libcamera: camera_sensor: Reverse the key and value of test pattern mode map

The key and value of the test pattern mode are originally the index of
v4l2 control and the corresponding test pattern mode control value.
This key and value are useful in the initialization for reporting
available test pattern modes. However, the map of the reversed key and
value is much more useful in applying a requested test pattern mode.
Reverses the key and value of the map as the initialization is one
time but the test pattern mode request will be multiple times.

Signed-off-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 87668509..9fdb8c09 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -320,11 +320,22 @@ void CameraSensor::initTestPatternModes(
 		return;
 	}
 
+	/*
+	 * Create a map that associates the V4L2 control index to the test
+	 * pattern mode by reversing the testPatternModes map provided by the
+	 * camera sensor properties. This makes it easier to verify if the
+	 * control index is supported in the below for loop that creates the
+	 * list of supported test patterns.
+	 */
+	std::map<int32_t, int32_t> indexToTestPatternMode;
+	for (const auto &it : testPatternModes)
+		indexToTestPatternMode[it.second] = it.first;
+
 	for (const ControlValue &value : v4l2TestPattern->second.values()) {
 		const int32_t index = value.get<int32_t>();
 
-		const auto it = testPatternModes.find(index);
-		if (it == testPatternModes.end()) {
+		const auto it = indexToTestPatternMode.find(index);
+		if (it == indexToTestPatternMode.end()) {
 			LOG(CameraSensor, Debug)
 				<< "Test pattern mode " << index << " ignored";
 			continue;