Background color of text in SVG

问题:

I want to color the background of svg text similar to background-color in css

I was only able to find documentation on fill, which colors the text itself

Is it even possible?

回答1:

No this is not possible, SVG elements do not have background-... presentation attributes.

To simulate this effect you could draw a rectangle behind the text attribute with fill="green" or something similar (filters). Using JavaScript you could do the following:

var ctx = document.getElementById("the-svg"),
textElm = ctx.getElementById("the-text"),
SVGRect = textElm.getBBox();

var rect = document.createElementNS("http://www.w3.org/2000/svg", "rect");
    rect.setAttribute("x", SVGRect.x);
    rect.setAttribute("y", SVGRect.y);
    rect.setAttribute("width", SVGRect.width);
    rect.setAttribute("height", SVGRect.height);
    rect.setAttribute("fill", "yellow");
    ctx.insertBefore(rect, textElm);

回答2:

You could use a filter to generate the background.

<svg width="100%" height="100%">
  <defs>
    <filter x="0" y="0" width="1" height="1" id="solid">
      <feFlood flood-color="yellow"/>
      <feComposite in="SourceGraphic"/>
    </filter>
  </defs>
<text filter="url(#solid)" x="20" y="50" font-size="50">solid background</text>
</svg>

回答3:

No, you can not add background color to SVG elements. You can do it programmatically with d3.

var text = d3.select("text");
var bbox = text.node().getBBox();
var padding = 2;
var rect = self.svg.insert("rect", "text")
    .attr("x", bbox.x - padding)
    .attr("y", bbox.y - padding)
    .attr("width", bbox.width + (padding*2))
    .attr("height", bbox.height + (padding*2))
    .style("fill", "red");

回答4:

The solution I have used is:

<svg>
  <line x1="100" y1="100" x2="500", y2="100" style="stroke:black; stroke-width: 2"/>    
  <text x="150" y="105" style="stroke:white; stroke-width:0.6em">Hello World!</text>
  <text x="150" y="105" style="fill:black">Hello World!</text>  
</svg>

A duplicate text item is being placed, with stroke and stroke-width attributes. The stroke should match the background colour, and the stroke-width should be just big enough to create a "splodge" on which to write the actual text.

A bit of a hack and there are potential issues, but works for me!

回答5:

Answer by Robert Longson (@RobertLongson) with modifications:

<svg width="100%" height="100%">
  <defs>
    <filter x="0" y="0" width="1" height="1" id="solid">
      <feFlood flood-color="yellow"/>
      <feComposite in="SourceGraphic" operator="xor"/>
    </filter>
  </defs>
  <text filter="url(#solid)" x="20" y="50" font-size="50"> solid background </text>
  <text x="20" y="50" font-size="50">solid background</text>
</svg>

and we have no bluring and no heavy "getBBox" :) Padding is provided by white spaces in text-element with filter. It's worked for me

回答6:

this is my favorite hack (not sure it should work). It refer an element that is not yet displayed, and it works pretty well

<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 620 40" preserveAspectRatio="xMidYMid meet">
    <defs>
        <filter x="-0.02" y="0" width="1.04" height="1.1" id="removebackground">
            <feFlood flood-color="#00ffff"/>
        </filter>
    </defs>

    <!--Draw the text--> 
    <use xlink:href="#mygroup" filter="url(#removebackground)" />
    <g id="mygroup">
        <text id="text1" x="9" y="20" style="text-anchor:start;font-size:14px;">custom text with background</text>  
        <line x1="200" y1="18" x2="200" y2="36" stroke="#000" stroke-width="5"/> 
        <line x1="120" y1="27" x2="203" y2="27" stroke="#000" stroke-width="5"/> 
    </g>
</svg>

回答7:

Instead of using a <text> tag, the <foreignObject> tag can be used, which allows for XHTML content with CSS.

回答8:

You can add style to your text:

  style="-webkit-tap-highlight-color: rgba(0, 0, 0, 0); 
    text-shadow: rgb(255, 255, 255) -2px -2px 0px, rgb(255, 255, 255) -2px 2px 0px, 
     rgb(255, 255, 255) 2px -2px 0px, rgb(255, 255, 255) 2px 2px 0px;"

White, in this example. Does not work in IE :)