问题
I\'m working on a web project that involves a dynamically generated map of the US coloring different states based on a set of data.
This SVG file gives me a good blank map of the US and is very easy to change the color of each state. The difficulty is that IE browsers don\'t support SVG so in order for me to use the handy syntax the svg offers, I\'ll need to convert it to a JPG.
Ideally, I\'d like to do this with only the GD2 library but could also use ImageMagick. I have absolutely no clue how to do this.
Any solution that would allow me to dynamically change the colors of states on a map of the US will be considered. The key is that it is easy to change the colors on the fly and that it is cross browser. PHP/Apache solutions only, please.
回答1:
That's funny you asked this, I just did this recently for my work's site and I was thinking I should write a tutorial... Here is how to do it with PHP/Imagick, which uses ImageMagick:
$usmap = '/path/to/blank/us-map.svg';
$im = new Imagick();
$svg = file_get_contents($usmap);
/*loop to color each state as needed, something like*/
$idColorArray = array(
"AL" => "339966"
,"AK" => "0099FF"
...
,"WI" => "FF4B00"
,"WY" => "A3609B"
);
foreach($idColorArray as $state => $color){
//Where $color is a RRGGBB hex value
$svg = preg_replace(
'/id="'.$state.'" style="fill:#([0-9a-f]{6})/'
, 'id="'.$state.'" style="fill:#'.$color
, $svg
);
}
$im->readImageBlob($svg);
/*png settings*/
$im->setImageFormat("png24");
$im->resizeImage(720, 445, imagick::FILTER_LANCZOS, 1); /*Optional, if you need to resize*/
/*jpeg*/
$im->setImageFormat("jpeg");
$im->adaptiveResizeImage(720, 445); /*Optional, if you need to resize*/
$im->writeImage('/path/to/colored/us-map.png');/*(or .jpg)*/
$im->clear();
$im->destroy();
the steps regex color replacement may vary depending on the svg path xml and how you id & color values are stored. If you don't want to store a file on the server, you can output the image as base 64 like
<?php echo '<img src="data:image/jpg;base64,' . base64_encode($im) . '" />';?>
(before you use clear/destroy) but ie has issues with PNG as base64 so you'd probably have to output base64 as jpeg
you can see an example here I did for a former employer's sales territory map:
Start: https://upload.wikimedia.org/wikipedia/commons/1/1a/Blank_US_Map_(states_only).svg
.svg){kind=spacer}
Finish:
Edit
Since writing the above, I've come up with 2 improved techniques:
1) instead of a regex loop to change the fill on state , use CSS to make style rules like
<style type="text/css">
#CA,#FL,HI{
fill:blue;
}
#Al, #NY, #NM{
fill:#cc6699;
}
/*etc..*/
</style>
and then you can do a single text replace to inject your css rules into the svg before proceeding with the imagick jpeg/png creation. If the colors don't change, check to make sure you don't have any inline fill styles in your path tags overriding the css.
2) If you don't have to actually create a jpeg/png image file (and don't need to support outdated browsers), you can manipulate the svg directly with jQuery. You can't access the svg paths when embedding the svg using img or object tags, so you'll have to directly include the svg xml in your webpage html like:
<div>
<?php echo file_get_contents('/path/to/blank/us-map.svg');?>
</div>
then changing the colors is as easy as:
<script type="text/javascript" src="/path/to/jquery.js"></script>
<script type="text/javascript">
$('#CA').css('fill', 'blue');
$('#NY').css('fill', '#ff0000');
</script>
回答2:
You mention that you are doing this because IE doesn't support SVG.
The good news is that IE does support vector graphics. Okay, so it's in the form of a language called VML which only IE supports, rather than SVG, but it is there, and you can use it.
Google Maps, among others, will detect the browser capabilities to determine whether to serve SVG or VML.
Then there's the Raphael library, which is a Javascript browswer-based graphics library, which supports either SVG or VML, again depending on the browser.
Another one which may help: SVGWeb.
All of which means that you can support your IE users without having to resort to bitmap graphics.
See also the top answer to this question, for example: XSL Transform SVG to VML
回答3:
When converting SVG to transparent PNG, dont forget to put this BEFORE $imagick->readImageBlob():
$imagick->setBackgroundColor(new ImagickPixel('transparent'));
回答4:
This is v. easy, have been doing work on this for the past few weeks.
You need the Batik SVG Toolkit. Download, and place the files in the same directory as the SVG you want to convert to a JPEG, also make sure you unzip it first.
Open the terminal, and run this command:
java -jar batik-rasterizer.jar -m image/jpeg -q 0.8 NAME_OF_SVG_FILE.svg
That should output a JPEG of the SVG file. Really easy. You can even just place it in a loop and convert loads of SVGs,
import os
svgs = ('test1.svg', 'test2.svg', 'etc.svg')
for svg in svgs:
os.system('java -jar batik-rasterizer.jar -m image/jpeg -q 0.8 '+str(svg)+'.svg')
回答5:
I do not know of a standalone PHP / Apache solution, as this would require a PHP library that can read and render SVG images. I'm not sure such a library exists - I don't know any.
ImageMagick is able to rasterize SVG files, either through the command line or the PHP binding, IMagick, but seems to have a number of quirks and external dependencies as shown e.g. in this forum thread. I think it's still the most promising way to go, it's the first thing I would look into if I were you.
回答6:
This is a method for converting a svg picture to a gif using standard php GD tools
1) You put the image into a canvas element in the browser:
<canvas id=myCanvas></canvas>
<script>
var Key='picturename'
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
base_image = new Image();
base_image.src = myimage.svg;
base_image.onload = function(){
//get the image info as base64 text string
var dataURL = canvas.toDataURL();
//Post the image (dataURL) to the server using jQuery post method
$.post('ProcessPicture.php',{'TheKey':Key,'image': dataURL ,'h': canvas.height,'w':canvas.width,"stemme":stemme } ,function(data,status){ alert(data+' '+status) });
}
</script>
And then convert it at the server (ProcessPicture.php) from (default) png to gif and save it. (you could have saved as png too then use imagepng instead of image gif):
//receive the posted data in php
$pic=$_POST['image'];
$Key=$_POST['TheKey'];
$height=$_POST['h'];
$width=$_POST['w'];
$dir='../gif/'
$gifName=$dir.$Key.'.gif';
$pngName=$dir.$Key.'.png';
//split the generated base64 string before the comma. to remove the 'data:image/png;base64, header created by and get the image data
$data = explode(',', $pic);
$base64img = base64_decode($data[1]);
$dimg=imagecreatefromstring($base64img);
//in order to avoid copying a black figure into a (default) black background you must create a white background
$im_out = ImageCreateTrueColor($width,$height);
$bgfill = imagecolorallocate( $im_out, 255, 255, 255 );
imagefill( $im_out, 0,0, $bgfill );
//Copy the uploaded picture in on the white background
ImageCopyResampled($im_out, $dimg ,0, 0, 0, 0, $width, $height,$width, $height);
//Make the gif and png file
imagegif($im_out, $gifName);
imagepng($im_out, $pngName);
回答7:
You can use Raphaël—JavaScript Library and achieve it easily. It will work in IE also.
回答8:
$command = 'convert -density 300 ';
if(Input::Post('height')!='' && Input::Post('width')!=''){
$command.='-resize '.Input::Post('width').'x'.Input::Post('height').' ';
}
$command.=$svg.' '.$source;
exec($command);
@unlink($svg);
or using : potrace demo :Tool4dev.com
来源：https://stackoverflow.com/questions/4809194/convert-svg-image-to-png-with-php