How to format the x-axis and y axis label colors in a ngx-charts line chart

Question

I am using ngx-charts for plotting time series data.

I am using their example

<ngx-charts-line-chart
      [view]="view"
      [scheme]="colorScheme"
      [results]="multi"
      [gradient]="gradient"
      [xAxis]="showXAxis"
      [yAxis]="showYAxis"
      [legend]="showLegend"
      [showXAxisLabel]="showXAxisLabel"
      [showYAxisLabel]="showYAxisLabel"
      [xAxisLabel]="xAxisLabel"
      [yAxisLabel]="yAxisLabel"
      [autoScale]="autoScale"
      (select)="onSelect($event)">
    </ngx-charts-line-chart>

It does have a color scheme option but that only changes the color of the line and their corresponding domains.

There is another option of xAxisTickFormatting and yAxisTickFormatting but I am not sure of how to use it

I want the color of the x-axis and y-axis labels to be similar to this example https://swimlane.github.io/ngx-charts/#/ngx-charts/line-chart

Answer 1

If you have dark background in your application and want to use light colors for your ngx charts then you can use this method. It will use official code for ngx dark theme and show light colors for the chart labels. You can also change the color code in sccss variables and things work as you need.

I solved it using the way used on the official website. In you application SCSS file for styles, add the following styles:

.dark {
  /**
     * Backgrounds
     */
  $color-bg-darkest: #13141b;
  $color-bg-darker: #1b1e27;
  $color-bg-dark: #232837;
  $color-bg-med: #2f3646;
  $color-bg-light: #455066;
  $color-bg-lighter: #5b6882;

  /**
     * Text
     */
  $color-text-dark: #72809b;
  $color-text-med-dark: #919db5;
  $color-text-med: #A0AABE;
  $color-text-med-light: #d9dce1;
  $color-text-light: #f0f1f6;
  $color-text-lighter: #fff;

  background: $color-bg-darker;

  .ngx-charts {

    text {
      fill: $color-text-med;
    }

    .tooltip-anchor {
      fill: rgb(255, 255, 255);
    }

    .gridline-path {
      stroke: $color-bg-med;
    }

    .refline-path {
      stroke: $color-bg-light;
    }

    .reference-area {
      fill: #fff;
    }

    .grid-panel {
      &.odd {
        rect {
          fill: rgba(255, 255, 255, 0.05);
        }
      }
    }

    .force-directed-graph {
      .edge {
        stroke: $color-bg-light;
      }
    }

    .number-card {
      p {
        color: $color-text-light;
      }
    }

    .gauge {
      .background-arc {
        path {
          fill: $color-bg-med;
        }
      }

      .gauge-tick {
        path {
          stroke: $color-text-med;
        }

        text {
          fill: $color-text-med;
        }
      }
    }

    .linear-gauge {
      .background-bar {
        path {
          fill: $color-bg-med;
        }
      }

      .units {
        fill: $color-text-dark;
      }
    }

    .timeline {
      .brush-background {
        fill: rgba(255, 255, 255, 0.05);
      }

      .brush {
        .selection {
          fill: rgba(255, 255, 255, 0.1);
          stroke: #aaa;
        }
      }
    }

    .polar-chart .polar-chart-background {
      fill: rgb(30, 34, 46);
    }

  }

  .chart-legend {
    .legend-labels {
      background: rgba(255, 255, 255, 0.05) !important;
    }

    .legend-item {
      &:hover {
        color: #fff;
      }
    }

    .legend-label {
      &:hover {
        color: #fff !important;
      }

      .active {
        .legend-label-text {
          color: #fff !important;
        }
      }
    }

    .scale-legend-label {
      color: $color-text-med;
    }
  }

  .advanced-pie-legend {
    color: $color-text-med;

    .legend-item {
      &:hover {
        color: #fff !important;
      }
    }
  }

  .number-card .number-card-label {
    font-size: 0.8em;
    color: $color-text-med;
  }
}

Once this has been added make sure you have this scss file linked in your angular.json file. After that you just have to add class dark in the first wrapping component of your ngx chart like this for example:

<div class="areachart-wrapper dark">
    <ngx-charts-area-chart 
        [view]="view" 
        [scheme]="colorScheme" 
        [results]="data" 
        [gradient]="gradient" 
        [xAxis]="showXAxis"
        [yAxis]="showYAxis" 
        [legend]="showLegend" 
        [showXAxisLabel]="showXAxisLabel" 
        [showYAxisLabel]="showYAxisLabel"
        [xAxisLabel]="xAxisLabel" 
        [yAxisLabel]="yAxisLabel" 
        [autoScale]="autoScale" 
        [curve]="curve" 
        (select)="onSelect($event)">
    </ngx-charts-area-chart>
 </div>

This will make your charts look exactly as shown on the official website with dark theme for the charts: https://swimlane.github.io/ngx-charts/#/ngx-charts/bar-vertical.