Question

如下图所示，我有一个用'Chart JS'创建的图表。该图表包含具有各种曲线的线性线。我用各种颜色的“背景色”绘制了这些线之间的区域。

我的问题是，当我在这张图表上创建一个随机点时，我只想创建一个基于颜色的if语句。

例如，有一个点称为A，该变量称为B。如果A点在黄色区域，则B为1。如果A点位于浅灰色区域，则B为2。像这样的东西。

这是图片：

这是示例代码：

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.bundle.min.js"></script>
<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chart.js@2.8.0"></script>
<script type="text/javascript">
    var x_A = new Array(2, 2, 2.5, 2.5, 2);
    var y_A = new Array(2.5 , 3 , 3.5, 2.5 , 2.5);
    var c_A = [];
    for (var i = 0; i < x_A.length; i++) {
        var obj = { x: x_A[i], y: y_A[i] };
        c_A.push(obj);
    }
    var x_B = new Array(0, 1.5, 1.5, 0);
    var y_B = new Array(0, 2, 0.5, 0);
    var c_B = [];
    for (var i = 0; i < x_B.length; i++) {
        var obj = { x: x_B[i], y: y_B[i] };
        c_B.push(obj);
    }
    var x_C = new Array(1.5, 1.5, 2, 2, 1.5);
    var y_C = new Array(0.5, 2, 3, 2.5, 0.5);
    var c_C = [];
    for (var i = 0; i < x_C.length; i++) {
        var obj = { x: x_C[i], y: y_C[i] };
        c_C.push(obj);
    }
    var r_A = 'rgba(220, 20, 60,1)';
    var r_B = 'rgba(255, 255, 56,1)';
    var r_C = 'rgba(34, 139, 34,1)';
    var ctx = document.getElementById('myChart').getContext('2d');
    var myChart = new Chart(ctx, {
        type: 'line',
        data: {
            datasets: [
                {
                    label: 'X',
                    showLine: true,
                    fill: true,
                    pointRadius: 7,
                    data: [{
                        x: 1,
                        y: 0.9
                    }],
                    borderWidth: 1,
                    pointBackgroundColor: "#000000",
                    lineTension: 0,
                },
                {
                    label:'Zone A',
                    showLine: true,
                    fill: true,
                    backgroundColor: r_A,
                    pointRadius: 0,
                    data: c_A,
                    borderWidth: 1,
                    borderColor: "#000000",
                    lineTension: 0,
                },
                {
                    label: 'Zone B',
                    showLine: true,
                    fill: true,
                    backgroundColor: r_B,
                    pointRadius: 0,
                    data: c_B,
                    borderWidth: 1,
                    borderColor: "#000000",
                    lineTension: 0,
                },
                {
                    label: 'Zone C',
                    showLine: true,
                    fill: true,
                    backgroundColor: r_C,
                    pointRadius: 0,
                    data: c_C,
                    borderWidth: 1,
                    borderColor: "#000000",
                    lineTension: 0,
                },
            ]
        },
        options: {
            title: {
                display: false,
            },
            tooltips: {
                mode: 'nearest',
                intersect: true
            },
            scales: {
                xAxes: [{
                    type: 'linear',
                    position: 'bottom',
                    gridLines:
                    {
                        display: false
                    },
                    scaleLabel: {
                        display: true
                    }
                }],
                yAxes: [{
                    gridLines:
                    {
                        display: false
                    },
                    scaleLabel: {
                        display: true,
                    }
                }]
            }
        }
    });
</script>

<link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">
<html>
<body>
    <div class="w3-row">
        <div class="w3-col s3"><p></p></div>
        <div class="w3-col s6" align="center"><canvas id="myChart" height="220"></canvas></div>
    </div>
    <div class="w3-row" align="center"><h2>Color Zone where the point X is located: </h2></div>
</body>
</html>

这是CodePen：

My Sample Example: CodePen

根据图表JS中的背景色确定点的面积

0 个答案: