canvg处理svg转png

来源：https://github.com/canvg/canvg

Include the following files in your page:

<script type="text/javascript" src="http://canvg.github.io/canvg/rgbcolor.js">script> 
<script type="text/javascript" src="http://canvg.github.io/canvg/StackBlur.js">script>
<script type="text/javascript" src="http://canvg.github.io/canvg/canvg.js">script> 

Put a canvas on your page

<canvas id="canvas" width="1000px" height="600px">canvas> 

Example canvg calls:

<script type="text/javascript">
window.onload = function() {
  //load '../path/to/your.svg' in the canvas with id = 'canvas'
  canvg('canvas', '../path/to/your.svg')

  //load a svg snippet in the canvas with id = 'drawingArea'
  canvg(document.getElementById('drawingArea'), '')

  //ignore mouse events and animation
  canvg('canvas', 'file.svg', { ignoreMouse: true, ignoreAnimation: true }) 
}
</script>

The third parameter is options:

• log: true => console.log information
• ignoreMouse: true => ignore mouse events
• ignoreAnimation: true => ignore animations
• ignoreDimensions: true => does not try to resize canvas
• ignoreClear: true => does not clear canvas
• offsetX: int => draws at a x offset
• offsetY: int => draws at a y offset
• scaleWidth: int => scales horizontally to width
• scaleHeight: int => scales vertically to height
• renderCallback: function => will call the function after the first render is completed
• forceRedraw: function => will call the function on every frame, if it returns true, will redraw
• useCORS: true => will attempt to use CORS on images to not taint canvas

You can call canvg without parameters to replace all svg images on a page. See the example.

There is also a built in extension method to the canvas context to draw svgs similar to the way drawImage works:

var c = document.getElementById('canvas');
var ctx = c.getContext('2d');
ctx.drawSvg(SVG_XML_OR_PATH_TO_SVG, dx, dy, dw, dh);

自己将canvans转svg的两种实现方式：

//直接svgBase64转Png	
/* function getBase64PNG(svgStr,themeSize) {
	  var image = new Image();
	  image.src = svgStr;
	  
      var canvas = document.createElement("canvas");
      canvas.width = 300;
      canvas.height = 300;
      var ctx = canvas.getContext("2d");
      if(themeSize==3){
      	  ctx.drawImage(image, 0, 0);
      }else if(themeSize==2){
	      ctx.drawImage(image, 50, 50);
      }else if(themeSize==1){
      	  ctx.drawImage(image, 100, 100);
      }
      var dataURL = canvas.toDataURL("image/png");
      return dataURL
} */
/**
*直接svg转Png的pngBase64
*/
function getBase64PNG(svgStr,themeSize) {
      var canvas = document.createElement("canvas");
      canvas.width = 300;
      canvas.height = 300;
      var ctx = canvas.getContext("2d");
      if(themeSize==3){
      	  ctx.drawSvg(svgStr, 0, 0, 300, 300);
      }else if(themeSize==2){
	      ctx.drawSvg(svgStr, 50, 50, 200, 200);
      }else if(themeSize==1){
      	  ctx.drawSvg(svgStr, 100, 100, 100, 100);
      }
      var dataURL = canvas.toDataURL("image/png");
      return dataURL
}