Rasterizer doesn't render transparencies inside shapes

[ricotheque]

Tried rasterizing this search icon SVG. Ended up with this:

require_once( __DIR__ . '/php-svg-master/autoloader.php' );

use SVG\SVG;

$svg = 'source.svg';
$test = SVG::fromFile( $svg );

$raster_image = $test->toRasterImage( 36, 36 );

imagepng( $raster_image, 'test.png', 9 );
imagejpeg( $raster_image, 'test.jpg', 100 );

Is this a limitation of the GD rendering library?

[meyfa]

Thanks for opening this issue, I'm looking into it.

[meyfa]

The problem seems to stem from the fact that the rasterizer treats every subpath as being completely unrelated to the previous ones, without taking into account that SVG imposes certain fill rules for cases where subpaths overlap.

I have no idea yet how to fix this, but it definitely needs attention.

Thanks again for reporting the problem!

[winkbrace]

Really unfortunate since this is quite an important requirement. It would have been so nice to be able to do this without phantom.js :/

I've tried to come up with a way to calculate the inner space and redraw a transparent layer over it, but that's rather difficult and won't even solve all cases. It's far easier to make the final transformation step with a nodejs tool like svg2png.

[andykirk]

I came across this issue and though I'd post my solution to rendering the PNG, using Imagick:

// Save the SVG first:
// ($image is the SVG as per docs, $svg_filename is the path and name of file to output)
file_put_contents($svg_filename, $image->toXMLString());

// Create a new Imagick:
$im = new Imagick();
$im->readImageBlob(file_get_contents($svg_filename));

// This is for PNG24, but can be any output Imagick supports:
$im->setImageFormat("png24");

// $png_filename is the file path and name for resultant raster image:
$im->writeImage($png_filename);
$im->clear();
$im->destroy();

Hope that helps someone.

Cheers

[meyfa]

This will probably come as a surprise to everyone involved (myself included), but I finally implemented this. See PR #136.
The icon now renders just fine using the exact same code from above:

I'd thank you for your patience, but I doubt this is still useful to any of the original participants of this discussion. Still it will hopefully benefit people that ran into this more recently!