✨ feat: initial commit

src/lib/processing/image-processor.ts

@@ -0,0 +1,149 @@
+import sharp from "sharp";
+import type { ImageConfig } from "../protocol/index.ts";
+import { ImageProcessingError } from "../utils/errors.ts";
+
+/**
+ * Image processor for loading, generating, and preparing images.
+ * Handles image operations using the Sharp library including resizing,
+ * format conversion, and test pattern generation.
+ */
+export class ImageProcessor {
+  /**
+   * Creates a new ImageProcessor instance.
+   * @param config Image configuration containing default size,
+   * JPEG quality, and checkerboard settings
+   */
+  constructor(private config: ImageConfig) {}
+
+  /**
+   * Load an image from a file path
+   * @param imagePath Path to the image file
+   * @returns Sharp instance
+   */
+  public async loadFromFile(imagePath: string): Promise<sharp.Sharp> {
+    try {
+      return sharp(imagePath);
+    } catch (error) {
+      throw new ImageProcessingError(
+        `Failed to load image from ${imagePath}: ${error}`,
+      );
+    }
+  }
+
+  /**
+   * Generate a checkerboard test pattern
+   * @param size Image size [width, height]
+   * @param squares Number of squares per side
+   * @returns Buffer containing PNG image data
+   */
+  public async generateCheckerboard(
+    size: [number, number] = this.config.defaultSize,
+    squares: number = this.config.checkerboardSquares,
+  ): Promise<Buffer> {
+    const [width, height] = size;
+    const squareWidth = Math.floor(width / squares);
+    const squareHeight = Math.floor(height / squares);
+
+    // Create SVG checkerboard pattern
+    const svgPattern = this.createCheckerboardSVG(
+      width,
+      height,
+      squareWidth,
+      squareHeight,
+      squares,
+    );
+
+    try {
+      return await sharp(Buffer.from(svgPattern)).png().toBuffer();
+    } catch (error) {
+      throw new ImageProcessingError(
+        `Failed to generate checkerboard: ${error}`,
+      );
+    }
+  }
+
+  /**
+   * Prepare an image as JPEG bytes
+   * @param imageInput Sharp instance or buffer
+   * @param targetSize Target size [width, height]
+   * @returns JPEG image as Buffer
+   */
+  public async prepareImage(
+    imageInput: sharp.Sharp | Buffer,
+    targetSize: [number, number] = this.config.defaultSize,
+  ): Promise<Buffer> {
+    try {
+      const pipeline = Buffer.isBuffer(imageInput)
+        ? sharp(imageInput)
+        : imageInput;
+
+      return await pipeline
+        .resize(targetSize[0], targetSize[1], {
+          fit: "fill",
+          kernel: "lanczos3",
+        })
+        .toColorspace("srgb")
+        .jpeg({
+          quality: this.config.jpegQuality,
+          optimiseCoding: true,
+          mozjpeg: false,
+          chromaSubsampling: "4:2:0",
+        })
+        .toBuffer();
+    } catch (error) {
+      throw new ImageProcessingError(`Failed to prepare image: ${error}`);
+    }
+  }
+
+  /**
+   * Load and prepare an image from file as JPEG bytes
+   * @param imagePath Path to the image file
+   * @param targetSize Target size [width, height]
+   * @returns JPEG image as Buffer
+   */
+  public async prepareFromFile(
+    imagePath: string,
+    targetSize: [number, number] = this.config.defaultSize,
+  ): Promise<Buffer> {
+    const image = await this.loadFromFile(imagePath);
+    return this.prepareImage(image, targetSize);
+  }
+
+  /**
+   * Create SVG markup for a checkerboard pattern.
+   * Generates alternating black and white squares.
+   * @private
+   * @param width Total image width in pixels
+   * @param height Total image height in pixels
+   * @param squareWidth Width of each square in pixels
+   * @param squareHeight Height of each square in pixels
+   * @param squares Number of squares per row/column
+   * @returns SVG string containing the checkerboard pattern
+   */
+  private createCheckerboardSVG(
+    width: number,
+    height: number,
+    squareWidth: number,
+    squareHeight: number,
+    squares: number,
+  ): string {
+    let rects = "";
+
+    for (let row = 0; row < squares; row++) {
+      for (let col = 0; col < squares; col++) {
+        if ((row + col) % 2 === 0) {
+          const x = col * squareWidth;
+          const y = row * squareHeight;
+          rects += `<rect x="${x}" y="${y}" width="${squareWidth}" height="${squareHeight}" fill="black"/>`;
+        }
+      }
+    }
+
+    return `
+      <svg width="${width}" height="${height}" xmlns="http://www.w3.org/2000/svg">
+        <rect width="${width}" height="${height}" fill="white"/>
+        ${rects}
+      </svg>
+    `;
+  }
+}