draw diagonal lines in div background with CSS

问题

I have a div for a preview box:

HTML:

<div class=\"preview-content\">PREVIEW</div>

CSS:

.preview-content {
    background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAQAAAAECAYAAACp8Z5+AAAAGklEQVQIW2NkYGD4D8SMQAwGcAY2AbBKDBUAVuYCBQPd34sAAAAASUVORK5CYII=) repeat;
    width: 100%;
    min-height: 300px;
    max-height: 300px;
    line-height: 300px;
    text-align: center;
    vertical-align: middle;
     font-size: 2em;
}

Question: how to add diagonal lines to div background like in the picture?

note: with CSS only if possible

$\"preview\"$

Thank you in advance.

回答1:

You can do it something like this:

<style>
    .background {
        background-color: #BCBCBC;
        width: 100px;
        height: 50px;
        padding: 0; 
        margin: 0
    }
    .line1 {
        width: 112px;
        height: 47px;
        border-bottom: 1px solid red;
        -webkit-transform:
            translateY(-20px)
            translateX(5px)
            rotate(27deg); 
        position: absolute;
        /* top: -20px; */
    }
    .line2 {
        width: 112px;
        height: 47px;
        border-bottom: 1px solid green;
        -webkit-transform:
            translateY(20px)
            translateX(5px)
            rotate(-26deg);
        position: absolute;
        top: -33px;
        left: -13px;
    }
</style>
<div class="background">
    <div class="line1"></div>
    <div class="line2"></div>
</div>

Here is a jsfiddle.

Improved version of answer for your purpose.

回答2:

Almost perfect solution, that automatically scales to dimensions of an element would be usage of CSS3 linear-gradient connected with calc() as shown below. Main drawback is of course compatibility. Code below works in Firefox 25 and Explorer 10 and 11, but in Chrome (I've tested v30 and v32 dev) there are some subtle problems with lines disappearing if they are too narrow. Moreover disappearing depends on the box dimensions – style below works for div { width: 100px; height: 100px}, but fails for div { width: 200px; height: 200px} for which in my tests 0.8px in calculations needs to be replaced with at least 1.1048507095px for diagonals to be shown and even then line rendering quality is quite poor. Let's hope this Chrome bug will be solved soon.

.crossed {
     background: 
         linear-gradient(to top left,
             rgba(0,0,0,0) 0%,
             rgba(0,0,0,0) calc(50% - 0.8px),
             rgba(0,0,0,1) 50%,
             rgba(0,0,0,0) calc(50% + 0.8px),
             rgba(0,0,0,0) 100%),
         linear-gradient(to top right,
             rgba(0,0,0,0) 0%,
             rgba(0,0,0,0) calc(50% - 0.8px),
             rgba(0,0,0,1) 50%,
             rgba(0,0,0,0) calc(50% + 0.8px),
             rgba(0,0,0,0) 100%);
}

<textarea class="crossed"></textarea>

回答3:

You can use SVG to draw the lines.

.diag {
    background: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' version='1.1' preserveAspectRatio='none' viewBox='0 0 100 100'><path d='M1 0 L0 1 L99 100 L100 99' fill='black' /><path d='M0 99 L99 0 L100 1 L1 100' fill='black' /></svg>");
    background-repeat:no-repeat;
    background-position:center center;
    background-size: 100% 100%, auto;
}

<div class="diag" style="width: 300px; height: 100px;"></div>

Have a play here: http://jsfiddle.net/tyw7vkvm

回答4:

All other answers to this 3-year old question require CSS3 (or SVG). However, it can also be done with nothing but lame old CSS2:

.crossed {
    position: relative;
    width: 300px;
    height: 300px;
}

.crossed:before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    top: 1px;
    bottom: 1px;
    border-width: 149px;
    border-style: solid;
    border-color: black white;
}

.crossed:after {
    content: '';
    position: absolute;
    left: 1px;
    right: 1px;
    top: 0;
    bottom: 0;
    border-width: 149px;
    border-style: solid;
    border-color: white transparent;
}

<div class='crossed'></div>

Explanation, as requested:

Rather than actually drawing diagonal lines, it occurred to me we can instead color the so-called negative space triangles adjacent to where we want to see these lines. The trick I came up with to accomplish this exploits the fact that multi-colored CSS borders are bevelled diagonally:

.borders {
    width: 200px;
    height: 100px;
    background-color: black;
    border-width: 40px;
    border-style: solid;
    border-color: red blue green yellow;
}

<div class='borders'></div>

To make things fit the way we want, we choose an inner rectangle with dimensions 0 and LINE_THICKNESS pixels, and another one with those dimensions reversed:

.r1 { width: 10px;
      height: 0;
      border-width: 40px;
      border-style: solid;
      border-color: red blue;
      margin-bottom: 10px; }
.r2 { width: 0;
      height: 10px;
      border-width: 40px;
      border-style: solid;
      border-color: blue transparent; }

<div class='r1'></div><div class='r2'></div>

Finally, use the :before and :after pseudo-selectors and position relative/absolute as a neat way to insert the borders of both of the above rectangles on top of each other into your HTML element of choice, to produce a diagonal cross. Note that results probably look best with a thin LINE_THICKNESS value, such as 1px.

回答5:

Please check the following.

<canvas id="myCanvas" width="200" height="100"></canvas>
<div id="mydiv"></div>

JS:

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.strokeStyle="red";
ctx.moveTo(0,100);
ctx.lineTo(200,0);
ctx.stroke();
ctx.moveTo(0,0);
ctx.lineTo(200,100);
ctx.stroke();

CSS:

html, body { 
  margin: 0;
  padding: 0;
}

#myCanvas {
  padding: 0;
  margin: 0;
  width: 200px;
  height: 100px;
}

#mydiv {
  position: absolute;
  left: 0px;
  right: 0;
  height: 102px;
  width: 202px;
  background: rgba(255,255,255,0);
  padding: 0;
  margin: 0;
}

jsfiddle

回答6:

you can use a CSS3 transform Property:

div
{
transform:rotate(Xdeg);
-ms-transform:rotate(Xdeg); /* IE 9 */
-webkit-transform:rotate(Xdeg); /* Safari and Chrome */
}

Xdeg = your value

For example...

You can make more div and use a z-index property. So,make a div with line, and rotate it.

回答7:

If you'd like the cross to be partially transparent, the naive approach would be to make linear-gradient colors semi-transparent. But that doesn't work out good due to the alpha blending at the intersection, producing a differently colored diamond. The solution to this is to leave the colors solid but add transparency to the gradient container instead:

.cross {
  position: relative;
}
.cross::after {
  pointer-events: none;
  content: "";
  position: absolute;
  top: 0; bottom: 0; left: 0; right: 0;
}

.cross1::after {
  background:
    linear-gradient(to top left, transparent 45%, rgba(255,0,0,0.35) 46%, rgba(255,0,0,0.35) 54%, transparent 55%),
    linear-gradient(to top right, transparent 45%, rgba(255,0,0,0.35) 46%, rgba(255,0,0,0.35) 54%, transparent 55%);
}

.cross2::after {
  background:
    linear-gradient(to top left, transparent 45%, rgb(255,0,0) 46%, rgb(255,0,0) 54%, transparent 55%),
    linear-gradient(to top right, transparent 45%, rgb(255,0,0) 46%, rgb(255,0,0) 54%, transparent 55%);
  opacity: 0.35;
}

div { width: 180px; text-align: justify; display: inline-block; margin: 20px; }

<div class="cross cross1">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam et dui imperdiet, dapibus augue quis, molestie libero. Cras nisi leo, sollicitudin nec eros vel, finibus laoreet nulla. Ut sit amet leo dui. Praesent rutrum rhoncus mauris ac ornare. Donec in accumsan turpis, pharetra eleifend lorem. Ut vitae aliquet mi, id cursus purus.</div>

<div class="cross cross2">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam et dui imperdiet, dapibus augue quis, molestie libero. Cras nisi leo, sollicitudin nec eros vel, finibus laoreet nulla. Ut sit amet leo dui. Praesent rutrum rhoncus mauris ac ornare. Donec in accumsan turpis, pharetra eleifend lorem. Ut vitae aliquet mi, id cursus purus.</div>

回答8:

intrepidis' answer on this page using a background SVG in CSS has the advantage of scaling nicely to any size or aspect ratio, though the SVG uses <path>s with a fill that doesn't scale so well.

I've just updated the SVG code to use <line> instead of <path> and added non-scaling-stroke vector-effect to prevent the strokes scaling with the container:

<svg xmlns='http://www.w3.org/2000/svg' version='1.1' preserveAspectRatio='none' viewBox='0 0 100 100'>
  <line x1='0' y1='0' x2='100' y2='100' stroke='black' vector-effect='non-scaling-stroke'/>
  <line x1='0' y1='100' x2='100' y2='0' stroke='black' vector-effect='non-scaling-stroke'/>
</svg>

Here's that dropped into the CSS from the original answer (with HTML made resizable):

.diag {
  background: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' version='1.1' preserveAspectRatio='none' viewBox='0 0 100 100'><line x1='0' y1='0' x2='100' y2='100' stroke='black' vector-effect='non-scaling-stroke'/><line x1='0' y1='100' x2='100' y2='0' stroke='black' vector-effect='non-scaling-stroke'/></svg>");
  background-repeat: no-repeat;
  background-position: center center;
  background-size: 100% 100%, auto;
}

<div class="diag" style="width: 200px; height: 150px; border: 1px solid; resize: both; overflow: auto"></div>

回答9:

.borders {
    width: 200px;
    height: 100px;
    background-color: black;
    border-width: 40px;
    border-style: solid;
    border-color: red blue green yellow;
}

<div class='borders'></div>

来源：https://stackoverflow.com/questions/18012420/draw-diagonal-lines-in-div-background-with-css

标签

css

background

line

css-shapes

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