4 changed files with 82 additions and 46 deletions
--- a/examples/area.html
+++ b/examples/area.html
@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta content="text/html;charset=utf-8" http-equiv="Content-Type">
+    <meta content="utf-8" http-equiv="encoding">
+
+    <script src="../dist/index.dev.js" type="text/javascript"></script>
+  </head>
+  <body>
+    <div id="chart" style="width: 50%; height: 500px;"></div>
+
+    <script type="text/javascript">
+      let options = {
+        renderLegend: false, usePanning: false,
+        axis: {
+          y: { invert: false, range: [0, 100] },
+          x: { format: 'numeric', range: [0, 100] },
+        },
+        zoomEvents: {
+          mouse: { zoom: { isActive: false, orientation: 'horizontal' } },
+          scroll: { zoom: { isActive: false, orientation: 'horizontal' } }
+        },
+      }
+      const data1 = [[0,0], [35, 40], [65, 60], [100, 100]];
+      const data2 = [[0,0], [35, 50], [65, 65], [80, 100]];
+      const data3 = [[0,0], [35, 20], [65, 50], [100, 80]];
+      var pod = new LinePod(
+        document.getElementById('chart'),
+        [
+          { target: 'test1', datapoints: data1, color: 'green' },
+          { target: 'test2', datapoints: data2, color: 'blue', renderArea: 'Below' },
+          { target: 'test3', datapoints: data3, color: 'orange', renderArea: 'Above' },
+        ],
+        options
+      );
+      pod.render();      
+    </script>
+  </body>
+</html>
--- a/src/index.ts
+++ b/src/index.ts
@ -1,5 +1,5 @@
 import { ChartwerkPod, VueChartwerkPodMixin, TimeFormat, CrosshairOrientation, BrushOrientation, yAxisOrientation } from '@chartwerk/core';
-import { LineTimeSerie, LineOptions, MouseObj } from './types';
+import { LineTimeSerie, LineOptions, MouseObj, AreaType } from './types';
 import { Markers } from './components/markers';
 import { Segments } from './components/segments';

@ -14,14 +14,9 @@ const METRIC_CIRCLE_RADIUS = 1.5;
 const CROSSHAIR_CIRCLE_RADIUS = 3;
 const CROSSHAIR_BACKGROUND_RAIDUS = 9;
 const CROSSHAIR_BACKGROUND_OPACITY = 0.3;
-
+type Generator = d3.Line<[number, number]> | d3.Area<[number, number]>;

 class LinePod extends ChartwerkPod<LineTimeSerie, LineOptions> {
-  lineGenerator = null;
-  areaGenerator = null;
-  lineGeneratorY1 = null;
-  areaGeneratorY1 = null;
-
  private _markersLayer: Markers = null;
  private _segmentsLayer: Segments = null;

@ -40,15 +35,14 @@ class LinePod extends ChartwerkPod<LineTimeSerie, LineOptions> {
    this.clearAllMetrics();

    this.updateCrosshair();
-    this.initLineGenerator();
-    this.initAreaGenerator();

    if(!this.series.isSeriesAvailable) {
      this.renderNoDataPointsMessage();
      return;
    }
    for(const serie of this.series.visibleSeries) {
-      this._renderMetric(serie);
+      const generator = this.getRenderGenerator(serie.renderArea, serie.yOrientation);
+      this._renderMetric(serie, generator);
    }
    if(this._markersConf !== undefined) {
      this._markersLayer = new Markers(this.d3Node, this._markersConf, this.state, this.margin);
@ -65,31 +59,28 @@ class LinePod extends ChartwerkPod<LineTimeSerie, LineOptions> {
    this._markersLayer?.clear();
  }

-  initLineGenerator(): void {
-    this.lineGenerator = d3.line()
-      .x(d => this.state.xScale(d[0]))
-      .y(d => this.state.yScale(d[1]));
-    this.lineGeneratorY1 = d3.line()
-      .x(d => this.state.xScale(d[0]))
-      .y(d => this.state.y1Scale(d[1]));
-  }
-
-  initAreaGenerator(): void {
-    this.areaGenerator = d3.area()
-      .x(d => this.state.xScale(d[0]))
-      .y1(d => this.state.yScale(d[1]))
-      .y0(d => this.height);
-    this.areaGeneratorY1 = d3.area()
-      .x(d => this.state.xScale(d[0]))
-      .y1(d => this.state.y1Scale(d[1]))
-      .y0(d => this.height);
-  }

-  getRenderGenerator(renderArea: boolean, yOrientation: yAxisOrientation): any {
-    if(renderArea) {
-      return yOrientation === yAxisOrientation.LEFT ? this.areaGenerator : this.areaGeneratorY1;
+  getRenderGenerator(renderArea: AreaType, yOrientation: yAxisOrientation): Generator {
+    const yScale = yOrientation === yAxisOrientation.LEFT ? this.state.yScale : this.state.y1Scale;
+    switch(renderArea) {
+      case AreaType.NONE:
+        // return line generator
+        return d3.line()
+          .x(d => this.state.xScale(d[0]))
+          .y(d => yScale(d[1]));
+      case AreaType.ABOVE:
+        return d3.area()
+          .x(d => this.state.xScale(d[0]))
+          .y0(this.height)
+          .y1(d => yScale(d[1]));
+      case AreaType.BELOW:
+        return d3.area()
+          .x(d => this.state.xScale(d[0]))
+          .y0(d => yScale(d[1]))
+          .y1(0);
+      default:
+        throw new Error(`Unknown type of renderArea: ${renderArea}`);
    }
-    return yOrientation === yAxisOrientation.LEFT ? this.lineGenerator : this.lineGeneratorY1;
  }

  _renderDots(serie: LineTimeSerie): void {
@ -105,9 +96,9 @@ class LinePod extends ChartwerkPod<LineTimeSerie, LineOptions> {
      .attr('cy', d => this.state.getYScaleByOrientation(serie.yOrientation)(d[1]));
  }

-  _renderLines(serie: LineTimeSerie): void {
-    const fillColor = serie.renderArea ? serie.color : 'none';
-    const fillOpacity = serie.renderArea ? 0.5 : 'none';
+  _renderLines(serie: LineTimeSerie, generator: Generator): void {
+    const fillColor = serie.renderArea !== AreaType.NONE ? serie.color : 'none';
+    const fillOpacity = serie.renderArea !== AreaType.NONE ? 0.5 : 'none';

    this.metricContainer
      .append('path')
@ -120,12 +111,12 @@ class LinePod extends ChartwerkPod<LineTimeSerie, LineOptions> {
      .attr('stroke-opacity', 0.7)
      .attr('pointer-events', 'none')
      .style('stroke-dasharray', serie.dashArray)
-      .attr('d', this.getRenderGenerator(serie.renderArea, serie.yOrientation));
+      .attr('d', generator);
  }

-  _renderMetric(serie: LineTimeSerie): void {
+  _renderMetric(serie: LineTimeSerie, generator: Generator): void {
    if(serie.renderLines === true) {
-      this._renderLines(serie);
+      this._renderLines(serie, generator);
    }

    if(serie.renderDots === true) {
@ -490,4 +481,4 @@ export const VueChartwerkLinePod = {
  }
 };

-export { LineTimeSerie, LineOptions, TimeFormat, LinePod };
+export { LineTimeSerie, LineOptions, TimeFormat, LinePod, AreaType };
--- a/src/models/line_series.ts
+++ b/src/models/line_series.ts
@ -1,5 +1,5 @@
 import { CoreSeries, yAxisOrientation } from '@chartwerk/core';
-import { LineTimeSerie } from '../types';
+import { LineTimeSerie, AreaType } from '../types';

 import * as _ from 'lodash';

@ -10,7 +10,7 @@ const LINE_SERIE_DEFAULTS = {
  renderLines: true,
  dashArray: '0',
  class: '',
-  renderArea: false,
+  renderArea: AreaType.NONE,
  yOrientation: yAxisOrientation.LEFT,
 };

--- a/src/types.ts
+++ b/src/types.ts
@ -2,12 +2,18 @@ import { Serie, Options } from '@chartwerk/core';
 import { AxisRange } from '@chartwerk/core/dist/types';

 type LineTimeSerieParams = {
-  maxLength: number,
-  renderDots: boolean,
-  renderLines: boolean, // TODO: refactor same as scatter-pod
+  maxLength: number;
+  renderDots: boolean;
+  renderLines: boolean; // TODO: refactor same as scatter-pod
  dashArray: string; // dasharray attr, only for lines
  class: string; // option to add custom class to each serie element
-  renderArea: boolean; // TODO: move to render type
+  renderArea: AreaType; // default is none
+}
+
+export enum AreaType {
+  NONE = 'None',
+  ABOVE = 'Above',
+  BELOW = 'Below',
 }

 export type LineTimeSerie = Serie & Partial<LineTimeSerieParams>;