ai-agent-book 精选快照（<2MB 代码与文档，来自 github.com/bojieli/ai-agent-book）

chapter9/browser-use-rpa/browser-use/browser_use/browser/watchdogs/screenshot_watchdog.py

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+"""Screenshot watchdog for handling screenshot requests using CDP."""
+
+from typing import TYPE_CHECKING, Any, ClassVar
+
+from bubus import BaseEvent
+from cdp_use.cdp.page import CaptureScreenshotParameters
+
+from browser_use.browser.events import ScreenshotEvent
+from browser_use.browser.views import BrowserError
+from browser_use.browser.watchdog_base import BaseWatchdog
+from browser_use.observability import observe_debug
+
+if TYPE_CHECKING:
+	pass
+
+
+class ScreenshotWatchdog(BaseWatchdog):
+	"""Handles screenshot requests using CDP."""
+
+	# Events this watchdog listens to
+	LISTENS_TO: ClassVar[list[type[BaseEvent[Any]]]] = [ScreenshotEvent]
+
+	# Events this watchdog emits
+	EMITS: ClassVar[list[type[BaseEvent[Any]]]] = []
+
+	@observe_debug(ignore_input=True, ignore_output=True, name='screenshot_event_handler')
+	async def on_ScreenshotEvent(self, event: ScreenshotEvent) -> str:
+		"""Handle screenshot request using CDP.
+
+		Args:
+			event: ScreenshotEvent with optional full_page and clip parameters
+
+		Returns:
+			Dict with 'screenshot' key containing base64-encoded screenshot or None
+		"""
+		self.logger.debug('[ScreenshotWatchdog] Handler START - on_ScreenshotEvent called')
+		try:
+			# Get CDP client and session for current target
+			cdp_session = await self.browser_session.get_or_create_cdp_session()
+
+			# Prepare screenshot parameters
+			params = CaptureScreenshotParameters(format='png', captureBeyondViewport=False)
+
+			# Take screenshot using CDP
+			self.logger.debug(f'[ScreenshotWatchdog] Taking screenshot with params: {params}')
+			result = await cdp_session.cdp_client.send.Page.captureScreenshot(params=params, session_id=cdp_session.session_id)
+
+			# Return base64-encoded screenshot data
+			if result and 'data' in result:
+				self.logger.debug('[ScreenshotWatchdog] Screenshot captured successfully')
+				return result['data']
+
+			raise BrowserError('[ScreenshotWatchdog] Screenshot result missing data')
+		except Exception as e:
+			self.logger.error(f'[ScreenshotWatchdog] Screenshot failed: {e}')
+			raise
+		finally:
+			# Try to remove highlights even on failure
+			try:
+				await self.browser_session.remove_highlights()
+			except Exception:
+				pass