[{"id":29822,"web_url":"https://patchwork.libcamera.org/comment/29822/","msgid":"<20240611010801.GF31989@pendragon.ideasonboard.com>","date":"2024-06-11T01:08:01","subject":"Re: [PATCH v7 3/4] ipa: libipa: pwl: Clean up Pwl class to match\n\tlibcamera","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Paul,\n\nThank you for the patch. Jut a few comments below about the things I've\nnoticed.\n\nOn Mon, Jun 10, 2024 at 11:19:40PM +0900, Paul Elder wrote:\n> Clean up the Pwl class copied from the Raspberry Pi IPA to align it more\n> with the libcamera style.\n> \n> Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>\n> Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>\n> Acked-by: David Plowman <david.plowman@raspberrypi.com>\n> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>\n> \n> ---\n> No change in v7\n> \n> Changes in v6:\n> - move adding pwl to meson here\n> \n> Changes in v5:\n> - fix documentation order\n> - fix some typos\n> - add the Vector-based PointF\n> \n> Changes in v4:\n> - update to apply to new copy of pwl\n> - add documentation\n> - fix doxygen\n> \n> No change in v3\n> \n> Changes in v2:\n> - s/FPoint/PointF/g\n> - improve documentation\n> - s/matchDomain/extendDomain/\n> ---\n>  src/ipa/libipa/meson.build |   2 +\n>  src/ipa/libipa/pwl.cpp     | 365 +++++++++++++++++++++++++++++--------\n>  src/ipa/libipa/pwl.h       | 123 +++++--------\n>  3 files changed, 344 insertions(+), 146 deletions(-)\n> \n> diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build\n> index 7ce885da7b99..8ec9c7847348 100644\n> --- a/src/ipa/libipa/meson.build\n> +++ b/src/ipa/libipa/meson.build\n> @@ -8,6 +8,7 @@ libipa_headers = files([\n>      'fc_queue.h',\n>      'histogram.h',\n>      'module.h',\n> +    'pwl.h',\n>  ])\n>  \n>  libipa_sources = files([\n> @@ -18,6 +19,7 @@ libipa_sources = files([\n>      'fc_queue.cpp',\n>      'histogram.cpp',\n>      'module.cpp',\n> +    'pwl.cpp',\n>  ])\n>  \n>  libipa_includes = include_directories('..')\n> diff --git a/src/ipa/libipa/pwl.cpp b/src/ipa/libipa/pwl.cpp\n> index e39123767aa6..8f8ee17e84e4 100644\n> --- a/src/ipa/libipa/pwl.cpp\n> +++ b/src/ipa/libipa/pwl.cpp\n> @@ -1,19 +1,120 @@\n>  /* SPDX-License-Identifier: BSD-2-Clause */\n>  /*\n>   * Copyright (C) 2019, Raspberry Pi Ltd\n> + * Copyright (C) 2024, Ideas on Board Oy\n>   *\n> - * piecewise linear functions\n> + * Piecewise linear functions\n>   */\n>  \n> +#include \"pwl.h\"\n> +\n>  #include <cassert>\n\nassert.h\n\nDidn't checkstyle.py warn you ?\n\n>  #include <cmath>\n> +#include <sstream>\n>  #include <stdexcept>\n>  \n> -#include \"pwl.h\"\n> +#include <libcamera/geometry.h>\n> +\n> +/**\n> + * \\file pwl.h\n> + * \\brief Piecewise linear functions\n> + */\n> +\n> +namespace libcamera {\n> +\n> +namespace ipa {\n> +\n> +/**\n> + * \\class Pwl\n> + * \\brief Describe a univariate piecewise linear function in real space\n> + */\n> +\n> +/**\n> + * \\typedef Pwl::PointF\n> + * \\brief Describe a point in two-dimensional real space\n> + */\n> +\n> +/**\n> + * \\enum Pwl::PerpType\n> + * \\brief Type of perpendicular found when inverting a piecewise linear function\n> + *\n> + * \\var Pwl::PerpType::None\n> + * \\brief No perpendicular found\n> + *\n> + * \\var Pwl::PerpType::Start\n> + * \\brief Start of Pwl is closest point\n> + *\n> + * \\var Pwl::PerpType::End\n> + * \\brief End of Pwl is closest point\n> + *\n> + * \\var Pwl::PerpType::Vertex\n> + * \\brief Vertex of Pwl is closest point\n> + *\n> + * \\var Pwl::PerpType::Perpendicular\n> + * \\brief True perpendicular found\n> + */\n>  \n> -using namespace RPiController;\n> +/**\n> + * \\class Pwl::Interval\n> + * \\brief Describe an interval in one-dimensional real space\n> + */\n> +\n> +/**\n> + * \\fn Pwl::Interval::Interval(double _start, double _end)\n> + * \\brief Construct an interval\n> + * \\param _start Start of the interval\n> + * \\param _end End of the interval\n> + */\n> +\n> +/**\n> + * \\fn Pwl::Interval::contains\n> + * \\brief Check if a given value falls within the interval\n> + * \\param value Value to check\n> + */\n> +\n> +/**\n> + * \\fn Pwl::Interval::clamp\n> + * \\brief Clamp a value such that it is within the interval\n> + * \\param value Value to clamp\n> + */\n> +\n> +/**\n> + * \\fn Pwl::Interval::len\n> + * \\brief Compute the length of the interval\n> + */\n>  \n> -int Pwl::read(const libcamera::YamlObject &params)\n> +/**\n> + * \\var Pwl::Interval::start\n> + * \\brief Start of the interval\n> + */\n> +\n> +/**\n> + * \\var Pwl::Interval::end\n> + * \\brief End of the interval\n> + */\n> +\n> +/**\n> + * \\fn Pwl::Pwl(std::vector<PointF> const &points)\n> + * \\brief Construct a piecewise linear function from a list of 2D points\n> + * \\param points Vector of points from which to construct the piecewise linear function\n> + *\n> + * \\a points must be in ascending order of x-value.\n> + */\n> +\n> +/**\n> + * \\brief Populate the piecewise linear function from yaml data\n> + * \\param params Yaml data to populate the piecewise linear function with\n> + *\n> + * Any existing points in the piecewise linear function will *not* be\n> + * overwritten.\n> + *\n> + * The yaml data is expected to be a list with an even number of numerical\n> + * elements. These will be parsed in pairs into x and y points in the piecewise\n> + * linear function, and added in order. x must be monotonically increasing.\n> + *\n> + * \\return 0 on success, negative error code otherwise\n> + */\n> +int Pwl::readYaml(const libcamera::YamlObject &params)\n>  {\n>  \tif (!params.size() || params.size() % 2)\n>  \t\treturn -EINVAL;\n> @@ -24,64 +125,109 @@ int Pwl::read(const libcamera::YamlObject &params)\n>  \t\tauto x = it->get<double>();\n>  \t\tif (!x)\n>  \t\t\treturn -EINVAL;\n> -\t\tif (it != list.begin() && *x <= points_.back().x)\n> +\t\tif (it != list.begin() && *x <= points_.back().x())\n>  \t\t\treturn -EINVAL;\n>  \n>  \t\tauto y = (++it)->get<double>();\n>  \t\tif (!y)\n>  \t\t\treturn -EINVAL;\n>  \n> -\t\tpoints_.push_back(Point(*x, *y));\n> +\t\tpoints_.push_back(PointF({ *x, *y }));\n>  \t}\n>  \n>  \treturn 0;\n>  }\n>  \n> +/**\n> + * \\brief Append a point to the end of the piecewise linear function\n> + * \\param x x-coordinate of the point to add to the piecewise linear function\n> + * \\param y y-coordinate of the point to add to the piecewise linear function\n> + * \\param eps Epsilon for the minimum x distance between points (optional)\n> + *\n> + * The point's x-coordinate must be greater than the x-coordinate of the last\n> + * (= greatest) point already in the piecewise linear function.\n> + */\n>  void Pwl::append(double x, double y, const double eps)\n>  {\n> -\tif (points_.empty() || points_.back().x + eps < x)\n> -\t\tpoints_.push_back(Point(x, y));\n> +\tif (points_.empty() || points_.back().x() + eps < x)\n> +\t\tpoints_.push_back(PointF({ x, y }));\n>  }\n>  \n> +/**\n> + * \\brief Prepend a point to the beginning of the piecewise linear function\n> + * \\param x x-coordinate of the point to add to the piecewise linear function\n> + * \\param y y-coordinate of the point to add to the piecewise linear function\n> + * \\param eps Epsilon for the minimum x distance between points (optional)\n> + *\n> + * The point's x-coordinate must be less than the x-coordinate of the first\n> + * (= smallest) point already in the piecewise linear function.\n> + */\n>  void Pwl::prepend(double x, double y, const double eps)\n>  {\n> -\tif (points_.empty() || points_.front().x - eps > x)\n> -\t\tpoints_.insert(points_.begin(), Point(x, y));\n> +\tif (points_.empty() || points_.front().x() - eps > x)\n> +\t\tpoints_.insert(points_.begin(), PointF({ x, y }));\n>  }\n>  \n> +/**\n> + * \\brief Get the domain of the piecewise linear function\n> + * \\return An interval representing the domain\n> + */\n>  Pwl::Interval Pwl::domain() const\n>  {\n> -\treturn Interval(points_[0].x, points_[points_.size() - 1].x);\n> +\treturn Interval(points_[0].x(), points_[points_.size() - 1].x());\n>  }\n>  \n> +/**\n> + * \\brief Get the range of the piecewise linear function\n> + * \\return An interval representing the range\n> + */\n>  Pwl::Interval Pwl::range() const\n>  {\n> -\tdouble lo = points_[0].y, hi = lo;\n> +\tdouble lo = points_[0].y(), hi = lo;\n>  \tfor (auto &p : points_)\n> -\t\tlo = std::min(lo, p.y), hi = std::max(hi, p.y);\n> +\t\tlo = std::min(lo, p.y()), hi = std::max(hi, p.y());\n>  \treturn Interval(lo, hi);\n>  }\n>  \n> +/**\n> + * \\brief Check if the piecewise linear function is empty\n> + * \\return True if there are no points in the function, false otherwise\n> + */\n>  bool Pwl::empty() const\n>  {\n>  \treturn points_.empty();\n>  }\n>  \n> +/**\n> + * \\brief Evaluate the piecewise linear function\n> + * \\param[in] x The x value to input into the function\n> + * \\param[inout] spanPtr Initial guess for span\n> + * \\param[in] updateSpan Set to true to update spanPtr\n> + *\n> + * Evaluate Pwl, optionally supplying an initial guess for the\n> + * \"span\". The \"span\" may be optionally be updated. If you want to know\n> + * the \"span\" value but don't have an initial guess you can set it to\n> + * -1.\n> + *\n> + *  \\return The result of evaluating the piecewise linear function at position \\a x\n> + */\n>  double Pwl::eval(double x, int *spanPtr, bool updateSpan) const\n>  {\n> -\tint span = findSpan(x, spanPtr && *spanPtr != -1 ? *spanPtr : points_.size() / 2 - 1);\n> +\tint span = findSpan(x, spanPtr && *spanPtr != -1\n> +\t\t\t\t\t? *spanPtr\n> +\t\t\t\t\t: points_.size() / 2 - 1);\n>  \tif (spanPtr && updateSpan)\n>  \t\t*spanPtr = span;\n> -\treturn points_[span].y +\n> -\t       (x - points_[span].x) * (points_[span + 1].y - points_[span].y) /\n> -\t\t       (points_[span + 1].x - points_[span].x);\n> +\treturn points_[span].y() +\n> +\t       (x - points_[span].x()) * (points_[span + 1].y() - points_[span].y()) /\n> +\t\t       (points_[span + 1].x() - points_[span].x());\n>  }\n>  \n>  int Pwl::findSpan(double x, int span) const\n>  {\n>  \t/*\n>  \t * Pwls are generally small, so linear search may well be faster than\n> -\t * binary, though could review this if large PWls start turning up.\n> +\t * binary, though could review this if large Pwls start turning up.\n>  \t */\n>  \tint lastSpan = points_.size() - 2;\n>  \t/*\n> @@ -89,23 +235,36 @@ int Pwl::findSpan(double x, int span) const\n>  \t * control point\n>  \t */\n>  \tspan = std::max(0, std::min(lastSpan, span));\n> -\twhile (span < lastSpan && x >= points_[span + 1].x)\n> +\twhile (span < lastSpan && x >= points_[span + 1].x())\n>  \t\tspan++;\n> -\twhile (span && x < points_[span].x)\n> +\twhile (span && x < points_[span].x())\n>  \t\tspan--;\n>  \treturn span;\n>  }\n>  \n> -Pwl::PerpType Pwl::invert(Point const &xy, Point &perp, int &span,\n> +/**\n> + * \\brief Find perpendicular closest to a given point\n> + * \\param[in] xy Point to find the perpendicular to\n> + * \\param[out] perp The found perpendicular\n> + * \\param[inout] span The span left of the point to start searching from\n> + * \\param[in] eps Epsilon for the minimum x distance between points (optional)\n> + *\n> + * Find perpendicular closest to \\a xy, starting from \\a span+1 so you can call\n> + * it repeatedly to check for multiple closest points (set span to -1 on the\n> + * first call). Also returns \"pseudo\" perpendiculars; see PerpType enum.\n> + *\n> + * \\return Type of perpendicular found\n> + */\n> +Pwl::PerpType Pwl::invert(PointF const &xy, PointF &perp, int &span,\n>  \t\t\t  const double eps) const\n>  {\n>  \tassert(span >= -1);\n>  \tbool prevOffEnd = false;\n>  \tfor (span = span + 1; span < (int)points_.size() - 1; span++) {\n> -\t\tPoint spanVec = points_[span + 1] - points_[span];\n> -\t\tdouble t = ((xy - points_[span]) % spanVec) / spanVec.len2();\n> -\t\tif (t < -eps) /* off the start of this span */\n> -\t\t{\n> +\t\tPointF spanVec = points_[span + 1] - points_[span];\n> +\t\tdouble t = ((xy - points_[span]) * spanVec) / spanVec.len2();\n> +\t\tif (t < -eps) {\n> +\t\t\t/* off the start of this span */\n>  \t\t\tif (span == 0) {\n>  \t\t\t\tperp = points_[span];\n>  \t\t\t\treturn PerpType::Start;\n> @@ -113,15 +272,15 @@ Pwl::PerpType Pwl::invert(Point const &xy, Point &perp, int &span,\n>  \t\t\t\tperp = points_[span];\n>  \t\t\t\treturn PerpType::Vertex;\n>  \t\t\t}\n> -\t\t} else if (t > 1 + eps) /* off the end of this span */\n> -\t\t{\n> +\t\t} else if (t > 1 + eps) {\n> +\t\t\t/* off the end of this span */\n>  \t\t\tif (span == (int)points_.size() - 2) {\n>  \t\t\t\tperp = points_[span + 1];\n>  \t\t\t\treturn PerpType::End;\n>  \t\t\t}\n>  \t\t\tprevOffEnd = true;\n> -\t\t} else /* a true perpendicular */\n> -\t\t{\n> +\t\t} else {\n> +\t\t\t/* a true perpendicular */\n>  \t\t\tperp = points_[span] + spanVec * t;\n>  \t\t\treturn PerpType::Perpendicular;\n>  \t\t}\n> @@ -129,25 +288,36 @@ Pwl::PerpType Pwl::invert(Point const &xy, Point &perp, int &span,\n>  \treturn PerpType::None;\n>  }\n>  \n> +/**\n> + * \\brief Compute the inverse function\n> + * \\param[out] trueInverse True if the result is a proper/true inverse\n> + * \\param[in] eps Epsilon for the minimum x distance between points (optional)\n> + *\n> + * Indicate if it is a proper (true) inverse, or only a best effort (e.g.\n> + * input was non-monotonic).\n> + *\n> + * \\return The inverse piecewise linear function\n> + */\n>  Pwl Pwl::inverse(bool *trueInverse, const double eps) const\n\nAs trueInverse is an output parameter, Would it be better to return a\nstd::pair<Pwl, bool> ?\n\n>  {\n>  \tbool appended = false, prepended = false, neither = false;\n>  \tPwl inverse;\n>  \n> -\tfor (Point const &p : points_) {\n> -\t\tif (inverse.empty())\n> -\t\t\tinverse.append(p.y, p.x, eps);\n> -\t\telse if (std::abs(inverse.points_.back().x - p.y) <= eps ||\n> -\t\t\t std::abs(inverse.points_.front().x - p.y) <= eps)\n> +\tfor (PointF const &p : points_) {\n> +\t\tif (inverse.empty()) {\n> +\t\t\tinverse.append(p.y(), p.x(), eps);\n> +\t\t} else if (std::abs(inverse.points_.back().x() - p.y()) <= eps ||\n> +\t\t\t   std::abs(inverse.points_.front().x() - p.y()) <= eps) {\n>  \t\t\t/* do nothing */;\n> -\t\telse if (p.y > inverse.points_.back().x) {\n> -\t\t\tinverse.append(p.y, p.x, eps);\n> +\t\t} else if (p.y() > inverse.points_.back().x()) {\n> +\t\t\tinverse.append(p.y(), p.x(), eps);\n>  \t\t\tappended = true;\n> -\t\t} else if (p.y < inverse.points_.front().x) {\n> -\t\t\tinverse.prepend(p.y, p.x, eps);\n> +\t\t} else if (p.y() < inverse.points_.front().x()) {\n> +\t\t\tinverse.prepend(p.y(), p.x(), eps);\n>  \t\t\tprepended = true;\n> -\t\t} else\n> +\t\t} else {\n>  \t\t\tneither = true;\n> +\t\t}\n>  \t}\n>  \n>  \t/*\n> @@ -161,44 +331,53 @@ Pwl Pwl::inverse(bool *trueInverse, const double eps) const\n>  \treturn inverse;\n>  }\n>  \n> +/**\n> + * \\brief Compose two piecewise linear functions together\n> + * \\param[in] other The \"other\" piecewise linear function\n> + * \\param[in] eps Epsilon for the minimum x distance between points (optional)\n> + *\n> + * The \"this\" function is done first, and \"other\" after.\n> + *\n> + * \\return The composed piecewise linear function\n> + */\n>  Pwl Pwl::compose(Pwl const &other, const double eps) const\n>  {\n> -\tdouble thisX = points_[0].x, thisY = points_[0].y;\n> +\tdouble thisX = points_[0].x(), thisY = points_[0].y();\n>  \tint thisSpan = 0, otherSpan = other.findSpan(thisY, 0);\n> -\tPwl result({ { thisX, other.eval(thisY, &otherSpan, false) } });\n> +\tPwl result({ PointF({ thisX, other.eval(thisY, &otherSpan, false) }) });\n> +\n>  \twhile (thisSpan != (int)points_.size() - 1) {\n> -\t\tdouble dx = points_[thisSpan + 1].x - points_[thisSpan].x,\n> -\t\t       dy = points_[thisSpan + 1].y - points_[thisSpan].y;\n> +\t\tdouble dx = points_[thisSpan + 1].x() - points_[thisSpan].x(),\n> +\t\t       dy = points_[thisSpan + 1].y() - points_[thisSpan].y();\n>  \t\tif (std::abs(dy) > eps &&\n>  \t\t    otherSpan + 1 < (int)other.points_.size() &&\n> -\t\t    points_[thisSpan + 1].y >=\n> -\t\t\t    other.points_[otherSpan + 1].x + eps) {\n> +\t\t    points_[thisSpan + 1].y() >= other.points_[otherSpan + 1].x() + eps) {\n>  \t\t\t/*\n>  \t\t\t * next control point in result will be where this\n>  \t\t\t * function's y reaches the next span in other\n>  \t\t\t */\n> -\t\t\tthisX = points_[thisSpan].x +\n> -\t\t\t\t(other.points_[otherSpan + 1].x -\n> -\t\t\t\t points_[thisSpan].y) *\n> +\t\t\tthisX = points_[thisSpan].x() +\n> +\t\t\t\t(other.points_[otherSpan + 1].x() -\n> +\t\t\t\t points_[thisSpan].y()) *\n>  \t\t\t\t\tdx / dy;\n> -\t\t\tthisY = other.points_[++otherSpan].x;\n> +\t\t\tthisY = other.points_[++otherSpan].x();\n>  \t\t} else if (std::abs(dy) > eps && otherSpan > 0 &&\n> -\t\t\t   points_[thisSpan + 1].y <=\n> -\t\t\t\t   other.points_[otherSpan - 1].x - eps) {\n> +\t\t\t   points_[thisSpan + 1].y() <=\n> +\t\t\t\t   other.points_[otherSpan - 1].x() - eps) {\n>  \t\t\t/*\n>  \t\t\t * next control point in result will be where this\n>  \t\t\t * function's y reaches the previous span in other\n>  \t\t\t */\n> -\t\t\tthisX = points_[thisSpan].x +\n> -\t\t\t\t(other.points_[otherSpan + 1].x -\n> -\t\t\t\t points_[thisSpan].y) *\n> +\t\t\tthisX = points_[thisSpan].x() +\n> +\t\t\t\t(other.points_[otherSpan + 1].x() -\n> +\t\t\t\t points_[thisSpan].y()) *\n>  \t\t\t\t\tdx / dy;\n> -\t\t\tthisY = other.points_[--otherSpan].x;\n> +\t\t\tthisY = other.points_[--otherSpan].x();\n>  \t\t} else {\n>  \t\t\t/* we stay in the same span in other */\n>  \t\t\tthisSpan++;\n> -\t\t\tthisX = points_[thisSpan].x,\n> -\t\t\tthisY = points_[thisSpan].y;\n> +\t\t\tthisX = points_[thisSpan].x(),\n> +\t\t\tthisY = points_[thisSpan].y();\n>  \t\t}\n>  \t\tresult.append(thisX, other.eval(thisY, &otherSpan, false),\n>  \t\t\t      eps);\n> @@ -206,32 +385,47 @@ Pwl Pwl::compose(Pwl const &other, const double eps) const\n>  \treturn result;\n>  }\n>  \n> +/**\n> + * \\brief Apply function to (x,y) values at every control point\n> + * \\param f Function to be applied\n> + */\n>  void Pwl::map(std::function<void(double x, double y)> f) const\n>  {\n>  \tfor (auto &pt : points_)\n> -\t\tf(pt.x, pt.y);\n> +\t\tf(pt.x(), pt.y());\n>  }\n>  \n> +/**\n> + * \\brief Apply function to (x, y0, y1) values wherever either Pwl has a\n> + * control point.\n> + */\n>  void Pwl::map2(Pwl const &pwl0, Pwl const &pwl1,\n>  \t       std::function<void(double x, double y0, double y1)> f)\n>  {\n>  \tint span0 = 0, span1 = 0;\n> -\tdouble x = std::min(pwl0.points_[0].x, pwl1.points_[0].x);\n> +\tdouble x = std::min(pwl0.points_[0].x(), pwl1.points_[0].x());\n>  \tf(x, pwl0.eval(x, &span0, false), pwl1.eval(x, &span1, false));\n> +\n>  \twhile (span0 < (int)pwl0.points_.size() - 1 ||\n>  \t       span1 < (int)pwl1.points_.size() - 1) {\n>  \t\tif (span0 == (int)pwl0.points_.size() - 1)\n> -\t\t\tx = pwl1.points_[++span1].x;\n> +\t\t\tx = pwl1.points_[++span1].x();\n>  \t\telse if (span1 == (int)pwl1.points_.size() - 1)\n> -\t\t\tx = pwl0.points_[++span0].x;\n> -\t\telse if (pwl0.points_[span0 + 1].x > pwl1.points_[span1 + 1].x)\n> -\t\t\tx = pwl1.points_[++span1].x;\n> +\t\t\tx = pwl0.points_[++span0].x();\n> +\t\telse if (pwl0.points_[span0 + 1].x() > pwl1.points_[span1 + 1].x())\n> +\t\t\tx = pwl1.points_[++span1].x();\n>  \t\telse\n> -\t\t\tx = pwl0.points_[++span0].x;\n> +\t\t\tx = pwl0.points_[++span0].x();\n>  \t\tf(x, pwl0.eval(x, &span0, false), pwl1.eval(x, &span1, false));\n>  \t}\n>  }\n>  \n> +/**\n> + * \\brief Combine two Pwls\n> + *\n> + * Create a new Pwl where the y values are given by running f wherever either\n> + * has a knot.\n> + */\n>  Pwl Pwl::combine(Pwl const &pwl0, Pwl const &pwl1,\n>  \t\t std::function<double(double x, double y0, double y1)> f,\n>  \t\t const double eps)\n> @@ -243,27 +437,54 @@ Pwl Pwl::combine(Pwl const &pwl0, Pwl const &pwl1,\n>  \treturn result;\n>  }\n>  \n> -void Pwl::matchDomain(Interval const &domain, bool clip, const double eps)\n> +/**\n> + * \\brief Extend the domain of the piecewise linear function\n> + * \\param[in] domain The domain to extend to\n> + * \\param[in] clip True to keep the existing edge y values, false to extrapolate\n> + * \\param[in] eps Epsilon for the minimum x distance between points (optional)\n> + *\n> + * Extend the domain of the piecewise linear function to match \\a domain. If \\a\n> + * clip is set to true then the y values of the new edges will be the same as\n> + * the existing y values of the edge points of the pwl. If false, then the y\n> + * values will be extrapolated linearly from the existing edge points of the\n> + * pwl.\n> + */\n> +void Pwl::extendDomain(Interval const &domain, bool clip, const double eps)\n>  {\n>  \tint span = 0;\n> -\tprepend(domain.start, eval(clip ? points_[0].x : domain.start, &span),\n> +\tprepend(domain.start, eval(clip ? points_[0].x() : domain.start, &span),\n>  \t\teps);\n>  \tspan = points_.size() - 2;\n> -\tappend(domain.end, eval(clip ? points_.back().x : domain.end, &span),\n> +\tappend(domain.end, eval(clip ? points_.back().x() : domain.end, &span),\n>  \t       eps);\n>  }\n>  \n> +/**\n> + * \\brief Multiply the piecewise linear function\n> + * \\param d Scalar multiplier to multiply the function by\n> + * \\return This function, after it has been multiplied by \\a d\n> + */\n>  Pwl &Pwl::operator*=(double d)\n>  {\n>  \tfor (auto &pt : points_)\n> -\t\tpt.y *= d;\n> +\t\tpt[1] *= d;\n>  \treturn *this;\n>  }\n>  \n> -void Pwl::debug(FILE *fp) const\n> +/**\n> + * \\brief Assemble and return a string describing the piecewise linear function\n> + * \\return A string describing the piecewise linear function\n> + */\n> +std::string Pwl::toString() const\n>  {\n> -\tfprintf(fp, \"Pwl {\\n\");\n> +\tstd::stringstream ss;\n> +\tss << \"Pwl { \";\n>  \tfor (auto &p : points_)\n> -\t\tfprintf(fp, \"\\t(%g, %g)\\n\", p.x, p.y);\n> -\tfprintf(fp, \"}\\n\");\n> +\t\tss << \"(\" << p.x() << \", \" << p.y() << \") \";\n> +\tss << \"}\";\n> +\treturn ss.str();\n>  }\n> +\n> +} /* namespace ipa */\n> +\n> +} /* namespace libcamera */\n> diff --git a/src/ipa/libipa/pwl.h b/src/ipa/libipa/pwl.h\n> index 7d5e7e4d3fda..c73693341583 100644\n> --- a/src/ipa/libipa/pwl.h\n> +++ b/src/ipa/libipa/pwl.h\n> @@ -2,126 +2,101 @@\n>  /*\n>   * Copyright (C) 2019, Raspberry Pi Ltd\n>   *\n> - * piecewise linear functions interface\n> + * Piecewise linear functions interface\n>   */\n>  #pragma once\n>  \n>  #include <functional>\n>  #include <math.h>\n\ncmath\n\n> +#include <string>\n>  #include <vector>\n>  \n> +#include <libcamera/geometry.h>\n> +\n>  #include \"libcamera/internal/yaml_parser.h\"\n>  \n> -namespace RPiController {\n> +#include \"vector.h\"\n> +\n> +namespace libcamera {\n> +\n> +namespace ipa {\n>  \n>  class Pwl\n>  {\n>  public:\n> +\tusing PointF = Vector<double, 2>;\n\nPointF would hint Vector<float, 2>. We could name it PointD, but how\nabout just Point ?\n\n> +\n> +\tenum class PerpType {\n> +\t\tNone,\n> +\t\tStart,\n> +\t\tEnd,\n> +\t\tVertex,\n> +\t\tPerpendicular,\n> +\t};\n> +\n>  \tstruct Interval {\n>  \t\tInterval(double _start, double _end)\n> -\t\t\t: start(_start), end(_end)\n> -\t\t{\n> -\t\t}\n> -\t\tdouble start, end;\n> +\t\t\t: start(_start), end(_end) {}\n> +\n>  \t\tbool contains(double value)\n>  \t\t{\n>  \t\t\treturn value >= start && value <= end;\n>  \t\t}\n> -\t\tdouble clip(double value)\n> +\n> +\t\tdouble clamp(double value)\n>  \t\t{\n>  \t\t\treturn value < start ? start\n>  \t\t\t\t\t     : (value > end ? end : value);\n\n\t\t\treturn std::clamp(value, start, end);\n\t\nDon't forget to include <algorithm>\n\n>  \t\t}\n> +\n>  \t\tdouble len() const { return end - start; }\n\nlength()\n\n> +\n> +\t\tdouble start, end;\n>  \t};\n> -\tstruct Point {\n> -\t\tPoint() : x(0), y(0) {}\n> -\t\tPoint(double _x, double _y)\n> -\t\t\t: x(_x), y(_y) {}\n> -\t\tdouble x, y;\n> -\t\tPoint operator-(Point const &p) const\n> -\t\t{\n> -\t\t\treturn Point(x - p.x, y - p.y);\n> -\t\t}\n> -\t\tPoint operator+(Point const &p) const\n> -\t\t{\n> -\t\t\treturn Point(x + p.x, y + p.y);\n> -\t\t}\n> -\t\tdouble operator%(Point const &p) const\n> -\t\t{\n> -\t\t\treturn x * p.x + y * p.y;\n> -\t\t}\n> -\t\tPoint operator*(double f) const { return Point(x * f, y * f); }\n> -\t\tPoint operator/(double f) const { return Point(x / f, y / f); }\n> -\t\tdouble len2() const { return x * x + y * y; }\n> -\t\tdouble len() const { return sqrt(len2()); }\n> -\t};\n> +\n>  \tPwl() {}\n> -\tPwl(std::vector<Point> const &points) : points_(points) {}\n> -\tint read(const libcamera::YamlObject &params);\n> +\tPwl(std::vector<PointF> const &points)\n\nWe place the const keyword before the type. Same below.\n\n> +\t\t: points_(points) {}\n> +\tint readYaml(const libcamera::YamlObject &params);\n\nIf we move readYaml() out of the Vector class, it would be nice to do\nthe same here.\n\n> +\n>  \tvoid append(double x, double y, const double eps = 1e-6);\n>  \tvoid prepend(double x, double y, const double eps = 1e-6);\n\nDo we need all those functions in the public API ? prepend() seems used\ninternally only for instance, and append() seems to be used to construct\ndefault values, which could be better handled using the constructor that\ntakes a vector of points.\n\n> +\n>  \tInterval domain() const;\n>  \tInterval range() const;\n> +\n>  \tbool empty() const;\n\nMove empty() before domain() and range().\n\n> -\t/*\n> -\t * Evaluate Pwl, optionally supplying an initial guess for the\n> -\t * \"span\". The \"span\" may be optionally be updated.  If you want to know\n> -\t * the \"span\" value but don't have an initial guess you can set it to\n> -\t * -1.\n> -\t */\n> +\n>  \tdouble eval(double x, int *spanPtr = nullptr,\n\nWe don't suffix variable names with types.\n\n>  \t\t    bool updateSpan = true) const;\n> -\t/*\n> -\t * Find perpendicular closest to xy, starting from span+1 so you can\n> -\t * call it repeatedly to check for multiple closest points (set span to\n> -\t * -1 on the first call). Also returns \"pseudo\" perpendiculars; see\n> -\t * PerpType enum.\n> -\t */\n> -\tenum class PerpType {\n> -\t\tNone, /* no perpendicular found */\n> -\t\tStart, /* start of Pwl is closest point */\n> -\t\tEnd, /* end of Pwl is closest point */\n> -\t\tVertex, /* vertex of Pwl is closest point */\n> -\t\tPerpendicular /* true perpendicular found */\n> -\t};\n> -\tPerpType invert(Point const &xy, Point &perp, int &span,\n> +\n> +\tPerpType invert(PointF const &xy, PointF &perp, int &span,\n>  \t\t\tconst double eps = 1e-6) const;\n\nAdd a blank line here, the next two functions are not related.\n\nActually this function isn't used (based on what I could see in the RPi\nIPA, and in the patches you have posted to the list on top of this\nseries), should we drop it ? You could then drop PerpType too.\n\n> -\t/*\n> -\t * Compute the inverse function. Indicate if it is a proper (true)\n> -\t * inverse, or only a best effort (e.g. input was non-monotonic).\n> -\t */\n>  \tPwl inverse(bool *trueInverse = nullptr, const double eps = 1e-6) const;\n> -\t/* Compose two Pwls together, doing \"this\" first and \"other\" after. */\n>  \tPwl compose(Pwl const &other, const double eps = 1e-6) const;\n> -\t/* Apply function to (x,y) values at every control point. */\n> +\n>  \tvoid map(std::function<void(double x, double y)> f) const;\n> -\t/*\n> -\t * Apply function to (x, y0, y1) values wherever either Pwl has a\n> -\t * control point.\n> -\t */\n> +\n>  \tstatic void map2(Pwl const &pwl0, Pwl const &pwl1,\n>  \t\t\t std::function<void(double x, double y0, double y1)> f);\n\nNever used either.\n\n> -\t/*\n> -\t * Combine two Pwls, meaning we create a new Pwl where the y values are\n> -\t * given by running f wherever either has a knot.\n> -\t */\n> +\n>  \tstatic Pwl\n>  \tcombine(Pwl const &pwl0, Pwl const &pwl1,\n>  \t\tstd::function<double(double x, double y0, double y1)> f,\n>  \t\tconst double eps = 1e-6);\n> -\t/*\n> -\t * Make \"this\" match (at least) the given domain. Any extension my be\n> -\t * clipped or linear.\n> -\t */\n> -\tvoid matchDomain(Interval const &domain, bool clip = true,\n> -\t\t\t const double eps = 1e-6);\n> +\n> +\tvoid extendDomain(Interval const &domain, bool clip = true,\n> +\t\t\t  const double eps = 1e-6);\n\nNot used.\n\n> +\n>  \tPwl &operator*=(double d);\n> -\tvoid debug(FILE *fp = stdout) const;\n> +\n> +\tstd::string toString() const;\n>  \n>  private:\n>  \tint findSpan(double x, int span) const;\n> -\tstd::vector<Point> points_;\n> +\tstd::vector<PointF> points_;\n>  };\n>  \n> -} /* namespace RPiController */\n> +} /* namespace ipa */\n> +\n> +} /* namespace libcamera */","headers":{"Return-Path":"<libcamera-devel-bounces@lists.libcamera.org>","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 71730BD87C\n\tfor <parsemail@patchwork.libcamera.org>;\n\tTue, 11 Jun 2024 01:08:25 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 707796545E;\n\tTue, 11 Jun 2024 03:08:24 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 1C41161A20\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tTue, 11 Jun 2024 03:08:22 +0200 (CEST)","from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi\n\t[81.175.209.231])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 4E3F47E0;\n\tTue, 11 Jun 2024 03:08:09 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"eS7Sa7PF\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1718068089;\n\tbh=yWGkPy9jQItR4XO2WLOFPL1VJsURpPae/LWWrw3yp7s=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=eS7Sa7PFi3FkWt31BykkHh07ltqEnquIQGCLx1LqZ1Qohw9o3HAowaHjjWRphzRyq\n\tqU9ft4KasChlfdfcAq/yldGNbdD/beLuRp2dG2ES0Ja6ZsY5yCg8n0+A6BxPa5zM2O\n\tlJo6ob8lENxmM17E7vNC34rt+Jnsw7/dhbWiR/Xg=","Date":"Tue, 11 Jun 2024 04:08:01 +0300","From":"Laurent Pinchart <laurent.pinchart@ideasonboard.com>","To":"Paul Elder <paul.elder@ideasonboard.com>","Cc":"libcamera-devel@lists.libcamera.org,\n\tStefan Klug <stefan.klug@ideasonboard.com>,\n\tDavid Plowman <david.plowman@raspberrypi.com>,\n\tKieran Bingham <kieran.bingham@ideasonboard.com>","Subject":"Re: [PATCH v7 3/4] ipa: libipa: pwl: Clean up Pwl class to match\n\tlibcamera","Message-ID":"<20240611010801.GF31989@pendragon.ideasonboard.com>","References":"<20240610141941.2947785-1-paul.elder@ideasonboard.com>\n\t<20240610141941.2947785-4-paul.elder@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","In-Reply-To":"<20240610141941.2947785-4-paul.elder@ideasonboard.com>","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"<libcamera-devel.lists.libcamera.org>","List-Unsubscribe":"<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>","List-Archive":"<https://lists.libcamera.org/pipermail/libcamera-devel/>","List-Post":"<mailto:libcamera-devel@lists.libcamera.org>","List-Help":"<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>","List-Subscribe":"<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>"}}]