如何用内嵌svg画一个以圆圈为中心的数字? [英] How to draw a number centered inside a circle with inline svg?

问题描述

我正在尝试编写Django模板标记，该标记将在圆内生成一个数字作为内嵌svg.

I'm trying to write a Django template tag that will generate a number inside a circle as an inline svg.

数学运算非常简单(real_fontsize中的软键因子除外-我认为它与数字短于最高字符短有关.. ??)

The math is pretty straight-forward (except for the fudge-factor in real_fontsize -- I'm thinking it has to do with numerals being shorter than the tallest character..?)

@register.inclusion_tag('numcircle.html')
def numcircle(n, size=36, border=4, color='white', background="black", **kw):
    """Draw a circle with a number inside.
    """
    kw['padding'] = kw.get('padding', 2)
    kw['num'] = n
    kw['size'] = size
    kw['border'] = border
    kw['center'] = size / 2
    kw['radius'] = (size / 2) - border
    kw['color'] = color
    kw['background'] = background
    kw['fontsize'] = size - (2 * (border + kw['padding']))
    real_fontsize = kw['fontsize'] * (0.8 if kw['fontsize'] > 25 else 1)
    kw['ypos'] = kw['center'] + real_fontsize / 2 - kw['border'] + kw.get('yadjust', 0)
    kw['xpos'] = kw.get('xpos', size / 2)
    return kw

模板:

<svg width="{{ size }}" height="{{ size }}" viewBox="0 0 {{ size }} {{ size }}">
    <circle cx="{{ center }}"
            cy="{{ center }}"
            r="{{ radius }}"
            stroke="{{ color }}"
            stroke-width="{{ border }}"
            fill="{{ background }}"/>
    <text font-size="{{ fontsize }}"
          fill="{{ color }}"
          font-family="Verdana"
          text-anchor="middle"
          alignment-baseline="baseline"
          x="{{ xpos }}"
          y="{{ ypos }}">{{ num }}</text>
</svg>

它会生成一个svg，可以在我测试过的所有浏览器中很好地呈现，但本地iPad浏览器除外，该数字与圆圈的底部齐平(而不是在中心).

it produces an svg that renders very nicely in all browsers I have tested, except the native iPad browser, where the number is flush with the bottom of the circle (and not in the center)..

<svg width="44" height="44" viewBox="0 0 44 44">
<circle cx="22"
        cy="22"
        r="20"
        stroke="white"
        stroke-width="2"
        fill="#21435F"/>
<text font-size="36"
      fill="white"
      font-family="Verdana"
      text-anchor="middle"
      alignment-baseline="baseline"
      x="22"
      y="34.4">1</text>
</svg>

有没有办法以跨浏览器(IE9 +)的方式解决此问题?

Is there any way to work around this issue in a cross-browser (IE9+) fashion?

jsfiddle: http://jsfiddle.net/onLyh6bm/

jsfiddle: http://jsfiddle.net/onLyh6bm/

(在任何浏览器中，使用alignment-baseline: middle似乎都不会在中间对齐..: http://jsfiddle.net/68oamxdo/1/)

(using alignment-baseline: middle doesn't seem to align in the middle in any browser..: http://jsfiddle.net/68oamxdo/1/)

推荐答案

您不能真正依赖alignment-baseline属性.对此的支持充其量是不完整的.

You can't really rely on the alignment-baseline property. Support for it is pretty spotty at best.

即使受支持，alignment-baseline: middle也不真正将字符垂直居中.实际上，没有任何方法可以准确可靠地做到这一点.

Even when it is supported, alignment-baseline: middle doesn't really vertically centre the characters. There is, in fact, no way to do it accurately and reliably.

您可以使用text-anchor="middle"来水平居中，这在任何地方都受支持.

You can centre horizontally with text-anchor="middle", which is supported everywhere.

IMO，在垂直情况下，您可以做的最好的就是我在此答案中提出的解决方案: https://stackoverflow. com/a/19273331/1292848

IMO, the best you can do in the vertical case, is the solution I propose in this answer: https://stackoverflow.com/a/19273331/1292848

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