The span-selector panel was rendered directly onto the spectrum canvas
every frame via DrawSelf, doing ~30 TextWidth + ~11 TextOut Canvas calls.
On Cocoa these text ops are very expensive (~10.6 ms/frame, ~30% of a
core) and dominated DrawSpectrum.
Render the panel once into a per-pixel-alpha cache bitmap and only
composite it over the spectrum each frame; rebuild only when state
changes (rate, hover, hidden, bounds). The cache is built with the
two-background method (render over black and white, derive straight
alpha + color) so layered semi-transparent button fills and antialiased
text composite over the live spectrum exactly as before.
Cuts the overlay phase from ~10.6 ms to ~0.2 ms per frame; DrawSpectrum
drops ~13.8 ms -> ~2.7 ms. Mirrors the caching VfoOverlay already uses.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
On macOS Cocoa, TBitmap.pf32bit stores pixels in ARGB order
(byte0=A, byte1=R, byte2=G, byte3=B) rather than BGRA used on
Linux/Windows. All raw ScanLine pixel blending and channel mapping
is now guarded with { DARWIN} to use the correct offsets.
Also fix PortAudio library discovery on macOS: probe .dylib names
(including Homebrew paths) before falling through to .so/.dll.
- Add SampleRateOverlay.pas: TCustomControl overlay (top-left of spectrum)
with hide-panel button and 6 span buttons (48k–1536k), same hit-test
pattern as VfoOverlay
- Consolidate toolbar: move PanelTopVfoGroup and PanelSMeterRight into
PanelToolbar (height 72) instead of floating on the form
- Remove PanelSpanButtons (alTop spacer) that caused the ~1cm black strip
at the top of the spectrum
- Add separator line inside PanelToolbar anchored to its bottom edge,
with 16px left/right margins
- Fix left panel blocks starting Y offset (was 38, now 0)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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