根据背景颜色更改文本颜色

Is it possible to dynamically change the text color based on the background color using CSS, or JS if it's not possible with CSS? I have a image that comes under the text. My text color is white, but the image has a white shape on. And when text goes above the white shape, I need to change the text color in a darker color.

是否可以使用CSS动态更改基于背景颜色的文本颜色，或者如果CSS无法使用JS，则可以动态更改文本颜色？我有一个文字下面的图像。我的文字颜色为白色，但图像上有白色。当文本超出白色形状时，我需要更深颜色的文本颜色。

HTML:

HTML：

<div class="biography">
            <img src="http://s16.postimg.org/c09zw94jp/author_photo.png" alt="author" class="bio-img">
            <div class="biography-text">
                <p>
                    Lorem ipsum dolor sit amet, consectetur adipiscing elit <br>
                    Vestibulum pellentesque auctor quam a sollicitudin.<br>
                    Pellentesque accumsan a sem eget dictum.
                </p>
                <p>
                    Morbi dictum lorem tortor, id consequat libero gravida ut.<br>
Nullam dictum sed massa et bibendum.
                </p>
                <p>Praesent sed dui mattis, dictum urna sit amet, imperdiet purus.</p>
                <p> Suspendisse potenti.</p>
            </div>
        </div>

CSS:

CSS：

body {
  background-color: #7ccbe6;
}
.biography {
    min-height: 410px;
}
.biography .biography-text {
    position: relative;
    margin-top: -420px;
    padding: 82px 130px 0 380px;
    z-index: 1;
}

.biography-text {
    color: #fff;
}

Here's a Codepen to see the better picture.

这是一个Codepen，可以看到更好的图片。

4 个解决方案

#1

Probably you need this:

可能你需要这个：

Change text color based on brightness of the covered background area?

根据覆盖的背景区域的亮度更改文本颜色？

var rgb = [255, 0, 0];

setInterval(function() {
  var c = 'rgb(' + rgb[0] + ',' + rgb[1] + ',' + rgb[2] + ')';
  var o = Math.round(((parseInt(rgb[0]) * 299) + (parseInt(rgb[1]) * 587) + (parseInt(rgb[2]) * 114)) / 1000);
  (o > 125) ? $('#bg').css('color', 'black'): $('#bg').css('color', 'white'); //http://www.w3.org/TR/AERT#color-contrast
  $('#bg').css('background-color', c);
  rgb[0] = Math.round(Math.random() * 255);
  rgb[1] = Math.round(Math.random() * 255);
  rgb[2] = Math.round(Math.random() * 255);
}, 1000);

JSFiddle

的jsfiddle

Updated:

更新：

Use this example on JSFiddle, just change background color

在JSFiddle上使用此示例，只需更改背景颜色

#2

I do realize you are looking for a JS solution. However, if anyone wants a css solution here is a solution http://codepen.io/hellouniverse/pen/JNwvyL

我确实意识到你正在寻找一个JS解决方案。但是，如果有人想要一个css解决方案，这里有一个解决方案http://codepen.io/hellouniverse/pen/JNwvyL

$bg-color: black;  // This can change
$white : #fff;
$black : #000;

@function set-text-color($color) {
    @if (lightness( $color ) > 50) {
      @return $black; // Lighter color, return black
    }
    @else {
      @return $white; // Darker color, return white
    }
}

.text--color {
    background: $bg-color;
    color: set-text-color($bg-color);
}

// this is here just for demon purpose
.text {
    padding: 10px;
    text-align: center;
}


<p class="text text--color">I change in color</p>

#3

For this kind of problem I'd use a pure CSS solution to outline the text...

对于这类问题，我会使用纯CSS解决方案来概述文本......

.biography-text {
    color: #fff;
    font-weight: bold;
    letter-spacing: 2px;
    text-shadow: 1px 1px 0 #333,
        -1px -1px 0 #333,
        1px -1px 0 #333,
        -1px 1px 0 #333,
        2px 2px 5px rgba(0,0,0,0.65);
}

Change the letter-spacing and the final directive of the text-shadow property according to your needs.

根据您的需要更改text-shadow属性的字母间距和最终指令。

#4

There are some ways to achieve this. You could render the image on a (hidden) canvas and parse the image colors to know which color the text should be. You could also do the same with php and pre process the image color information.

有一些方法可以实现这一目标。您可以在（隐藏）画布上渲染图像并解析图像颜色以了解文本应该是哪种颜色。您也可以使用php执行相同操作并预处理图像颜色信息。

I also found this JavaScript library that could help you: http://www.kennethcachia.com/background-check/. (You could wrap each letter in a span element to determine the right color to use per letter.)

我还发现这个JavaScript库可以帮到你：http：//www.kennethcachia.com/background-check/。（您可以在span元素中包装每个字母，以确定每个字母使用的正确颜色。）

#1