|
|
|
|
Bookmark this on Delicious
Share on Facebook
 Slashdot It!
Digg  imageantialias
Should antialias functions be used or not
(PHP 4 >= 4.3.2, PHP 5)
Code Examples / Notes » imageantialiasphp
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! voinic
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); ?> n-dream
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; } } trimbo
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 ); ?> jb
Official GD Lib manual link: http://www.boutell.com/gd/manual2.0.33.html#gdImageSetAntiAliased godfather of image processing
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
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 '$destImage' (e.g. display or output to file!) ?> ulrich mierendorff
I've written a php function which draws antialiased and filled elliptic arcs (segments of ellipses or full ellipses). It does not require the imageantialias function of php! It's available at http://icewind.ic.funpic.de/index.php?content=ellipse Best Regards, Ulrich klaas
I have optimized the "imageSmoothLine" function by logang. sample and download at: http://www.kosmokrator.com/download/php/ sebbi
I did a search in google and got following url: http://www.isocalc.com/tutorials/antialias.htm With this tutorial I was able to write a function to convert this algorithm into php, the result for a filled circel is this: <?php function imagefilledcircleantialiased(&$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. klaas
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 ); ?> |
Change Language
gd_info getimagesize image_type_to_extension image_type_to_mime_type image2wbmp imagealphablending imageantialias imagearc imagechar imagecharup imagecolorallocate imagecolorallocatealpha imagecolorat imagecolorclosest imagecolorclosestalpha imagecolorclosesthwb imagecolordeallocate imagecolorexact imagecolorexactalpha imagecolormatch imagecolorresolve imagecolorresolvealpha imagecolorset imagecolorsforindex imagecolorstotal imagecolortransparent imageconvolution imagecopy imagecopymerge imagecopymergegray imagecopyresampled imagecopyresized imagecreate imagecreatefromgd2 imagecreatefromgd2part imagecreatefromgd imagecreatefromgif imagecreatefromjpeg imagecreatefrompng imagecreatefromstring imagecreatefromwbmp imagecreatefromxbm imagecreatefromxpm imagecreatetruecolor imagedashedline imagedestroy imageellipse imagefill imagefilledarc imagefilledellipse imagefilledpolygon imagefilledrectangle imagefilltoborder imagefilter imagefontheight imagefontwidth imageftbbox imagefttext imagegammacorrect imagegd2 imagegd imagegif imagegrabscreen imagegrabwindow imageinterlace imageistruecolor imagejpeg imagelayereffect imageline imageloadfont imagepalettecopy imagepng imagepolygon imagepsbbox imagepsencodefont imagepsextendfont imagepsfreefont imagepsloadfont imagepsslantfont imagepstext imagerectangle imagerotate imagesavealpha imagesetbrush imagesetpixel imagesetstyle imagesetthickness imagesettile imagestring imagestringup imagesx imagesy imagetruecolortopalette imagettfbbox imagettftext imagetypes imagewbmp imagexbm iptcembed iptcparse jpeg2wbmp png2wbmp |
