We'll use this function to position the caret when the user taps a text
input control.
Very little of the code in this patch is actually new. Most of it is
restoring code that we previously removed from the engine. I've made
some small changes to the restored code to handle the lack of a DOM. The
only major change is to RenderObject::createPositionWithAffinity, which
now just returns the values it captures instead of trying to compute a
DOM position.
TextAffinity and TextPosition are lifted from package:flutter. Once this
patch rolls into package:flutter, I'll remove the declarations there.
The primary goal of this change was to remove EventTarget from the
sky_engine C++ code. Since EventTarget is so core to the entire event
system that sky_engine was based on, this is a rather invasive change.
As such, it had some knock-on effects. I deleted some of the files
that were affected, and cauterised the remainder.
In many cases, a file would depend on another file that it didn't
include directly, but instead included indirectly via another file
that I deleted. When this happened, if the features that this broke
were obsolete, I sometimes just removed the features instead.
Specifically:
- removed EventTarget
- removed EventQueue, since without a target, what's a queue going to
do?
- same with EventDispatch*
- removed ExecutionContext, since it had an EventQueue and nothing
else it did was relevant to Sky anymore
- removed ActiveDOMObject, which was all about ExecutionContexts
- removed ContextLifecycleNotifier since it dependend on
ExecutionContext and ActiveDOMObject
- removed the other Lifecycle classes for consistency, and replaced
them with four booleans in the Document class
- removed some of the attributes that are no longer relevant from
IDLExtendedAttributes (ConstructorCallWith and
CallWith=ExecutionContext)
- removed the Document member on DOMDartState since we never set it to
anything but null.
- removed BuiltinSky::InstallWindow since it relied on the Document
member of DOMDartState
- removed EventHandler, EventListener, and mentions of those in
various binding scripts
- removed NewEventHandler, since we're not using that either
- removed the following interfaces from the Sky Dart API:
- EventTarget
- EventListener (since without a target, there's no way to listen)
- FocusEvent (since it's only member was an EventTarget)
- HashChangeEvent (mostly by accident, but it's defunct anyway)
- FontFace (it used ConstructorCallWith=ExecutionContext)
- changed the following interfaces of the Sky DART API:
- MediaQueryList is no longer an EventTarget
- Node is no longer an EventTarget
- Document no longer has defaultView (depended on
DOMDartState's document)
- DocumentFragment, Element, Range, and Text no longer have a
constructor (they all depended on DOMDartState's document, which
is now gone)
- Event lost its EventTarget members and path.
- Window lost its WindowTimers partial interface (it used
EventTarget and ExecutionContext a lot)
- removed numerous hacks in the bindings around features that are now
gone, like addEventListener
- removed a bunch of console logging code, since that relied on
ExecutionContext
- cauterised the wound in FontFace.cpp by removing constructors and
methods that called now-removed features
- same with MediaQuery and friends
- same with some editor features and focus-related features
- same with Document
- removed DOMTimer classes since they use ExecutionContexts
