Image Splitter — C# source

// Image splitter — tile geometry — C# port of the image-splitter tool.

using System;
using System.Collections.Generic;

// One cut of the grid: the source rectangle that becomes a tile. In the
// browser tool this rect is drawImage'd into its own canvas and encoded
// to PNG; the geometry here is the deterministic part of that pipeline.
public readonly record struct TileRect(int X, int Y, int Width, int Height)
{
    public override string ToString() =>
        $"src=({X}, {Y}) {Width}x{Height}";
}

public static class ImageSplitter
{
    // Split a width x height image into rows x cols tiles, row-major.
    // Mirrors splitToTiles in typescript.ts: tileW = floor(width / cols),
    // tileH = floor(height / rows) — integer division IS Math.Floor for
    // positives, so a 1024px width over 3 cols yields 341px tiles and the
    // last 1px column is dropped, exactly like the TS.
    public static List<TileRect> SplitTiles(int width, int height, int rows, int cols)
    {
        int tileW = width / cols;
        int tileH = height / rows;
        var tiles = new List<TileRect>(capacity: rows * cols);
        for (int row = 0; row < rows; row++)
        {
            for (int col = 0; col < cols; col++)
            {
                tiles.Add(new TileRect(col * tileW, row * tileH, tileW, tileH));
            }
        }
        return tiles;
    }
}

public static class Program
{
    // 1024x768 image, 2 rows x 3 cols -> six 341x384 tiles.
    public static void Main()
    {
        foreach (TileRect tile in ImageSplitter.SplitTiles(1024, 768, 2, 3))
        {
            Console.WriteLine(tile);
        }
    }
}