We currently delete a single code unit. If the user presses backspace on
a multi code point emoji, they are going to expect the entire emoji to
be removed. This now matches the behavior of Chrome and Firefox.
Both sides of the Editing internals now have to deal with some awkward
converting between UTF-8 and UTF-16, but the upside is that it
immediately exposed an issue with the `insertText` command: instead of
dealing with code units, it was iterating over code points causing the
selection to be updated only once instead of twice. This resulted in the
final selection potentially ending up in between a surrogate pair.
Fixes#5547 (pasting/typing surrogate pairs).
Major browsers seem to preserve `white-space: pre/pre-wrap` styles in a
`<div>` when deleting the current selection through an editing command.
The idiomatic way to support this is to have a command with a "relevant
CSS property" to make sure the value is recorded and restored where
appropriate, however, no such command exists.
Create a custom command (internal to Ladybird) that implements this
behavior.
The editing command that relies the most on this, `insertLinebreak`,
did not perform a layout update after inserting a `<br>` which caused
this algorithm to always return false. But instead of actually building
the layout tree needlessly, we can check the DOM tree instead.
The spec calls for a couple of very specific whitespace padding
techniques whenever we canonicalize whitespace during the execution of
editing commands, but it seems that other browsers have a simpler
strategy - let's adopt theirs!
We do not fire `beforeinput` events since other browsers do not seem to
do so either.
The spec asks us to check whether a command's action modified the DOM
tree. This means adding or removing nodes and attributes, or changing
character data anywhere in the tree. We have
`Document::dom_tree_version()` for node updates, but for character data
a new version number is introduced that allows us to easily keep track
of any text changes in the entire tree.
Both Chrome and Firefox return `true` whenever the value string provided
is an invalid color or the current color. Spec issue raised:
https://github.com/w3c/editing/issues/476
Anchor the minimum functionality for this. WPT has an extensive suite
to test editing functionalities, but they all take a long time to
execute - so let's have a simple regression test in-tree for now.
This input event handling change is intended to address the following
design issues:
- Having `DOM::Position` is unnecessary complexity when `Selection`
exists because caret position could be described by the selection
object with a collapsed state. Before this change, we had to
synchronize those whenever one of them was modified, and there were
already bugs caused by that, i.e., caret position was not changed when
selection offset was modified from the JS side.
- Selection API exposes selection offset within `<textarea>` and
`<input>`, which is not supposed to happen. These objects should
manage their selection state by themselves and have selection offset
even when they are not displayed.
- `EventHandler` looks only at `DOM::Text` owned by `DOM::Position`
while doing text manipulations. It works fine for `<input>` and
`<textarea>`, but `contenteditable` needs to consider all text
descendant text nodes; i.e., if the cursor is moved outside of
`DOM::Text`, we need to look for an adjacent text node to move the
cursor there.
With this change, `EventHandler` no longer does direct manipulations on
caret position or text content, but instead delegates them to the active
`InputEventsTarget`, which could be either
`FormAssociatedTextControlElement` (for `<input>` and `<textarea>`) or
`EditingHostManager` (for `contenteditable`). The `Selection` object is
used to manage both selection and caret position for `contenteditable`,
and text control elements manage their own selection state that is not
exposed by Selection API.
This change improves text editing on Discord, as now we don't have to
refocus the `contenteditable` element after character input. The problem
was that selection manipulations from the JS side were not propagated
to `DOM::Position`.
I expect this change to make future correctness improvements for
`contenteditable` (and `designMode`) easier, as now it's decoupled from
`<input>` and `<textarea>` and separated from `EventHandler`, which is
quite a busy file.
