Add a non-blocking variant of hs.image.imageFromURL

[andweeb]

My use case in particular falls within the context of hs.chooser choices, each choice item needing an icon image from an external URL as shown in the gif below.

Due to the blocking nature of hs.image.imageFromURL, using it blocks not only the chooser modal itself but the entire application in general, which isn't a great experience. For example attempting to load http://deelay.me/20000/https://i.imgur.com/2lrs7zF.jpg (simulated delay of 20s) blocks the whole app for the full 20 seconds.

It'd be awesome if there were a way to fetch images from URLs without blocking the main application thread.

[latenitefilms]

@andweeb - I've added an optional callback in #2227. Let me know if that works as you intended.

[andweeb]

Wow thanks so much for the help! I'll try that as soon as I have time today and report back. :)

Edit: Works perfectly, thank you!

[idr4n]

Wow thanks so much for the help! I'll try that as soon as I have time today and report back. :)

Edit: Works perfectly, thank you!

@andweeb @latenitefilms Do you guys mind telling me how to use the callback in this case so I can get the icons of the URL asynchronously?

Basically, I'm pulling the tabs from Safari and their URL's into a chooser, pretty much looks like the gif above. As mentioned by @andweeb, user experience is not great if using hs.image.imageFromURL without a callback. However, as mentioned in the docs, when using the callback, the function returns nil right away, and so the images don't show when I trigger the chooser.

This is a sample code of the chooser:

tabs_chooser:choices(function()
	local _, result = hs.osascript.applescript(tabsScript)
	local lines = {}
	for line in string.gmatch(result, "(.-)\n") do
		table.insert(lines, line)
	end
	local tabs = {}
	for _, tab in pairs(lines) do
		local winID, tabNumber, tabTitle, url = string.match(tab, "(.*);(.*);(.*);(.*)")
		-- local img = hs.image.imageFromURL("https://www.google.com/s2/favicons?sz=64&domain_url=" .. url)
		local img = hs.image.imageFromURL("https://www.google.com/s2/favicons?sz=64&domain_url=" .. url, function() end)
		table.insert(tabs, {
			text = tabTitle,
			subText = url,
			win = winID,
			tab = tabNumber,
			image = img,
		})
	end
	return tabs
end)

hs.hotkey.bind("alt", "'", function()
	tabs_chooser:refreshChoicesCallback(true)
	tabs_chooser:show()
end)

Thanks in advance!

[latenitefilms]

Here's an example:

print("before")
hs.image.imageFromURL("https://latenitefilms.com/media/2013/09/latenitefilms_text.png", function(img)
    print(string.format("Here's your image: %s", img))
end)
print("after")

This will output:

2022-08-05 11:50:09: before
2022-08-05 11:50:09: after
2022-08-05 11:50:09: Here's your image: hs.image:  (0x600000b9ddb8)

Callback's obviously happen asynchronously, so you'd need to update your chooser results AFTER the image callback is triggered.

[idr4n]

Thanks for your reply @latenitefilms. OK, so I can use the fetched image in the callback as a parameter. Great! However, how can I update the chooser results while the chooser is visible (i.e, after being triggered with chooser:show())?