imagearc
(PHP 4, PHP 5, PHP 7, PHP 8)
imagearc — 画椭圆弧
说明
imagearc(
resource
int
int
int
int
int
int
int
): bool
resource
$image,int
$cx,int
$cy,int
$w,int
$h,int
$s,int
$e,int
$color): bool
imagearc() 以
cx，cy（图像左上角为 0, 0）为中心在
image 所代表的图像中画一个椭圆弧。w
和 h 分别指定了椭圆的宽度和高度，起始和结束点以
s 和 e
参数以角度指定。0°位于三点钟位置，以顺时针方向绘画。
示例 #1 用 imagearc() 画一个圆
<?php
// 创建一个 200X200 的图像
$img = imagecreatetruecolor(200, 200);
// 分配颜色
$white = imagecolorallocate($img, 255, 255, 255);
$black = imagecolorallocate($img, 0, 0, 0);
// 画一个黑色的圆
imagearc($img, 100, 100, 150, 150, 0, 360, $black);
// 将图像输出到浏览器
header("Content-type: image/png");
imagepng($img);
// 释放内存
imagedestroy($img);
?>
add a note
User Contributed Notes 20 notes
chandlerklebs at gmail dot com ¶
10 years ago
This is an example script I wrote for myself to help me learn how to used the imagearc functions. Maybe if will also help others.
<?php
//example PHP script of imagearc functions
$image_width=360;$image_height=360;
$img = imagecreatetruecolor($image_width,$image_height); //make image variable
//create a background color by making a filled rectangle
$color = imagecolorallocate($img,255,255,255);
imagefilledrectangle($img,0,0,$image_width,$image_height,$color);
$r=$image_width/2 - $image_width/32 ; //radius
$cx=$image_width/2;
$cy=$image_height/2;
$color = imagecolorallocate($img,0,0,0);
imagearc($img, $cx, $cy, $r*2, $r*2, 0, 360, $color); //regular outlines arc
imagefilledarc($img, $cx, $cy, $r*1, $r*1, 0, 90, $color,IMG_ARC_CHORD); //filled triangle with chord of circle
imagefilledarc($img, $cx, $cy, $r*1, $r*1, 180, 270, $color,IMG_ARC_PIE); //pie slice
$font_number=5; //can use built in fonts numbered 1 to 5
$string="Hello world!";
imagestring($img, $font_number, $cx-(imagefontwidth($font_number)*strlen($string))/2, $cy-120, $string, $color);
header("Content-type: image/png");
imagepng($img);// output image in the browser
$filename="imagearc";
imagepng($img,"./frames/$filename.png",9); //make highly compressed png
imagedestroy($img);
?>
anton dot vandeghinste at telenet dot be ¶
12 years ago
I needed an arc with a thick border and i didn't like to use 359.9 as end angle so i made a function that works pretty well:
<?php
function imagearcthick($image, $x, $y, $w, $h, $s, $e, $color, $thick = 1)
{
if($thick == 1)
{
return imagearc($image, $x, $y, $w, $h, $s, $e, $color);
}
for($i = 1;$i<($thick+1);$i++)
{
imagearc($image, $x, $y, $w-($i/5), $h-($i/5),$s,$e,$color);
imagearc($image, $x, $y, $w+($i/5), $h+($i/5), $s, $e, $color);
}
}
?>
eamon at hostelworld dot com ¶
18 years ago
Right...
possibly the easiest way of drawing a filled circle:
Loop through the imagearc function incrementing the diameter by one pixel:
<?
// --- code fragment --- //
for($i=1; $i<$Diameter; $i++){
imagearc($Image, $CenterX, $CenterY, $i, $i, $Start, $End, $Color);
}
// --------------------- //
?>
This works great for circles with diameters up to about 60 or 70 pixels wide. After that, you start to get pixle gaps.
jinny at 263 dot net ¶
20 years ago
imagesetstyle() sets the style to be used by all line drawing functions when drawing with the special color .
Here goes a example of drawing a dashed-line circle.enjoy!
<?php
header("Content-type: image/jpeg");
$im = imagecreate(100,100);
$b = imagecolorallocate ($im, 0, 0, 0);
$w = imagecolorallocate ($im, 255, 255, 255);
$style = array ($b,$b,$b,$b,$b,$w,$w,$w,$w,$w);
imagesetstyle ($im, $style);
imagearc($im,50,50,100,100,0,360,IMG_COLOR_STYLED);
imagejpeg($im);
imagedestroy($im);
?>
lucas dot delmas at live dot fr ¶
8 years ago
The imagearc function has a precision of one degree. The function truncates the $start and $end values to the inferior degree.
For example if the starting angle you calculated is : -178.62450462172°
and the ending angle is : -152.78056427917°
imagearc will draw a curve from -178° to -152°.
If you need accurate curves drawing, you need to use a loop to draw little step-by-step lines. By creating a large number of short enough lines, you will create the impression of a curve with accuracy.
marc at resiteit dot com ¶
20 years ago
Round cornered anti-aliased dynamically sized button.
$w=40;
$h=20;
$im = ImageCreate($w,$h);
$white=ImageColorAllocate($im,255,255,255);
ImageFilledRectangle($im,0,0,$w,$h,$white);
imagecolortransparent ($im, $white);
ImageTTFText ($im, $h+ceil($h/3)+1, 0, -1, $h-1, $col1, "arialbd.ttf", "O");
ImageTTFText ($im, $h+ceil($h/3)+1, 0, $w-$h, $h-1, $col1, "arialbd.ttf", "O");
ImageTTFText ($im, $h+ceil($h/3)+1, 0, 1, $h-1, $col1, "arialbd.ttf", "O");
ImageTTFText ($im, $h+ceil($h/3)+1, 0, $w-$h-2, $h-1, $col1, "arialbd.ttf", "O");
$points=array(
1,round($h/2),
round($h/4),$h-round($h/4),
round($h/2),$h,
$w-(round($h/2)),$h,
$w-(round($h/4)),$h-round($h/4),
$w-2,round($h/2),
$w-round($h/4),round($h/4),
$w-round($h/2),0,
round($h/2),0,
round($h/4),round($h/4)
);
imagefilledpolygon ($im, $points, 10, $col1);
header("content-type: image/gif");
header("Content-Disposition: filename=name.gif");
ImageGif($im);
ImageDestroy($im);
cleverphp ¶
4 years ago
imagearc example works not well,as it lacks of this line
"$white = imagecolorallocate($img, 255, 255, 255);
imagefill($img,0,0,$white);
$black = imagecolorallocate($img, 0, 0, 0);
"
joe dot tym at gmail dot com ¶
9 years ago
I didn't have much luck with the other two functions, one of them makes circles that look like they've been printed on a dot-matrix printer. This simple function builds a border out of circles, seems to work nicely.
<?php
function imagearcunfilled($image,$x,$y,$width,$height,$border_thickness, $color) {
imagesetthickness($image, 1);
$x_radius = $width / 2;
$y_radius = $height / 2;
for ($i = 0; $i < 360; $i++) {
if (TRUE) {
$x2 = $x + cos($i) * $x_radius;
$y2 = $y + sin($i) * $y_radius;
imagefilledarc($image,$x2,$y2,$border_thickness,$border_thickness,0,360,$color,IMG_ARC_PIE);
}
}
}
?>
mojiro at awmn dot net ¶
16 years ago
A previous for the Rotated (Filled)Ellipse note from(nojer2 at yahoo dot com, 02-Apr-2001 12:06) has a mistake, at the second arc. Replace them with the following listing.
if ($filled) {
triangle($im, $cx, $cy, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour);
triangle($im, $cx, $cy, $cx-$px, $cy-$py, $cx-$x, $cy-$y, $colour);
} else {
imageline($im, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour);
imageline($im, $cx-$px, $cy-$py, $cx-$x, $cy-$y, $colour);
}
jerryscript at aol dot com ¶
18 years ago
[note-Apache/1.3.29 (Win32) PHP/4.3.4]
The imagearc (and imageellipse) functions do not accept line thicknesses when drawn from 0 to 360 degrees.
Drawing from 0 to 359 and again from 359 to 360 does create an ellipse with the current line thickness.
Jerry