Clarify the usage of "Position" in Hover

[cdietrich]

I am experimenting with implementing a Language Server Hover Service and i stumbled over the definition of the Position Parameter in that service.

e.g. if i hover on (the middle of) the second character i get requested with Position {line: 0, character: 2}
although position says character is zero based

[dbaeumer]

Christian Dietrich (@cdietrich) the position in a hover should also be 0 based. So if you hover over the second character on the first line position should be (0,1). I tested it with my test bed and this is actually correct. Do you have a special file I could look at. There might be a problem in VS Code itself requesting a hover at the wrong position.

[cdietrich]

i just have a file Like

Hello World!

in increased the font size about 3 times
and hover on the H

then i get requests like

{"jsonrpc":"2.0","id":104,"method":"textDocument/hover","params":{"textDocument":{"uri":"file:///Users/dietrich/git/xtext-languageserver-example/demo/a.mydsl"},"position":{"line":0,"character":1}}}

and requests like

{"jsonrpc":"2.0","id":102,"method":"textDocument/hover","params":{"textDocument":{"uri":"file:///Users/dietrich/git/xtext-languageserver-example/demo/a.mydsl"},"position":{"line":0,"character":0}}}

although i hover on the Honly

i expect to get always {"line":0,"character":0}}

this happens with the release and the insider version as well

[cdietrich]

For easyness of reproduction i extended the node language server example as follows

capabilities: {
            // Tell the client that the server works in FULL text document sync mode
            textDocumentSync: documents.syncKind,
            // Tell the client that the server support code complete
            completionProvider: {
                resolveProvider: true
            },
            hoverProvider : true
        }

connection.onHover(
    (p : TextDocumentPositionParams) : Hover => {
        console.log(p.position.character);

        return {
            contents: "xxxxx" + p.position.character,
            range : {
                start : {line: 0, character: 0},
                end : {line: 0, character: 10}
            }
        }

    }   )
;

[cdietrich]

[dbaeumer]

Christian Dietrich (@cdietrich) I fully agree that the character position should stay the same.

alexandrudima since I receive the position from the editor is this something that is known?

[alexdima]

The positions in the editor correspond to the "gaps" in between characters.

So, given the text abc:

• the mouse event for the cursor being clearly in front of a:
  • position: (1,1), range: (1,1)->(1,1)
• the mouse event for the cursor being on top of a (but in the first half):
  • position: (1,1), range: (1,1)->(1,2)
• the mouse event for the cursor being on top of a (but in the second half):
  • position: (1,2), range: (1,1)->(1,2)
• the mouse event for the cursor being pixel-perfect in between a and b:
  • position: (1,2), range: (1,2)->(1,2)

So the position expresses where the cursor would go if the user would click.

I think the hover editor contribution uses that position and doesn't use the range at all to invoke the hover provider. Perhaps this is a case where the hover provider should have received a range and not a position as an argument, as the range describes better where the mouse is hovering.

https://microsoft.github.io/monaco-editor/playground.html#interacting-with-the-editor-listening-to-mouse-events is a good test page to see this in action with the note that the positions there are 1-based, and also columns are 1-based

[dbaeumer]

Christian Dietrich (@cdietrich) was alexandrudima answer sufficient for you ?

[dbaeumer]

I am closing the issue. Please ping if something is unclear.