[libcamera-devel] [PATCH/RFC 10/12] libcamera: v4l2_device: Add method to enumerate all discrete frame sizes

[Laurent Pinchart]

From: Niklas Söderlund <niklas.soderlund at ragnatech.se>

Allow the video device to be interrogated about which discrete frame
sizes it supports.

Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
---
 src/libcamera/include/v4l2_device.h |  4 +++
 src/libcamera/v4l2_device.cpp       | 51 +++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
index 2e7bd1e7f4cc..481d63d9cc4c 100644
--- a/src/libcamera/include/v4l2_device.h
+++ b/src/libcamera/include/v4l2_device.h
@@ -8,6 +8,8 @@
 #define __LIBCAMERA_V4L2_DEVICE_H__
 
 #include <atomic>
+#include <map>
+#include <set>
 #include <string>
 #include <vector>
 
@@ -126,6 +128,8 @@ public:
 
 	int getFormat(V4L2DeviceFormat *format);
 	int setFormat(V4L2DeviceFormat *format);
+	std::map<unsigned int, std::vector<Size>>
+	enumerateFrameSizes(std::set<unsigned int> pixelformats);
 
 	int exportBuffers(BufferPool *pool);
 	int importBuffers(BufferPool *pool);
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 8366ffc4db55..d26a89f4a27d 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -564,6 +564,57 @@ int V4L2Device::setFormatMultiplane(V4L2DeviceFormat *format)
 	return 0;
 }
 
+/**
+ * \brief Enumerate all discrete frame sizes for a set of pixel formats
+ * \param[in] pixelformats A set of pixel formats to enumerate sizes for
+ *
+ * Enumerate all discrete frame sizes reported by the video device.
+ *
+ * \return A map of pixel format to frame sizes
+ */
+std::map<unsigned int, std::vector<Size>>
+V4L2Device::enumerateFrameSizes(std::set<unsigned int> pixelformats)
+{
+	std::map<unsigned int, std::vector<Size>> sizes;
+	int ret;
+
+	for (unsigned int pixelformat : pixelformats) {
+		struct v4l2_frmsizeenum frameSize = {};
+		unsigned int index = 0;
+
+		frameSize.pixel_format = pixelformat;
+
+		while (true) {
+			frameSize.index = index;
+
+			ret = ioctl(fd_, VIDIOC_ENUM_FRAMESIZES, &frameSize);
+			if (ret) {
+				ret = -errno;
+
+				if (ret == -EINVAL)
+					break;
+
+				if (ret != -ENOTTY)
+					LOG(V4L2, Error)
+						<< "Unable to enumerate frame size"
+						<< strerror(-ret);
+
+				return {};
+			}
+
+			if (frameSize.type != V4L2_FRMSIZE_TYPE_DISCRETE)
+				return {};
+
+			sizes[pixelformat].push_back(Size(frameSize.discrete.width,
+							  frameSize.discrete.height));
+
+			index++;
+		}
+	}
+
+	return sizes;
+}
+
 int V4L2Device::requestBuffers(unsigned int count)
 {
 	struct v4l2_requestbuffers rb = {};
-- 
Regards,

Laurent Pinchart