CEF Python
Python bindings for the Chromium Embedded Framework (CEF)
Off-screen rendering
오프스크린 렌더링, 줄여서 OSR, 윈도우리스 렌더링이라고도 하는 것은 실제로 보이는 창을 만들지 않고 페이지를 메모리 버퍼에 렌더링하는 방법입니다.
이 렌더링 방법에는 장점이 있고 단점도 있습니다.
주된 용도는 웹 페이지 렌더링을 자체 렌더링 시스템이 있는 앱에 통합할 수 있고, 그릴 픽셀 버퍼가 제공된 경우에만 웹 브라우저 콘텐츠를 그릴 수 있다는 것입니다.
CEF Python은 Kivy, Panda3D, Pygame/PyOpenGl과 같은 프레임워크와 CEF 오프스크린 렌더링을 통합하는 몇 가지 예를 제공합니다.
"""
Example of using CEF browser in off-screen rendering mode
(windowless) to create a screenshot of a web page. This
example doesn't depend on any third party GUI framework.
This example is discussed in Tutorial in the Off-screen
rendering section.
Before running this script you have to install Pillow image
library (PIL module):
pip install Pillow
With optionl arguments to this script you can resize viewport
so that screenshot includes whole page with height like 5000px
which would be an equivalent of scrolling down multiple pages.
By default when no arguments are provided will load cefpython
project page on Github with 5000px height.
Usage:
python screenshot.py
python screenshot.py https://github.com/cztomczak/cefpython 1024 5000
python screenshot.py https://www.google.com/ncr 1024 768
Tested configurations:
- CEF Python v57.0+
- Pillow 2.3.0 / 4.1.0
NOTE: There are limits in Chromium on viewport size. For some
websites with huge viewport size it won't work. In such
case it is required to reduce viewport size to an usual
size of a window and perform scrolling programmatically
using javascript while making a screenshot for each of
the scrolled region. Then at the end combine all the
screenshots into one. To force a paint event in OSR
mode call cef.Invalidate().
"""
from cefpython3 import cefpython as cef
import os
import platform
import subprocess
import sys
try:
from PIL import Image, __version__ as PILLOW_VERSION
except ImportError:
print("[screenshot.py] Error: PIL module not available. To install"
" type: pip install Pillow")
sys.exit(1)
# Config
URL = "https://github.com/cztomczak/cefpython"
VIEWPORT_SIZE = (1024, 5000)
SCREENSHOT_PATH = os.path.join(os.path.abspath(os.path.dirname(__file__)),
"screenshot.png")
def main():
check_versions()
sys.excepthook = cef.ExceptHook # To shutdown all CEF processes on error
if os.path.exists(SCREENSHOT_PATH):
print("[screenshot.py] Remove old screenshot")
os.remove(SCREENSHOT_PATH)
command_line_arguments()
# Off-screen-rendering requires setting "windowless_rendering_enabled"
# option.
settings = {
"windowless_rendering_enabled": True,
}
switches = {
# GPU acceleration is not supported in OSR mode, so must disable
# it using these Chromium switches (Issue #240 and #463)
"disable-gpu": "",
"disable-gpu-compositing": "",
# Tweaking OSR performance by setting the same Chromium flags
# as in upstream cefclient (Issue #240).
"enable-begin-frame-scheduling": "",
"disable-surfaces": "", # This is required for PDF ext to work
}
browser_settings = {
# Tweaking OSR performance (Issue #240)
"windowless_frame_rate": 30, # Default frame rate in CEF is 30
}
cef.Initialize(settings=settings, switches=switches)
create_browser(browser_settings)
cef.MessageLoop()
cef.Shutdown()
print("[screenshot.py] Opening screenshot with default application")
open_with_default_application(SCREENSHOT_PATH)
def check_versions():
ver = cef.GetVersion()
print("[screenshot.py] CEF Python {ver}".format(ver=ver["version"]))
print("[screenshot.py] Chromium {ver}".format(ver=ver["chrome_version"]))
print("[screenshot.py] CEF {ver}".format(ver=ver["cef_version"]))
print("[screenshot.py] Python {ver} {arch}".format(
ver=platform.python_version(),
arch=platform.architecture()[0]))
print("[screenshot.py] Pillow {ver}".format(ver=PILLOW_VERSION))
assert cef.__version__ >= "57.0", "CEF Python v57.0+ required to run this"
def command_line_arguments():
if len(sys.argv) == 4:
url = sys.argv[1]
width = int(sys.argv[2])
height = int(sys.argv[3])
if url.startswith("http://") or url.startswith("https://"):
global URL
URL = url
else:
print("[screenshot.py] Error: Invalid url argument")
sys.exit(1)
if width > 0 and height > 0:
global VIEWPORT_SIZE
VIEWPORT_SIZE = (width, height)
else:
print("[screenshot.py] Error: Invalid width and height")
sys.exit(1)
elif len(sys.argv) > 1:
print("[screenshot.py] Error: Expected arguments: url width height")
sys.exit(1)
def create_browser(settings):
# Create browser in off-screen-rendering mode (windowless mode)
# by calling SetAsOffscreen method. In such mode parent window
# handle can be NULL (0).
parent_window_handle = 0
window_info = cef.WindowInfo()
window_info.SetAsOffscreen(parent_window_handle)
print("[screenshot.py] Viewport size: {size}"
.format(size=str(VIEWPORT_SIZE)))
print("[screenshot.py] Loading url: {url}"
.format(url=URL))
browser = cef.CreateBrowserSync(window_info=window_info,
settings=settings,
url=URL)
browser.SetClientHandler(LoadHandler())
browser.SetClientHandler(RenderHandler())
browser.SendFocusEvent(True)
# You must call WasResized at least once to let know CEF that
# viewport size is available and that OnPaint may be called.
browser.WasResized()
def save_screenshot(browser):
# Browser object provides GetUserData/SetUserData methods
# for storing custom data associated with browser. The
# "OnPaint.buffer_string" data is set in RenderHandler.OnPaint.
buffer_string = browser.GetUserData("OnPaint.buffer_string")
if not buffer_string:
raise Exception("buffer_string is empty, OnPaint never called?")
image = Image.frombytes("RGBA", VIEWPORT_SIZE, buffer_string,
"raw", "RGBA", 0, 1)
image.save(SCREENSHOT_PATH, "PNG")
print("[screenshot.py] Saved image: {path}".format(path=SCREENSHOT_PATH))
# See comments in exit_app() why PostTask must be used
cef.PostTask(cef.TID_UI, exit_app, browser)
def open_with_default_application(path):
if sys.platform.startswith("darwin"):
subprocess.call(("open", path))
elif os.name == "nt":
# noinspection PyUnresolvedReferences
os.startfile(path)
elif os.name == "posix":
subprocess.call(("xdg-open", path))
def exit_app(browser):
# Important note:
# Do not close browser nor exit app from OnLoadingStateChange
# OnLoadError or OnPaint events. Closing browser during these
# events may result in unexpected behavior. Use cef.PostTask
# function to call exit_app from these events.
print("[screenshot.py] Close browser and exit app")
browser.CloseBrowser()
cef.QuitMessageLoop()
class LoadHandler(object):
def OnLoadingStateChange(self, browser, is_loading, **_):
"""Called when the loading state has changed."""
if not is_loading:
# Loading is complete
sys.stdout.write(os.linesep)
print("[screenshot.py] Web page loading is complete")
print("[screenshot.py] Will save screenshot in 2 seconds")
# Give up to 2 seconds for the OnPaint call. Most of the time
# it is already called, but sometimes it may be called later.
cef.PostDelayedTask(cef.TID_UI, 2000, save_screenshot, browser)
def OnLoadError(self, browser, frame, error_code, failed_url, **_):
"""Called when the resource load for a navigation fails
or is canceled."""
if not frame.IsMain():
# We are interested only in loading main url.
# Ignore any errors during loading of other frames.
return
print("[screenshot.py] ERROR: Failed to load url: {url}"
.format(url=failed_url))
print("[screenshot.py] Error code: {code}"
.format(code=error_code))
# See comments in exit_app() why PostTask must be used
cef.PostTask(cef.TID_UI, exit_app, browser)
class RenderHandler(object):
def __init__(self):
self.OnPaint_called = False
def GetViewRect(self, rect_out, **_):
"""Called to retrieve the view rectangle which is relative
to screen coordinates. Return True if the rectangle was
provided."""
# rect_out --> [x, y, width, height]
rect_out.extend([0, 0, VIEWPORT_SIZE[0], VIEWPORT_SIZE[1]])
return True
def OnPaint(self, browser, element_type, paint_buffer, **_):
"""Called when an element should be painted."""
if self.OnPaint_called:
sys.stdout.write(".")
sys.stdout.flush()
else:
sys.stdout.write("[screenshot.py] OnPaint")
self.OnPaint_called = True
if element_type == cef.PET_VIEW:
# Buffer string is a huge string, so for performance
# reasons it would be better not to copy this string.
# I think that Python makes a copy of that string when
# passing it to SetUserData.
buffer_string = paint_buffer.GetBytes(mode="rgba",
origin="top-left")
# Browser object provides GetUserData/SetUserData methods
# for storing custom data associated with browser.
browser.SetUserData("OnPaint.buffer_string", buffer_string)
else:
raise Exception("Unsupported element_type in OnPaint")
if __name__ == '__main__':
main()
사용자 이벤트를 CEF 로 전달하는 방법
WARNING |
ChatGPT 답변 결과임. 검증 필요. |
CefPython을 PyOpenGL로 렌더링하면서 사용자 이벤트(마우스 클릭, 키보드 입력 등)를 처리하는 방법은 CEF의 SendMouseClickEvent 및 SendKeyEvent API를 활용하는 방식입니다.
이벤트를 OpenGL 컨텍스트에서 감지하고, 이를 CEF에 전달해 브라우저가 상호작용하도록 합니다.
아래는 PyOpenGL에서 CEF로 사용자 이벤트를 전달하는 기본적인 흐름을 설명합니다:
from cefpython3 import cefpython as cef
from OpenGL.GL import *
from OpenGL.GLUT import *
import sys
# 초기 설정
browser = None
window_width = 800
window_height = 600
def main():
global browser
# 초기화
cef.Initialize()
glutInit(sys.argv)
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
glutInitWindowSize(window_width, window_height)
glutCreateWindow(b"CEF with PyOpenGL")
# 브라우저 생성
browser_settings = {}
browser = cef.CreateBrowserSync(url="https://www.python.org",
window_title="CEF Python with OpenGL",
window_info=cef.WindowInfo())
browser.SetClientHandler(LoadHandler())
# OpenGL 초기화
glutDisplayFunc(render)
glutReshapeFunc(on_resize)
glutMouseFunc(on_mouse_click)
glutMotionFunc(on_mouse_move)
glutKeyboardFunc(on_key)
glutMainLoop()
# 종료
cef.Shutdown()
# 렌더링 함수
def render():
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
if browser:
browser.SendFocusEvent(True)
cef.MessageLoopWork()
glutSwapBuffers()
glutPostRedisplay()
# 윈도우 리사이즈 처리
def on_resize(width, height):
global window_width, window_height
window_width = width
window_height = height
glViewport(0, 0, width, height)
if browser:
browser.WasResized()
# 마우스 클릭 이벤트 처리
def on_mouse_click(button, state, x, y):
if browser:
cef.ButtonType = cef.MOUSEBUTTON_LEFT if button == 0 else cef.MOUSEBUTTON_RIGHT
mouse_event = {
"x": x,
"y": y,
"modifiers": cef.EVENTFLAG_LEFT_MOUSE_BUTTON if button == 0 else 0
}
mouse_type = cef.MOUSEBUTTON_LEFT if button == 0 else cef.MOUSEBUTTON_RIGHT
browser.SendMouseClickEvent(mouse_event["x"], mouse_event["y"], mouse_type,
mouseUp=(state == 0), clickCount=1)
# 마우스 이동 이벤트 처리
def on_mouse_move(x, y):
if browser:
mouse_event = {"x": x, "y": y, "modifiers": 0}
browser.SendMouseMoveEvent(mouse_event["x"], mouse_event["y"], mouseLeave=False)
# 키보드 이벤트 처리
def on_key(key, x, y):
if browser:
key_event = {
"type": cef.KEYEVENT_CHAR,
"windows_key_code": ord(key),
"native_key_code": ord(key),
"modifiers": 0,
"is_system_key": False
}
browser.SendKeyEvent(key_event)
# 브라우저 로드 핸들러 (필요시 구현)
class LoadHandler(object):
def OnLoadingStateChange(self, browser, is_loading, **_):
if not is_loading:
print("Page Loaded")
if __name__ == "__main__":
main()
전체 흐름:
- OpenGL에서 마우스/키보드 이벤트 감지
- glutMouseFunc, glutKeyboardFunc와 같은 GLUT 콜백을 사용해 이벤트를 처리합니다.
- CEF로 이벤트 전달
- SendMouseClickEvent, SendMouseMoveEvent, SendKeyEvent를 사용해 CEF에 이벤트를 보냅니다.