imagearc

(PHP 4, PHP 5, PHP 7)

imagearc — 画椭圆弧

说明

bool imagearc ( resource $image , int $cx , int $cy , int $w , int $h , int $s , int $e , int $color )

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。

Example #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);
?>

参见 imageellipse()，imagefilledellipse() 和 imagefilledarc()。

User Contributed Notes

lucas dot delmas at live dot fr 08-Jul-2013 04:15


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.

joe dot tym at gmail dot com 03-Oct-2012 02:08


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);


                }


        }


}


?>

chandlerklebs at gmail dot com 08-Jan-2012 07:24


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);

?>

ajim1417 at gmail dot com 29-Jan-2010 04:42


I wrote a simple function that can draws an arc counter-clockwisekly. Here it is :



<?php



function imagearcCC(&$im, $cx, $cy, $w, $h, $s, $e, $c) {

$start = 360 - $e;

$end = 360 - $s;

return imagearc($im, $cx, $cy, $w, $h, $start, $end, $c);

}



?>



The params of this function is exactly the same as the usual imagearc function.

anton dot vandeghinste at telenet dot be 13-Dec-2009 04:27


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);

    }

}

?>

mojiro at awmn dot net 13-Dec-2005 09:28


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 26-Dec-2003 11:05


[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

eamon at hostelworld dot com 17-Dec-2003 04:24


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.

logang at deltatee dot com 05-Aug-2003 05:19


Heres a function to make a curve between two points... This will be a downward curve but it wouldn't be hard to make a similar function to make an upward curve. The first point has to be to the left of the second point ($x1 < $x2), and height is actually backwards. The larger height is the less of a crest the curve has. I imagine with a few modifications this functions could make upward curves as well.



function ImageCurveDown ($image, $x1, $y1, $x2, $y2, $height, $color) {

    $presicion = 1;



    for ($left = ($x1-$x2); $left < 0; $left++){

        if ($y1 < $y2) {

            $cy = $y2 + $height;

            $cx = $x1 - $left;

        } else {

            $cy = $y1 + $height;

            $cx = $x2 + $left;

        }

        $nx1 = abs($x1 - $cx);

        $ny1 = abs($y1 - $cy);

        $nx2 = abs($x2 - $cx);

        $ny2 = abs($y2 - $cy);



        if ($y1 < $y2) {

            if ($nx2 == 0 || $ny1 == 0) continue;

            $angle1 = atan($height/$nx2);

            $A1 = $nx2/cos ($angle1);

            $B1 = $ny2/sin ($angle1);

            $angle2 = pi()/2 +atan($left/$ny1);

            $A2 = $nx1/cos ($angle2);

            $B2 = $ny1/sin ($angle2);

        } else {

            if ($ny2 == 0 || $nx1 == 0) continue;

            $angle1 = atan($ny2/$nx2);

            $A1 = abs($nx2/cos ($angle1));

            $B1 = abs($ny2/sin ($angle1));

            $angle2 = atan($height/$nx1);

            $A2 = abs ($nx1/cos ($angle2));

            $B2 = abs($ny1/sin ($angle2));

        }



        if (abs($A1 - $A2) < $presicion && abs ($B1 - $B2) < $presicion) {

            ImageArc($image, $cx, $cy, $A1*2, $B1*2, 180+rad2deg($angle2), 360-rad2deg($angle1), $color);

        }

    }

}

23-Jan-2003 05:55


Please note that in order to draw a complete circle or ellipse (without using the imageellipse) you mustn't use 0? for both s and e. If you do this you will get, umm, nothing. Instead set s to 0? and e to 360? to get a complete circle or ellipse.

jinny at 263 dot net 14-May-2002 07:27


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);

?>

arve at skogvold dot as 30-Nov-2001 10:04


I found a better way for drawing a pie chart:





header ("Content-type: image/png");


$diameter = 100;


$radius = $diameter / 2;


$centerX = $radius;


$centerY = $radius;





$im = @ImageCreate ($diameter, $diameter)


    or die ("Cannot Initialize new GD image stream");





$background = ImageColorAllocate ($im, 0, 0, 0);


$red = ImageColorAllocate ($im, 176, 0, 0);





function fill_arc($start, $end, $color) {


    global $diameter, $centerX, $centerY, $im, $radius;


    imagearc($im, $centerX, $centerY, $diameter, $diameter, $start, $end, $color); 


    imageline($im, $centerX, $centerY, $centerX + cos(deg2rad($start)) * $radius, $centerY + sin(deg2rad($start)) * $radius, $color);


    imageline($im, $centerX, $centerY, $centerX + cos(deg2rad($end)) * $radius, $centerY + sin(deg2rad($end)) * $radius, $color);


    imagefill ($im,$centerX + $radius * 0.5 *cos(deg2rad($start+($end-$start)/2)), $centerY + $radius * 0.5 * sin(deg2rad($start+($end-$start)/2)), $color);


    }








fill_arc(0,30,$red);


// Will make a red filled arc, starting at 0 degrees, ending at 30 degrees





ImagePng ($im);

marc at resiteit dot com 08-Nov-2001 10:04


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);

foripepe at yahoo dot com 02-Sep-2001 06:56


To fill an arc (DiameterX != DiameterY):





<?


function imagefilledarc($Image, $CenterX, $CenterY, $DiameterX, $DiameterY, $Start, $End, $Color) {


    // To draw the arc


    imagearc($Image, $CenterX, $CenterY, $DiameterX, $DiameterY, $Start, $End, $Color);


    // To close the arc with 2 lines between the center and the 2 limits of the arc


    $x = $CenterX + (cos(deg2rad($Start))*($DiameterX/2));


    $y = $CenterY + (sin(deg2rad($Start))*($DiameterY/2));


    imageline($Image, $x, $y, $CenterX, $CenterY, $Color);


    $x = $CenterX + (cos(deg2rad($End))*($DiameterX/2));


    $y = $CenterY + (sin(deg2rad($End))*($DiameterY/2));


    imageline($Image, $x, $y, $CenterX, $CenterY, $Color);


    // To fill the arc, the starting point is a point in the middle of the closed space


    $x = $CenterX + (cos(deg2rad(($Start+$End)/2))*($DiameterX/4));


    $y = $CenterY + (sin(deg2rad(($Start+$End)/2))*($DiameterY/4));


    imagefilltoborder($Image, $x, $y, $Color, $Color);


}


?>





To close the arc with 2 lines (DiameterX != DiameterY):





<?


function imagenofilledarc($Image, $CenterX, $CenterY, $DiameterX, $DiameterY, $Start, $End, $Color) {


    // To draw the arc


    imagearc($Image, $CenterX, $CenterY, $DiameterX, $DiameterY, $Start, $End, $Color);


    // To close the arc with 2 lines between the center and the 2 limits of the arc


    $x = $CenterX + (cos(deg2rad($Start))*($DiameterX/2));


    $y = $CenterY + (sin(deg2rad($Start))*($DiameterY/2));


    imageline($Image, $x, $y, $CenterX, $CenterY, $Color);


    $x = $CenterX + (cos(deg2rad($End))*($DiameterX/2));


    $y = $CenterY + (sin(deg2rad($End))*($DiameterY/2));


    imageline($Image, $x, $y, $CenterX, $CenterY, $Color);


}


?>





An example:


<?


    $destImage = imagecreate( 216, 152 );


    $c0 = imagecolorallocate( $destImage, 0, 255, 255 );


    $c1 = imagecolorallocate( $destImage, 0, 0, 0 );


    $c2 = imagecolorallocate( $destImage, 255, 0, 0 );


    ImageFilledRectangle ( $destImage, 0, 0, 216, 152, $c0 );


    imagefilledarc( $destImage, 108, 76, 180, 80, 0, 130, $c1 );


    imagenofilledarc( $destImage, 108, 76, 180, 80, 0, 130, $c2 );


    header("content-type: image/PNG");


    ImagePNG( $destImage );


    ImageDestroy( $destImage );


?>

nojer2 at yahoo dot com 01-Apr-2001 11:18


Here's a dashed circle function:





<?php


function dashedcircle($im, $cx, $cy, $radius, $colour, $dashsize=5) {





   $dash=false;


   for ($angle=0; $angle<=(180+$dashsize); $angle+=$dashsize) {


      $x = ($radius * cos(deg2rad($angle)));


      $y = ($radius * sin(deg2rad($angle)));





      if ($dash) {


         imageline($im, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour); 


         imageline($im, $cx-$px, $cx-$py, $cx-$x, $cy-$y, $colour); 


      }


      $dash=!$dash;


      $px=$x;


      $py=$y;


   } 


}


?>

nojer2 at yahoo dot com 01-Apr-2001 11:06


Here's the function to draw rotated ellipses again. This time I've optimised it a bit, fixed the no-fill bug, and used a 'squishratio' rather than a 'radiusmodifier', to make the curves perfect, so ignore my previous version.





<?php


function rotatedellipse($im, $cx, $cy, $width, $height, $rotateangle, $colour, $filled=true) {


   $step=2;


   $cosangle=cos(deg2rad($rotateangle));


   $sinangle=sin(deg2rad($rotateangle));





   $squishratio = $height/$width;


   $nopreviouspoint = true;


   for ($angle=0; $angle<=(180+$step); $angle+=$step) {


       


      $ox = ($width * cos(deg2rad($angle)));


      $oy = ($width * sin(deg2rad($angle))) * $squishratio;





      $x =  + (($ox * $cosangle) - ($oy * $sinangle));


      $y = $centrey + (($ox * $sinangle) + ($oy * $cosangle));


  


      if ($nopreviouspoint) {


        $px=$x;


        $py=$y;


        $nopreviouspoint=false;


      }





      if ($filled) {


         triangle($im, $cx, $cy, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour);


         triangle($im, $cx, $cy, $cx-$px, $cx-$py, $cx-$x, $cy-$y, $colour);


      } else {


         imageline($im, $cx+$px, $cy+$py, $cx+$x, $cy+$y, $colour); 


         imageline($im, $cx-$px, $cx-$py, $cx-$x, $cy-$y, $colour); 


      }


      $px=$x;


      $py=$y;


   } 


}





function triangle($im, $x1,$y1, $x2,$y2, $x3,$y3, $colour) {


   $coords = array($x1,$y1, $x2,$y2, $x3,$y3);


   imagefilledpolygon($im, $coords, 3, $colour); 


}


?>

cbriou at orange-art dot fr 18-Sep-2000 04:03


There is another way to fill an arc :





<?php


// To draw the arc


$Color = imagecolorallocate($Image, $Red, $Green, $Blue);


imagearc($Image, $CenterX, $CenterY, $Diameter, $Diameter, $Start, $End, $Color);


// To close the arc with 2 lines between the center and the 2 limits of the arc


$x = $CenterX + (cos(deg2rad($Start))*($Diameter/2));


$y = $CenterY + (sin(deg2rad($Start))*($Diameter/2));


imageline($Image, $x, $y, $CenterX, $CenterY, $Color);


$x = $CenterX + (cos(deg2rad($End))*($Diameter/2));


$y = $CenterY + (sin(deg2rad($End))*($Diameter/2));


imageline($Image, $x, $y, $CenterX, $CenterY, $Color);


// To fill the arc, the starting point is a point in the middle of the closed space


$x = $CenterX + (cos(deg2rad(($Start+$End)/2))*($Diameter/4));


$y = $CenterY + (sin(deg2rad(($Start+$End)/2))*($Diameter/4));


imagefilltoborder($Image, $x, $y, $Color, $Color);


?>

timothyhouck at yahoo dot com 17-Aug-2000 12:58


To do filled arcs, try something like this:





<?php


$diameter = 50;


imagearc($image, 25, 25, $diameter, $diameter, $start, $end, $color);


while($diameter > 0) {


  imagearc($image, 25, 25, $diameter, $diameter, $start, $start + 1, $color);


  imagearc($image, 25, 25, $diameter, $diameter, $end - 1, $end, $color);


  $diameter--;


}


?>





...well you get the point.  It's a kludge, and *very* slow, but it's free.

travis at duluth dot com 23-Dec-1999 03:36


The wierd thing is that the first two integers tell where to place the "circle".


So for example I first create the "pallet" to place the circle on.


$image = imagecreate(500, 500);  


(this makes a huge 500x500 gif :) )


$colorBody = imagecolorallocate($image, 0, 0, 0);


(make the default color of the "pallet" black


$circleColor = imagecolorallocate($image, 255, 0, 255);


(going to make the circle an ugly pink color)


imagearc($image, 250, 250, 300, 300, 0, 360, $circleColor);


Places the image in the center (250,250) and the circle is 300 pixels in diameter.





Hope this helps.


 


Travis Kent Beste