[libcamera-devel] [PATCH v3 14/14] [PoC] QCam: Control demo: A SineWave Brightness

[Laurent Pinchart]

From: Kieran Bingham <kieran.bingham at ideasonboard.com>

As an example of how to add a control to each request, set the
Brightness value with a changing value against the buffer time stamps.
The Brightness will go up and down following a sine wave to visualise
the control effect on the video stream.

Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
Changes since v2:

- Take controls min/max values into account
---
 src/qcam/main_window.cpp | 29 ++++++++++++++++++++++++++++-
 src/qcam/main_window.h   |  3 +++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
index 16b123132dd9..bfd3af1e4b92 100644
--- a/src/qcam/main_window.cpp
+++ b/src/qcam/main_window.cpp
@@ -5,6 +5,7 @@
  * main_window.cpp - qcam - Main application window
  */
 
+#include <cmath>
 #include <iomanip>
 #include <iostream>
 #include <string>
@@ -21,7 +22,8 @@
 using namespace libcamera;
 
 MainWindow::MainWindow(const OptionsParser::Options &options)
-	: options_(options), isCapturing_(false)
+	: options_(options), isCapturing_(false),
+	  brightness_(nullptr), gain_(nullptr)
 {
 	int ret;
 
@@ -88,6 +90,14 @@ int MainWindow::openCamera()
 
 	std::cout << "Using camera " << camera_->name() << std::endl;
 
+	const ControlInfoMap &controls = camera_->controls();
+	auto iter = controls.find(Brightness);
+	if (iter != controls.end())
+		brightness_ = &iter->second;
+	iter = controls.find(ManualGain);
+	if (iter != controls.end())
+		gain_ = &iter->second;
+
 	camera_->requestCompleted.connect(this, &MainWindow::requestComplete);
 
 	return 0;
@@ -184,6 +194,14 @@ void MainWindow::stopCapture()
 	config_.reset();
 }
 
+static int sineWaveValue(Buffer *buffer, const ControlInfo *info)
+{
+	unsigned int millisec = buffer->timestamp() / 1000000;
+	constexpr float rads = 2 * M_PI / 180;
+	return (sin(0.036 * rads * millisec) + 1) / 2 *
+	       (info->max().getInt() - info->min().getInt());
+}
+
 void MainWindow::requestComplete(Request *request,
 				 const std::map<Stream *, Buffer *> &buffers)
 {
@@ -213,6 +231,15 @@ void MainWindow::requestComplete(Request *request,
 		return;
 	}
 
+	/*
+	 * A demonstration control, which has a distinct visual effect.
+	 * Scale the brightness up and down with a sine wave.
+	 */
+	if (brightness_)
+		request->controls()[Brightness] = sineWaveValue(buffer, brightness_);
+	if (gain_)
+		request->controls()[ManualGain] = sineWaveValue(buffer, gain_);
+
 	request->setBuffers(buffers);
 	camera_->queueRequest(request);
 }
diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h
index fe565cbcb460..0a52399edc74 100644
--- a/src/qcam/main_window.h
+++ b/src/qcam/main_window.h
@@ -48,6 +48,9 @@ private:
 	bool isCapturing_;
 	std::unique_ptr<CameraConfiguration> config_;
 
+	const ControlInfo *brightness_;
+	const ControlInfo *gain_;
+
 	ViewFinder *viewfinder_;
 };
 
-- 
Regards,

Laurent Pinchart