App-Music-ChordPro
view release on metacpan or search on metacpan
lib/ChordPro/lib/SVGPDF/Contrib/Bogen.pm view on Meta::CPAN
#! perl
use v5.26;
use strict;
use warnings;
package SVGPDF::Contrib::Bogen;
=head1 NAME
SVGPDF::Contrib::Bogen - Circular and elliptic curves
=head1 SYNOPSIS
$context->bogen( $x1,$y1, $x2,$y2, $r, @opts);
$context->bogen_ellip( $x1,$y1, $x2,$y2, $rx,$ry, @opts);
=head1 DESCRIPTION
This package contains functions to draw circular and elliptic curves.
This code is developed by Phil Perry, based on old PDF::API2 code and
friendly contributed to the SVGPDF project.
=cut
use Math::Trig;
=over
=item $context->bogen_ellip($x1,$y1, $x2,$y2, $rx,$ry, @opts)
This is a variant of the original C<bogen()> call from PDF::Builder, which
drew a segment (arc) of a circle, which was adapted here by Phil Perry to draw
an elliptical arc.
(German for I<bow>, as in a segment (arc) of an ellipse), this is a
segment of an ellipse defined by the intersection of two ellipses of given x
and y radii, with the two intersection points as inputs. There are four
possible resulting arcs, which can be selected with opts C<large> and C<dir>.
This extends the path along an arc of an ellipse of the specified x and y radii
between C<[$x1,$y1]> to C<[$x2,$y2]>. The current position is then set
to the endpoint of the arc (C<[$x2,$y2]>).
Options (C<@opts>)
=over
=item 'move' => move_flag
Set C<move> to a I<true> value if this arc is the beginning of a new
path instead of the continuation of an existing path. Note that the default
(C<move> => I<false>) is
I<not> a straight line to I<P1> and then the arc, but a blending into the curve
from the current point. It will often I<not> pass through I<P1>! Set to
I<true>, there will be a jump (move) from the current point to I<P1>, to where
the arc will start.
=item 'large' => larger_arc_flag
Set C<large> to a I<true> value to draw the larger ("outer") arc between the
two points, instead of the smaller one. Both arcs are
drawn I<clockwise> from I<P1> to I<P2>. The default value of I<false> draws
the smaller arc.
=item 'dir' => draw_direction
Set C<dir> to a I<true> value to draw the mirror image of the specified arc
(flip it over, so that its center point is on the other side of the line
connecting the two points). Both arcs (small or large) are drawn
I<counter-clockwise> from I<P1> to I<P2>. The default (I<false>) draws
clockwise arcs.
=item 'rotate' => axis_rotation
A non-zero value is the degrees to rotate the axes of the ellipse (in a
counter-clockwise manner). For example, C<'rotate'=E<gt>45> will have the
ellipse's +X axis pointing "northeast" and the +Y axis pointing "northwest".
The default value is 0 (no rotation).
=item 'full' => color_spec
If given (no default), draw the full ellipse (not just the arc)
in this color, with a dot at its center. This may be useful
for diagnostic and development purposes, to show the ellipse from which
the arc is obtained.
=back
B<Note:>
If the given radii C<$rx> and C<$ry> are too small for the points
I<P1> and I<P2> to fit on the specified ellipse, they will be proportionately
scaled up untilthe points fit on the ellipse.
This is a silent error, as due to rounding, given points (even if correct)
may not exactly fit on the ellipse. Further note that the algorithm only
enlarges the radii until a sweep of 180 degrees is obtained, so it is possible
that the ellipse will be smaller than your intended one!
=back
=cut
lib/ChordPro/lib/SVGPDF/Contrib/Bogen.pm view on Meta::CPAN
# self = graphics context
# rx and ry = radii
# alpha and beta = starting and ending sweeps (degrees)
# x' and y' = P1'
# x2 and y2 = last point (if needed)
# dir = 1 CW, 0 CCW
# rotate = axis rotation in radians
# returns nothing. curve called to output the curve to PDF
sub _arc2points {
my ($self, $rx,$ry, $alpha,$beta, $x1,$y1, $x2,$y2, $dir, $rotate) = @_;
my (@points, $x,$y, $p0_x,$p0_y, $p1_x,$p1_y, $p2_x,$p2_y, $p3_x,$p3_y);
$dir = !$dir;
# @points is relative to starting point of arc
@points = _arctocurve($rx,$ry, $alpha,$beta, $dir,$rotate);
# counterrotate all start/end/control points around P1 by -rotate degrees
if ($rotate) {
my $r = $rotate; # already in radians
my $cosR = cos($r);
my $sinR = sin($r);
my ($x,$y, $xr,$yr);
for (my $i=0; $i<@points; $i+=2) {
$x = $points[$i]; $y = $points[$i+1];
$xr = $x1 + $cosR*($x-$x1) - $sinR*($y-$y1);
$yr = $y1 + $sinR*($x-$x1) + $cosR*($y-$y1);
$points[$i] = $xr; $points[$i+1] = $yr;
}
}
$p0_x = shift @points;
$p0_y = shift @points;
$x = $x1 - $p0_x;
$y = $y1 - $p0_y;
while (scalar @points > 0) {
$p1_x = $x + shift @points;
$p1_y = $y + shift @points;
$p2_x = $x + shift @points;
$p2_y = $y + shift @points;
# if we run out of data points, use the end point instead
if (scalar @points == 0) {
$p3_x = $x2;
$p3_y = $y2;
} else {
$p3_x = $x + shift @points;
$p3_y = $y + shift @points;
}
$self->curve($p1_x,$p1_y, $p2_x,$p2_y, $p3_x,$p3_y);
shift @points;
shift @points;
}
return $self;
}
# input: x and y axis radii
# sweep start and end angles (degrees)
# sweep direction (0=CCW (default), or 1=CW)
# axis rotation (radians, + = CCW, default = 0)
# output: two endpoints and two control points for
# the Bezier curve describing the arc
# maximum 30 degrees of sweep: is broken up into smaller
# arc segments if necessary
# if crosses 0 degree angle in either sweep direction, split there at 0
# if alpha=beta (0 degree sweep) or either radius <= 0, fatal error
sub _arctocurve {
my ($rx,$ry, $alpha,$beta, $dir,$rot) = @_;
if (!defined $rot) { $rot = 0; } # default is no rotation
if (!defined $dir) { $dir = 0; } # default is CCW sweep
# check for non-positive radius
if ($rx <= 0 || $ry <= 0) {
die "curve request with radius not > 0 ($rx, $ry)";
}
# check for zero degrees of sweep
if ($alpha == $beta) {
die "curve request with zero degrees of sweep ($alpha to $beta)";
}
# constrain alpha and beta to 0..360 range so 0 crossing check works
while ($alpha < 0.0) { $alpha += 360.0; }
while ( $beta < 0.0) { $beta += 360.0; }
while ($alpha > 360.0) { $alpha -= 360.0; }
while ( $beta > 360.0) { $beta -= 360.0; }
# Note that there is a problem with the original code, when the 0 degree
# angle is crossed. It especially shows up in arc() and pie(). Therefore,
# split the original sweep at 0 degrees, if it crosses that angle.
if (!$dir && $alpha > $beta) { # CCW pass over 0 degrees
if ($alpha == 360.0 && $beta == 0.0) { # oddball case
return (_arctocurve($rx,$ry, 0.0,360.0, 0,$rot));
} elsif ($alpha == 360.0) { # alpha to 360 would be null
return (_arctocurve($rx,$ry, 0.0,$beta, 0,$rot));
} elsif ($beta == 0.0) { # 0 to beta would be null
return (_arctocurve($rx,$ry, $alpha,360.0, 0,$rot));
} else {
return (
_arctocurve($rx,$ry, $alpha,360.0, 0,$rot),
_arctocurve($rx,$ry, 0.0,$beta, 0,$rot)
);
}
}
if ($dir && $alpha < $beta) { # CW pass over 0 degrees
if ($alpha == 0.0 && $beta == 360.0) { # oddball case
return (_arctocurve($rx,$ry, 360.0,0.0, 1,$rot));
} elsif ($alpha == 0.0) { # alpha to 0 would be null
return (_arctocurve($rx,$ry, 360.0,$beta, 1,$rot));
} elsif ($beta == 360.0) { # 360 to beta would be null
return (_arctocurve($rx,$ry, $alpha,0.0, 1,$rot));
} else {
return (
_arctocurve($rx,$ry, $alpha,0.0, 1,$rot),
_arctocurve($rx,$ry, 360.0,$beta, 1,$rot)
);
}
}
# limit arc length to 30 degrees, for reasonable smoothness
# none of the long arcs or short resulting arcs cross 0 degrees
if (abs($beta-$alpha) > 30) {
return (
_arctocurve($rx,$ry, $alpha,($beta+$alpha)/2, $dir,$rot),
_arctocurve($rx,$ry, ($beta+$alpha)/2,$beta, $dir,$rot)
);
} else {
# calculate cubic Bezier points (start, two control, end)
my ($p0_x,$p0_y, $p1_x,$p1_y, $p2_x,$p2_y, $p3_x,$p3_y);
# Note that we can't use deg2rad(), because closed arcs (circle() and
# ellipse()) are 0-360 degrees, which deg2rad treats as 0-0 radians!
my $aa = $alpha * 3.141593 / 180;
my $bb = $beta * 3.141593 / 180;
my $bcp = (4.0/3 * (1 - cos(($bb - $aa)/2)) / sin(($bb - $aa)/2));
my $sin_alpha = sin($aa);
my $sin_beta = sin($bb);
my $cos_alpha = cos($aa);
my $cos_beta = cos($bb);
$p0_x = $rx * $cos_alpha;
$p0_y = $ry * $sin_alpha;
$p1_x = $rx * ($cos_alpha - $bcp * $sin_alpha);
$p1_y = $ry * ($sin_alpha + $bcp * $cos_alpha);
$p2_x = $rx * ($cos_beta + $bcp * $sin_beta);
$p2_y = $ry * ($sin_beta - $bcp * $cos_beta);
$p3_x = $rx * $cos_beta;
$p3_y = $ry * $sin_beta;
return ($p0_x,$p0_y, $p1_x,$p1_y, $p2_x,$p2_y, $p3_x,$p3_y);
}
}
# Circular arc ('bogen'), by PDF::API2 and anhanced by PDF::Builder.
=over
=item $content->bogen($x1,$y1, $x2,$y2, $radius, $move, $larger, $reverse)
=item $content->bogen($x1,$y1, $x2,$y2, $radius, $move, $larger)
=item $content->bogen($x1,$y1, $x2,$y2, $radius, $move)
=item $content->bogen($x1,$y1, $x2,$y2, $radius)
(I<bogen> is German for I<bow>, as in a segment (arc) of a circle. This is a
segment of a circle defined by the intersection of two circles of a given
radius, with the two intersection points as inputs. There are B<four> possible
resulting arcs, which can be selected with C<$larger> and C<$reverse>.)
This extends the path along an arc of a circle of the specified radius
between C<[$x1,$y1]> to C<[$x2,$y2]>. The current position is then set
to the endpoint of the arc (C<[$x2,$y2]>).
Set C<$move> to a I<true> value if this arc is the beginning of a new
path instead of the continuation of an existing path. Note that the default
(C<$move> = I<false>) is
I<not> a straight line to I<P1> and then the arc, but a blending into the curve
from the current point. It will often I<not> pass through I<P1>!
Set C<$larger> to a I<true> value to draw the larger ("outer") arc between the
two points, instead of the smaller one. Both arcs are drawn I<clockwise> from
I<P1> to I<P2>. The default value of I<false> draws the smaller arc.
Note that the "other" circle's larger arc is used (the center point is
"flipped" across the line between I<P1> and I<P2>), rather than using the
"remainder" of the smaller arc's circle (which would necessitate reversing the
direction of travel along the arc -- see C<$reverse>).
Set C<$reverse> to a I<true> value to draw the mirror image of the
specified arc (flip it over, so that its center point is on the other
side of the line connecting the two points). Both arcs are drawn
I<counter-clockwise> from I<P1> to I<P2>. The default (I<false>) draws
clockwise arcs. An arc is B<always> drawn from I<P1> to I<P2>; the direction
(clockwise or counter-clockwise) may be chosen.
The C<$radius> value cannot be smaller than B<half> the distance from
C<[$x1,$y1]> to C<[$x2,$y2]>. If it is too small, the radius will be set to
half the distance between the points (resulting in an arc that is a
semicircle). This is a silent error.
=back
=cut
sub bogen {
my ($self, $x1,$y1, $x2,$y2, $r, $move, $larc, $spf) = @_;
my ($p0_x,$p0_y, $p1_x,$p1_y, $p2_x,$p2_y, $p3_x,$p3_y);
my ($dx,$dy, $x,$y, $alpha,$beta, $alpha_rad, $d,$z, $dir, @points);
if ($x1 == $x2 && $y1 == $y2) {
die "bogen requires two distinct points";
}
if ($r <= 0.0) {
die "bogen requires a positive radius";
}
$move = 0 if !defined $move;
$larc = 0 if !defined $larc;
$spf = 0 if !defined $spf;
$dx = $x2 - $x1;
$dy = $y2 - $y1;
$z = sqrt($dx**2 + $dy**2);
$alpha_rad = asin($dy/$z); # |dy/z| guaranteed <= 1.0
$alpha_rad = pi - $alpha_rad if $dx < 0;
# alpha is direction of vector P1 to P2
$alpha = rad2deg($alpha_rad);
# use the complementary angle for flipped arc (arc center on other side)
# effectively clockwise draw from P2 to P1
$alpha -= 180 if $spf;
$d = 2*$r;
( run in 1.503 second using v1.01-cache-2.11-cpan-524268b4103 )