capture_devtools_bg.py

"""
Capture a screenshot of the Dev Tools Chrome browser window WITHOUT bringing it
to the foreground, using the Win32 PrintWindow API.
Usage: python capture_devtools_bg.py [output_path]
"""
import ctypes
import ctypes.wintypes
import subprocess
import sys

# We need win32 modules
try:
    import win32gui
    import win32ui
    import win32con
    HAS_WIN32 = True
except ImportError:
    HAS_WIN32 = False

from PIL import Image


def get_devtools_pids():
    """Get all PIDs of chrome.exe processes using the chrome-devtools-profile."""
    result = subprocess.run(
        'wmic process where "name=\'chrome.exe\' and commandline like \'%chrome-devtools-profile%\'" get processid',
        shell=True, capture_output=True, text=True
    )
    pids = set()
    for line in result.stdout.splitlines():
        line = line.strip()
        if line.isdigit():
            pids.add(int(line))
    return pids


def find_main_chrome_window(pids):
    """Find the main Chrome window HWND from the set of PIDs."""
    GetWindowThreadProcessId = ctypes.windll.user32.GetWindowThreadProcessId
    IsWindowVisible = ctypes.windll.user32.IsWindowVisible
    GetWindowTextW = ctypes.windll.user32.GetWindowTextW
    GetWindowTextLengthW = ctypes.windll.user32.GetWindowTextLengthW
    EnumWindows = ctypes.windll.user32.EnumWindows
    WNDENUMPROC = ctypes.WINFUNCTYPE(ctypes.c_bool, ctypes.wintypes.HWND, ctypes.wintypes.LPARAM)

    candidates = []

    def callback(hwnd, _):
        if not IsWindowVisible(hwnd):
            return True
        pid = ctypes.wintypes.DWORD()
        GetWindowThreadProcessId(hwnd, ctypes.byref(pid))
        if pid.value in pids:
            length = GetWindowTextLengthW(hwnd)
            if length > 0:
                buf = ctypes.create_unicode_buffer(length + 1)
                GetWindowTextW(hwnd, buf, length + 1)
                title = buf.value
                # Skip small dialog/notification windows; keep the main browser
                if title and 'wants to' not in title:
                    candidates.append((hwnd, title))
        return True

    EnumWindows(WNDENUMPROC(callback), 0)
    if candidates:
        # Prefer the one with the longest title (usually the main content window)
        candidates.sort(key=lambda x: len(x[1]), reverse=True)
        return candidates[0]
    return None, None


def capture_window_background_pil(hwnd, output_path):
    """Capture window using PIL ImageGrab with GetWindowRect (no foreground needed
    if window is visible, but won't capture if occluded)."""
    rect = ctypes.wintypes.RECT()
    ctypes.windll.user32.GetWindowRect(hwnd, ctypes.byref(rect))
    from PIL import ImageGrab
    img = ImageGrab.grab(bbox=(rect.left, rect.top, rect.right, rect.bottom))
    img.save(output_path)
    return True


def capture_window_background_win32(hwnd, output_path):
    """Capture window content using PrintWindow - works even if window is behind others."""
    rect = ctypes.wintypes.RECT()
    ctypes.windll.user32.GetWindowRect(hwnd, ctypes.byref(rect))
    width = rect.right - rect.left
    height = rect.bottom - rect.top

    hwndDC = win32gui.GetWindowDC(hwnd)
    mfcDC = win32ui.CreateDCFromHandle(hwndDC)
    saveDC = mfcDC.CreateCompatibleDC()

    saveBitMap = win32ui.CreateBitmap()
    saveBitMap.CreateCompatibleBitmap(mfcDC, width, height)
    saveDC.SelectObject(saveBitMap)

    # PW_RENDERFULLCONTENT = 2 captures even DWM-composited content
    result = ctypes.windll.user32.PrintWindow(hwnd, saveDC.GetSafeHdc(), 2)

    bmpinfo = saveBitMap.GetInfo()
    bmpstr = saveBitMap.GetBitmapBits(True)

    img = Image.frombuffer('RGB', (bmpinfo['bmWidth'], bmpinfo['bmHeight']),
                           bmpstr, 'raw', 'BGRX', 0, 1)
    img.save(output_path)

    win32gui.DeleteObject(saveBitMap.GetHandle())
    saveDC.DeleteDC()
    mfcDC.DeleteDC()
    win32gui.ReleaseDC(hwnd, hwndDC)
    return True


if __name__ == '__main__':
    output = sys.argv[1] if len(sys.argv) > 1 else 'devtools_screenshot.png'

    pids = get_devtools_pids()
    if not pids:
        print("ERROR: No chrome-devtools-profile processes found.")
        sys.exit(1)
    print(f"Found {len(pids)} devtools PIDs")

    hwnd, title = find_main_chrome_window(pids)
    if not hwnd:
        print("ERROR: Could not find Dev Tools Chrome window.")
        sys.exit(1)
    print(f"Found window: '{title}' (HWND {hwnd})")

    if HAS_WIN32:
        print("Using PrintWindow (background capture)...")
        capture_window_background_win32(hwnd, output)
    else:
        print("win32gui not available, falling back to PIL grab (may capture foreground)...")
        capture_window_background_pil(hwnd, output)

    print(f"Saved to: {output}")