使用 angularjs 单击 2 个结果 div 后，在 2 个 div 之间画一条线

Question

一旦用户单击，我有 2 个 DIV 需要用一条线连接。我以角度开发我的项目。谁能帮我？我真的需要解决方案。

查看我的 sn-p 以获得更清晰的信息。

.padding-answer-line-mapping
{
    padding-bottom:8px;
}

.answer-container
{
    width:40px;
    height:40px;
    background-color:#ccc;
    border:1px solid #ccc;
    margin:2px;
    float:left;
    text-align:center;
    padding-top:8px;
    cursor:pointer;
    position:relative;
}

.answer-container:hover, .answer-container:focus, .answer-container:active
{
    background-color: #0076e9;
    color: white;
    border: 1px solid #0076e9;
}

.round-pointer-right
{
    position: absolute;
    background-color:#ccc;
    cursor:pointer;
    width:10px;
    height:10px;
    border-radius: 50%;
    right:0px;
    top:14px;
    margin-right:-20px;
}

.round-pointer-left
{
    position: absolute;
    background-color:#ccc;
    cursor:pointer;
    width:10px;
    height:10px;
    border-radius: 50%;
    left:0px;
    top:14px;
    margin-left:-20px;
}

<link href="http://code.ionicframework.com/1.3.1/css/ionic.css" rel="stylesheet"/>
Match the following items.

<div class="row padding-answer-line-mapping">
    <div class="col answer-container">
        One
        <div class="round-pointer-right"></div>
    </div>
    <div class="col">
        
    </div>
    <div class="col answer-container">
        2
        <div class="round-pointer-left"></div>
    </div>
</div>
<div class="row padding-answer-line-mapping">
    <div class="col answer-container">
        Two
        <div class="round-pointer-right"></div>
    </div>
    <div class="col">
        
    </div>
    <div class="col answer-container">
        1
        <div class="round-pointer-left"></div>
    </div>
</div>

Answer 1

您可以在画布上下文中使用lineTo。详情请见https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D。

首先，在 html 上定义一个画布：

<canvas id="connection-canvas"></canvas>

那么你可以在上面画一条线：

function drawLine(p1, p2) {
  var canvas = document.getElementById("connection-canvas");
  var ctx = canvas.getContext("2d");

  ctx.beginPath();
  ctx.moveTo(p1.x, p1.y);
  ctx.lineTo(p2.x, p2.y);
  ctx.stroke();
}

您只需要计算出“圆形指针”的偏移量：

function getPoint(answerElement) {
    var roundPointer = answerElement.lastElementChild;

    return {
        y: answerElement.offsetTop + roundPointer.offsetTop + roundPointer.offsetHeight / 2,
        x: answerElement.offsetLeft + roundPointer.offsetLeft + roundPointer.offsetWidth / 2
    };
}

因此，您可以使用这两个函数获取“圆形指针”的中心点，并在画布中从它到另一个“圆形指针”绘制一条线，假设画布位于同一个答案容器的偏移父级上并且它的大小必须足够大。

接下来，您必须处理选择两个答案以将它们连接起来。下面有一个演示给你。如果您更改答案，此演示不会处理擦除一行。

var lastSelection;

// Add click listener for answer-container
function listenToClick() {
    var rows = document.querySelectorAll('.row'),
        row;
    var cols, col;

    for (row = 0; row < rows.length; row++) {
        cols = rows[row].children;

        for (col = 0; col < cols.length; col++) {
            // Bind information about which answer is this,
            // so we can prevent from connecting two answers on
            // same column.
            cols[col].addEventListener('click', selectAnswer.bind({
                row: row,
                col: col,
                element: cols[col]
            }));
        }
    }
}

// This is fired when a answer-container is clicked.
function selectAnswer(event) {
    if (lastSelection) {
        lastSelection.element.classList.remove('selected');
    }

    if (!lastSelection || lastSelection.col === this.col) {
        lastSelection = this;
        this.element.classList.add('selected');
    } else {
        drawLine(getPoint(this.element), getPoint(lastSelection.element));
        lastSelection = null;
    }
}

function getPoint(answerElement) {
    var roundPointer = answerElement.lastElementChild;

    return {
        y: answerElement.offsetTop + roundPointer.offsetTop + roundPointer.offsetHeight / 2,
        x: answerElement.offsetLeft + roundPointer.offsetLeft + roundPointer.offsetWidth / 2
    };
}

function drawLine(p1, p2) {
    var canvas = document.getElementById("connection-canvas");
    var ctx = canvas.getContext("2d");

    ctx.beginPath();
    ctx.moveTo(p1.x, p1.y);
    ctx.lineTo(p2.x, p2.y);
    ctx.stroke();
}

function resizeCanvas() {
    var canvas = document.getElementById("connection-canvas");
    var ctx = canvas.getContext("2d");

    ctx.canvas.width  = window.innerWidth;
    ctx.canvas.height = window.innerHeight;
}

listenToClick();
resizeCanvas();

.padding-answer-line-mapping
{
    padding-bottom:8px;
}

.answer-container
{
    width:40px;
    height:40px;
    background-color:#ccc;
    border:1px solid #ccc;
    margin:2px;
    float:left;
    text-align:center;
    padding-top:8px;
    cursor:pointer;
    position:relative;
}

.answer-container:hover, .answer-container:focus, .answer-container:active
{
    background-color: #0076e9;
    color: white;
    border: 1px solid #0076e9;
}

.round-pointer-right
{
    position: absolute;
    background-color:#ccc;
    cursor:pointer;
    width:10px;
    height:10px;
    border-radius: 50%;
    right:0px;
    top:14px;
    margin-right:-20px;
}

.round-pointer-left
{
    position: absolute;
    background-color:#ccc;
    cursor:pointer;
    width:10px;
    height:10px;
    border-radius: 50%;
    left:0px;
    top:14px;
    margin-left:-20px;
}

.selected {
    background-color: red;
}

<link href="//code.ionicframework.com/1.3.1/css/ionic.css" rel="stylesheet"/>
Match the following items.

 <canvas id="connection-canvas" style="position: absolute; top: 0; left: 0; right: 0; bottom: 0"></canvas>
<div class="row padding-answer-line-mapping">
    <div class="col answer-container">
        One
        <div class="round-pointer-right"></div>
    </div>
    <div class="col">
        
    </div>
    <div class="col answer-container">
        2
        <div class="round-pointer-left"></div>
    </div>
</div>
<div class="row padding-answer-line-mapping">
    <div class="col answer-container">
        Two
        <div class="round-pointer-right"></div>
    </div>
    <div class="col">
        
    </div>
    <div class="col answer-container">
        1
        <div class="round-pointer-left"></div>
    </div>
</div>

Answer 2

这是一个使用 SVG 的解决方案：

点击左右框后，它会在最后点击的两个元素之间画一条线。

var leftEl, rightEl;
function drawLine(leftEl, rightEl) {
  var width = $(rightEl).offset().left - $(leftEl).offset().left;
  var height = $(leftEl).offset().top - $(rightEl).offset().top;
  if (height == 0) {
    height = 2;
  }
  var line = $("<div style='position: absolute; width: "+Math.abs(width)+"px; height: "+Math.abs(height)+"px;'><svg style='width: 100%; height: 100%;'><line x1='"+(height > 0 ? '0' : '100%')+"' y1='100%' ' x2='"+(height > 0 ? '100%' : '0')+"' y2='0' style='stroke:rgb(255,0,0);stroke-width:2'/></svg></div>");
  $('.container').append(line);
  myPos = height > 0 ? 'left bottom' : 'left top';
  ofPos = height == 2 ? 'center center-12' : 'left+5 top+5'
  
  if (leftEl.data('line')) {
    leftEl.data('line').remove()
  }
  if (rightEl.data('line')) {
    rightEl.data('line').remove()
  }
  
  line.position({
    my: myPos,
    at: ofPos,
    of: leftEl
  })
  
  leftEl.data('line', line)
  rightEl.data('line', line)
}

$('.box-left,.box-right').on('click', function() {
  if ($(this).hasClass('box-left')) {
    leftEl = this
  }
  if($(this).hasClass('box-right')) {
    rightEl = this
  }
  if (leftEl && rightEl) {
    drawLine(
      $(leftEl).parent().find('.round-pointer-right'),
      $(rightEl).parent().find('.round-pointer-left')
    );
    leftEl = rightEl = null;
  }
});

.container {
  position: relative;
}
.padding-answer-line-mapping
{
    padding-bottom:8px;
}

.answer-container
{
    width:40px;
    height:40px;
    background-color:#ccc;
    border:1px solid #ccc;
    margin:2px;
    float:left;
    text-align:center;
    padding-top:8px;
    cursor:pointer;
    position:relative;
}

.answer-container:hover, .answer-container:focus, .answer-container:active
{
    background-color: #0076e9;
    color: white;
    border: 1px solid #0076e9;
}

.round-pointer-right
{
    position: absolute;
    background-color:#ccc;
    cursor:pointer;
    width:10px;
    height:10px;
    border-radius: 50%;
    right:0px;
    top:14px;
    margin-right:-20px;
}

.round-pointer-left
{
    position: absolute;
    background-color:#ccc;
    cursor:pointer;
    width:10px;
    height:10px;
    border-radius: 50%;
    left:0px;
    top:14px;
    margin-left:-20px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.css" />
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"></script>

<link href="http://code.ionicframework.com/1.3.1/css/ionic.css" rel="stylesheet"/>
Match the following items.

<div class="container">
<div class="row padding-answer-line-mapping">
    <div class="col answer-container box-left">
        One
        <div class="round-pointer-right"></div>
    </div>
    <div class="col">
        
    </div>
    <div class="col answer-container box-right">
        2
        <div class="round-pointer-left"></div>
    </div>
</div>
<div class="row padding-answer-line-mapping">
    <div class="col answer-container box-left">
        Two
        <div class="round-pointer-right"></div>
    </div>
    <div class="col">
        
    </div>
    <div class="col answer-container box-right">
        1
        <div class="round-pointer-left"></div>
    </div>
</div>
<div class="row padding-answer-line-mapping">
    <div class="col answer-container box-left">
        Three
        <div class="round-pointer-right"></div>
    </div>
    <div class="col">
        
    </div>
    <div class="col answer-container box-right">
        3
        <div class="round-pointer-left"></div>
    </div>
</div>
</div>

更新

我还添加了一个选项，可以在再次单击已经有一行的框时删除一行。