Downloading a plotly plot as png in python interactive does not appear to actually save anywhere

[geophpherie]

Environment data

• VS Code version: 1.38.0
• Extension version (available under the Extensions sidebar): 2019.9.34474
• OS and version: MacOS 10.14.6
• Python version (& distribution if applicable, e.g. Anaconda): 3.7.4
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): conda
• Relevant/affected Python packages and their versions: plotly 4.1.0
• Jedi or Language Server? (i.e. what is "python.jediEnabled" set to; more info How to update the language server to the latest stable version vscode-python#3977): True

Expected behaviour

After generating a plotly plot in Python Interactive, I want to save/download the plot as a png. I click on the little camera icon to “download plot as a png”. Two small screens appear saying “taking a snapshot, this may take a few seconds” then “Snapshot succeeded - newplot.png”. I would expect that file to then exist in my workspace.

Actual behaviour

The file does not appear in my workspace, and searching on my computer does not show any file existing.

Steps to reproduce:

1. Generate plotly plot in python interactive window.

import plotly.express as px

iris = px.data.iris()
px.scatter(iris, x="sepal_width", y="sepal_length")

2. Click download plot as png.
3. Unable to find said file.

Logs

Not comfortable dumping those right now because this is my work machine.

[rchiodo]

I believe this is a limitation of the webview API of VS Code (which the plotly code is running inside of)

It looks like under the covers plotly is doing this:

if(canUseSaveLink) {
            blob = helpers.createBlob(url, format);
            objectUrl = helpers.createObjectURL(blob);

            saveLink.href = objectUrl;
            saveLink.download = name;
            document.body.appendChild(saveLink);
            saveLink.click();

            document.body.removeChild(saveLink);
            helpers.revokeObjectURL(objectUrl);
            blob = null;

            return resolve(name);
        }

(https://github.com/plotly/plotly.js/blob/7e789b35e9daa5ca8243febe0027d29d402ff772/src/snapshot/filesaver.js#L55)

We might be able to override the 'saveLink' on a document node, not sure.

[rchiodo]

SO is saying yes, we can override the link click. Just need to figure out what to do with it:

document.addEventListener('click', event => {
    let node = event && event.target;
    while (node) {
        if (node.tagName && node.tagName === 'A' && node.href) {
            // Handle click here by posting data back to VS Code
            // for your extension to handle
            vscode.postMessage({ ... });
            event.preventDefault();
            return;
        }
        node = node.parentNode;
    }
}, true);``

[DonJayamanne]

Validated