention the 'Pie Chart Demo.py' in the Examples/Plotting dir in Pythonista. Great demo how to easily create a pie chart with some nice features. It's so easy to understand. Then I am pretty sure if you use a ui.ImageContext to draw into you could return that image for the clipboard. Possibly the matplotlib gives a more direct way. Just interesting

@ccc
Hi
I had checked this page but they only support iCloud file storage, that will say Apple apps storage, like Notes, but not iCloud Drive storage of all other apps, what does Workflow app.
In Workflow, you can save a file to the ICloud Drive of another app, like Documents, FileBrowser, Pages, Numbers etc...

@ccc
It's exactly like you can manually do in Pythonista by
- edit
- select a file
- share
- add to ICloud Drive

But automatically

All this talk about iCloud illustrates one of the reasons why I'm not looking for a "write to file" solution.

Clipboard would be fine, though "trashing" the clipboard should only be done if necessary. It seems that it is.

Something for y'all to pick the bits out of...

A reply from @WorkflowHQ on Twitter contained the following...

"Also regarding sending images, Workflow can decode base64 encoded images."

Does this help us here? Can we encode images base64?

@MartinPacker Encoding images as base64 should be fairly straightforward in Python. Do you have any more details?

https://forum.omz-software.com/topic/2974/need-python-script-to-decode-or-encode-in-base64

I figured out how to do it without using the clipboard. The trick is basically to use "Get Contents of URL" with a data: URI that gets passed to the workflow via the workflow:// scheme, containing base64-encoded image data.

Here's the script:

import webbrowser
import base64
from PIL import Image
import io
from urllib.parse import quote

img = Image.open('test:Lenna')

buffer = io.BytesIO()
img.save(buffer, 'PNG')
data_uri = 'data:image/png;base64,' + base64.b64encode(buffer.getvalue()).decode('ascii')

webbrowser.open('workflow://run-workflow?name=EditBase64Image&input=' + quote(data_uri, ''))

...and the workflow should be something like this:

invalid base64 encode.
remove 'data:image/png;base64,' like this:

data_uri  = base64.b64encode(buffer.getvalue()).decode('ascii')

now it works