py: Move MappedFrameBuffer to libcamera.utils

Move MappedFrameBuffer to libcamera.utils, instead of extending
FrameBuffer class with a new mmap() method. This keeps us more aligned
to the C++ API.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/py/cam/cam.py

@@ -9,6 +9,7 @@
 import argparse
 import binascii
 import libcamera as libcam
+import libcamera.utils
 import sys
 import traceback
 
@@ -327,7 +328,7 @@ def request_handler(state, ctx, req):
 
         crcs = []
         if ctx['opt-crc']:
-            with fb.mmap() as mfb:
+            with libcamera.utils.MappedFrameBuffer(fb) as mfb:
                 plane_crcs = [binascii.crc32(p) for p in mfb.planes]
                 crcs.append(plane_crcs)
 
@@ -345,7 +346,7 @@ def request_handler(state, ctx, req):
                 print(f'\t{ctrl} = {val}')
 
         if ctx['opt-save-frames']:
-            with fb.mmap() as mfb:
+            with libcamera.utils.MappedFrameBuffer(fb) as mfb:
                 filename = 'frame-{}-{}-{}.data'.format(ctx['id'], stream_name, ctx['reqs-completed'])
                 with open(filename, 'wb') as f:
                     for p in mfb.planes:

src/py/cam/cam_qt.py

@@ -9,6 +9,7 @@ from PIL import Image
 from PIL.ImageQt import ImageQt
 from PyQt5 import QtCore, QtGui, QtWidgets
 import libcamera as libcam
+import libcamera.utils
 import numpy as np
 import sys
 
@@ -285,7 +286,7 @@ class MainWindow(QtWidgets.QWidget):
         controlsLayout.addStretch()
 
     def buf_to_qpixmap(self, stream, fb):
-        with fb.mmap() as mfb:
+        with libcamera.utils.MappedFrameBuffer(fb) as mfb:
             cfg = stream.configuration
 
             if cfg.pixel_format == libcam.formats.MJPEG:

src/py/libcamera/__init__.py

@@ -2,83 +2,3 @@
 # Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
 
 from ._libcamera import *
-
-
-class MappedFrameBuffer:
-    def __init__(self, fb):
-        self.__fb = fb
-
-    def __enter__(self):
-        import os
-        import mmap
-
-        fb = self.__fb
-
-        # Collect information about the buffers
-
-        bufinfos = {}
-
-        for i in range(fb.num_planes):
-            fd = fb.fd(i)
-
-            if fd not in bufinfos:
-                buflen = os.lseek(fd, 0, os.SEEK_END)
-                bufinfos[fd] = {'maplen': 0, 'buflen': buflen}
-            else:
-                buflen = bufinfos[fd]['buflen']
-
-            if fb.offset(i) > buflen or fb.offset(i) + fb.length(i) > buflen:
-                raise RuntimeError(f'plane is out of buffer: buffer length={buflen}, ' +
-                                   f'plane offset={fb.offset(i)}, plane length={fb.length(i)}')
-
-            bufinfos[fd]['maplen'] = max(bufinfos[fd]['maplen'], fb.offset(i) + fb.length(i))
-
-        # mmap the buffers
-
-        maps = []
-
-        for fd, info in bufinfos.items():
-            map = mmap.mmap(fd, info['maplen'], mmap.MAP_SHARED, mmap.PROT_READ | mmap.PROT_WRITE)
-            info['map'] = map
-            maps.append(map)
-
-        self.__maps = tuple(maps)
-
-        # Create memoryviews for the planes
-
-        planes = []
-
-        for i in range(fb.num_planes):
-            fd = fb.fd(i)
-            info = bufinfos[fd]
-
-            mv = memoryview(info['map'])
-
-            start = fb.offset(i)
-            end = fb.offset(i) + fb.length(i)
-
-            mv = mv[start:end]
-
-            planes.append(mv)
-
-        self.__planes = tuple(planes)
-
-        return self
-
-    def __exit__(self, exc_type, exc_value, exc_traceback):
-        for p in self.__planes:
-            p.release()
-
-        for mm in self.__maps:
-            mm.close()
-
-    @property
-    def planes(self):
-        return self.__planes
-
-
-def __FrameBuffer__mmap(self):
-    return MappedFrameBuffer(self)
-
-
-FrameBuffer.mmap = __FrameBuffer__mmap

src/py/libcamera/meson.build

@@ -72,6 +72,10 @@ run_command('ln', '-fsT', files('__init__.py'),
             meson.current_build_dir() / '__init__.py',
             check: true)
 
+run_command('ln', '-fsT', meson.current_source_dir() / 'utils',
+            meson.current_build_dir() / 'utils',
+            check: true)
+
 install_data(['__init__.py'], install_dir : destdir)
 
 # \todo Generate stubs when building. See https://peps.python.org/pep-0484/#stub-files

src/py/libcamera/utils/MappedFrameBuffer.py

@@ -0,0 +1,74 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+# Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
+
+class MappedFrameBuffer:
+    def __init__(self, fb):
+        self.__fb = fb
+
+    def __enter__(self):
+        import os
+        import mmap
+
+        fb = self.__fb
+
+        # Collect information about the buffers
+
+        bufinfos = {}
+
+        for i in range(fb.num_planes):
+            fd = fb.fd(i)
+
+            if fd not in bufinfos:
+                buflen = os.lseek(fd, 0, os.SEEK_END)
+                bufinfos[fd] = {'maplen': 0, 'buflen': buflen}
+            else:
+                buflen = bufinfos[fd]['buflen']
+
+            if fb.offset(i) > buflen or fb.offset(i) + fb.length(i) > buflen:
+                raise RuntimeError(f'plane is out of buffer: buffer length={buflen}, ' +
+                                   f'plane offset={fb.offset(i)}, plane length={fb.length(i)}')
+
+            bufinfos[fd]['maplen'] = max(bufinfos[fd]['maplen'], fb.offset(i) + fb.length(i))
+
+        # mmap the buffers
+
+        maps = []
+
+        for fd, info in bufinfos.items():
+            map = mmap.mmap(fd, info['maplen'], mmap.MAP_SHARED, mmap.PROT_READ | mmap.PROT_WRITE)
+            info['map'] = map
+            maps.append(map)
+
+        self.__maps = tuple(maps)
+
+        # Create memoryviews for the planes
+
+        planes = []
+
+        for i in range(fb.num_planes):
+            fd = fb.fd(i)
+            info = bufinfos[fd]
+
+            mv = memoryview(info['map'])
+
+            start = fb.offset(i)
+            end = fb.offset(i) + fb.length(i)
+
+            mv = mv[start:end]
+
+            planes.append(mv)
+
+        self.__planes = tuple(planes)
+
+        return self
+
+    def __exit__(self, exc_type, exc_value, exc_traceback):
+        for p in self.__planes:
+            p.release()
+
+        for mm in self.__maps:
+            mm.close()
+
+    @property
+    def planes(self):
+        return self.__planes

src/py/libcamera/utils/__init__.py

@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+# Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
+
+from .MappedFrameBuffer import MappedFrameBuffer