{"id":9429,"url":"https://patchwork.libcamera.org/api/1.1/patches/9429/?format=json","web_url":"https://patchwork.libcamera.org/patch/9429/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/1.1/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20200829115429.30010-4-david.plowman@raspberrypi.com>","date":"2020-08-29T11:54:24","name":"[libcamera-devel,v5,3/8] libcamera: Add Transform enum to represent 2D plane transforms.","commit_ref":null,"pull_url":null,"state":"accepted","archived":false,"hash":"092bbe9d14a005a5f9d2fcef74b10fab3d18188e","submitter":{"id":42,"url":"https://patchwork.libcamera.org/api/1.1/people/42/?format=json","name":"David Plowman","email":"david.plowman@raspberrypi.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/9429/mbox/","series":[{"id":1252,"url":"https://patchwork.libcamera.org/api/1.1/series/1252/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=1252","date":"2020-08-29T11:54:21","name":"2D transforms","version":5,"mbox":"https://patchwork.libcamera.org/series/1252/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/9429/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/9429/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 918BBBF019\n\tfor ;\n\tSat, 29 Aug 2020 11:54:41 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 5F52C62933;\n\tSat, 29 Aug 2020 13:54:41 +0200 (CEST)","from mail-wm1-x331.google.com (mail-wm1-x331.google.com\n\t[IPv6:2a00:1450:4864:20::331])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 650C262927\n\tfor ;\n\tSat, 29 Aug 2020 13:54:37 +0200 (CEST)","by mail-wm1-x331.google.com with SMTP id v4so691191wmj.5\n\tfor ;\n\tSat, 29 Aug 2020 04:54:37 -0700 (PDT)","from pi4-davidp.lan (plowpeople3.plus.com. 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charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"We implement 2D transforms as an enum class with 8 elements,\nconsisting of the usual 2D plane transformations (flips, rotations\netc.).\n\nThe transform is made up of 3 bits, indicating whether the transform\nincludes: a transpose, a horizontal flip (mirror) and a vertical flip.\n\nSigned-off-by: David Plowman \nReviewed-by: Laurent Pinchart \nReviewed-by: Kieran Bingham \n---\n include/libcamera/meson.build | 1 +\n include/libcamera/transform.h | 73 ++++++++\n src/libcamera/meson.build | 1 +\n src/libcamera/transform.cpp | 312 ++++++++++++++++++++++++++++++++++\n 4 files changed, 387 insertions(+)\n create mode 100644 include/libcamera/transform.h\n create mode 100644 src/libcamera/transform.cpp","diff":"diff --git a/include/libcamera/meson.build b/include/libcamera/meson.build\nindex cdb8e03..7fae5e5 100644\n--- a/include/libcamera/meson.build\n+++ b/include/libcamera/meson.build\n@@ -19,6 +19,7 @@ libcamera_public_headers = files([\n 'span.h',\n 'stream.h',\n 'timer.h',\n+ 'transform.h',\n ])\n \n include_dir = join_paths(libcamera_include_dir, 'libcamera')\ndiff --git a/include/libcamera/transform.h b/include/libcamera/transform.h\nnew file mode 100644\nindex 0000000..7d88937\n--- /dev/null\n+++ b/include/libcamera/transform.h\n@@ -0,0 +1,73 @@\n+/* SPDX-License-Identifier: LGPL-2.1-or-later */\n+/*\n+ * Copyright (C) 2020, Raspberry Pi (Trading) Limited\n+ *\n+ * transform.h - 2D plane transforms\n+ */\n+\n+#ifndef __LIBCAMERA_TRANSFORM_H__\n+#define __LIBCAMERA_TRANSFORM_H__\n+\n+#include \n+\n+namespace libcamera {\n+\n+enum class Transform : int {\n+\tIdentity = 0,\n+\tRot0 = Identity,\n+\tHFlip = 1,\n+\tVFlip = 2,\n+\tHVFlip = HFlip | VFlip,\n+\tRot180 = HVFlip,\n+\tTranspose = 4,\n+\tRot270 = HFlip | Transpose,\n+\tRot90 = VFlip | Transpose,\n+\tRot180Transpose = HFlip | VFlip | Transpose\n+};\n+\n+constexpr Transform operator&(Transform t0, Transform t1)\n+{\n+\treturn static_cast(static_cast(t0) & static_cast(t1));\n+}\n+\n+constexpr Transform operator|(Transform t0, Transform t1)\n+{\n+\treturn static_cast(static_cast(t0) | static_cast(t1));\n+}\n+\n+constexpr Transform operator^(Transform t0, Transform t1)\n+{\n+\treturn static_cast(static_cast(t0) ^ static_cast(t1));\n+}\n+\n+constexpr Transform &operator&=(Transform &t0, Transform t1)\n+{\n+\treturn t0 = t0 & t1;\n+}\n+\n+constexpr Transform &operator|=(Transform &t0, Transform t1)\n+{\n+\treturn t0 = t0 | t1;\n+}\n+\n+constexpr Transform &operator^=(Transform &t0, Transform t1)\n+{\n+\treturn t0 = t0 ^ t1;\n+}\n+\n+Transform operator*(Transform t0, Transform t1);\n+\n+Transform operator-(Transform t);\n+\n+constexpr bool operator!(Transform t)\n+{\n+\treturn t == Transform::Identity;\n+}\n+\n+Transform transformFromRotation(int angle, bool *success = nullptr);\n+\n+const char *transformToString(Transform t);\n+\n+} /* namespace libcamera */\n+\n+#endif /* __LIBCAMERA_TRANSFORM_H__ */\ndiff --git a/src/libcamera/meson.build b/src/libcamera/meson.build\nindex af2f3d9..edec55e 100644\n--- a/src/libcamera/meson.build\n+++ b/src/libcamera/meson.build\n@@ -44,6 +44,7 @@ libcamera_sources = files([\n 'sysfs.cpp',\n 'thread.cpp',\n 'timer.cpp',\n+ 'transform.cpp',\n 'utils.cpp',\n 'v4l2_controls.cpp',\n 'v4l2_device.cpp',\ndiff --git a/src/libcamera/transform.cpp b/src/libcamera/transform.cpp\nnew file mode 100644\nindex 0000000..88798d4\n--- /dev/null\n+++ b/src/libcamera/transform.cpp\n@@ -0,0 +1,312 @@\n+/* SPDX-License-Identifier: LGPL-2.1-or-later */\n+/*\n+ * Copyright (C) 2020, Raspberry Pi (Trading) Limited\n+ *\n+ * transform.cpp - 2D plane transforms.\n+ */\n+\n+#include \n+\n+/**\n+ * \\file transform.h\n+ * \\brief Enum to represent and manipulate 2D plane transforms.\n+ */\n+\n+namespace libcamera {\n+\n+/**\n+ * \\enum Transform\n+ * \\brief Enum to represent a 2D plane transform.\n+ *\n+ * The Transform can take 8 distinct values, representing the usual 2D plane\n+ * transforms listed below. Each of these transforms can be constructed\n+ * out of 3 basic operations, namely a horizontal flip (mirror), a vertical\n+ * flip, and a transposition (about the main diagonal). The transforms are\n+ * encoded such that a single bit indicates the presence of each of the 3\n+ * basic operations:\n+ *\n+ * - bit 0 - presence of a horizontal flip\n+ * - bit 1 - presence of a vertical flip\n+ * - bit 2 - presence of a transposition.\n+ *\n+ * We regard these 3 basic operations as being applied in a specific order:\n+ * first the two flip operations (actually they commute, so the order between\n+ * them is unimportant) and finally any transpose operation.\n+ *\n+ * Functions are provided to manipulate directly the bits within the transform\n+ * encoding, but there are also higher-level functions to invert and compose\n+ * transforms. Transforms are composed according to the usual mathematical\n+ * convention such that the right transform is applied first, and the left\n+ * transform is applied second.\n+ *\n+ * Finally, we have a total of 8 distinct transformations, as follows (a\n+ * couple of them have additional synonyms for convenience). We illustrate each\n+ * with its nominal effect on a rectangle with vertices labelled A, B, C and D.\n+ *\n+ * **Identity**\n+ *\n+ * Identity transform.\n+~~~\n+ A-B A-B\n+Input image | | goes to output image | |\n+ C-D C-D\n+~~~\n+ * Numeric value: 0 (no bits set).\n+ *\n+ * **Rot0**\n+ *\n+ * Synonym for `Identity` (zero degree rotation).\n+ *\n+ * **HFlip**\n+ *\n+ * Horizontal flip.\n+~~~\n+ A-B B-A\n+Input image | | goes to output image | |\n+ C-D D-C\n+~~~\n+ * Numeric value: 1 (horizontal flip bit set only).\n+ *\n+ * **VFlip**\n+ *\n+ * Vertical flip.\n+~~~\n+ A-B C-D\n+Input image | | goes to output image | |\n+ C-D A-B\n+~~~\n+ * Numeric value: 2 (vertical flip bit set only).\n+ *\n+ * **HVFlip**\n+ *\n+ * Horizontal and vertical flip (identical to a 180 degree rotation).\n+~~~\n+ A-B D-C\n+Input image | | goes to output image | |\n+ C-D B-A\n+~~~\n+ * Numeric value: 3 (horizontal and vertical flip bits set).\n+ *\n+ * **Rot180**\n+ *\n+ * Synonym for `HVFlip` (180 degree rotation).\n+ *\n+ * **Transpose**\n+ *\n+ * Transpose (about the main diagonal).\n+~~~\n+ A-B A-C\n+Input image | | goes to output image | |\n+ C-D B-D\n+~~~\n+ * Numeric value: 4 (transpose bit set only).\n+ *\n+ * **Rot270**\n+ *\n+ * Rotation by 270 degrees clockwise (90 degrees anticlockwise).\n+~~~\n+ A-B B-D\n+Input image | | goes to output image | |\n+ C-D A-C\n+~~~\n+ * Numeric value: 5 (transpose and horizontal flip bits set).\n+ *\n+ * **Rot90**\n+ *\n+ * Rotation by 90 degrees clockwise (270 degrees anticlockwise).\n+~~~\n+ A-B C-A\n+Input image | | goes to output image | |\n+ C-D D-B\n+~~~\n+ * Numeric value: 6 (transpose and vertical flip bits set).\n+ *\n+ * **Rot180Transpose**\n+ *\n+ * Rotation by 180 degrees followed by transpose (alternatively, transposition\n+ * about the \"opposite diagonal\").\n+~~~\n+ A-B D-B\n+Input image | | goes to output image | |\n+ C-D C-A\n+~~~\n+ * Numeric value: 7 (all bits set).\n+ *\n+ * \\sa https://en.wikipedia.org/wiki/Examples_of_groups#dihedral_group_of_order_8\n+ *\n+ * The set of 2D plane transforms is also known as the symmetry group of a\n+ * square, described in the link. Note that the group can be generated by\n+ * only 2 elements (the horizontal flip and a 90 degree rotation, for\n+ * example), however, the encoding used here makes the presence of the vertical\n+ * flip explicit.\n+ */\n+\n+/**\n+ * \\fn operator &(Transform t0, Transform t1)\n+ * \\brief Apply bitwise AND operator between the bits in the two transforms.\n+ * \\param[in] t0 The first transform.\n+ * \\param[in] t1 The second transform.\n+ */\n+\n+/**\n+ * \\fn operator |(Transform t0, Transform t1)\n+ * \\brief Apply bitwise OR operator between the bits in the two transforms.\n+ * \\param[in] t0 The first transform.\n+ * \\param[in] t1 The second transform.\n+ */\n+\n+/**\n+ * \\fn operator ^(Transform t0, Transform t1)\n+ * \\brief Apply bitwise XOR operator between the bits in the two transforms.\n+ * \\param[in] t0 The first transform.\n+ * \\param[in] t1 The second transform.\n+ */\n+\n+/**\n+ * \\fn operator &=(Transform &t0, Transform t1)\n+ * \\brief Apply bitwise AND-assignment operator between the bits in the two\n+ * transforms.\n+ * \\param[in] t0 The first transform.\n+ * \\param[in] t1 The second transform.\n+ */\n+\n+/**\n+ * \\fn operator |=(Transform &t0, Transform t1)\n+ * \\brief Apply bitwise OR-assignment operator between the bits in the two\n+ * transforms.\n+ * \\param[in] t0 The first transform.\n+ * \\param[in] t1 The second transform.\n+ */\n+\n+/**\n+ * \\fn operator ^=(Transform &t0, Transform t1)\n+ * \\brief Apply bitwise XOR-assignment operator between the bits in the two\n+ * transforms.\n+ * \\param[in] t0 The first transform.\n+ * \\param[in] t1 The second transform.\n+ */\n+\n+/**\n+ * \\brief Compose two transforms together.\n+ * \\param[in] t1 The second transform.\n+ * \\param[in] t0 The first transform.\n+ *\n+ * Composing transforms follows the usual mathematical convention for\n+ * composing functions. That is, when performing `t1 * t0`, \\a t0 is applied\n+ * first, and then \\a t1.\n+ * For example, `Transpose * HFlip` performs `HFlip` first and then the\n+ * `Transpose` yielding `Rot270`, as shown below.\n+~~~\n+ A-B B-A B-D\n+Input image | | -> HFLip -> | | -> Transpose -> | | = Rot270\n+ C-D D-C A-C\n+~~~\n+ * Note that composition is generally non-commutative for Transforms,\n+ * and not the same as XOR-ing the underlying bit representations.\n+ */\n+Transform operator*(Transform t1, Transform t0)\n+{\n+\t/*\n+\t * Reorder the operations so that we imagine doing t0's transpose\n+\t * (if any) after t1's flips. The effect is to swap t1's hflips for\n+\t * vflips and vice versa, after which we can just xor all the bits.\n+\t */\n+\tTransform reordered = t1;\n+\tif (!!(t0 & Transform::Transpose)) {\n+\t\treordered = t1 & Transform::Transpose;\n+\t\tif (!!(t1 & Transform::HFlip))\n+\t\t\treordered |= Transform::VFlip;\n+\t\tif (!!(t1 & Transform::VFlip))\n+\t\t\treordered |= Transform::HFlip;\n+\t}\n+\n+\treturn reordered ^ t0;\n+}\n+\n+/**\n+ * \\brief Invert a transform.\n+ * \\param[in] t The transform to be inverted.\n+ *\n+ * That is, we return the transform such that `t * (-t)` and `(-t) * t` both\n+ * yield the identity transform.\n+ */\n+Transform operator-(Transform t)\n+{\n+\t/* All are self-inverses, except for Rot270 and Rot90. */\n+\tstatic const Transform inverses[] = {\n+\t\tTransform::Identity,\n+\t\tTransform::HFlip,\n+\t\tTransform::VFlip,\n+\t\tTransform::HVFlip,\n+\t\tTransform::Transpose,\n+\t\tTransform::Rot90,\n+\t\tTransform::Rot270,\n+\t\tTransform::Rot180Transpose\n+\t};\n+\n+\treturn inverses[static_cast(t)];\n+}\n+\n+/**\n+ * \\fn operator!(Transform t)\n+ * \\brief Return `true` if the transform is the `Identity`, otherwise `false`.\n+ * \\param[in] t The transform to be tested.\n+ */\n+\n+/**\n+ * \\brief Return the transform representing a rotation of the given angle\n+ * clockwise.\n+ * \\param[in] angle The angle of rotation in a clockwise sense. Negative values\n+ * can be used to represent anticlockwise rotations.\n+ * \\param[out] success Set to `true` if the angle is a multiple of 90 degrees,\n+ * otherwise `false`.\n+ * \\return The transform corresponding to the rotation if \\a success was set to\n+ * `true`, otherwise the `Identity` transform.\n+ */\n+Transform transformFromRotation(int angle, bool *success)\n+{\n+\tangle = angle % 360;\n+\tif (angle < 0)\n+\t\tangle += 360;\n+\n+\tif (success != nullptr)\n+\t\t*success = true;\n+\n+\tswitch (angle) {\n+\tcase 0:\n+\t\treturn Transform::Identity;\n+\tcase 90:\n+\t\treturn Transform::Rot90;\n+\tcase 180:\n+\t\treturn Transform::Rot180;\n+\tcase 270:\n+\t\treturn Transform::Rot270;\n+\t}\n+\n+\tif (success != nullptr)\n+\t\t*success = false;\n+\n+\treturn Transform::Identity;\n+}\n+\n+/**\n+ * \\brief Return a character string describing the transform.\n+ * \\param[in] t The transform to be described.\n+ */\n+const char *transformToString(Transform t)\n+{\n+\tstatic const char *strings[] = {\n+\t\t\"identity\",\n+\t\t\"hflip\",\n+\t\t\"vflip\",\n+\t\t\"hvflip\",\n+\t\t\"transpose\",\n+\t\t\"rot270\",\n+\t\t\"rot90\",\n+\t\t\"rot180transpose\"\n+\t};\n+\n+\treturn strings[static_cast(t)];\n+}\n+\n+} /* namespace libcamera */\n","prefixes":["libcamera-devel","v5","3/8"]}