Closes#98
This finishes my initial refactoring of the dynamic system to add
support for several dataflows including:
- Pure data sources that can be implemented using an `Owned<T>` at the
root of a graph of `Dynamic<U>`/`DynamicReader<U>`s.
- Read-only data sinks. I thought this would be more useful across other
widgets, but in general, Progress and Label seem like the only types
that this applies to currently.
- The ability to mix/match Dynamic/DynamicReader in tuple-based
for_each/map_each.
This cascaded into a lot more work than expected. However, in general,
if one clones a `WidgetInstance` and shares it between two windows, it
should now work. Widget authors must ensure that when they cache
information, they do so with either a `WidgetCacheKey` or use a
`WindowLocal<T>` if per-window state is desired.
This is demonstrated in the debug-window example, where the counter of
open windows is next to a clone of the same button from the main window
that opens a new window.
While this was a workaround for a docs.rs issue (Px/Lp are not
linked), I decided having the shorter import path would look better in
the examples.
It probably wasn't necessary to update all of the references in the
internal code, but I decided it was worth the consistency.
The Container code was causing small rounding errors when laying out
that would cause the layout to sometimes me larger by a pixel. I
searched for all locations we are applying padding and added rounding
calls.
Refs #92
Debug printing widgets was quite verbose. While developing a widget, you
often want to see a full debug printout, but this feature assumes that
debug printing a WidgetInstance should show a summary of the widget, not
a full debug printout containing cached glyph information of every
label.
By default, summarize just calls Debug, but this extra layer allows
widgets to provide a more condensed summary and exclude details like
caches.
Originally, adding dbg!() around the theme example's UI yielded a
whopping 20,324 lines of text. The summary code only prints 3,858
lines.
measure() now is layout(). LayoutContext can either persist layout
information or be used temporarily for measurement. While this caching
is constantly thrown out currently, this is a step towards being able to
only re-layout widgets if they've been invalidated.
