Method _drawTargetLine

src/core/JustGage.js:754–814

* Draw target line at specified value * @private

()

   * @private
   */
  _drawTargetLine() {
    const config = this.config;

    if (config.targetLine == null) {
      return;
    }

    const { widgetW, widgetH, dx, dy } = this._calculateGaugeGeometry();

    // Calculate reversed target value if needed (same as original implementation)
    let targetValue = config.targetLine;
    if (config.reverse) {
      targetValue = config.max + config.min - config.targetLine;
    }

    // Calculate angle based on gauge type (matching SVG renderer logic)
    let alpha;
    if (config.donut) {
      // Donut gauges use different angle calculation with 2x factor
      alpha = (1 - (2 * (targetValue - config.min)) / (config.max - config.min)) * Math.PI;
    } else {
      // Standard gauge angle calculation
      alpha = (1 - (targetValue - config.min) / (config.max - config.min)) * Math.PI;
    }

    let Ro = widgetW / 2 - widgetW / 10;
    let Ri = Ro - (widgetW / GAUGE_WIDTH_DIVISOR) * config.gaugeWidthScale;
    let Cx, Cy, Xo, Yo, Xi, Yi;

    if (config.donut) {
      Ro = widgetW / 2 - widgetW / 30;
      Ri = Ro - (widgetW / GAUGE_WIDTH_DIVISOR) * config.gaugeWidthScale;

      Cx = widgetW / 2 + dx;
      Cy = widgetH / 2 + dy;

      Xo = Cx + Ro * Math.cos(alpha);
      Yo = Cy - Ro * Math.sin(alpha);
      Xi = Cx + Ri * Math.cos(alpha);
      Yi = Cy - Ri * Math.sin(alpha);
    } else {
      Cx = widgetW / 2 + dx;
      Cy = widgetH / 1.25 + dy;

      Xo = Cx + Ro * Math.cos(alpha);
      Yo = Cy - Ro * Math.sin(alpha);
      Xi = Cx + Ri * Math.cos(alpha);
      Yi = Cy - Ri * Math.sin(alpha);
    }

    // Create path from inner to outer radius (like original)
    const pathData = `M ${Xi} ${Yi} L ${Xo} ${Yo}`;

    this.canvas.targetLine = this.renderer.path(pathData).attr({
      stroke: config.targetLineColor,
      'stroke-width': config.targetLineWidth,
    });