Allow formatting breakdown charts with lambda expr

Relates to #252

examples/Console/Charts/Program.cs

@@ -19,10 +19,10 @@ namespace Charts
 
             // Render a breakdown chart
             AnsiConsole.WriteLine();
-            Render("Languages", new BreakdownChart()
+            Render("Languages used", new BreakdownChart()
                 .FullSize()
                 .Width(60)
-                .TagValueFormat("{0}%")
+                .ShowPercentage()
                 .AddItem("SCSS", 37, Color.Red)
                 .AddItem("HTML", 28.3, Color.Blue)
                 .AddItem("C#", 22.6, Color.Green)

src/Spectre.Console.Tests/Unit/BreakdownChartTests.cs

@@ -42,14 +42,14 @@ namespace Spectre.Console.Tests.Unit
 
         [Fact]
         [Expectation("TagFormat")]
-        public async Task Should_Render_Correctly_With_Specific_Tag_Formatter()
+        public async Task Should_Render_Correctly_With_Specific_Value_Formatter()
         {
             // Given
             var console = new FakeConsole(width: 80);
             var chart = Fixture.GetChart()
                 .Width(60)
                 .Culture("sv-SE")
-                .TagValueFormat("{0}%");
+                .UseValueFormatter((v, c) => string.Format(c, "{0}%", v));
 
             // When
             console.Render(chart);

src/Spectre.Console/Extensions/BreakdownChartExtensions.cs

@@ -141,16 +141,53 @@ namespace Spectre.Console
         /// Tags will be shown.
         /// </summary>
         /// <param name="chart">The breakdown chart.</param>
-        /// <param name="format">The tag value format.</param>
+        /// <param name="func">The value formatter to use.</param>
         /// <returns>The same instance so that multiple calls can be chained.</returns>
-        public static BreakdownChart TagValueFormat(this BreakdownChart chart, string? format)
+        public static BreakdownChart UseValueFormatter(this BreakdownChart chart, Func<double, CultureInfo, string>? func)
         {
             if (chart is null)
             {
                 throw new ArgumentNullException(nameof(chart));
             }
 
-            chart.TagValueFormat = format;
+            chart.ValueFormatter = func;
+            return chart;
+        }
+
+        /// <summary>
+        /// Tags will be shown.
+        /// </summary>
+        /// <param name="chart">The breakdown chart.</param>
+        /// <param name="func">The value formatter to use.</param>
+        /// <returns>The same instance so that multiple calls can be chained.</returns>
+        public static BreakdownChart UseValueFormatter(this BreakdownChart chart, Func<double, string>? func)
+        {
+            if (chart is null)
+            {
+                throw new ArgumentNullException(nameof(chart));
+            }
+
+            chart.ValueFormatter = func != null
+                ? (value, _) => func(value)
+                : null;
+
+            return chart;
+        }
+
+        /// <summary>
+        /// Tags will be shown.
+        /// </summary>
+        /// <param name="chart">The breakdown chart.</param>
+        /// <returns>The same instance so that multiple calls can be chained.</returns>
+        public static BreakdownChart ShowPercentage(this BreakdownChart chart)
+        {
+            if (chart is null)
+            {
+                throw new ArgumentNullException(nameof(chart));
+            }
+
+            chart.ValueFormatter = (value, culture) => string.Format(culture, "{0}%", value);
+
             return chart;
         }
 

src/Spectre.Console/Widgets/Charts/BreakdownChart.cs

@@ -31,9 +31,9 @@ namespace Spectre.Console
         public bool ShowTagValues { get; set; } = true;
 
         /// <summary>
-        /// Gets or sets the tag value format.
+        /// Gets or sets the tag value formatter.
         /// </summary>
-        public string? TagValueFormat { get; set; }
+        public Func<double, CultureInfo, string>? ValueFormatter { get; set; }
 
         /// <summary>
         /// Gets or sets a value indicating whether or not the
@@ -91,7 +91,7 @@ namespace Spectre.Console
                     Width = width,
                     Culture = Culture,
                     ShowTagValues = ShowTagValues,
-                    TagValueFormat = TagValueFormat,
+                    ValueFormatter = ValueFormatter,
                 });
             }
 

src/Spectre.Console/Widgets/Charts/BreakdownTags.cs

@@ -12,7 +12,7 @@ namespace Spectre.Console
         public int? Width { get; set; }
         public CultureInfo? Culture { get; set; }
         public bool ShowTagValues { get; set; } = true;
-        public string? TagValueFormat { get; set; }
+        public Func<double, CultureInfo, string>? ValueFormatter { get; set; }
 
         public BreakdownTags(List<IBreakdownChartItem> data)
         {
@@ -56,16 +56,21 @@ namespace Spectre.Console
 
         private string FormatValue(IBreakdownChartItem item, CultureInfo culture)
         {
-            var formatter = TagValueFormat ?? "{0}";
+            var formatter = ValueFormatter ?? DefaultFormatter;
 
             if (ShowTagValues)
             {
                 return string.Format(culture, "{0} [grey]{1}[/]",
                     item.Label.EscapeMarkup(),
-                    string.Format(culture, formatter, item.Value));
+                    formatter(item.Value, culture));
             }
 
             return item.Label.EscapeMarkup();
         }
+
+        private static string DefaultFormatter(double value, CultureInfo culture)
+        {
+            return value.ToString(culture);
+        }
     }
 }

src/Spectre.Console/Widgets/ProgressBar.cs

@@ -44,6 +44,11 @@ namespace Spectre.Console
                 bars = Math.Max(0, bars);
             }
 
+            if (bars < 0)
+            {
+                yield break;
+            }
+
             yield return new Segment(new string(token, bars), style);
 
             if (ShowValue)