[libcamera-devel] [RFC 1/2] libcamera: v4l2_subdevice: Replace ImageFormats with a map

Kieran Bingham kieran.bingham at ideasonboard.com
Thu Jul 2 16:13:12 CEST 2020


Hi Laurent,

On 02/07/2020 15:04, Laurent Pinchart wrote:
> Hi Niklas,
> 
> Thank you for the patch.
> 
> On Wed, Jul 01, 2020 at 11:16:49PM +0200, Niklas Söderlund wrote:
>> Replace the V4L2Subdevice usage of the ImageForamts class with a
> 
> s/ImageForamts/ImageFormats/
> 
>> std::map and the utils::map_keys() helper.
>>
>> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
>> ---
>>  include/libcamera/internal/camera_sensor.h  |  6 ++----
>>  include/libcamera/internal/v4l2_subdevice.h |  4 +++-
>>  src/libcamera/camera_sensor.cpp             | 12 ++++++------
>>  src/libcamera/v4l2_subdevice.cpp            | 16 ++++++++--------
>>  test/v4l2_subdevice/list_formats.cpp        | 16 ++++++++--------
>>  5 files changed, 27 insertions(+), 27 deletions(-)
>>
>> diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
>> index 7f07413f95602881..06c8292ca30129de 100644
>> --- a/include/libcamera/internal/camera_sensor.h
>> +++ b/include/libcamera/internal/camera_sensor.h
>> @@ -16,13 +16,11 @@
>>  
>>  #include "libcamera/internal/formats.h"
>>  #include "libcamera/internal/log.h"
>> +#include "libcamera/internal/v4l2_subdevice.h"
>>  
>>  namespace libcamera {
>>  
>>  class MediaEntity;
>> -class V4L2Subdevice;
>> -
>> -struct V4L2SubdeviceFormat;
>>  
>>  struct CameraSensorInfo {
>>  	std::string model;
>> @@ -75,7 +73,7 @@ private:
>>  
>>  	std::string model_;
>>  
>> -	ImageFormats formats_;
>> +	V4L2Subdevice::Formats formats_;
>>  	Size resolution_;
>>  	std::vector<unsigned int> mbusCodes_;
>>  	std::vector<Size> sizes_;
>> diff --git a/include/libcamera/internal/v4l2_subdevice.h b/include/libcamera/internal/v4l2_subdevice.h
>> index a3ecf123f640dd54..02ee3e914a8b1d92 100644
>> --- a/include/libcamera/internal/v4l2_subdevice.h
>> +++ b/include/libcamera/internal/v4l2_subdevice.h
>> @@ -32,6 +32,8 @@ struct V4L2SubdeviceFormat {
>>  class V4L2Subdevice : public V4L2Device
>>  {
>>  public:
>> +	using Formats = std::map<unsigned int, std::vector<SizeRange>>;
>> +
>>  	enum Whence {
>>  		ActiveFormat,
>>  		TryFormat,
>> @@ -51,7 +53,7 @@ public:
>>  	int setSelection(unsigned int pad, unsigned int target,
>>  			 Rectangle *rect);
>>  
>> -	ImageFormats formats(unsigned int pad);
>> +	Formats formats(unsigned int pad);
>>  
>>  	int getFormat(unsigned int pad, V4L2SubdeviceFormat *format,
>>  		      Whence whence = ActiveFormat);
>> diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
>> index b14b4051dca606b9..3c9b05feef4e0861 100644
>> --- a/src/libcamera/camera_sensor.cpp
>> +++ b/src/libcamera/camera_sensor.cpp
>> @@ -18,7 +18,6 @@
>>  
>>  #include "libcamera/internal/formats.h"
>>  #include "libcamera/internal/utils.h"
>> -#include "libcamera/internal/v4l2_subdevice.h"
>>  
>>  /**
>>   * \file camera_sensor.h
>> @@ -245,15 +244,15 @@ int CameraSensor::init()
>>  
>>  	/* Enumerate, sort and cache media bus codes and sizes. */
>>  	formats_ = subdev_->formats(pad_);
>> -	if (formats_.isEmpty()) {
>> +	if (formats_.empty()) {
>>  		LOG(CameraSensor, Error) << "No image format found";
>>  		return -EINVAL;
>>  	}
>>  
>> -	mbusCodes_ = formats_.formats();
>> +	mbusCodes_ = utils::map_keys(formats_);
>>  	std::sort(mbusCodes_.begin(), mbusCodes_.end());
>>  
>> -	for (const auto &format : formats_.data()) {
>> +	for (const auto &format : formats_) {
>>  		const std::vector<SizeRange> &ranges = format.second;
>>  		std::transform(ranges.begin(), ranges.end(), std::back_inserter(sizes_),
>>  			       [](const SizeRange &range) { return range.max; });
>> @@ -359,9 +358,10 @@ V4L2SubdeviceFormat CameraSensor::getFormat(const std::vector<unsigned int> &mbu
>>  	uint32_t bestCode = 0;
>>  
>>  	for (unsigned int code : mbusCodes) {
>> -		const std::vector<SizeRange> &ranges = formats_.sizes(code);
>> +		if (formats_.find(code) == formats_.end())
>> +			continue;
>>  
>> -		for (const SizeRange &range : ranges) {
>> +		for (const SizeRange &range : formats_.at(code)) {
> 
> 		const auto formats = formats_.find(code);
> 		if (formats == formats_.end())
> 			continue;
> 
> 		for (const SizeRange &range : formats->second) {
> 
> to avoid a double lookup. Feel free to rename formats to ranges or to
> iter (or to something else) if you think it would be more readable.
> 
>>  			const Size &sz = range.max;
>>  
>>  			if (sz.width < size.width || sz.height < size.height)
>> diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
>> index 32c6c7acc11a6a3f..6dbe6d7590e4ae16 100644
>> --- a/src/libcamera/v4l2_subdevice.cpp
>> +++ b/src/libcamera/v4l2_subdevice.cpp
>> @@ -217,6 +217,11 @@ uint8_t V4L2SubdeviceFormat::bitsPerPixel() const
>>   * any device left open will be closed, and any resources released.
>>   */
>>  
>> +/**
>> + * \typedef V4L2Subdevice::Formats
>> + * \brief A map of supported media bus formats to frame sizes
>> + */
>> +
>>  /**
>>   * \enum V4L2Subdevice::Whence
>>   * \brief Specify the type of format for getFormat() and setFormat() operations
>> @@ -340,9 +345,9 @@ int V4L2Subdevice::setSelection(unsigned int pad, unsigned int target,
>>   *
>>   * \return A list of the supported device formats
>>   */
>> -ImageFormats V4L2Subdevice::formats(unsigned int pad)
>> +V4L2Subdevice::Formats V4L2Subdevice::formats(unsigned int pad)
>>  {
>> -	ImageFormats formats;
>> +	Formats formats;
>>  
>>  	if (pad >= entity_->pads().size()) {
>>  		LOG(V4L2, Error) << "Invalid pad: " << pad;
>> @@ -354,12 +359,7 @@ ImageFormats V4L2Subdevice::formats(unsigned int pad)
>>  		if (sizes.empty())
>>  			return {};
>>  
>> -		if (formats.addFormat(code, sizes)) {
>> -			LOG(V4L2, Error)
>> -				<< "Could not add sizes for media bus code "
>> -				<< code << " on pad " << pad;
>> -			return {};
>> -		}
>> +		formats[code] = sizes;
> 
> Do we want to keep the error check ? If so, it could be done with
> insert(), which returns a std::pair<iterator, bool> where the bool tells
> whether the insertion takes place or an element was already present.
> With C++17 that could be written
> 
> 		const auto [iter, success] = formats.insert(sizes);
> 		if (!success) {
> 			...
> 		}
> 
> but with C++14 we would need
> 
> 		const auto inserted = formats.insert(sizes);
> 		if (!inserted.second) {
> 			...
> 		}
> 
> which is less nice. Maybe it's not worth it.
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 

With [0], GCC 11 will move to C++17 by default, and that .first .second
usage from std::pair makes me cringe horribly every time I see it.

What points hold us back from moving to C++17 ? and do you foresee a
particular point that we could upgrade? or are we going to remain at
C++14 for the foreseeable future ?


[0]
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=0801f419440c14f6772b28f763ad7d40f7f7a580
(c++: Change the default dialect to C++17.)

--
Kieran


>>  	}
>>  
>>  	return formats;
>> diff --git a/test/v4l2_subdevice/list_formats.cpp b/test/v4l2_subdevice/list_formats.cpp
>> index a55af1100d9ab498..a6044c044036acd4 100644
>> --- a/test/v4l2_subdevice/list_formats.cpp
>> +++ b/test/v4l2_subdevice/list_formats.cpp
>> @@ -47,29 +47,29 @@ void ListFormatsTest::printFormats(unsigned int pad,
>>  int ListFormatsTest::run()
>>  {
>>  	/* List all formats available on existing "Scaler" pads. */
>> -	ImageFormats formats;
>> +	V4L2Subdevice::Formats formats;
>>  
>>  	formats = scaler_->formats(0);
>> -	if (formats.isEmpty()) {
>> +	if (formats.empty()) {
>>  		cerr << "Failed to list formats on pad 0 of subdevice "
>>  		     << scaler_->entity()->name() << endl;
>>  		return TestFail;
>>  	}
>> -	for (unsigned int code : formats.formats())
>> -		printFormats(0, code, formats.sizes(code));
>> +	for (unsigned int code : utils::map_keys(formats))
>> +		printFormats(0, code, formats[code]);
>>  
>>  	formats = scaler_->formats(1);
>> -	if (formats.isEmpty()) {
>> +	if (formats.empty()) {
>>  		cerr << "Failed to list formats on pad 1 of subdevice "
>>  		     << scaler_->entity()->name() << endl;
>>  		return TestFail;
>>  	}
>> -	for (unsigned int code : formats.formats())
>> -		printFormats(1, code, formats.sizes(code));
>> +	for (unsigned int code : utils::map_keys(formats))
>> +		printFormats(1, code, formats[code]);
>>  
>>  	/* List format on a non-existing pad, format vector shall be empty. */
>>  	formats = scaler_->formats(2);
>> -	if (!formats.isEmpty()) {
>> +	if (!formats.empty()) {
>>  		cerr << "Listing formats on non-existing pad 2 of subdevice "
>>  		     << scaler_->entity()->name()
>>  		     << " should return an empty format list" << endl;
> 

-- 
Regards
--
Kieran


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