imagearc

(PHP 4, PHP 5, PHP 7, PHP 8)

imagearc — Draws an arc

Descrizione

imagearc(
    GdImage $image,
    int $center_x,
    int $center_y,
    int $width,
    int $height,
    int $start_angle,
    int $end_angle,
    int $color
): bool

imagearc() draws an arc of circle centered at the given coordinates.

Elenco dei parametri

image: Una risorsa immagine, restituita da una delle funzioni di creazione immagine, come imagecreatetruecolor().
center_x: x-coordinate of the center.
center_y: y-coordinate of the center.
width: The arc width.
height: The arc height.
start_angle: The arc start angle, in degrees.
end_angle: The arc end angle, in degrees. 0° is located at the three-o'clock position, and the arc is drawn clockwise.
color: A color identifier created with imagecolorallocate().

Valori restituiti

Restituisce true in caso di successo, false in caso di fallimento.

Log delle modifiche

Versione	Descrizione
8.0.0	`image` expects a GdImage instance now; previously, a valid `gd` resource was expected.

Esempi

Example #1 Drawing a circle with imagearc()

<?php

// create a 200*200 image
$img = imagecreatetruecolor(200, 200);

// allocate some colors
$white = imagecolorallocate($img, 255, 255, 255);
$red   = imagecolorallocate($img, 255,   0,   0);
$green = imagecolorallocate($img,   0, 255,   0);
$blue  = imagecolorallocate($img,   0,   0, 255);

// draw the head
imagearc($img, 100, 100, 200, 200,  0, 360, $white);
// mouth
imagearc($img, 100, 100, 150, 150, 25, 155, $red);
// left and then the right eye
imagearc($img,  60,  75,  50,  50,  0, 360, $green);
imagearc($img, 140,  75,  50,  50,  0, 360, $blue);

// output image in the browser
header("Content-type: image/png");
imagepng($img);

?>

Il precedente esempio visualizzerà qualcosa simile a:

Output of example : Drawing a circle with imagearc()

Vedere anche:

imagefilledarc() - Draw a partial arc and fill it
imageellipse() - Draw an ellipse
imagefilledellipse() - Draw a filled ellipse

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User Contributed Notes 20 notes

down

jinny at 263 dot net ¶

23 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);
?>

down

chandlerklebs at gmail dot com ¶

13 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);
?>

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eamon at hostelworld dot com ¶

21 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.

down

cleverphp ¶

7 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);
"

down

marc at resiteit dot com ¶

23 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);

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jerryscript at aol dot com ¶

21 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

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foripepe at yahoo dot com ¶

24 years ago

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 );

?>

down

travis at duluth dot com ¶

25 years ago

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

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joe dot tym at gmail dot com ¶

12 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);

                }

        }

}

?>

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mojiro at awmn dot net ¶

19 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);
}