fix: set image levels atomically in heatmap update

sync_video_test.py

@@ -859,10 +859,9 @@ class VideoSyncWindow:
         cp = r["cp"]
         k = max(1, cp.shape[1] // 1200)
         img = np.ascontiguousarray(cp[:, ::k].T)  # (lags', pixels) col-major x=lag
-        self.img.setImage(img, autoLevels=False)
         v0 = float(np.percentile(img, 1))
         v1 = float(max(np.max(img), v0 + 1e-6))
-        self.img.setLevels(v0, v1)
+        self.img.setImage(img, levels=(v0, v1), autoLevels=False)
         lag_s = r["lags"][::k] / (r["up"] * ctx.fps)
         self.p_h.setXRange(self.lag_sec - 2, self.lag_sec + 2, padding=0)
         self.p_h.setYRange(0, img.shape[1], padding=0)