feat: waveform view/selection state + band/handle painting

main.py

@@ -3946,29 +3946,70 @@ class AudioWaveform(QWidget):
     def __init__(self, parent=None):
         super().__init__(parent)
         self._peaks: list[float] = []
-        self.setFixedHeight(48)
+        self._view_start = 0.0
+        self._view_dur = 0.0
+        self._sel: tuple[float, float] | None = None
+        self._playhead: float | None = None
+        self.setFixedHeight(96)
         self.setToolTip("Waveform of the current audio area (↻ to refresh)")
 
     def set_peaks(self, peaks: list[float]) -> None:
         self._peaks = list(peaks or [])
         self.update()
 
+    def set_view(self, start: float, dur: float) -> None:
+        self._view_start = start
+        self._view_dur = dur
+        self.update()
+
+    def set_selection(self, start: float, end: float) -> None:
+        if self._view_dur > 0:
+            lo = self._view_start
+            hi = self._view_start + self._view_dur
+            start = min(max(start, lo), hi)
+            end = min(max(end, lo), hi)
+        if start > end:
+            start, end = end, start
+        self._sel = (start, end)
+        self.update()
+
+    def selection(self) -> tuple[float, float] | None:
+        return self._sel
+
+    def set_playhead(self, t: float | None) -> None:
+        self._playhead = t
+        self.update()
+
     def clear(self) -> None:
         self._peaks = []
+        self._sel = None
+        self._playhead = None
         self.update()
 
     def paintEvent(self, _ev):
+        from core.waveform import t_to_x
         p = QPainter(self)
         p.fillRect(self.rect(), QColor(30, 30, 30))
-        if not self._peaks:
-            return
         w = self.width(); h = self.height(); mid = h / 2
+        if self._peaks:
             n = len(self._peaks)
             p.setPen(QPen(QColor(0, 220, 190)))
             for i, v in enumerate(self._peaks):
                 x = int(i * w / n)
                 bar_h = v * (h - 4) / 2
                 p.drawLine(x, int(mid - bar_h), x, int(mid + bar_h))
+        if self._sel and self._view_dur > 0:
+            x1 = t_to_x(self._sel[0], w, self._view_start, self._view_dur)
+            x2 = t_to_x(self._sel[1], w, self._view_start, self._view_dur)
+            p.fillRect(QRect(x1, 0, max(1, x2 - x1), h), QColor(0, 200, 180, 50))
+            p.setPen(QPen(QColor(0, 220, 190), 2))
+            p.drawLine(x1, 0, x1, h)
+            p.drawLine(x2, 0, x2, h)
+        if (self._playhead is not None and self._view_dur > 0
+                and self._view_start <= self._playhead <= self._view_start + self._view_dur):
+            px = t_to_x(self._playhead, w, self._view_start, self._view_dur)
+            p.setPen(QPen(QColor(255, 255, 255, 160), 1))
+            p.drawLine(px, 0, px, h)
 
 
 class MainWindow(QMainWindow):

tests/test_ui_structure.py

@@ -398,6 +398,22 @@ def test_waveform_strip_present_and_safe(win):
     win._on_wave_refresh()
 
 
+def test_waveform_view_and_selection(win):
+    w = win._wave
+    w.set_view(10.0, 4.0)
+    w.set_selection(11.0, 12.5)
+    assert w._view_start == 10.0 and w._view_dur == 4.0
+    assert w.selection() == (11.0, 12.5)
+    # selection clamps into the view window and keeps start < end
+    w.set_selection(9.0, 20.0)
+    s, e = w.selection()
+    assert s >= 10.0 and e <= 14.0 and s < e
+    w.set_peaks([0.1, 0.9, 0.3])   # still paints without crashing
+    w.set_playhead(11.5)
+    w.clear()                       # resets display state
+    assert w.selection() is None
+
+
 def test_audition_button_present_and_safe(win):
     from PyQt6.QtWidgets import QPushButton
     assert isinstance(win._btn_audio_play, QPushButton)