852121 - Provide a way to move the location of the selection caret

Status: RESOLVED WORKSFORME

(Firefox for Metro Graveyard :: Input, defect)

Description

[Jim Mathies [:jimm]]

We need a way to move the caret location without the use of simulated mouse events. AFAICT no such controlling interface exists. I've looked at the following:

http://mxr.mozilla.org/mozilla-central/source/content/base/public/nsISelectionDisplay.idl
http://mxr.mozilla.org/mozilla-central/source/content/base/public/nsISelectionListener.idl
http://mxr.mozilla.org/mozilla-central/source/content/base/public/nsISelectionPrivate.idl
http://mxr.mozilla.org/mozilla-central/source/content/base/public/nsISelectionController.idl
http://mxr.mozilla.org/mozilla-central/source/content/base/public/nsISelection.idl
http://mxr.mozilla.org/mozilla-central/source/editor/idl/nsIEditor.idl
http://mxr.mozilla.org/mozilla-central/source/dom/interfaces/base/nsIFocusManager.idl

I've also experimented around with ranges. I was hoping something like this might work in a text input:

let cp = document.caretPositionFromPoint(aX, aY);
let selection = document.getSelection();
selection.removeAllRanges();
let range = content.document.createRange();
range.setStart(cp.offsetNode.firstChild, cp.offset);
selection.addRange(range);

which adds the range but clears the focus caret from the editor.

Thus far I haven't found any way to do this.

Comment 1

[Jim Mathies [:jimm]]

Ehsan, you seem to be the go to guy for selection. Curious if you can tell me if I've missed an interface that allows us to do this, or if my guess is right and we currently don't support it. Android gets around this by simulating mouse clicks which I do not want to do here unless absolutely necessary.

The immediate need only applies to nsIEditor elements like text areas or boxes. Although it would be cool if we could do it in generic content as well.

Comment 2

[Jim Mathies [:jimm]]

Hmm, when you call caretPositionFromPoint with coordinates that are located within a text area, you would expect to get the offset within the input. However in the result 'offsetNode' is set to the text area and 'offset' is the offset within the document of offsetNode.

If this is the case and by design, this api isn't of any use if you want to get caret positions within input elements.

Comment 3

[(no longer active)]

For input type=text and textarea, you want HTML{Input,TextArea}Element.selectionStart/End.

For regular selections, you should use nsISelection to change the position of a collapsed selection.

(In reply to Jim Mathies [:jimm] from comment #2)
> Hmm, when you call caretPositionFromPoint with coordinates that are located
> within a text area, you would expect to get the offset within the input.
> However in the result 'offsetNode' is set to the text area and 'offset' is
> the offset within the document of offsetNode.

Yes, that is by design.

Comment 4

[Jim Mathies [:jimm]]

(In reply to :Ehsan Akhgari (needinfo? me!) from comment #3)
> For input type=text and textarea, you want
> HTML{Input,TextArea}Element.selectionStart/End.
> 
> For regular selections, you should use nsISelection to change the position
> of a collapsed selection.
> 

I will try that, thanks.