main

services/stickerSheetService.ts

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+import sharp from 'sharp';
+import path from 'path';
+import fs from 'fs';
+import { v4 as uuidv4 } from 'uuid';
+
+// Paper Dimensions (at 300 DPI)
+const PAPER_SIZES: Record<string, { width: number, height: number }> = {
+    'A4': { width: 2480, height: 3508 }, // 210mm x 297mm
+    'Letter': { width: 2550, height: 3300 }, // 8.5in x 11in
+    'A5': { width: 1748, height: 2480 } // 148mm x 210mm
+};
+
+export const stickerSheetService = {
+
+    /**
+     * Add a white border and optional cut line to an image.
+     * @param inputPath Path to the source image (sticker).
+     * @param borderWidth Width of the white contour in pixels (default 40).
+     */
+    async addCutContour(inputPath: string, borderWidth: number = 40): Promise<Buffer> {
+        // 1. Load Image
+        const image = sharp(inputPath);
+        const metadata = await image.metadata();
+        if (!metadata.width || !metadata.height) throw new Error("Invalid image metadata");
+
+        // 2. Create Mask (Alpha Channel)
+        const alpha = await image.clone()
+            .toColourspace('b-w')
+            .ensureAlpha()
+            .extractChannel(3) // Get alpha channel
+            .raw()
+            .toBuffer();
+
+        // 3. Dilate Mask to create Border Shape
+        // Proper dilation requires morphological operations which Sharp doesn't support natively well for complex shapes without external libs.
+        // TRICK: We will blur the alpha channel and threshold it to simulate dilation/expansion.
+        const expandedMask = await sharp(alpha, { raw: { width: metadata.width, height: metadata.height, channels: 1 } })
+            .blur(borderWidth) // Spread the alpha
+            .threshold(10)     // Binarize to create hard edge
+            .toBuffer();
+
+        // 4. Create White Silhouette using the expanded mask
+        const whiteBackground = await sharp({
+            create: {
+                width: metadata.width,
+                height: metadata.height,
+                channels: 4,
+                background: { r: 255, g: 255, b: 255, alpha: 1 }
+            }
+        })
+            .joinChannel(expandedMask) // Apply mask
+            .png()
+            .toBuffer();
+
+        // 5. Composite Original Image ON TOP of White Silhouette
+        return sharp(whiteBackground)
+            .composite([{ input: inputPath }])
+            .withMetadata({ density: 300 }) // Enforce 300 DPI
+            .png()
+            .toBuffer();
+    },
+
+    /**
+     * Generate a BLACKOUT mask for Cricut Cut Lines.
+     * Returns a binary verification image (Black shape on transparent background).
+     */
+    async generateCutMask(inputPath: string, borderWidth: number = 40): Promise<Buffer> {
+        // 1. Load Image
+        const image = sharp(inputPath);
+        const metadata = await image.metadata();
+        if (!metadata.width || !metadata.height) throw new Error("Invalid image metadata");
+
+        // 2. Extract Alpha
+        const alpha = await image.clone()
+            .toColourspace('b-w')
+            .ensureAlpha()
+            .extractChannel(3)
+            .raw()
+            .toBuffer();
+
+        // 3. Dilate (Same logic as addCutContour to match perfectly)
+        const expandedMask = await sharp(alpha, { raw: { width: metadata.width, height: metadata.height, channels: 1 } })
+            .blur(borderWidth)
+            .threshold(10)
+            .toBuffer();
+
+        // 4. Create BLACK Silhouette
+        return sharp({
+            create: {
+                width: metadata.width,
+                height: metadata.height,
+                channels: 4,
+                background: { r: 0, g: 0, b: 0, alpha: 1 } // BLACK
+            }
+        })
+            .joinChannel(expandedMask) // Apply same mask
+            .withMetadata({ density: 300 }) // Enforce 300 DPI
+            .png()
+            .toBuffer();
+    },
+
+    /**
+     * Arrange multiple stickers onto a single sheet.
+     * @param stickerPaths Array of absolute paths to sticker images.
+     * @param options Configuration for the sheet (target dimensions, paper size name)
+     */
+    async generateSheet(stickerPaths: string[], options: { width: number, height: number, paperSizeName?: string }): Promise<Buffer> {
+        const { width, height } = options;
+
+        // Target 4-5 columns for A4/Letter at 2500px width.
+        // If width is ~5000px (High Res A4), we still want ~4-5 columns? 
+        // Or do we want more stickers if we have them?
+        // Usually a sticker sheet has a fixed number of stickers. 
+        // Let's assume we want a standard grid. 
+        // Let's base sticker size on WIDTH.
+        // 4 cols + 5 gaps = width.
+        // stickerW * 4 + gap * 5 = width.
+        // let gap = stickerW / 10.
+        // stickerW * 4 + stickerW/2 = width => 4.5 stickerW = width.
+
+        const COLS = 4;
+        // Calculation:
+        // Width = COLS * StickerW + (COLS + 1) * GAP
+        // Let GAP = StickerW * 0.1
+        // Width = 4 * S + 5 * 0.1 * S = 4.5 S
+        const stickerWidth = Math.floor(width / (COLS + (COLS + 1) * 0.1));
+        const gap = Math.floor(stickerWidth * 0.1);
+
+        console.log(`[StickerService] Generating Sheet ${width}x${height}. Sticker W: ${stickerWidth}, Gap: ${gap}`);
+
+        const composites: sharp.OverlayOptions[] = [];
+
+        let currentX = gap;
+        let currentY = gap;
+        let maxHeightInRow = 0;
+
+        for (const stickerPath of stickerPaths) {
+            let stickerBuffer;
+            try {
+                stickerBuffer = await this.addCutContour(stickerPath, Math.floor(stickerWidth * 0.05)); // Scale border too
+            } catch (e) {
+                console.error(`Failed to process sticker ${stickerPath}`, e);
+                continue;
+            }
+
+            // Resize to target width
+            const resizedSticker = await sharp(stickerBuffer)
+                .resize({ width: stickerWidth })
+                .toBuffer();
+
+            const meta = await sharp(resizedSticker).metadata();
+            const w = meta.width || stickerWidth;
+            const h = meta.height || stickerWidth;
+
+            // Check if fits in current row
+            if (currentX + w + gap > width) {
+                // Next Row
+                currentX = gap;
+                currentY += maxHeightInRow + gap;
+                maxHeightInRow = 0;
+            }
+
+            // Check if fits in page (vertical)
+            if (currentY + h + gap > height) {
+                console.warn("Sheet full, skipping remaining stickers");
+                break;
+            }
+
+            composites.push({
+                input: resizedSticker,
+                top: currentY,
+                left: currentX
+            });
+
+            currentX += w + gap;
+            if (h > maxHeightInRow) maxHeightInRow = h;
+        }
+
+        // Create Sheet Canvas
+        return sharp({
+            create: {
+                width: width,
+                height: height,
+                channels: 4,
+                background: { r: 255, g: 255, b: 255, alpha: 0 } // Transparent
+            }
+        })
+            .composite(composites)
+            .png()
+            .toBuffer();
+    }
+};