The canvas below is painted entirely by Pascal. Every rectangle, rounded corner and glyph position is computed inside the module and pushed through the 28-call drawing ABI; the host only executes the calls. Clicks, the wheel and the keyboard go back the other way through the platform ABI.
Try: click the buttons, tick the check box and click again,
and click a button then drag off it before releasing — that last
one must not count, because a click is a press and a release
on the same control. In FmxDashboard, drag the track bar and
pick a size: the panels are laid out by Align, not by
coordinates.
In FmxFonts, pick a family and watch the ruled lines move with
it — they are drawn at the offsets font_metrics
reported, so they are the measurement, not a decoration. Tick
Underline and nothing moves, which is correct: underline and
strikeout do not change a font's metrics. The four bundled
families are WOFF2 files this page ships and caches in IndexedDB, so
they measure the same on every machine; Show system fonts asks
Chromium for the ones actually installed here (it prompts, which is
why it is a button rather than something the page does on its own).
All three apps are ordinary Delphi FMX projects — a .dpr,
a form unit with {$R *.fmx} and a designed
.fmx. build_examples.cmd builds the same
files into Windows executables.