From c5280986f6028d2436cee52b9ab60c11fbd35724 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Sun, 23 Aug 2026 14:45:48 +0200
Subject: [PATCH] feat(core): add ascii and ppm frame renderers

---
 src/Chip8.Core/AsciiScreen.cs     | 87 +++++++++++++++++++++++++++++++
 src/Chip8.Core/Export/PpmImage.cs | 71 +++++++++++++++++++++++++
 2 files changed, 158 insertions(+)
 create mode 100644 src/Chip8.Core/AsciiScreen.cs
 create mode 100644 src/Chip8.Core/Export/PpmImage.cs

diff --git a/src/Chip8.Core/AsciiScreen.cs b/src/Chip8.Core/AsciiScreen.cs
new file mode 100644
index 0000000..2ecf47a
--- /dev/null
+++ b/src/Chip8.Core/AsciiScreen.cs
@@ -0,0 +1,87 @@
+using System.Text;
+
+namespace Chip8.Core;
+
+public static class AsciiScreen
+{
+    public static string render(bool[] display, char on = '#', char off = ' ')
+    {
+        var builder = new StringBuilder((Machine.displayWidth + 1) * Machine.displayHeight);
+
+        for (int row = 0; row < Machine.displayHeight; row++)
+        {
+            for (int col = 0; col < Machine.displayWidth; col++)
+            {
+                builder.Append(display[row * Machine.displayWidth + col] ? on : off);
+            }
+            builder.Append('\n');
+        }
+
+        return builder.ToString();
+    }
+
+    public static string renderFramed(bool[] display, char on = '#', char off = ' ')
+    {
+        var builder = new StringBuilder();
+        string border = new string('-', Machine.displayWidth);
+
+        builder.Append('+').Append(border).Append("+\n");
+        for (int row = 0; row < Machine.displayHeight; row++)
+        {
+            builder.Append('|');
+            for (int col = 0; col < Machine.displayWidth; col++)
+            {
+                builder.Append(display[row * Machine.displayWidth + col] ? on : off);
+            }
+            builder.Append("|\n");
+        }
+        builder.Append('+').Append(border).Append("+\n");
+
+        return builder.ToString();
+    }
+
+    public static int litPixelCount(bool[] display)
+    {
+        int lit = 0;
+        foreach (bool pixel in display)
+        {
+            if (pixel)
+            {
+                lit++;
+            }
+        }
+        return lit;
+    }
+
+    public static string render(Video video, string palette = " #*@")
+    {
+        var builder = new StringBuilder((video.width + 1) * video.height);
+
+        for (int row = 0; row < video.height; row++)
+        {
+            for (int col = 0; col < video.width; col++)
+            {
+                builder.Append(palette[video.colorAt(col, row)]);
+            }
+            builder.Append('\n');
+        }
+
+        return builder.ToString();
+    }
+
+    public static int litPixelCount(Video video)
+    {
+        int lit = 0;
+        for (int row = 0; row < video.height; row++)
+        {
+            for (int col = 0; col < video.width; col++)
+            {
+                if (video.colorAt(col, row) != 0)
+                {
+                    lit++;
+                }
+            }
+        }
+        return lit;
+    }
+}
diff --git a/src/Chip8.Core/Export/PpmImage.cs b/src/Chip8.Core/Export/PpmImage.cs
new file mode 100644
index 0000000..e094fbd
--- /dev/null
+++ b/src/Chip8.Core/Export/PpmImage.cs
@@ -0,0 +1,71 @@
+using System;
+using System.IO;
+using System.Text;
+
+namespace Chip8.Core.Export;
+
+public static class PpmImage
+{
+    public static byte[] fromMonochrome(bool[] pixels, int width, int height, Palette palette, int scale = 1)
+    {
+        if (pixels.Length < width * height)
+        {
+            throw new ArgumentException("pixel buffer is smaller than " + width + "x" + height, nameof(pixels));
+        }
+        return build(width, height, scale, palette, (x, y) => pixels[y * width + x] ? 1 : 0);
+    }
+
+    public static byte[] fromVideo(Video video, Palette palette, int scale = 1) =>
+        build(video.width, video.height, scale, palette, video.colorAt);
+
+    public static byte[] fromMachine(Machine machine, Palette palette, int scale = 1)
+    {
+        if (machine.platform == Platform.Chip8)
+        {
+            return fromMonochrome(machine.display, Machine.displayWidth, Machine.displayHeight, palette, scale);
+        }
+        return fromVideo(machine.video, palette, scale);
+    }
+
+    public static void writeFile(string path, byte[] ppm) => File.WriteAllBytes(path, ppm);
+
+    static byte[] build(int width, int height, int scale, Palette palette, Func<int, int, int> colorAt)
+    {
+        if (scale < 1)
+        {
+            throw new ArgumentOutOfRangeException(nameof(scale), "scale must be at least 1");
+        }
+
+        int outWidth = width * scale;
+        int outHeight = height * scale;
+        byte[] header = Encoding.ASCII.GetBytes("P6\n" + outWidth + " " + outHeight + "\n255\n");
+
+        var output = new byte[header.Length + outWidth * outHeight * 3];
+        Array.Copy(header, output, header.Length);
+
+        int cursor = header.Length;
+        for (int y = 0; y < height; y++)
+        {
+            int rowStart = cursor;
+            for (int x = 0; x < width; x++)
+            {
+                Rgb color = palette.resolve(colorAt(x, y));
+                for (int sx = 0; sx < scale; sx++)
+                {
+                    output[cursor++] = color.r;
+                    output[cursor++] = color.g;
+                    output[cursor++] = color.b;
+                }
+            }
+
+            int rowBytes = outWidth * 3;
+            for (int sy = 1; sy < scale; sy++)
+            {
+                Array.Copy(output, rowStart, output, cursor, rowBytes);
+                cursor += rowBytes;
+            }
+        }
+
+        return output;
+    }
+}