为什么div和旋转的div(三角形)之间有间隙-前端问题

Why there is a gap between div and rotated div (triangle)(为什么div和旋转的div(三角形)之间有间隙)

本文介绍了为什么div和旋转的div(三角形)之间有间隙的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在尝试在 HTML/CSS 中为我的移动应用程序制作此形状:

这就是我制作形状的方式:

我创建了第一个 div 来做斜线.我做了一个响应三角形(我从这个

在上图中，您可以看到绘制了相同的三角形，但在左侧它启用了抗锯齿，在右侧它被禁用.如您所见，启用抗锯齿后，当三角形仅通过部分像素时，像素为灰色阴影.但是，禁用时，像素将填充为纯黑色或纯白色，并且形状看起来参差不齐.

<小时>

使用 背面可见性:隐藏； 或在缩放/转换时重叠具有负边距的元素是避免此问题的更好选择.

演示不使用backface-visibility: hidden;

html,身体 {变换:比例(.8)；}.边界{宽度:100.13723%；底部填充:5.24078%；位置:相对；溢出:隐藏；背景颜色:白色；}.boundary:之前{内容: '';位置:绝对；顶部:0；左:0；宽度:100%；高度:100%；变换原点:左上角；变换:旋转(3度)；背景颜色:绿色；}.inner {高度:100%；宽度:100%；背景颜色:绿色；}

<div class="boundary"></div><div 类="内部">Lorem ipsum dolor sit amet，consectetur adipiscing elit，sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.Duis aute irure dolor在 voluptate velit esse cillum dolore eu fugiat nulla pariatur 受到谴责.Exceptioneur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est labourum.</div>

<小时>

使用 backface-visibility: hidden;

的演示

html,身体 {变换:比例(.8)；}.边界{宽度:100.13723%；底部填充:5.24078%；位置:相对；溢出:隐藏；背景颜色:白色；}.boundary:之前{内容: '';位置:绝对；顶部:0；左:0；宽度:100%；高度:100%；变换原点:左上角；变换:旋转(3度)；背景颜色:绿色；}.inner {高度:100%；宽度:100%；背景颜色:绿色；背面可见性:隐藏；-webkit-backface-visibility:隐藏；}

<div class="boundary"></div><div 类="内部">Lorem ipsum dolor sit amet，consectetur adipiscing elit，sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.Duis aute irure dolor在 voluptate velit esse cillum dolore eu fugiat nulla pariatur 受到谴责.Exceptioneur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est labourum.</div>

<小时>

演示由 OP in comment 通过使用 backface-visibility: hidden; 和具有 negative margin

的重叠元素解决

html,身体 {变换:比例(.75)；}.inner {高度:100%；宽度:100%；背景颜色:绿色；背面可见性:隐藏；-webkit-backface-visibility:隐藏；}.inner-2 {背景颜色:红色；背面可见性:隐藏；-webkit-backface-visibility:隐藏；}.inner-3 {背景颜色:蓝色；背面可见性:隐藏；-webkit-backface-visibility:隐藏；}.边界{宽度:100.13723%；底部填充:5.24078%；位置:相对；溢出:隐藏；背景颜色:白色；边距顶部:-2px；}.boundary:之前{内容: '';位置:绝对；顶部:0；左:0；宽度:100%；高度:100%；变换原点:左上角；变换:旋转(3度)；背景颜色:绿色；背面可见性:隐藏；}.boundary-2 {背景颜色:绿色；}.boundary-2:之前 {变换原点:右上角；变换:旋转(-3度)；背景颜色:红色；}.boundary-3 {背景颜色:红色；}.boundary-3:之前 {变换原点:左上角；变换:旋转(3度)；背景颜色:蓝色；}

<div class="boundary"></div><div 类="内部">Lorem ipsum dolor sit amet，consectetur adipiscing elit，sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.Duis aute irure dolor在 voluptate velit esse cillum dolore eu fugiat nulla pariatur 受到谴责.Exceptioneur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est labourum.</div><div class="boundary boundary-2"></div><div class="inner inner-2">Lorem ipsum dolor sit amet，consectetur adipiscing elit，sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.Duis aute irure dolor在 voluptate velit esse cillum dolore eu fugiat nulla pariatur 受到谴责.Exceptioneur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est labourum.</div><div class="boundary boundary-3"></div><div class="inner inner-3">Lorem ipsum dolor sit amet，consectetur adipiscing elit，sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.Duis aute irure dolor在 voluptate velit esse cillum dolore eu fugiat nulla pariatur 受到谴责.Exceptioneur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est labourum.</div>

PS:不要忘记使用 viewport meta 标签来获得响应.

来源 Antialiasing-101

I am trying to do this shape in HTML/CSS for my mobile app: https://embed.plnkr.co/9k8jbJyzUiSMSoSHlOti/

.boundary {
  width: 100.13723%;
  padding-bottom: 5.24078%;
  position: relative;
  overflow: hidden;
  background-color: white;
}

.boundary:before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  transform-origin: top left;
  transform: rotate(3deg);
  background-color: green;
}

.inner {
  height: 100%;
  width: 100%;
  background-color: green;
}

<div class="boundary"></div>
<div class="inner">
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis auteirure dolor
  in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>

In my browser, when I inspect the element and change the zoom (to 75%), there is a gap between 2 <div>. When I deploy my application in my device, I can see this same gap.

What is going on ?

This is how I make the shape:

I create a first div to do the inclined line. I make a responsive triangle (I picked some information from this Question)

1) In my div, I insert a first pseudo-element and give it 100% width and height of parent. I apply a rotation : I define a transform origin in the top left, and rotate the pseudo element 3 degrees clockwise with transform: rotate(3deg)

2) I have to adjust width and height: I use percentages and padding-bottom to maintain the aspect ratio (more information here) so:

[rectangle height] : padding-bottom = tan(3deg) * 100% = 100.13723% (100% is the screen width) [hypotenuse of triangle = new rectangle width] : width = tan(3deg) * 100% / sin(3deg) = 5.24078%.

3) To hide the unwanted parts of the pseudo element (everything that overflows the <div> with the red border) I set overflow: hidden on the container.

I make a second <div> after the first inclined <div>. This <div> is simple, without special transformation, and contains Lorem ipsum.

解决方案

This usually happens while transforming elements because browser starts doing antialiasing with elements' edges.

Antialiasing is something of an unsung hero in web graphics; it’s the reason we have clear text and smooth vector shapes on our screens.

While zooming out/in browser doesn't rescale element properly, e.g. if you zoom out an element of 1px height to 0.75%, browser should redraw element to 0.75px but browser cannot draw 0.75px, it either can create it 1 or it will try to make edges smooth with making pixel blur or 50% opacity.

In above picture you can see the same triangle being drawn, but on the left it has antialiasing enabled and on the right it’s been disabled. As you can see, when antialiasing is enabled the pixels are shades of gray when the triangle only passes through part of the pixel. When disabled, however, the pixel is filled in as either solid black or solid white and the shape looks jagged.

Using backface-visibility: hidden; or overlapping elements with negative margins while scaling/transforming is the better option to avoid this issue.

Demo without using backface-visibility: hidden;

html,
body {
  transform: scale(.8);
}

.boundary {
  width: 100.13723%;
  padding-bottom: 5.24078%;
  position: relative;
  overflow: hidden;
  background-color: white;
}

.boundary:before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  transform-origin: top left;
  transform: rotate(3deg);
  background-color: green;
}

.inner {
  height: 100%;
  width: 100%;
  background-color: green;
}

<div class="boundary"></div>
<div class="inner">
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
  in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>

Demo with using backface-visibility: hidden;

html,
body {
  transform: scale(.8);
}

.boundary {
  width: 100.13723%;
  padding-bottom: 5.24078%;
  position: relative;
  overflow: hidden;
  background-color: white;
}

.boundary:before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  transform-origin: top left;
  transform: rotate(3deg);
  background-color: green;
}

.inner {
  height: 100%;
  width: 100%;
  background-color: green;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

<div class="boundary"></div>
<div class="inner">
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
  in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>

Demo provided by OP in comment solved by using backface-visibility: hidden; and overlapping elements with negative margin

html,
body {
  transform: scale(.75);
}

.inner {
  height: 100%;
  width: 100%;
  background-color: green;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.inner-2 {
  background-color: red;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.inner-3 {
  background-color: blue;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.boundary {
  width: 100.13723%;
  padding-bottom: 5.24078%;
  position: relative;
  overflow: hidden;
  background-color: white;
  margin-top: -2px;
}

.boundary:before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  transform-origin: top left;
  transform: rotate(3deg);
  background-color: green;
  backface-visibility: hidden;
}

.boundary-2 {
  background-color: green;
}

.boundary-2:before {
  transform-origin: top right;
  transform: rotate(-3deg);
  background-color: red;
}

.boundary-3 {
  background-color: red;
}

.boundary-3:before {
  transform-origin: top left;
  transform: rotate(3deg);
  background-color: blue;
}

<div class="boundary"></div>
<div class="inner">
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
  in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>

<div class="boundary boundary-2"></div>
<div class="inner inner-2">
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
  in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>

<div class="boundary boundary-3"></div>
<div class="inner inner-3">
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
  in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>

PS: Don't forget to use viewport meta tag for responsiveness.

Source Antialiasing-101

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