Add visual workflow builder, fix critical bugs, and add Arabic i18n support

src/js/workflow/nodes/remove-blank-pages-node.ts

@@ -0,0 +1,90 @@
+import { ClassicPreset } from 'rete';
+import { BaseWorkflowNode } from './base-node';
+import { pdfSocket } from '../sockets';
+import type { SocketData } from '../types';
+import { requirePdfInput, processBatch } from '../types';
+import { PDFDocument } from 'pdf-lib';
+import * as pdfjsLib from 'pdfjs-dist';
+
+export class RemoveBlankPagesNode extends BaseWorkflowNode {
+  readonly category = 'Edit & Annotate' as const;
+  readonly icon = 'ph-file-minus';
+  readonly description = 'Remove blank pages automatically';
+
+  constructor() {
+    super('Remove Blank Pages');
+    this.addInput('pdf', new ClassicPreset.Input(pdfSocket, 'PDF'));
+    this.addOutput('pdf', new ClassicPreset.Output(pdfSocket, 'PDF'));
+    this.addControl(
+      'threshold',
+      new ClassicPreset.InputControl('number', { initial: 250 })
+    );
+  }
+
+  private async isPageBlank(
+    page: pdfjsLib.PDFPageProxy,
+    threshold: number
+  ): Promise<boolean> {
+    const viewport = page.getViewport({ scale: 0.5 });
+    const canvas = document.createElement('canvas');
+    canvas.width = viewport.width;
+    canvas.height = viewport.height;
+    const ctx = canvas.getContext('2d')!;
+    await page.render({ canvasContext: ctx, viewport, canvas }).promise;
+
+    const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
+    const data = imageData.data;
+    let totalBrightness = 0;
+    for (let i = 0; i < data.length; i += 4) {
+      totalBrightness += (data[i] + data[i + 1] + data[i + 2]) / 3;
+    }
+    const avgBrightness = totalBrightness / (data.length / 4);
+    return avgBrightness > threshold;
+  }
+
+  async data(
+    inputs: Record<string, SocketData[]>
+  ): Promise<Record<string, SocketData>> {
+    const pdfInputs = requirePdfInput(inputs, 'Remove Blank Pages');
+
+    const threshCtrl = this.controls['threshold'] as
+      | ClassicPreset.InputControl<'number'>
+      | undefined;
+    const threshold = Math.max(200, Math.min(255, threshCtrl?.value ?? 250));
+
+    return {
+      pdf: await processBatch(pdfInputs, async (input) => {
+        const pdfjsDoc = await pdfjsLib.getDocument({ data: input.bytes })
+          .promise;
+        const srcDoc = await PDFDocument.load(input.bytes);
+        const nonBlankIndices: number[] = [];
+
+        for (let i = 1; i <= pdfjsDoc.numPages; i++) {
+          const page = await pdfjsDoc.getPage(i);
+          const blank = await this.isPageBlank(page, threshold);
+          if (!blank) {
+            nonBlankIndices.push(i - 1);
+          } else {
+            console.log(`Page ${i} detected as blank, removing`);
+          }
+        }
+
+        if (nonBlankIndices.length === 0) {
+          throw new Error('All pages are blank');
+        }
+
+        const newDoc = await PDFDocument.create();
+        const copiedPages = await newDoc.copyPages(srcDoc, nonBlankIndices);
+        copiedPages.forEach((page) => newDoc.addPage(page));
+
+        const pdfBytes = await newDoc.save();
+        return {
+          type: 'pdf',
+          document: newDoc,
+          bytes: new Uint8Array(pdfBytes),
+          filename: input.filename.replace(/\.pdf$/i, '_cleaned.pdf'),
+        };
+      }),
+    };
+  }
+}