The FLX will contain a font manifest JSON file that maps font family names
to custom font assets. Flutter will provide a FontSelector that loads
fonts on demand and caches typeface and style data.
We used to share memory between Dart strings and WTF::String objects by
way of the Dart externalized strings. That used to be important when the
DOM shared many strings between C++ and Dart. However, now that we don't
retain strings in C++ much anymore, we don't need this complexity.
This patch removes DartStringCache and the integration. It also unwinds
several cases where we were converting back and forth between
WTF::String and std::string for no reason. Now we use std::string more
consistently.
For the case of ParagraphBuilder::addText, we now take a raw const
char*, which more closely matches the API the DartVM exposes. That means
we do a single copy out of the VM and into the render tree at that
point.
The NewTextPainter is still disabled by default. A future patch will flip the
flag to enable it.
This patch uses a new approach to writing bindings by encoding data into array
buffers. This approach is more efficient than the existing IDL based approach.
If this works out well, we should convert our other performance-sensitive
interfaces to this approach in future patches.
This patch start down the road of implementing text layout and painting without
the DOM. We can construct a basic paragraph consisting of a single run of text
and we can get through layout without crashing.
Rather than using the DOM to upload text and styling information into the
engine, this patch begins sketching a more direct API that bypasses the DOM and
CSS. Currently, this API doesn't do anything, but it's a first step.
The approach is to have a ParagraphBuilder object that can record a tree of
style interior nodes and text leaves. The build() function then applies
container-level styling information (such as TextAlign) and returns a Paragraph
object that can undergo layout and paint.
The inputs to the builder process are immutable style objects constructed from
primitive values. These primitives are currently carbon-copies of the primitive
we use in the framework today. After this patch lands, I'll convert the frame
to re-expose these values instead of re-defining them.
