ChartJS 在刻度之间放置 y 轴标签 [英] ChartJS place y-axis labels between ticks

问题描述

我有以下图表:

但是，我想将 y 轴标签移动如下:

However, i'd like to shift the y axis labels to be the following:

是否可以使用 ChartJS 在刻度线之间移动 y 轴标签，如上面的示例图像所示?

Is it possible to move the y axis labels in between the tick marks with ChartJS, like shown in the example image above?

功能类似于options.scales.yAxes[].ticks.position 选项，不同之处在于它目前被定义为在y 轴的x 方向，因为我在 y 轴的 y 方向需要它.更好的是，自动居中.

Functionality is similar to the options.scales.yAxes[].ticks.position option, except currently it is defined as in the x direction for the y axis, where as I need it in the y direction for the y axis. And better yet, automatically centered.

推荐答案

遗憾的是，目前 ChartJS 中没有为此提供内置方法.

Unfortunately, there is no built-in method in ChartJS for this, at the moment.

您宁愿需要创建一个图表插件来实现这一点.

You would rather need to create a chart plugin to achieve that.

plugins: [{
   beforeDraw: function(chart) {
      var ctx = chart.ctx;
      var yAxis = chart.scales['y-axis-0'];
      var tickGap = yAxis.getPixelForTick(1) - yAxis.getPixelForTick(0);
      yAxis.options.ticks.fontColor = 'transparent'; // hide original tick
      // loop through ticks array
      Chart.helpers.each(yAxis.ticks, function(tick, index) {
         if (index === yAxis.ticks.length - 1) return;
         var xPos = yAxis.right;
         var yPos = yAxis.getPixelForTick(index);
         var xPadding = 10;
         // draw tick
         ctx.save();
         ctx.textBaseline = 'middle';
         ctx.textAlign = 'right';
         ctx.fillStyle = 'rgba(0, 0, 0, 0.8)';
         ctx.fillText(tick, xPos - xPadding, yPos + tickGap / 2);
         ctx.restore();
      });
   }
}]

^{注意:这将隐藏第一个刻度(从 0 开始)}

^{note: this will hide the first tick (which begins at 0)}

ᴡᴏʀᴋɪɴɢ ᴇxᴀᴍᴘʟᴇ ⧩

var barChart = new Chart(ctx, {
   type: 'bar',
   data: {
      labels: ['Jan', 'Feb', 'Mar'],
      datasets: [{
         label: 'BAR',
         data: [10, 20, 30],
         backgroundColor: 'rgba(0, 119, 204, 0.5)'
      }]
   },
   options: {
      responsive: false,
      scales: {
         yAxes: [{
            ticks: {
               beginAtZero: true
            }
         }]
      }
   },
   plugins: [{
      beforeDraw: function(chart) {
         var ctx = chart.ctx;
         var yAxis = chart.scales['y-axis-0'];
         var tickGap = yAxis.getPixelForTick(1) - yAxis.getPixelForTick(0);
         yAxis.options.ticks.fontColor = 'transparent'; // hide original tick
         // loop through ticks array
         Chart.helpers.each(yAxis.ticks, function(tick, index) {
            if (index === yAxis.ticks.length - 1) return;
            var xPos = yAxis.right;
            var yPos = yAxis.getPixelForTick(index);
            var xPadding = 10;
            // draw tick
            ctx.save();
            ctx.textBaseline = 'middle';
            ctx.textAlign = 'right';
            ctx.fillStyle = 'rgba(0, 0, 0, 0.8)';
            ctx.fillText(tick, xPos - xPadding, yPos + tickGap / 2);
            ctx.restore();
         });
      }
   }]
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.6.0/Chart.min.js"></script>
<canvas id="ctx" height="200"></canvas>

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