Add half-block support to Canvas

src/Extensions/Spectre.Console.ImageSharp/CanvasImage.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using SixLabors.ImageSharp;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Processing.Processors.Transforms;
@@ -33,6 +34,7 @@ public sealed class CanvasImage : Renderable
     /// <summary>
     /// Gets or sets the render width of the canvas.
     /// </summary>
+    [Obsolete("Not used anymore. Will be removed in future update.")]
     public int PixelWidth { get; set; } = 2;
 
     /// <summary>
@@ -73,27 +75,23 @@ public sealed class CanvasImage : Renderable
     /// <inheritdoc/>
     protected override Measurement Measure(RenderOptions options, int maxWidth)
     {
-        if (PixelWidth < 0)
-        {
-            throw new InvalidOperationException("Pixel width must be greater than zero.");
-        }
-
+        var pixelWidth = options.Unicode ? 1 : 2;
         var width = MaxWidth ?? Width;
-        if (maxWidth < width * PixelWidth)
+        if (maxWidth < width * pixelWidth)
         {
             return new Measurement(maxWidth, maxWidth);
         }
 
-        return new Measurement(width * PixelWidth, width * PixelWidth);
+        return new Measurement(width * pixelWidth, width * pixelWidth);
     }
 
     /// <inheritdoc/>
     protected override IEnumerable<Segment> Render(RenderOptions options, int maxWidth)
     {
         var image = Image;
-
         var width = Width;
         var height = Height;
+        var pixelWidth = options.Unicode ? 1 : 2;
 
         // Got a max width?
         if (MaxWidth != null)
@@ -103,10 +101,10 @@ public sealed class CanvasImage : Renderable
         }
 
         // Exceed the max width when we take pixel width into account?
-        if (width * PixelWidth > maxWidth)
+        if (width * pixelWidth > maxWidth)
         {
-            height = (int)(height * (maxWidth / (float)(width * PixelWidth)));
-            width = maxWidth / PixelWidth;
+            height = (int)(height * (maxWidth / (float)(width * pixelWidth)));
+            width = maxWidth / pixelWidth;
         }
 
         // Need to rescale the pixel buffer?
@@ -120,7 +118,6 @@ public sealed class CanvasImage : Renderable
         var canvas = new Canvas(width, height)
         {
             MaxWidth = MaxWidth,
-            PixelWidth = PixelWidth,
             Scale = false,
         };
 

src/Extensions/Spectre.Console.ImageSharp/CanvasImageExtensions.cs

@@ -47,6 +47,7 @@ public static class CanvasImageExtensions
     /// <param name="image">The canvas image.</param>
     /// <param name="width">The pixel width.</param>
     /// <returns>The same instance so that multiple calls can be chained.</returns>
+    [Obsolete("Not used anymore. Will be removed in future update.")]
     public static CanvasImage PixelWidth(this CanvasImage image, int width)
     {
         if (image is null)

src/Spectre.Console.Testing/Extensions/TestConsoleExtensions.cs

@@ -29,6 +29,18 @@ public static partial class TestConsoleExtensions
         return console;
     }
 
+    /// <summary>
+    /// Sets whether or not Unicode is supported.
+    /// </summary>
+    /// <param name="console">The console.</param>
+    /// <param name="enable">Whether or not Unicode is supported.</param>
+    /// <returns>The same instance so that multiple calls can be chained.</returns>
+    public static TestConsole SupportsUnicode(this TestConsole console, bool enable)
+    {
+        console.Profile.Capabilities.Unicode = enable;
+        return console;
+    }
+
     /// <summary>
     /// Makes the console interactive.
     /// </summary>

src/Spectre.Console.Tests/Expectations/Widgets/Canvas/Render.Unicode.verified.txt

@@ -0,0 +1,3 @@
+▀   ▀
+     
+▀   ▀

src/Spectre.Console.Tests/Expectations/Widgets/Canvas/Render_MaxWidth.Unicode.verified.txt

@@ -0,0 +1,3 @@
+▀         
+          
+          

src/Spectre.Console.Tests/Expectations/Widgets/Canvas/Render_NarrowTerminal.Unicode.verified.txt

@@ -0,0 +1,3 @@
+▀         
+          
+          

src/Spectre.Console.Tests/Expectations/Widgets/Canvas/Render_Nested.Unicode.verified.txt

@@ -0,0 +1,3 @@
+┌────┐
+│ ▀▄ │
+└────┘

src/Spectre.Console.Tests/Unit/Widgets/CanvasTests.cs

@@ -28,13 +28,16 @@ public class CanvasTests
         }
     }
 
-    [Fact]
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
     [Expectation("Render")]
-    public async Task Should_Render_Canvas_Correctly()
+    public async Task Should_Render_Canvas_Correctly(bool supportsUnicode)
     {
         // Given
         var console = new TestConsole()
             .Colors(ColorSystem.Standard)
+            .SupportsUnicode(supportsUnicode)
             .EmitAnsiSequences();
 
         var canvas = new Canvas(width: 5, height: 5);
@@ -47,16 +50,21 @@ public class CanvasTests
         console.Write(canvas);
 
         // Then
-        await Verifier.Verify(console.Output);
+        await Verifier
+            .Verify(console.Output)
+            .UseMethodName(supportsUnicode ? "Unicode" : "NonUnicode");
     }
 
-    [Fact]
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
     [Expectation("Render_Nested")]
-    public async Task Simple_Measure()
+    public async Task Simple_Measure(bool supportsUnicode)
     {
         // Given
         var console = new TestConsole()
             .Colors(ColorSystem.Standard)
+            .SupportsUnicode(supportsUnicode)
             .EmitAnsiSequences();
 
         var panel = new Panel(new Canvas(width: 2, height: 2)
@@ -67,17 +75,22 @@ public class CanvasTests
         console.Write(panel);
 
         // Then
-        await Verifier.Verify(console.Output);
+        await Verifier
+            .Verify(console.Output)
+            .UseMethodName(supportsUnicode ? "Unicode" : "NonUnicode");
     }
 
-    [Fact]
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
     [Expectation("Render_NarrowTerminal")]
-    public async Task Should_Scale_Down_Canvas_Is_Bigger_Than_Terminal()
+    public async Task Should_Scale_Down_Canvas_Is_Bigger_Than_Terminal(bool supportsUnicode)
     {
         // Given
         var console = new TestConsole()
             .Width(10)
             .Colors(ColorSystem.Standard)
+            .SupportsUnicode(supportsUnicode)
             .EmitAnsiSequences();
 
         var canvas = new Canvas(width: 20, height: 10);
@@ -88,19 +101,27 @@ public class CanvasTests
         console.Write(canvas);
 
         // Then
-        await Verifier.Verify(console.Output);
+        await Verifier
+            .Verify(console.Output)
+            .UseMethodName(supportsUnicode ? "Unicode" : "NonUnicode");
     }
 
-    [Fact]
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
     [Expectation("Render_MaxWidth")]
-    public async Task Should_Scale_Down_Canvas_If_MaxWidth_Is_Set()
+    public async Task Should_Scale_Down_Canvas_If_MaxWidth_Is_Set(bool supportsUnicode)
     {
         // Given
         var console = new TestConsole()
             .Colors(ColorSystem.Standard)
+            .SupportsUnicode(supportsUnicode)
             .EmitAnsiSequences();
 
-        var canvas = new Canvas(width: 20, height: 10) { MaxWidth = 10 };
+        var canvas = new Canvas(width: 20, height: 10)
+        {
+            MaxWidth = 10
+        };
         canvas.SetPixel(0, 0, Color.Aqua);
         canvas.SetPixel(19, 9, Color.Aqua);
 
@@ -108,16 +129,22 @@ public class CanvasTests
         console.Write(canvas);
 
         // Then
-        await Verifier.Verify(console.Output);
+        await Verifier
+            .Verify(console.Output)
+            .UseMethodName(supportsUnicode ? "Unicode" : "NonUnicode");
     }
 
-    [Fact]
-    public void Should_Not_Render_Canvas_If_Canvas_Cannot_Be_Scaled_Down()
+    [Theory]
+    [InlineData(true, 5)]
+    [InlineData(false, 10)]
+    public void Should_Not_Render_Canvas_If_Canvas_Cannot_Be_Scaled_Down(
+        bool supportsUnicode, int consoleWidth)
     {
         // Given
         var console = new TestConsole()
-            .Width(10)
+            .Width(consoleWidth)
             .Colors(ColorSystem.Standard)
+            .SupportsUnicode(supportsUnicode)
             .EmitAnsiSequences();
 
         var canvas = new Canvas(width: 20, height: 2);

src/Spectre.Console/Widgets/Canvas.cs

@@ -7,6 +7,11 @@ public sealed class Canvas : Renderable
 {
     private readonly Color?[,] _pixels;
 
+    private const string Transparent = " ";
+    private const string DoubleTransparent = "  ";
+    private const string UpperHalfBlock = "▀";
+    private const string LowerHalfBlock = "▄";
+
     /// <summary>
     /// Gets the width of the canvas.
     /// </summary>
@@ -31,6 +36,7 @@ public sealed class Canvas : Renderable
     /// <summary>
     /// Gets or sets the pixel width.
     /// </summary>
+    [Obsolete("Not used anymore. Will be removed in future update.")]
     public int PixelWidth { get; set; } = 2;
 
     /// <summary>
@@ -72,31 +78,25 @@ public sealed class Canvas : Renderable
     /// <inheritdoc/>
     protected override Measurement Measure(RenderOptions options, int maxWidth)
     {
-        if (PixelWidth < 0)
-        {
-            throw new InvalidOperationException("Pixel width must be greater than zero.");
-        }
-
+        var pixelWidth = options.Unicode ? 1 : 2;
         var width = MaxWidth ?? Width;
 
-        if (maxWidth < width * PixelWidth)
-        {
-            return new Measurement(maxWidth, maxWidth);
-        }
-
-        return new Measurement(width * PixelWidth, width * PixelWidth);
+        return maxWidth < width * pixelWidth
+            ? new Measurement(maxWidth, maxWidth)
+            : new Measurement(width * pixelWidth, width * pixelWidth);
     }
 
     /// <inheritdoc/>
     protected override IEnumerable<Segment> Render(RenderOptions options, int maxWidth)
     {
-        if (PixelWidth < 0)
-        {
-            throw new InvalidOperationException("Pixel width must be greater than zero.");
+        return options.Unicode
+            ? RenderUnicode(maxWidth)
+            : RenderNonUnicode(maxWidth);
     }
 
+    private IEnumerable<Segment> RenderUnicode(int maxWidth)
+    {
         var pixels = _pixels;
-        var pixel = new string(' ', PixelWidth);
         var width = Width;
         var height = Height;
 
@@ -108,14 +108,86 @@ public sealed class Canvas : Renderable
         }
 
         // Exceed the max width when we take pixel width into account?
-        if (width * PixelWidth > maxWidth)
+        if (width > maxWidth)
         {
-            height = (int)(height * (maxWidth / (float)(width * PixelWidth)));
-            width = maxWidth / PixelWidth;
+            height = (int)(height * (maxWidth / (float)(width)));
+            width = maxWidth;
 
-            // If it's not possible to scale the canvas sufficiently, it's too small to render.
             if (height == 0)
             {
+                // If it's not possible to scale the canvas sufficiently, it's too small to render.
+                yield break;
+            }
+        }
+
+        // Need to rescale the pixel buffer?
+        if (Scale && (width != Width || height != Height))
+        {
+            pixels = ScaleDown(width, height);
+        }
+
+        for (var y = 0; y < height; y += 2)
+        {
+            for (var x = 0; x < width; x++)
+            {
+                var upper = pixels[x, y];
+                var lower = y < height - 1 ? pixels[x, y + 1] : null;
+
+                if (upper == null && lower == null)
+                {
+                    // None visible
+                    yield return new Segment(Transparent);
+                }
+                else if (upper != null && lower != null)
+                {
+                    // Both pixels visible
+                    yield return new Segment(
+                        UpperHalfBlock, new Style(
+                            foreground: upper,
+                            background: lower));
+                }
+                else if (upper != null)
+                {
+                    // Upper visible
+                    yield return new Segment(
+                        UpperHalfBlock, new Style(
+                            foreground: upper));
+                }
+                else if (lower != null)
+                {
+                    // Lower visible
+                    yield return new Segment(
+                        LowerHalfBlock, new Style(
+                            foreground: lower));
+                }
+            }
+
+            yield return Segment.LineBreak;
+        }
+    }
+
+    private IEnumerable<Segment> RenderNonUnicode(int maxWidth)
+    {
+        var pixels = _pixels;
+        var width = Width;
+        var height = Height;
+
+        // Got a max width?
+        if (MaxWidth != null)
+        {
+            height = (int)(height * ((float)MaxWidth.Value) / Width);
+            width = MaxWidth.Value;
+        }
+
+        // Exceed the max width when we take pixel width into account?
+        if (width * 2 > maxWidth)
+        {
+            height = (int)(height * (maxWidth / (float)(width * 2)));
+            width = maxWidth / 2;
+
+            if (height == 0)
+            {
+                // If it's not possible to scale the canvas sufficiently, it's too small to render.
                 yield break;
             }
         }
@@ -133,11 +205,11 @@ public sealed class Canvas : Renderable
                 var color = pixels[x, y];
                 if (color != null)
                 {
-                    yield return new Segment(pixel, new Style(background: color));
+                    yield return new Segment(DoubleTransparent, new Style(background: color));
                 }
                 else
                 {
-                    yield return new Segment(pixel);
+                    yield return new Segment(DoubleTransparent);
                 }
             }