…2869)

## Summary

- Ctrl+wheel now zooms the panadapter bandwidth in/out by ×1.5 per
scroll step,
  anchoring on the frequency under the mouse cursor.
- Plain wheel scroll is unchanged — it continues to tune the VFO.

## Implementation

Single change in `SpectrumWidget::wheelEvent`: after the debounce/step
calculation, an early branch catches `Qt::ControlModifier` and runs the
cursor-anchored zoom, then returns before the existing VFO tune path.

The zoom math mirrors the existing NativeGesture pinch-to-zoom exactly:

```cpp
const double mouseXFrac = ev->position().x() / width() - 0.5;
const double anchorMhz  = m_centerMhz + mouseXFrac * m_bandwidthMhz;
const double newCenter  = std::max(anchorMhz - mouseXFrac * newBw, newBw / 2.0);
```

The `std::max(..., newBw / 2.0)` clamp prevents the left edge from going
below 0 Hz, consistent with PR #2867.

## UX consistency note

The existing `+`/`−` zoom buttons use a different anchor policy: zoom-in
re-centers on the active VFO frequency (added in #1932 to prevent
repeated
clicks pushing the slice off-screen), zoom-out keeps the pan center
fixed.
That behavior makes sense for a discrete click where the cursor position
carries no intent.

Ctrl+wheel is a continuous, cursor-positioned interaction — the user is
looking at a specific part of the spectrum when they scroll.
Cursor-anchored
zoom is therefore the correct policy here, matching the NativeGesture
pinch-to-zoom and every major spectrum/map application that implements
scroll-to-zoom. The button inconsistency is deliberate and acceptable.

Ctrl is already the modifier used for dBm-scale drag (PR #2717) and
waterfall time-scale drag (PR #2783), so Ctrl+wheel is consistent with
the existing convention of Ctrl = “modify the view, not the VFO.”

## Testing

- Scroll wheel without Ctrl: VFO tunes as before, no regression.
- Ctrl+scroll up: bandwidth narrows, cursor frequency stays fixed.
- Ctrl+scroll down: bandwidth widens, cursor frequency stays fixed.
- Ctrl+scroll at band edge: 0 Hz clamp prevents left edge going
negative.
- Ctrl+scroll at BW limits: clamped to `m_minBwMhz`/`m_maxBwMhz`, no
crash.
- Pinch-to-zoom: unaffected.

Fixes #1518

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

…inter path

The rebase accidentally reverted PR aethersdr#2826 (commit 4d5b4d7). Restoring
src/gui/SpectrumWidget.cpp from current main brings back:
- setFftLineWidth() update() trigger so slider repaints immediately
- drawLine = m_fftLineWidth > 0.0f "off" gate
- cosmetic pen built from m_fftLineWidth so slider value is honored
- and the unrelated improvements that landed after PR base (panadapter
  center clamp aethersdr#2867, waterfall stale-echo animation guard)

All rigctld work in this PR is unaffected.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

…dr#1518) (aethersdr#2869)

## Summary

- Ctrl+wheel now zooms the panadapter bandwidth in/out by ×1.5 per
scroll step,
  anchoring on the frequency under the mouse cursor.
- Plain wheel scroll is unchanged — it continues to tune the VFO.

## Implementation

Single change in `SpectrumWidget::wheelEvent`: after the debounce/step
calculation, an early branch catches `Qt::ControlModifier` and runs the
cursor-anchored zoom, then returns before the existing VFO tune path.

The zoom math mirrors the existing NativeGesture pinch-to-zoom exactly:

```cpp
const double mouseXFrac = ev->position().x() / width() - 0.5;
const double anchorMhz  = m_centerMhz + mouseXFrac * m_bandwidthMhz;
const double newCenter  = std::max(anchorMhz - mouseXFrac * newBw, newBw / 2.0);
```

The `std::max(..., newBw / 2.0)` clamp prevents the left edge from going
below 0 Hz, consistent with PR aethersdr#2867.

## UX consistency note

The existing `+`/`−` zoom buttons use a different anchor policy: zoom-in
re-centers on the active VFO frequency (added in aethersdr#1932 to prevent
repeated
clicks pushing the slice off-screen), zoom-out keeps the pan center
fixed.
That behavior makes sense for a discrete click where the cursor position
carries no intent.

Ctrl+wheel is a continuous, cursor-positioned interaction — the user is
looking at a specific part of the spectrum when they scroll.
Cursor-anchored
zoom is therefore the correct policy here, matching the NativeGesture
pinch-to-zoom and every major spectrum/map application that implements
scroll-to-zoom. The button inconsistency is deliberate and acceptable.

Ctrl is already the modifier used for dBm-scale drag (PR aethersdr#2717) and
waterfall time-scale drag (PR aethersdr#2783), so Ctrl+wheel is consistent with
the existing convention of Ctrl = “modify the view, not the VFO.”

## Testing

- Scroll wheel without Ctrl: VFO tunes as before, no regression.
- Ctrl+scroll up: bandwidth narrows, cursor frequency stays fixed.
- Ctrl+scroll down: bandwidth widens, cursor frequency stays fixed.
- Ctrl+scroll at band edge: 0 Hz clamp prevents left edge going
negative.
- Ctrl+scroll at BW limits: clamped to `m_minBwMhz`/`m_maxBwMhz`, no
crash.
- Pinch-to-zoom: unaffected.

Fixes aethersdr#1518

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

…aethersdr#783) (aethersdr#2867)

## Summary

Fixes aethersdr#783 — at MW/LW frequencies the spectrum waterfall could display a
left edge below 0 Hz when dragging, zooming, or keyboard-navigating the
panadapter.

**Root cause:** No lower-bound clamp existed on the panadapter center
frequency. The left edge is `center − bandwidth/2`; when center drops
below `bandwidth/2`, the left edge goes negative, displaying sub-zero
spectrum that doesn't physically exist.

**Fix:** Apply `center = std::max(center, bandwidth / 2.0)` at every
code path that writes a new center value — both to `SpectrumWidget`'s
local state and to the radio command.

### Seven fix sites

**`src/gui/SpectrumWidget.cpp`**
1. `emitZoom` lambda — zoom-in/out buttons, clamp `newCenter` after
VFO-centering branch
2. BW drag `mouseMoveEvent` — clamp `zoomCenter` (anchor-anchored
center) after computing from drag position
3. Pan drag `mouseMoveEvent` — clamp `newCenter` before `m_centerMhz =`
and `emit centerChangeRequested`
4. `NativeGesture` pinch zoom — clamp `newCenter` after anchor
calculation

**`src/gui/MainWindow.cpp`**
5. `applyPanRangeRequest` — clamp `centerMhz` (passed by value)
immediately after the null-guard; this is the central choke point for
all `frequencyRangeChangeRequested` paths and keyboard zoom
6. `zoomActivePanadapter` lambda — clamp `newCenter` before
`sw->setFrequencyRange()` to avoid a visual desync before the radio
round-trip; `applyPanRangeRequest` (site 5) also clamps, providing
defense-in-depth
7. `centerChangeRequested` handler — pan drag bypasses
`applyPanRangeRequest` and sends directly to the radio; fetch bandwidth
from the pan model and clamp before the `sendCommand`

No upper-bound clamp is applied — the radio enforces its own band
limits.

### Out-of-scope observation

During testing on a FLEX-8400, the waterfall displays solid red
(out-of-band indicator) below approximately 200 kHz even after this fix.
This appears to be model-specific hardware behavior — other Flex models
may allow the receiver to tune lower. The red waterfall in that region
is the radio correctly reporting no valid spectrum data, not a
client-side rendering bug. This is left for a future investigation
scoped to that model's receive floor.

## Test plan

- [ ] Set slice to 1.0 MHz AM (MW), narrow panadapter to 3 MHz bandwidth
→ zoom out: left edge stops at 0 Hz
- [ ] Pan drag left past 0 Hz at 0.5 MHz → spectrum stops scrolling at
the 0 Hz boundary
- [ ] Keyboard `[` zoom-out at 160m (1.8 MHz) until left edge would go
below 0 Hz → clamps cleanly
- [ ] Trackpad/NativeGesture pinch-zoom out at LW → same
- [ ] Normal HF operation (14 MHz, 20 MHz BW) → no regression in zoom or
pan behavior
- [ ] Multi-panadapter: each pan is independently clamped (bandwidth
fetched per-pan from model)

🤖 Generated with [Claude Code](https://claude.ai/claude-code)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>