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eina: improve documentation for eina_bezier. 

Summary:
Adds missing @param docs and fixes an incorrectly documented one.
Clarifies difference between 'length' and 'position', specifying the
latter is a number between 0.0 and 1.0.  Improves verbage here and there
for grammatical correctness and internal consistency.

Subscribers: cedric

Differential Revision: https://phab.enlightenment.org/D5780

Signed-off-by: Cedric Bail <cedric@osg.samsung.com>
This commit is contained in:
Bryce Harrington 2018-02-14 12:00:44 -08:00 committed by Cedric Bail
parent ba64b372d3
commit 274730fc5f
2 changed files with 39 additions and 35 deletions
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10
src/lib/eina/eina_bezier.c
View File

@ -40,9 +40,9 @@ _eina_bezier_1st_derivative(const Eina_Bezier *bz,
*py = 3 * ( a * bz->start.y + b * bz->ctrl_start.y + c * bz->ctrl_end.y + d * bz->end.y);
}
// approximate sqrt(x*x + y*y) using alpha max plus beta min algorithm.
// With alpha = 1, beta = 3/8, giving results with a largest error less
// than 7% compared to the exact value.
// Approximate sqrt(x*x + y*y) using the alpha max plus beta min algorithm.
// This uses alpha = 1, beta = 3/8, which results in a maximum error of less
// than 7% compared to the correct value.
static double
_line_length(double x1, double y1, double x2, double y2)
{
@ -96,9 +96,9 @@ _eina_bezier_length_helper(const Eina_Bezier *b)
chord = _line_length(b->start.x, b->start.y, b->end.x, b->end.y);
if (fabsf(len - chord) > FLT_MIN) {
_eina_bezier_split(b, &left, &right); /* split in two */
_eina_bezier_split(b, &left, &right); /* split in two */
length =
_eina_bezier_length_helper(&left) + /* try left side */
_eina_bezier_length_helper(&left) + /* try left side */
_eina_bezier_length_helper(&right); /* try right side */
return length;

64
src/lib/eina/eina_bezier.h
View File

@ -52,14 +52,14 @@ struct _Eina_Bezier
* point cubic bezier curve.
*
* @param b The floating point bezier.
* @param start_x x coordinate of start point.
* @param start_y y coordinate of start point.
* @param ctrl_start_x x coordinate of 1st control point.
* @param ctrl_start_y y coordinate of 1st control point.
* @param ctrl_end_x x coordinate of 2nd control point.
* @param ctrl_end_y y coordinate of 2nd control point.
* @param end_x x coordinate of end point.
* @param end_y y coordinate of end point.
* @param start_x The x coordinate of the start point.
* @param start_y The y coordinate of the start point.
* @param ctrl_start_x The x coordinate of the 1st control point.
* @param ctrl_start_y The y coordinate of the 1st control point.
* @param ctrl_end_x The X coordinate of the 2nd control point.
* @param ctrl_end_y The Y coordinate of the 2nd control point.
* @param end_x The X coordinate of the end point.
* @param end_y The Y coordinate of the end point.
*
* @p b. No check is done on @p b.
* @since 1.16
@ -86,8 +86,8 @@ EAPI void eina_bezier_values_set(Eina_Bezier *b, double start_x, double start_y,
EAPI void eina_bezier_values_get(const Eina_Bezier *b, double *start_x, double *start_y, double *ctrl_start_x, double *ctrl_start_y, double *ctrl_end_x, double *ctrl_end_y, double *end_x, double *end_y) EINA_ARG_NONNULL(1);
/**
* @brief Returns the length of the given floating
* point cubic bezier curve.
* @brief Calculates the length of the given floating point cubic bezier
* curve.
*
* @param b The floating point bezier.
*
@ -97,11 +97,13 @@ EAPI void eina_bezier_values_get(const Eina_Bezier *b, double *start_x, double *
EAPI double eina_bezier_length_get(const Eina_Bezier *b) EINA_ARG_NONNULL(1);
/**
* @brief Returns the position of the given bezier
* at given length.
* @brief Returns the relative position on a bezier at a given length.
*
* @param b The floating point bezier.
* @param len The given length.
* @param len The length along the bezier curve.
*
* Calculates the proportional location on @p b as a number from
* 0.0 to 1.0 that corresponds to a distance @p len along it.
*
* @p b. No check is done on @p b.
* @since 1.16
@ -109,11 +111,12 @@ EAPI double eina_bezier_length_get(const Eina_Bezier *b) EINA_ARG_NONNULL(1);
EAPI double eina_bezier_t_at(const Eina_Bezier *b, double len) EINA_ARG_NONNULL(1);
/**
* @brief Gets the point on the bezier curve at
* position t.
* @brief Gets the point on the bezier curve at position t.
*
* @param b The floating point bezier.
* @param t The floating point position.
* @param t The floating point position between 0.0 and 1.0.
* @param[out] px The corresponding point's X coordinate.
* @param[out] py The corresponding point's Y coordinate.
*
* @p b. No check is done on @p b.
* @since 1.16
@ -121,11 +124,10 @@ EAPI double eina_bezier_t_at(const Eina_Bezier *b, double len) EINA_ARG_NONNULL(
EAPI void eina_bezier_point_at(const Eina_Bezier *b, double t, double *px, double *py) EINA_ARG_NONNULL(1);
/**
* @brief Returns the slope of the bezier
* at given length.
* @brief Determines the slope of the bezier at a given position.
*
* @param b The floating point bezier.
* @param len The given length.
* @param t The position along the bezier between 0.0 and 1.0.
*
* @p b. No check is done on @p b.
* @since 1.16
@ -133,10 +135,12 @@ EAPI void eina_bezier_point_at(const Eina_Bezier *b, double t, double *px, doubl
EAPI double eina_bezier_angle_at(const Eina_Bezier *b, double t) EINA_ARG_NONNULL(1);
/**
* @brief Splits the bezier at given length.
* @brief Splits the bezier at a given length.
*
* @param b The floating point bezier.
* @param len The given length.
* @param len The length along the bezier to make the split.
* @param[out] left The resultant split's left portion of the bezier.
* @param[out] right The resultant split's right portion of the bezier.
*
* @p b. No check is done on @p b.
* @since 1.16
@ -144,13 +148,13 @@ EAPI double eina_bezier_angle_at(const Eina_Bezier *b, double t) EINA_ARG_NONNUL
EAPI void eina_bezier_split_at_length(const Eina_Bezier *b, double len, Eina_Bezier *left, Eina_Bezier *right) EINA_ARG_NONNULL(1);
/**
* @brief Gets the bounds of the bezier.
* @brief Calculates and returns the bounding box for the bezier.
*
* @param b The floating point bezier.
* @param x x coordinate of bounding box.
* @param y y coordinate of bounding box.
* @param w width of bounding box.
* @param h height of bounding box.
* @param x The X coordinate of the bounding box.
* @param y The Y coordinate of the bounding box.
* @param w The width of the bounding box.
* @param h The height of the bounding box.
*
* @p b. No check is done on @p b.
* @since 1.17
@ -158,12 +162,12 @@ EAPI void eina_bezier_split_at_length(const Eina_Bezier *b, double len, Eina_Bez
EAPI void eina_bezier_bounds_get(const Eina_Bezier *b, double *x, double *y, double *w, double *h) EINA_ARG_NONNULL(1);
/**
* @brief Finds the bezier at the given interval.
* @brief Finds the bezier between the given interval.
*
* @param b The floating point bezier.
* @param t0 The start interval.
* @param t1 The end interval.
* @param result The result bezier.
* @param t0 The start of the interval.
* @param t1 The end of the interval.
* @param result The resulting bezier.
*
* @p b. No check is done on @p b.
* @since 1.17