chart.js 2.0当前鼠标坐标工具提示 [英] chart.js 2.0 current mouse coordinates tooltip

问题描述

我正在用chart.js实现一些点图。那里没有问题，但是我想做的是提供一个工具提示，而不仅仅是将其附加到给定的数据点。现在，您可以创建一个工具提示，它将在图表上给定数据点附近显示一个弹出窗口。例如，如果我有数据点[1,5]，[2,6]和[3,7]，它将很高兴地显示这三个数据点。

I am implementing some point charts with chart.js. No problems there, but what I want to do is have a tooltip that is not just attached to a given data point. Right now you can create a tooltip and it will display a popup near a given data point on the chart. For instance if I have the data points [1,5], [2,6], and [3,7] it will happily show those three data points.

但是我想要的是当我介于1.5和2.6之间时，确切地看到我在x轴上的位置。 1.5、1.6等。

But what I want is when I'm between 1,5 and 2,6 to see exactly where on the x axis I am. 1.5, 1.6, etc.

在chart.js调用的工具提示选项中，我可以执行以下操作：

Inside the tooltips options for the chart.js call I can do something like this:

工具提示：{
模式：'index'，
相交：false，
回调：{
页脚：function（tooltipItems，data）{
返回'x：'+ this._eventPosition.x +'y：'+ this._eventPosition.y;
}，
}，
footerFontStyle：'normal'
}

是x和y在画布上的位置，与实际的x和y图形坐标无关。我似乎在chart.js中找不到任何数据可以向我获取鼠标当前位置的实际图表x，y坐标。

But that is the position of x and y on the canvas and has nothing to do with the actual x and y graph coordinates. I can't seem to find any data available within chart.js that can get me the actual chart x,y coordinates of the current position of the mouse.

也请注意我不需要在工具提示页脚中使用它，而只是将其用作测试输出的便捷方法。我想要的是在固定位置上始终可见的工具提示，以显示鼠标悬停在其上的当前实际图表x位置，而与最近的数据点无关。

Also note I'm not needing it in the tooltip footer, I was just using that as a handy way to test output. What I would like is for an always visible tooltip in a fixed position to display the current actual chart x position that the mouse is hovering over regardless of the closest data point.

推荐答案

我终于收集了信息并进行了数学计算。这只是一个片段，向您展示是否有人遇到此问题。

I finally just gathered the information and did the math. Here is just a snippet to show you how if anyone else ever has this problem.

$(document).ready(function() {
  var ctx = $("#graph_1");
  var dataArray =  [ {x:1,y:1},{x:2,y:3},{x:3,y:5},{x:4,y:8},{x:5,y:7},{x:6,y:4},{x:7,y:2},{x:8,y:1} ];
  
  var myChart = new Chart(ctx, {
    type: 'scatter',
    data: {
      datasets: [{
        label: "test",
        fill: false,
        data: dataArray
      }]
    },
    options: {
      title: {
        display: true,
        text: 'Test Graph'
      },
      animation: {
        duration: 0,
      }, // general animation time
      hover: {
        animationDuration: 0,
      }, // duration of animations when hovering an item
      responsiveAnimationDuration: 0, // animation duration after a resize
      scales: {
        xAxes: [{
          display: true,
          scaleLabel: {
            display: true,
            labelString: 'x axis label'
          }
        }],
        yAxes: [{
          display: true,
          scaleLabel: {
            display: true,
            labelString: 'y axis label'
          }
        }]
      },
      tooltips: {
        mode: 'index',
        intersect: false,
        callbacks: {
          // Use the footer callback to display the sum of the items showing in the tooltip
          footer: function(tooltipItems, data) {
            //return 'x:' + this._eventPosition.x + ' y:' + this._eventPosition.y;
          },
        },
        footerFontStyle: 'normal'
      },
    }

  });

  ctx.mousemove(function(evt) {
    //console.log(evt.offsetX + "," + evt.offsetY);
    var ytop = myChart.chartArea.top;
    var ybottom = myChart.chartArea.bottom;
    var ymin = myChart.scales['y-axis-1'].min;
    var ymax = myChart.scales['y-axis-1'].max;
    var newy = '';
    var showstuff = 0;
    if (evt.offsetY <= ybottom && evt.offsetY >= ytop) {
      newy = Math.abs((evt.offsetY - ytop) / (ybottom - ytop));
      newy = (newy - 1) * -1;
      newy = newy * (Math.abs(ymax - ymin)) + ymin;
      showstuff = 1;
    }
    var xtop = myChart.chartArea.left;
    var xbottom = myChart.chartArea.right;
    var xmin = myChart.scales['x-axis-1'].min;
    var xmax = myChart.scales['x-axis-1'].max;
    var newx = '';
    if (evt.offsetX <= xbottom && evt.offsetX >= xtop && showstuff == 1) {
      newx = Math.abs((evt.offsetX - xtop) / (xbottom - xtop));
      newx = newx * (Math.abs(xmax - xmin)) + xmin;
    }
    if (newy != '' && newx != '') {
      //console.log(newx + ',' + newy);
      $("#graph_coords").html('Mouse Coordinates: ' + newx.toFixed(2) + ',' + newy.toFixed(2));
    }
  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<SCRIPT src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.6.0/Chart.min.js"></SCRIPT>

<DIV id="graph_coords"></DIV>
<DIV class="chart-container" style="position: relative; height:40vh; width:80vw;">
  <CANVAS id="graph_1" style="background-color: #CBCBCB;"></CANVAS>
</DIV>

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