Is it possible to have different legend background

问题:

See the example code:

var data = new google.visualization.DataTable();
    data.addColumn('string', 'Mac');
    data.addColumn('number', 'Score');
    data.addColumn({ type: 'string', role: 'style' });
    data.addRows([
       ['Mac model 12', 200, 'color: #8bba30; opacity: 0.75;'],
       ['Another Mac Model', 110, 'color: #ffcc33; opacity: 0.75;'],
    ]);
    var options = {
        title: '',
        width: 500,
        height: data.getNumberOfRows() * 40 + 100,
        hAxis: {
            minValue: 0,
            maxValue: 255,
            ticks: [0, 75, 150, 255],
            textPosition: 'out',
            side: 'top'
        },
        series: {
            0: { axis: 'Mac' },
            1: { axis: 'Score' }
        },
        chartArea: {
            top: 0,
            bottom: 50,
            right: 50,
            left: 150
        },
        legend: { position: 'none' },
        fontSize: 12,
        bar: {groupWidth: '75%'},
    };
    var chart = new google.visualization.BarChart(document.getElementById('apple_div'));
    chart.draw(data, options);
}

This is the output:

See, there are different colors for different bars. But I want different color and/or background-color for different legends on left side.

Can someone help me with this please?

I found following answer, Is it possible to show each legend in different color in google pie chart.

But it suggests on breaking down the chart(i.e. to draw separate charts for each rows), which is not desirable as there are large numbers of rows.

回答1:

Not sure what you mean by breaking the chart, but...

You can modify the chart svg, once the 'ready' event fires.

This example changes the color of the legend text to match the bar color.

google.charts.load('current', {
  callback: drawChart,
  packages: ['corechart']
});

function drawChart() {
  var colors = ['#8bba30', '#ffcc33'];
  var data = new google.visualization.DataTable();
  data.addColumn('string', 'Mac');
  data.addColumn('number', 'Score');
  data.addColumn({ type: 'string', role: 'style' });
  data.addRows([
     ['Mac model 12', 200, 'color: ' + colors[0] + '; opacity: 0.75;'],
     ['Another Mac Model', 110, 'color: ' + colors[1] + '; opacity: 0.75;'],
  ]);
  var options = {
      title: '',
      width: 500,
      height: data.getNumberOfRows() * 40 + 100,
      hAxis: {
          minValue: 0,
          maxValue: 255,
          ticks: [0, 75, 150, 255],
          textPosition: 'out',
          side: 'top'
      },
      series: {
          0: { axis: 'Mac' },
          1: { axis: 'Score' }
      },
      chartArea: {
          top: 0,
          bottom: 50,
          right: 50,
          left: 150
      },
      legend: { position: 'none' },
      fontSize: 12,
      bar: {groupWidth: '75%'},
  };

  var chartContainer = document.getElementById('apple_div');
  var chart = new google.visualization.BarChart(chartContainer);
  google.visualization.events.addListener(chart, 'ready', function () {
    var labels = chartContainer.getElementsByTagName('text');
    var colorIndex = 0;
    for (var i = 0; i < labels.length; i++) {
      if (labels[i].getAttribute('text-anchor') === 'end') {
        labels[i].setAttribute('fill', colors[colorIndex]);
        colorIndex++;
      }
    }
  });
  chart.draw(data, options);
}

<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="apple_div"></div>

As for background color, SVG elements do not have background
so you would have to draw your own rect for that...