Move web forerunner

Move web Development background

The good news ： There is no need to consider compatibility

• Because the emergence of smart phones is much later than computers , So the version of mobile browser is generally very high , therefore H5 and C3 Almost all of the new features support .

• There is no IE browser

The bad news ： Screen sizes vary

• Computer screens vary in size , How to solve ？

• Mobile devices have different screen sizes , Can use the layout Center （ Left and right blank ） How to solve it ？

Move web Preview and debug

F12 Developer tools = > Click on the phone icon = > Switch to mobile debugging mode = > Select the mobile device model or adjust the mobile device width

Features of mobile devices

Several noun concepts about screen

• Screen size

  The diagonal distance of the screen , Generally expressed in inches

  for example ：iPhone3 and iPhone4 All the screen sizes are 3.5 Inch

• Device physical pixels

  for example ：iPhone3 There are 320 x 480=153600 Physical pixel particles

  iPhone4 There are 640 x 960=614400 Physical pixel particles

• Physical resolution ( It is for hardware developers , Is the real resolution )

        iPhone3 The physical resolution is 320 x 480

        iPhone4 The physical resolution is 640 x 960

  Device pixel ratio （dpr）（ a key ）

• PC： The device pixel ratio is 1

• Move ：

Logical resolution （ a key ）( It is for software developers , Is the virtual resolution , Developers only need to know the logical resolution ) 

• iPhone3 and ihpone4 The logical resolution of is ：320 x 480

CSS Pixels （ a key ）

• What is it? ？ Is that we are css It's written in English px

stay iphone4 On the cell phone ：

problem ： stay css It's written in English 1px Wide and high red box , stay pc End 、iphone3、iphone4、iphoneX How many pixel particles are displayed on ？

pc End : 1 individual iphone3: 1 individual iphone4: 4 individual iphoneX: 9 individual

Multiple screens  

Device pixel ratio （dpr） How many times is the screen

Multigraph （ a key ）

Double ：

Industry UI Design drawings are generally in iphone6/7/8 Of 750*1334 Designed for Standards （ reason ： In mobile web On the rise iphone6/7/8 Screen size and physical resolution are the most mainstream ）. And converted to css Pixels need to be divided by 2, So we call it a double graph

Multigraph ：

Almost all the graphs used in the industry are double graphs , Only a few companies may use triples or even quadruples .

summary ：

• UI Design draft

  • It's OK to use several times of drawings in the design , If it is a double image, the measured pixel value should be divided by 2; If it is a triploid image, the measured pixel value should be divided by 3;

• picture

  • The size of the image displayed on the page is not determined by its own size , It is determined by the marked size of the design draft

  • Try to use a slightly larger picture , In case the picture becomes blurred ; But you can't use too large graphs , Because it will cause slow loading ; So moderate is the best .

viewport （ a key ）

• What is a viewport ？

  It is the rectangular area of the web page displayed by the browser , use CSS In other words “ How much space is available ”, It's basically equivalent to " window "

• What is the default viewport and the source of the default viewport ？

  demonstration ： first generation iPhone Release conference / complete + Chinese captions _ Bili, Bili _bilibili（ from 67 Minutes to watch ）

• What is an ideal viewport ？

  Is the size of the screen of the phone itself

How to set the viewport of the browser as the ideal viewport ？ The code is as follows ：

<meta name = "viewport" content="width=device-width, initial-scale=1, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no">

<!-- 
     explain ：
		meta： Provide meta information about the page （meta-information）
		viewport： viewport 
    width = device-width ：  Set the browser viewport width to the device width （ Ideal viewport ）
    initial-scale=1 ：  Set the initial scaling 
    maximum-scale = 1.0 ： The maximum scale that allows the user to zoom 
    minimum-scale = 1.0 ： The minimum scale that allows the user to zoom 
    user-scalable = no/0 ： Whether to allow users to zoom the page 
-->
<!-- 
     Add ： Generally, zoom should be disabled , The goal is to make web Apps look more like mobile apps , And it can also avoid some problems caused by scaling bug
		vscode Set up ：/Resources/app/extensions/emmet/node_modules/vscode-emmet-helper/lib/cjs/expand/expand-full.js
-->

Fluid layout

Percentage units

• px： Absolute units As many pixels as you write

• % ： Percentage units width and height Are based on the percentage of block level elements that contain it , Like the parent element div Width is 100px, Set child elements width: 50%, Then the width of the child element is 50px

application （ a key ）

Project practice

Preparation before actual combat

Style initialization

    * {
      box-sizing: border-box;
    }
    body {
      font-size: 12px;
    }
    /*  Clear the inner and outer margins of all our labels  */
    html,body,ul,li,ol,dl,dd,dt,p,h1,h2,h3,h4,h5,h6,form,fieldset,legend,img {
      margin: 0;
      padding: 0;
    }
    /* em  and  i  Italicized text does not tilt  */
    em,
    i {
        font-style: normal
    }
    /*  Get rid of li  The little dots of  */
    li {
        list-style: none
    }

    img {
        /* border 0  Take care of low version browsers   If   There will be a border problem if there are links outside the picture  */
        border: 0;
        /*  Cancel the problem of blank gap at the bottom of the picture  */
        vertical-align: middle
    }

    a {
        text-decoration: none
    }

    input, button {
      /*  Remove border  */
      border: 0;
      /*  Contour line  */
      outline: none;
    }
    .clearfix::after{
      content: '';
      display: block;
      clear: both;
      visibility: hidden;
      height: 0;
    }

Mainstream programs ：normalize.css

Official website ：Normalize.css: Make browsers render all elements more consistently.

Box model

/* Standard box model */
box-sizing: content-box;
/*C3 The box model */
box-sizing: border-box;

Layout ideas

From big to small From the outside in

matters needing attention

1. UI The picture is based on Iphone6/7/8 Designed for Standards , Its width is 750px, When we write css Pixels need to be divided by 2

2. Is the actual completion effect consistent with UI Keep the diagram consistent （ Restore 95% above ）

3. because UI The picture is based on Iphone6/7/8 Designed for Standards , So we should give priority to adaptation Iphone6/7/8,iphone6/7/8 Under the condition that this is no problem , Then adapt to other equipment

The holy grail layout （ a key ）

Realize the code of double wings :

  <style>
    * {
      box-sizing: border-box;
    }
    body {
      font-size: 12px;
    }
    /*  Clear the inner and outer margins of all our labels  */
    html,body,ul,li,ol,dl,dd,dt,p,h1,h2,h3,h4,h5,h6,form,fieldset,legend,img {
      margin: 0;
      padding: 0;
    }
    /* em  and  i  Italicized text does not tilt  */
    em,
    i {
        font-style: normal
    }
    /*  Get rid of li  The little dots of  */
    li {
        list-style: none
    }

    img {
        /* border 0  Take care of low version browsers   If   There will be a border problem if there are links outside the picture  */
        border: 0;
        /*  Cancel the problem of blank gap at the bottom of the picture  */
        vertical-align: middle
    }

    a {
        text-decoration: none
    }

    input, button {
      /*  Remove border  */
      border: 0;
      /*  Contour line  */
      outline: none;
    }
    .clearfix::after{
      content: '';
      display: block;
      clear: both;
      visibility: hidden;
      height: 0;
    }
    header {
      width: 100%;
      height: 100px;
    }
    .left {
      position: absolute;
      top: 0;
      left: 0;
      width: 100px;
      height: 100px;
      background-color: red;
    }
    .right {
      position: absolute;
      top: 0;
      right: 0;
      width: 100px;
      height: 100px;
      background-color: red;
    }
  </style>
</head>
<body>
  <header>
    <div class="left"></div>
    <div class="middle"></div>
    <div class="right"></div>
  </header>
</body>

There are two ways to realize that the middle box can empty the double wings on both sides ：

Understand knowledge :

Add about to a box padding or margin There are two ways not to break the parent box （ a key ）

1. padding or margin + Not set up width

   principle ： By default, block level elements always occupy the entire parent box in width , Even if you add about padding or margin, Nor will it break the parent box .

2. padding + C3 The box model

   Once a box is set width, Only in this way

Mode one :  width + padding+c3 The box model

    /*  Scheme 1  */
    .middle {
      width: 100%;
      height: 100px;
      padding: 0 100px;
      box-sizing: border-box;
      background-color: royalblue;
    }

Option two :  about padding or margin Empty the left and right sides

    /*  Option two  */
    .middle {
      height: 100px;
      /* margin: 0 100px; */
      padding: 0 100px;  /* padding It takes up the background color of the box  */
      background-color: royalblue;
    }