[libcamera-devel] [PATCH v2] libcamera: v4l2_videodevice: Add crop/selection control.

[Naushir Patuck]

Add control for cropping/selection on a V4L2 video device through
the VIDIOC_S_SELECTION ioctl. This is similar to the existing cropping
control available on V4L2 sub-devices.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
---
 src/libcamera/include/v4l2_videodevice.h |  5 +++
 src/libcamera/v4l2_videodevice.cpp       | 48 ++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/src/libcamera/include/v4l2_videodevice.h b/src/libcamera/include/v4l2_videodevice.h
index e4d35ab..d8edfde 100644
--- a/src/libcamera/include/v4l2_videodevice.h
+++ b/src/libcamera/include/v4l2_videodevice.h
@@ -182,6 +182,9 @@ public:
 	int setFormat(V4L2DeviceFormat *format);
 	ImageFormats formats();
 
+	int setCrop(Rectangle *rect);
+	int setCompose(Rectangle *rect);
+
 	int exportBuffers(unsigned int count,
 			  std::vector<std::unique_ptr<FrameBuffer>> *buffers);
 	int importBuffers(unsigned int count);
@@ -213,6 +216,8 @@ private:
 	int getFormatSingleplane(V4L2DeviceFormat *format);
 	int setFormatSingleplane(V4L2DeviceFormat *format);
 
+	int setSelection(unsigned int target, Rectangle *rect);
+
 	std::vector<unsigned int> enumPixelformats();
 	std::vector<SizeRange> enumSizes(unsigned int pixelFormat);
 
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index 8226773..01d9694 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -1499,6 +1499,54 @@ uint32_t V4L2VideoDevice::toV4L2Fourcc(PixelFormat pixelFormat, bool multiplanar
 	return 0;
 }
 
+/**
+ * \brief Set a crop rectangle on the V4L2 video device node
+ * \param[inout] rect The rectangle describing the crop target area
+ * \return 0 on success or a negative error code otherwise
+ */
+int V4L2VideoDevice::setCrop(Rectangle *rect)
+{
+	return setSelection(V4L2_SEL_TGT_CROP, rect);
+}
+
+/**
+ * \brief Set a compose rectangle on the V4L2 video device node
+ * \param[inout] rect The rectangle describing the compose target area
+ * \return 0 on success or a negative error code otherwise
+ */
+int V4L2VideoDevice::setCompose(Rectangle *rect)
+{
+	return setSelection(V4L2_SEL_TGT_COMPOSE, rect);
+}
+
+int V4L2VideoDevice::setSelection(unsigned int target, Rectangle *rect)
+{
+	struct v4l2_selection sel = {};
+
+	sel.type = bufferType_;
+	sel.target = target;
+	sel.flags = 0;
+
+	sel.r.left = rect->x;
+	sel.r.top = rect->y;
+	sel.r.width = rect->w;
+	sel.r.height = rect->h;
+
+	int ret = ioctl(VIDIOC_S_SELECTION, &sel);
+	if (ret < 0) {
+		LOG(V4L2, Error) << "Unable to set rectangle " << target
+				 << ": " << strerror(-ret);
+		return ret;
+	}
+
+	rect->x = sel.r.left;
+	rect->y = sel.r.top;
+	rect->w = sel.r.width;
+	rect->h = sel.r.height;
+
+	return 0;
+}
+
 /**
  * \class V4L2M2MDevice
  * \brief Memory-to-Memory video device
-- 
2.17.1