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Laurent Pinchart 1acad98f7d libcamera: object: Support reference arguments in invokeMethod()
Invoking a method that takes a reference argument with
Object::invokeMethod() results in a compilation error:

../test/object-invoke.cpp:131:11: error: no matching member function for call to 'invokeMethod'
                object_.invokeMethod(&InvokedObject::methodWithReference,
                ~~~~~~~~^~~~~~~~~~~~
../include/libcamera/object.h:33:7: note: candidate template ignored: deduced conflicting types for parameter 'Args' (<const int &> vs. <int>)
        void invokeMethod(void (T::*func)(Args...), ConnectionType type, Args... args)

This is due to the fact that implicit type conversions (from value to
reference in this case) takes place after template argument type
deduction, during overload resolution. A similar issue would occur if
T::func took a long argument and invokeMethod() was called with an in
argument.

Fix this by specifying to sets of argument types in the invokeMethod()
template, one for the arguments to the invoked method, and one for the
arguments to invokeMethod() itself. The compiler can then first perform
type deduction separately, and implicit conversion in a second step.

Reported-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
2020-01-03 16:29:02 +02:00
Documentation ipa: Switch to the plain C API 2019-11-20 21:48:00 +02:00
include libcamera: object: Support reference arguments in invokeMethod() 2020-01-03 16:29:02 +02:00
licenses licenses: add Apache-2.0 license 2019-08-12 10:34:13 +02:00
package/gentoo/media-libs/libcamera libcamera: controls: Auto-generate control_ids.h and control_ids.cpp 2019-10-05 20:02:51 +03:00
src libcamera: pipeline: uvcvideo: Fix crash when default entity is not found 2020-01-03 13:57:55 +02:00
test test: object-invoke: Test invocation of method taking a reference argument 2020-01-03 13:59:05 +02:00
utils utils: checkstyle.py: Add include checker 2019-10-23 17:12:34 +03:00
.clang-format clang-format: Don't indent namespaces 2019-09-23 09:50:08 +03:00
.gitignore git: Add .gitignore file 2018-12-14 13:23:07 +00:00
meson.build libcamera: Print backtrace on fatal errors 2019-11-26 18:47:15 +02:00
meson_options.txt meson: Rename 'tests' option to 'test' 2019-08-22 19:35:54 +03:00
README.rst README: Simplify a bit the build instructions 2019-11-18 02:28:55 +02:00

.. section-begin-libcamera

===========
 libcamera
===========

**A complex camera support library for Linux, Android, and ChromeOS**

Cameras are complex devices that need heavy hardware image processing
operations. Control of the processing is based on advanced algorithms that must
run on a programmable processor. This has traditionally been implemented in a
dedicated MCU in the camera, but in embedded devices algorithms have been moved
to the main CPU to save cost. Blurring the boundary between camera devices and
Linux often left the user with no other option than a vendor-specific
closed-source solution.

To address this problem the Linux media community has very recently started
collaboration with the industry to develop a camera stack that will be
open-source-friendly while still protecting vendor core IP. libcamera was born
out of that collaboration and will offer modern camera support to Linux-based
systems, including traditional Linux distributions, ChromeOS and Android.

.. section-end-libcamera
.. section-begin-getting-started

Getting Started
---------------

To fetch the sources, build and install:

::

  git clone git://linuxtv.org/libcamera.git
  cd libcamera
  meson build
  ninja -C build install

Dependencies
~~~~~~~~~~~~

The following Debian/Ubuntu packages are required for building libcamera.
Other distributions may have differing package names:

A C++ toolchain: [required]
	Either {g++, clang}

for libcamera: [required]
	meson ninja-build python3-yaml

for device hotplug enumeration: [optional]
	pkg-config libudev-dev

for qcam: [optional]
	qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5

for documentation: [optional]
	python3-sphinx doxygen

.. section-end-getting-started