fix graph and white background added

python_app/gui/controllers/web_controller.py

@@ -12,7 +12,6 @@ import threading
 import time
 from typing import TYPE_CHECKING
 
-import pyqtgraph as pg
 from PyQt6.QtCore import QBuffer, QIODevice, QObject, pyqtSignal
 from PyQt6.QtWidgets import QLineEdit, QSpinBox, QWidget
 
@@ -100,20 +99,13 @@ class WebBridge(QObject):
         self._frame: dict | None = None
         self._pending_lock = threading.Lock()
         self._pending_calls: set[_WebActionCall] = set()
-        self._closed = self._streaming = self._grabbing = False
-        self._dirty = True
+        self._closed = self._streaming = False
+        self._grabbed_revision: int | None = None  # plot revision shown by the last grab; None forces one
         self._last_png: str | None = None
         self._last_grab_s = 0.0
         self._frame_seq = self._snapshot_errors = 0
         self._action_requested.connect(self._run_action)
         self._streaming_changed.connect(self._set_streaming)
-        plots = pipeline.plots
-        plots.stack.currentChanged.connect(self._mark_dirty)
-        for plot in plots.stack.findChildren(pg.PlotWidget):
-            scene = plot.scene()
-            assert scene is not None
-            scene.changed.connect(self._mark_dirty)
-            plot.sigDeviceRangeChanged.connect(self._mark_dirty)
 
     def start_server(self) -> None:
         if self._closed or self._server is not None:
@@ -295,26 +287,19 @@ class WebBridge(QObject):
         if not self._closed:
             self._streaming = enabled
             if enabled:
-                self._dirty = True
-
-    def _mark_dirty(self, *_args: object) -> None:
-        if not self._closed and not self._grabbing:
-            self._dirty = True
+                self._grabbed_revision = None
 
     def _grab_frame_if_due(self) -> dict | None:
-        if self._closed or not self._streaming or not self._dirty:
+        plots = self._pipeline.plots
+        if self._closed or not self._streaming or plots.revision == self._grabbed_revision:
             return None
         now = time.monotonic()
         if now - self._last_grab_s < _GRAB_INTERVAL_S:
             return None
-        self._last_grab_s, self._dirty, self._grabbing = now, False, True
-        try:
-            png = self._grab_png()
-        except Exception:
-            self._dirty = True
-            raise
-        finally:
-            self._grabbing = False
+        self._last_grab_s = now
+        png = self._grab_png()
+        # Rendering applies pending resizes and lazy auto-ranges; this image already shows them.
+        self._grabbed_revision = plots.revision
         if png is None or png == self._last_png:
             return None
         self._last_png = png