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Last updated: Fri, 26 Jan 2007

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# imageantialias

(PHP 4 >= 4.3.2, PHP 5)

imageantialias -- Should antialias functions be used or not

## Описание

bool imageantialias ( resource image, bool on )

Activate the fast drawing antialiased methods for lines and wired polygons. It does not support alpha components. It works using a direct blend operation. It works only with truecolor images.

Thickness and styled are not supported.

Using antialiased primitives with transparent background color can end with some unexpected results. The blend method uses the background color as any other colors. The lack of alpha component support does not allow an alpha based antialiasing method.

## Список параметров

`image`

  An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().

`on`

  Wether to enable antialiasing or not.

## Возвращаемые значения

Возвращает `TRUE` в случае успешного завершения или `FALSE` в случае возникновения ошибки.

## Примечания

> Замечание: Эта функция доступна только в том случае, если PHP был скомпилирован со встроенной библиотекой GD.

## Смотрите также

imagecreatetruecolor()

add a note User Contributed Notes
imageantialias
Godfather of Image Processing
22-Feb-2007 10:05
`Of course, this IS a way to do antialiasing. Graphiccards do so. But for good results you should use at least a 4 times bigger source image than the destination to scale down. This is a 16 times higher fillrate. If you only use the proposed doublesized image, quality is still poor...`
padigan
06-Feb-2007 03:13
`If you can't be bothered creating (or searching for) a full screen antialias function.
You can actually cheat (well a bit of a dirty inefficient hack really!!)
and perform a fake antialias on an image by using 'imagecopyresampled'...
first create your source image twice the size of what you really want.
Then use 'imagecopyresampled' to shrink it to half the size, the function
automatically interpolates pixels to create an antialias effect!
I've used this in a pie chart function and it works brilliantly,
not as slow as I thought it might be!
the rough code below should give you the idea...
<?php
$realWidth = 500;
$realHeight = 500;
$srcWidth = $realWidth * 2;
$srcHeight = $realHeight * 2;
// create the larger source image
$srcImage = imagecreatetruecolor($srcWidth,$srcHeight);
// create the real/final image
$destImage = imagecreatetruecolor($realWidth,$realHeight);
// now do whatever you want to draw in the source image
// blah....
// now the picture is finished, do the shrink...
imagecopyresampled($destImage,$srcImage,0,0,0,0,
$realWidth,$realHeight,$srcWidth,$srcHeight);
// now just do whatever you want with '$destImage' (e.g. display or output to file!)
?>`
Ulrich Mierendorff
10-Aug-2006 12:39
`I've written a php function which draws antialiased and filled elliptic arcs (segments of ellipses or full ellipses). It does not require the imageantialias function of php!
It's available at
http://icewind.ic.funpic.de/index.php?content=ellipse
Best Regards,
Ulrich`
php at 3d-box dot com
08-Jul-2006 09:55
`This might help some people but I have created an antialiased, filled, ellipse function - the source for which is here:-
http://personal.3d-box.com/php/filledellipseaa.php
As the code is too much to put here!`
jb at flamedesign dot dk
30-Mar-2006 02:37
`Official GD Lib manual link:
http://www.boutell.com/gd/manual2.0.33.html#gdImageSetAntiAliased`
n-dream at gmx dot ch
18-Feb-2006 10:18
`The following function draws an AntiAliased (unfilled) Ellipse.
It is used just liked the nomral ImageEllipse function.
The optional parameter sets the number of segments...
function ImageEllipseAA( &$img, $x, $y, $w, $h,$color,$segments=70)
{
$w=$w/2;
$h=$h/2;
$jump=2*M_PI/$segments;
$oldx=$x+sin(-$jump)*$w;
$oldy=$y+cos(-$jump)*$h;
for($i=0;$i<2*(M_PI);$i+=$jump)
{
$newx=$x+sin($i)*$w;
$newy=$y+cos($i)*$h;
ImageLine($img,$newx,$newy,$oldx,$oldy,$color);
$oldx=$newx;
$oldy=$newy;
}
}`
klaas at kosmokrator dot com
15-Feb-2006 05:22
`Here is an optimized version of the optimized version of the antialiased circle function by sebbi: (more than 20 times faster)...
<?php
function imageSmoothCircle( &$img, $cx, $cy, $cr, $color ) {
$ir = $cr;
$ix = 0;
$iy = $ir;
$ig = 2 * $ir - 3;
$idgr = -6;
$idgd = 4 * $ir - 10;
$fill = imageColorExactAlpha( $img, $color[ 'R' ], $color[ 'G' ], $color[ 'B' ], 0 );
imageLine( $img, $cx + $cr - 1, $cy, $cx, $cy, $fill );
imageLine( $img, $cx - $cr + 1, $cy, $cx - 1, $cy, $fill );
imageLine( $img, $cx, $cy + $cr - 1, $cx, $cy + 1, $fill );
imageLine( $img, $cx, $cy - $cr + 1, $cx, $cy - 1, $fill );
$draw = imageColorExactAlpha( $img, $color[ 'R' ], $color[ 'G' ], $color[ 'B' ], 42 );
imageSetPixel( $img, $cx + $cr, $cy, $draw );
imageSetPixel( $img, $cx - $cr, $cy, $draw );
imageSetPixel( $img, $cx, $cy + $cr, $draw );
imageSetPixel( $img, $cx, $cy - $cr, $draw );
while ( $ix <= $iy - 2 ) {
if ( $ig < 0 ) {
$ig += $idgd;
$idgd -= 8;
$iy--;
} else {
$ig += $idgr;
$idgd -= 4;
}
$idgr -= 4;
$ix++;
imageLine( $img, $cx + $ix, $cy + $iy - 1, $cx + $ix, $cy + $ix, $fill );
imageLine( $img, $cx + $ix, $cy - $iy + 1, $cx + $ix, $cy - $ix, $fill );
imageLine( $img, $cx - $ix, $cy + $iy - 1, $cx - $ix, $cy + $ix, $fill );
imageLine( $img, $cx - $ix, $cy - $iy + 1, $cx - $ix, $cy - $ix, $fill );
imageLine( $img, $cx + $iy - 1, $cy + $ix, $cx + $ix, $cy + $ix, $fill );
imageLine( $img, $cx + $iy - 1, $cy - $ix, $cx + $ix, $cy - $ix, $fill );
imageLine( $img, $cx - $iy + 1, $cy + $ix, $cx - $ix, $cy + $ix, $fill );
imageLine( $img, $cx - $iy + 1, $cy - $ix, $cx - $ix, $cy - $ix, $fill );
$filled = 0;
for ( $xx = $ix - 0.45; $xx < $ix + 0.5; $xx += 0.2 ) {
for ( $yy = $iy - 0.45; $yy < $iy + 0.5; $yy += 0.2 ) {
if ( sqrt( pow( $xx, 2 ) + pow( $yy, 2 ) ) < $cr ) $filled += 4;
}
}
$draw = imageColorExactAlpha( $img, $color[ 'R' ], $color[ 'G' ], $color[ 'B' ], ( 100 - $filled ) );
imageSetPixel( $img, $cx + $ix, $cy + $iy, $draw );
imageSetPixel( $img, $cx + $ix, $cy - $iy, $draw );
imageSetPixel( $img, $cx - $ix, $cy + $iy, $draw );
imageSetPixel( $img, $cx - $ix, $cy - $iy, $draw );
imageSetPixel( $img, $cx + $iy, $cy + $ix, $draw );
imageSetPixel( $img, $cx + $iy, $cy - $ix, $draw );
imageSetPixel( $img, $cx - $iy, $cy + $ix, $draw );
imageSetPixel( $img, $cx - $iy, $cy - $ix, $draw );
}
}
$img = imageCreateTrueColor( 320, 240 );
imageSmoothCircle( $img, 160, 120, 100, array( 'R' => 0xCC, 'G' => 0x33, 'B' => 0x00 ) );
imageSmoothCircle( $img, 170, 110, 75, array( 'R' => 0xDD, 'G' => 0x66, 'B' => 0x00 ) );
imageSmoothCircle( $img, 180, 100, 50, array( 'R' => 0xEE, 'G' => 0x99, 'B' => 0x00 ) );
imageSmoothCircle( $img, 190, 90, 25, array( 'R' => 0xFF, 'G' => 0xCC, 'B' => 0x00 ) );
header( 'Content-Type: image/png' );
imagePNG( $img );
?>`
voinic at NOSgmailPAM dot com
12-Jan-2006 02:22
`The only trick I found to draw an antialiased polygon AND keep it transparent (to use them as overlays in google maps for example)... make two images and merge them. Order of operations is important and the transparency color of the final image must be set after the merge:
<?
header("Content-type: image/png");
$values = array(
40, 50, // Point 1 (x, y)
20, 240, // Point 2 (x, y)
60, 60, // Point 3 (x, y)
240, 20, // Point 4 (x, y)
50, 40, // Point 5 (x, y)
10, 10 // Point 6 (x, y)
);
$im = imagecreate(250, 250);
$bg = imagecolorallocate($im, 255, 255, 255);
$im2 = imagecreatetruecolor(250, 250);
$bg2 = imagecolorallocate($im2, 255, 255, 255);
imagefilledrectangle($im2,0,0,249,249,$bg2);
imagecolortransparent($im2, $bg);
imageantialias($im2, true);
$c_red = imagecolorallocate($im2, 255, 0, 0);
imagepolygon($im2, $values, 6, $c_red);
imageantialias($im2, false);
imagecopymerge($im, $im2,0,0,0,0,250,250,50);
imagecolortransparent($im, $bg);
$c_red_alpha = imagecolorallocatealpha($im, 255, 0, 0, 60);
imagefilledpolygon($im, $values, 6, $c_red_alpha);
imagepng($im);
imagedestroy($im);
imagedestroy($im2);
?>`
sebbi at conceptT dot com
26-Sep-2005 07:06
`I did a search in google and got following url:
http://www.isocalc.com/tutorials/antialias.htm
With this tutorial I was able to write a function to convert this algorithm into php, the result for a filled circel is this:
<?php
function imagefilledcircleantialiased(&$im, $cx, $cy, $r, $fgcolor, $bgcolor) {
$fgcolors = imagecolorsforindex($im,$fgcolor);
$bgcolors = imagecolorsforindex($im,$bgcolor);
for ( $x = $cx - $r; $x <= $cx + $r; $x++ ) {
for ( $y = $cy - $r; $y <= $cy + $r; $y++ ) {
$rx = $x - $cx; $ry = $y - $cy;
$ir = sqrt(( $rx == 0 ? 0 : pow($rx - 0.5*abs($rx)/$rx, 2) ) + ( $ry == 0 ? 0 : pow($ry - 0.5*abs($ry)/$ry, 2) ));
$or = sqrt(( $rx == 0 ? 0 : pow($rx + 0.5*abs($rx)/$rx, 2) ) + ( $ry == 0 ? 0 : pow($ry + 0.5*abs($ry)/$ry, 2) ));
if ( $or <= $r ) {
imagesetpixel($im, $x, $y, $fgcolor);
}
elseif ( $ir < $r ) {
$filled = 0;
for ( $xx = $x - 0.45; $xx < $x + 0.5; $xx+=0.1 ) {
for ( $yy = $y - 0.45; $yy < $y + 0.5; $yy+=0.1 ) {
$rxx = $xx - $cx; $ryy = $yy - $cy;
if ( sqrt(pow($rxx, 2) + pow($ryy, 2)) < $r ) $filled++;
}
}
$red = round($bgcolors['red'] + ( $fgcolors['red'] - $bgcolors['red'] ) * $filled / 100);
$green = round($bgcolors['green'] + ( $fgcolors['green'] - $bgcolors['green'] ) * $filled / 100);
$blue = round($bgcolors['blue'] + ( $fgcolors['blue'] - $bgcolors['blue'] ) * $filled / 100);
imagesetpixel($im, $x, $y, imagecolorclosest($im, $red, $green, $blue));
}
}
}
}
$width = 160;
$height = 200;
$r = 20;
$bgc = "651713";
$fgc = "b12b2c";
$im = imagecreate($width, $height);
$bgcolor = imagecolorallocate($im, hexdec(substr($bgc, 0, 2)), hexdec(substr($bgc, 2, 2)), hexdec(substr($bgc, 4, 2)));
for( $i = 0; $i < 100; $i++ ) {
imagecolorallocate($im, ( hexdec(substr($fgc, 0, 2)) + $i*hexdec(substr($bgc, 0, 2))) / ($i + 1), ( hexdec(substr($fgc, 2, 2)) + $i*hexdec(substr($bgc, 2, 2))) / ($i + 1), ( hexdec(substr($fgc, 4, 2)) + $i*hexdec(substr($bgc, 4, 2))) / ($i + 1));
}
$fgcolor = imagecolorclosest($im, hexdec(substr($fgc, 0, 2)), hexdec(substr($fgc, 2, 2)), hexdec(substr($fgc, 4, 2)));
imagefilledcircleantialiased($im, 80, 100, $r, $fgcolor, $bgcolor);
header("Content-Type: image/png");
imagepng($im);
?>
An improvement would be to draw the inner rectangle or more rectangles in the circle with the builtin rectangle function to reduce the usage of imagesetpixel() from (2*r)^2 to 2*Pi*(r + epsilon), in other words, the dependency on r would break down from square to linear.
Another improvement would be to determine filled and unfilled triangles in the observed pixel and calculate their areas, so we can get rid of the inner loops for getting the fraction filled/unfilled.
One can easily modify this function to solve other problems like lines, unfilled circles, etc.`
trimbo
06-Sep-2005 12:25
`So far using PHP 5.0.4 I've managed to get Imageantialias() to work well with:
ImageLine()
ImagePolygon()
but not with:
ImageArc()
ImageEllipse()
ImageFilled*()
You can still draw antialiased filled polygons by drawing a hollow polygon on top of a filled one with the same dimensions:
<?php
$points=array($x,$y, $x2,$y2, $x3,$y3);
imageFilledPolygon($im, $points, 3, $gray );
imagePolygon($im, $points, 3, $gray );
?>`
klaas at kosmokrator dot com
24-May-2004 07:21
`I have optimized the "imageSmoothLine" function by logang.
sample and download at:
http://www.kosmokrator.com/download/php/`
logang at deltatee dot com
05-Aug-2003 03:28
`I've writen some antialiasing functions for people who don't have the requirements for the builtin antialiasing.
You can download a copy at: http://grey.deltatee.com/image.phps`
Igor Garcia
30-Jun-2003 02:57
`This function its only available if you have the BUNDLED version of GD.
(PHP 4.3.2)`
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