Actual and forecast requests

Create a console project, add the ChartForgeX package, and replace Program.cs with this source. Run it to write SVG, PNG and HTML with the default system fonts.

For the same typography as the gallery, download the gallery-font recipe and copy the gallery’s fonts directory beside your program.

using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using ChartForgeX.Core;
using ChartForgeX.Primitives;
using ChartForgeX.Rendering;
using ChartForgeX.Themes;
using ChartForgeX.Topology;
using ChartForgeX.Typography;
using ChartForgeX.VisualArtifacts;
using ChartForgeX.VisualBlocks;

var mode = VisualThemeMode.Light;
var theme = VisualTheme.Graphite();
var model = DifferenceAreaRecipe.Create("step-end", mode);
var context = new VisualRenderContext(
    new VisualLayoutOptions(new VisualSize(800, 440)), theme, mode,
    new VisualFrame("Actual and forecast requests", "Paired values change at the following observation; missing sections stay open", showLegend: null, showSurface: false));
var prepared = model.Prepare(context);
File.WriteAllText("visual.svg", prepared.ToSvg());
File.WriteAllBytes("visual.png", prepared.ToPng());
File.WriteAllText("visual.html", prepared.ToArtifact("example", VisualArtifactKind.Chart).ToHtmlPage());

/// <summary>Builds actual-versus-forecast areas with crossings, gaps and stepped boundaries.</summary>
public static class DifferenceAreaRecipe {
    /// <summary>Creates the selected difference-area example from paired authored observations.</summary>
    public static Chart Create(string variant = "wide", VisualThemeMode mode = VisualThemeMode.Light) {
        if (variant is not ("wide" or "compact" or "sparse" or "options" or "compact-options" or "dated-gaps" or "compact-dated-gaps"
            or "step-start" or "step-middle" or "step-end" or "compact-step-middle"))
            throw new ArgumentOutOfRangeException(nameof(variant));
        var dated = variant is "dated-gaps" or "compact-dated-gaps";
        var stepped = variant is "step-start" or "step-middle" or "step-end" or "compact-step-middle";
        var day = new DateTime(2026, 3, 1, 0, 0, 0, DateTimeKind.Utc);
        var actual = new[] { 42d, 68, stepped ? 78 : 48, 60, 74, 46, 62 };
        var forecast = new[] { 56d, 54, stepped ? 62 : 60, 60, 58, 64, 50 };
        var pairs = new ChartDifferencePoint[actual.Length];
        for (var item = 0; item < pairs.Length; item++) pairs[item] = dated
            ? new ChartDifferencePoint(day.AddDays(item + (item >= 4 ? 2 : 0)), actual[item], forecast[item], item == 4)
            : new ChartDifferencePoint(item + 1, actual[item], forecast[item], stepped && item == 5);
        var chart = Chart.Create().WithXAxis(dated ? "Observation date (UTC)" : "Observation")
            .WithYAxis(dated ? "Primary reference" : "Completed requests");
        if (dated) {
            chart.ConfigureXAxis(axis => axis.WithTimeScale());
            var reference = ChartSeries.CreateLine(new ChartSeriesId("primary-reference"), "Primary reference",
                new[] { new ChartPoint(day, 1), new ChartPoint(day.AddDays(8), 2) });
            chart.AddSeries(reference);
        }
        var comparison = ChartSeries.CreateDifferenceArea(new ChartSeriesId("comparison"), "Actual and forecast", pairs);
        comparison.ConfigureDifferenceArea(options => {
            options.FirstName = "Actual"; options.SecondName = "Forecast";
            options.PositiveFill = ChartColor.FromHex("#267EAB"); options.NegativeFill = ChartColor.FromHex("#D47A34");
            options.PositiveFillOpacity = .48; options.NegativeFillOpacity = .48;
        }).ConfigureMarkers(markers => markers.Radius = 3);
        if (stepped) comparison.WithInterpolation(ChartInterpolation.Step, variant switch {
            "step-start" => ChartStepPosition.Start,
            "step-end" => ChartStepPosition.End,
            _ => ChartStepPosition.Middle
        });
        if (dated) {
            comparison.UseSecondaryYAxis().WithFillPattern(ChartFillPattern.DiagonalForward);
            chart.WithSecondaryYAxis("Completed requests");
        }
        return chart.AddSeries(comparison).WithValueFormat(ChartValueFormat.Number("0.##", CultureInfo.InvariantCulture));
    }
}

using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using ChartForgeX.Core;
using ChartForgeX.Primitives;
using ChartForgeX.Rendering;
using ChartForgeX.Themes;
using ChartForgeX.Topology;
using ChartForgeX.Typography;
using ChartForgeX.VisualArtifacts;
using ChartForgeX.VisualBlocks;

var mode = VisualThemeMode.Dark;
var theme = VisualTheme.Graphite();
var model = DifferenceAreaRecipe.Create("step-end", mode);
var context = new VisualRenderContext(
    new VisualLayoutOptions(new VisualSize(800, 440)), theme, mode,
    new VisualFrame("Actual and forecast requests", "Paired values change at the following observation; missing sections stay open", showLegend: null, showSurface: false));
var prepared = model.Prepare(context);
File.WriteAllText("visual.svg", prepared.ToSvg());
File.WriteAllBytes("visual.png", prepared.ToPng());
File.WriteAllText("visual.html", prepared.ToArtifact("example", VisualArtifactKind.Chart).ToHtmlPage());

/// <summary>Builds actual-versus-forecast areas with crossings, gaps and stepped boundaries.</summary>
public static class DifferenceAreaRecipe {
    /// <summary>Creates the selected difference-area example from paired authored observations.</summary>
    public static Chart Create(string variant = "wide", VisualThemeMode mode = VisualThemeMode.Light) {
        if (variant is not ("wide" or "compact" or "sparse" or "options" or "compact-options" or "dated-gaps" or "compact-dated-gaps"
            or "step-start" or "step-middle" or "step-end" or "compact-step-middle"))
            throw new ArgumentOutOfRangeException(nameof(variant));
        var dated = variant is "dated-gaps" or "compact-dated-gaps";
        var stepped = variant is "step-start" or "step-middle" or "step-end" or "compact-step-middle";
        var day = new DateTime(2026, 3, 1, 0, 0, 0, DateTimeKind.Utc);
        var actual = new[] { 42d, 68, stepped ? 78 : 48, 60, 74, 46, 62 };
        var forecast = new[] { 56d, 54, stepped ? 62 : 60, 60, 58, 64, 50 };
        var pairs = new ChartDifferencePoint[actual.Length];
        for (var item = 0; item < pairs.Length; item++) pairs[item] = dated
            ? new ChartDifferencePoint(day.AddDays(item + (item >= 4 ? 2 : 0)), actual[item], forecast[item], item == 4)
            : new ChartDifferencePoint(item + 1, actual[item], forecast[item], stepped && item == 5);
        var chart = Chart.Create().WithXAxis(dated ? "Observation date (UTC)" : "Observation")
            .WithYAxis(dated ? "Primary reference" : "Completed requests");
        if (dated) {
            chart.ConfigureXAxis(axis => axis.WithTimeScale());
            var reference = ChartSeries.CreateLine(new ChartSeriesId("primary-reference"), "Primary reference",
                new[] { new ChartPoint(day, 1), new ChartPoint(day.AddDays(8), 2) });
            chart.AddSeries(reference);
        }
        var comparison = ChartSeries.CreateDifferenceArea(new ChartSeriesId("comparison"), "Actual and forecast", pairs);
        comparison.ConfigureDifferenceArea(options => {
            options.FirstName = "Actual"; options.SecondName = "Forecast";
            options.PositiveFill = ChartColor.FromHex("#267EAB"); options.NegativeFill = ChartColor.FromHex("#D47A34");
            options.PositiveFillOpacity = .48; options.NegativeFillOpacity = .48;
        }).ConfigureMarkers(markers => markers.Radius = 3);
        if (stepped) comparison.WithInterpolation(ChartInterpolation.Step, variant switch {
            "step-start" => ChartStepPosition.Start,
            "step-end" => ChartStepPosition.End,
            _ => ChartStepPosition.Middle
        });
        if (dated) {
            comparison.UseSecondaryYAxis().WithFillPattern(ChartFillPattern.DiagonalForward);
            chart.WithSecondaryYAxis("Completed requests");
        }
        return chart.AddSeries(comparison).WithValueFormat(ChartValueFormat.Number("0.##", CultureInfo.InvariantCulture));
    }
}