libcamera: Add Transform enum to represent 2D plane transforms.

We implement 2D transforms as an enum class with 8 elements,
consisting of the usual 2D plane transformations (flips, rotations
etc.).

The transform is made up of 3 bits, indicating whether the transform
includes: a transpose, a horizontal flip (mirror) and a vertical flip.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/transform.h

@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Raspberry Pi (Trading) Limited
+ *
+ * transform.h - 2D plane transforms
+ */
+
+#ifndef __LIBCAMERA_TRANSFORM_H__
+#define __LIBCAMERA_TRANSFORM_H__
+
+#include <string>
+
+namespace libcamera {
+
+enum class Transform : int {
+	Identity = 0,
+	Rot0 = Identity,
+	HFlip = 1,
+	VFlip = 2,
+	HVFlip = HFlip | VFlip,
+	Rot180 = HVFlip,
+	Transpose = 4,
+	Rot270 = HFlip | Transpose,
+	Rot90 = VFlip | Transpose,
+	Rot180Transpose = HFlip | VFlip | Transpose
+};
+
+constexpr Transform operator&(Transform t0, Transform t1)
+{
+	return static_cast<Transform>(static_cast<int>(t0) & static_cast<int>(t1));
+}
+
+constexpr Transform operator|(Transform t0, Transform t1)
+{
+	return static_cast<Transform>(static_cast<int>(t0) | static_cast<int>(t1));
+}
+
+constexpr Transform operator^(Transform t0, Transform t1)
+{
+	return static_cast<Transform>(static_cast<int>(t0) ^ static_cast<int>(t1));
+}
+
+constexpr Transform &operator&=(Transform &t0, Transform t1)
+{
+	return t0 = t0 & t1;
+}
+
+constexpr Transform &operator|=(Transform &t0, Transform t1)
+{
+	return t0 = t0 | t1;
+}
+
+constexpr Transform &operator^=(Transform &t0, Transform t1)
+{
+	return t0 = t0 ^ t1;
+}
+
+Transform operator*(Transform t0, Transform t1);
+
+Transform operator-(Transform t);
+
+constexpr bool operator!(Transform t)
+{
+	return t == Transform::Identity;
+}
+
+constexpr Transform operator~(Transform t)
+{
+	return static_cast<Transform>(~static_cast<int>(t) & 7);
+}
+
+Transform transformFromRotation(int angle, bool *success = nullptr);
+
+const char *transformToString(Transform t);
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_TRANSFORM_H__ */