CairoContext::arc

cairo_arc

(PECL cairo >= 0.1.0)

CairoContext::arc -- cairo_arc — Adds a circular arc

说锟斤拷

锟斤拷锟斤拷锟斤拷锟斤拷锟� (method):

public CairoContext::arc ( float $x , float $y , float $radius , float $angle1 , float $angle2 ) : void

锟斤拷锟教伙拷锟斤拷锟�:

cairo_arc ( CairoContext $context , float $x , float $y , float $radius , float $angle1 , float $angle2 ) : void

Adds a circular arc of the given radius to the current path. The arc is centered at (x, y), begins at angle1 and proceeds in the direction of increasing angles to end at angle2. If angle2 is less than angle1 it will be progressively increased by 2*M_PI until it is greater than angle1. If there is a current point, an initial line segment will be added to the path to connect the current point to the beginning of the arc. If this initial line is undesired, it can be avoided by calling CairoContext::newSubPath() or procedural cairo_new_sub_path() before calling CairoContext::arc() or cairo_arc(). Angles are measured in radians. An angle of 0.0 is in the direction of the positive X axis (in user space). An angle of M_PI/2.0 radians (90 degrees) is in the direction of the positive Y axis (in user space). Angles increase in the direction from the positive X axis toward the positive Y axis. So with the default transformation matrix, angles increase in a clockwise direction. (To convert from degrees to radians, use degrees * (M_PI / 180.).) This function gives the arc in the direction of increasing angles; see CairoContext::arcNegative() or cairo_arc_negative() to get the arc in the direction of decreasing angles.

锟斤拷锟斤拷

context

A valid CairoContext object

x

x position

y

y position

radius

Radius of the arc

angle1

start angle

angle2

end angle

锟斤拷锟斤拷值

没锟叫凤拷锟斤拷值锟斤拷

锟斤拷锟斤拷

Example #1 锟斤拷锟斤拷锟斤拷锟斤拷锟�

<?php

$s = new CairoImageSurface(CairoFormat::ARGB32, 100, 100);
$c = new CairoContext($s);

$c->setSourceRgb(0, 0, 0);
$c->paint();

$c->setLineWidth(1);
$c->setSourceRgb(1, 1, 1);

for ($r = 50; $r > 0; $r -= 10) {
 $c->arc(50, 50, $r, 0, 2 * M_PI);
 $c->stroke();
 $c->fill();
}

$s->writeToPng(dirname(__FILE__) . '/CairoContext__arc.png');
?>

Example #2 锟斤拷锟教伙拷锟斤拷锟�

<?php

$s = cairo_image_surface_create(CAIRO_SURFACE_TYPE_IMAGE, 100, 100);
$c = cairo_create($s);

cairo_set_source_rgb($c, 0, 0, 0);
cairo_paint($c);

cairo_set_source_rgb($c, 1, 1, 1);
cairo_set_line_width($c, 1);

for ($r = 50; $r > 0; $r -= 10) {
 cairo_arc($c, 50, 50, $r, 0, 2 * M_PI);
 cairo_stroke($c);
 cairo_fill($c);
}

cairo_surface_write_to_png($s, dirname(__FILE__) . '/cairo_arc.png');
?>

锟轿硷拷