How to get current list of decorations OR handle decoration position change in VSCode Extension? - visual-studio-code

Question

Lets take this example into account.
I have a file with contents:
1: one
2: two
3: three
and I create a line decoration for line "two":
const position = new vscode.Position(1, 0);
const range = new vscode.Range(position, position);
const decoration = vscode.window.createTextEditorDecorationType({
gutterIconPath: context.asAbsolutePath('images/icon.svg')
});
vscode.window.activeTextEditor?.setDecorations(decoration, [range]);
that gives me
1: one
* 2: two
3: three
Next step:
I am changing file contents by adding a new line before line "two".
After that file looks like this:
1: one
2:
* 3: two
4: three
As you can see VSCode has updated my line decoration and now it is positioned on line 3 (instead of 2) which is totally correct and I've expected that.
And now the question:
how can I get this current updated position of my line decoration?
If I hold the range reference - it is still pointing to line 2.
What is the right way to handle this decoration changes?
Either of these 2 options would satisfy me:
a way to query all the current decoration positions displayed for currently open file
a way to subscribe to decoration / range changes so that I can handle those manually.
Maybe I am totally wrong and it should be done in another way.
Please advise!

Answer 1

So apparently there is no way to get all the current decorations for open file in VSCode. Here is an old issue without clear plans to be resolved https://github.com/microsoft/vscode/issues/54147.
I've found an internal method getLineDecorations - https://github.com/microsoft/vscode/blob/master/src/vs/editor/browser/widget/codeEditorWidget.ts#L1118 - and I was trying to reach to it via
vscode.window.activeTextEditor?._proxy
vscode.window.activeTextEditor?._runOnProxy
but I did not succeed.
So for now probably the only option that we have mentioned here https://github.com/microsoft/vscode/issues/54147#issuecomment-439177546 is:
to store a copy of all decoration positions
to update it manually on each text update via vscode.workspace.onDidChangeTextDocument handler
It is doable but very annoying that we have to do this stuff manually. ¯_(ツ)_/¯
Also very error prone )