change requests + allow transitioning between previews when multiple files are selected

frontend/src/components/tools/adjustContrast/AdjustContrastSingleStepSettings.tsx

@@ -0,0 +1,31 @@
+import React from 'react';
+import { Stack } from '@mantine/core';
+import { AdjustContrastParameters } from '../../../hooks/tools/adjustContrast/useAdjustContrastParameters';
+import AdjustContrastBasicSettings from './AdjustContrastBasicSettings';
+import AdjustContrastColorSettings from './AdjustContrastColorSettings';
+
+interface Props {
+  parameters: AdjustContrastParameters;
+  onParameterChange: <K extends keyof AdjustContrastParameters>(key: K, value: AdjustContrastParameters[K]) => void;
+  disabled?: boolean;
+}
+
+// Single-step settings used by Automate to configure Adjust Contrast in one panel
+export default function AdjustContrastSingleStepSettings({ parameters, onParameterChange, disabled }: Props) {
+  return (
+    <Stack gap="lg">
+      <AdjustContrastBasicSettings
+        parameters={parameters}
+        onParameterChange={onParameterChange}
+        disabled={disabled}
+      />
+      <AdjustContrastColorSettings
+        parameters={parameters}
+        onParameterChange={onParameterChange}
+        disabled={disabled}
+      />
+    </Stack>
+  );
+}
+
+

frontend/src/data/useTranslatedToolRegistry.tsx

@@ -15,6 +15,7 @@ import { reorganizePagesOperationConfig } from "../hooks/tools/reorganizePages/u
 import RemovePassword from "../tools/RemovePassword";
 import { SubcategoryId, ToolCategoryId, ToolRegistry } from "./toolsTaxonomy";
 import AdjustContrast from "../tools/AdjustContrast";
+import AdjustContrastSingleStepSettings from "../components/tools/adjustContrast/AdjustContrastSingleStepSettings";
 import { adjustContrastOperationConfig } from "../hooks/tools/adjustContrast/useAdjustContrastOperation";
 import { getSynonyms } from "../utils/toolSynonyms";
 import AddWatermark from "../tools/AddWatermark";
@@ -642,6 +643,7 @@ export function useFlatToolRegistry(): ToolRegistry {
         categoryId: ToolCategoryId.ADVANCED_TOOLS,
         subcategoryId: SubcategoryId.ADVANCED_FORMATTING,
         operationConfig: adjustContrastOperationConfig,
+        settingsComponent: AdjustContrastSingleStepSettings,
         synonyms: getSynonyms(t, "adjustContrast"),
       },
       repair: {

frontend/src/hooks/tools/adjustContrast/useAdjustContrastOperation.ts

@@ -3,6 +3,7 @@ import { ToolType, useToolOperation } from '../shared/useToolOperation';
 import { AdjustContrastParameters, defaultParameters } from './useAdjustContrastParameters';
 import { PDFDocument as PDFLibDocument } from 'pdf-lib';
 import { applyAdjustmentsToCanvas } from '../../../components/tools/adjustContrast/utils';
+import { pdfWorkerManager } from '../../../services/pdfWorkerManager';
 import { createFileFromApiResponse } from '../../../utils/fileResponseUtils';
 
 async function renderPdfPageToCanvas(pdf: any, pageNumber: number, scale: number): Promise<HTMLCanvasElement> {
@@ -19,11 +20,8 @@ async function renderPdfPageToCanvas(pdf: any, pageNumber: number, scale: number
 
 // adjustment logic moved to shared util
 
-async function processPdfClientSide(params: AdjustContrastParameters, files: File[]): Promise<File[]> {
-  const outputs: File[] = [];
-  const { pdfWorkerManager } = await import('../../../services/pdfWorkerManager');
-
-  for (const file of files) {
+// Render, adjust, and assemble all pages of a single PDF into a new PDF
+async function buildAdjustedPdfForFile(file: File, params: AdjustContrastParameters): Promise<File> {
     const arrayBuffer = await file.arrayBuffer();
     const pdf = await pdfWorkerManager.createDocument(arrayBuffer, {});
     const pageCount = pdf.numPages;
@@ -44,11 +42,37 @@ async function processPdfClientSide(params: AdjustContrastParameters, files: Fil
 
     const pdfBytes = await newDoc.save();
     const out = createFileFromApiResponse(pdfBytes, { 'content-type': 'application/pdf' }, file.name);
-    outputs.push(out);
     pdfWorkerManager.destroyDocument(pdf);
-  }
+    return out;
+}
 
-  return outputs;
+async function processPdfClientSide(params: AdjustContrastParameters, files: File[]): Promise<File[]> {
+  // Limit concurrency to avoid exhausting memory/CPU while still getting speedups
+  // Heuristic: use up to 4 workers on capable machines, otherwise 2-3
+  let CONCURRENCY_LIMIT = 2;
+  if (typeof navigator !== 'undefined' && typeof navigator.hardwareConcurrency === 'number') {
+    if (navigator.hardwareConcurrency >= 8) CONCURRENCY_LIMIT = 4;
+    else if (navigator.hardwareConcurrency >= 4) CONCURRENCY_LIMIT = 3;
+  }
+  CONCURRENCY_LIMIT = Math.min(CONCURRENCY_LIMIT, files.length);
+
+  const mapWithConcurrency = async <T, R>(items: T[], limit: number, worker: (item: T, index: number) => Promise<R>): Promise<R[]> => {
+    const results: R[] = new Array(items.length);
+    let nextIndex = 0;
+
+    const workers = new Array(Math.min(limit, items.length)).fill(0).map(async () => {
+      let current = nextIndex++;
+      while (current < items.length) {
+        results[current] = await worker(items[current], current);
+        current = nextIndex++;
+      }
+    });
+
+    await Promise.all(workers);
+    return results;
+  };
+
+  return mapWithConcurrency(files, CONCURRENCY_LIMIT, (file) => buildAdjustedPdfForFile(file, params));
 }
 
 export const adjustContrastOperationConfig = {
@@ -56,6 +80,8 @@ export const adjustContrastOperationConfig = {
   customProcessor: processPdfClientSide,
   operationType: 'adjustContrast',
   defaultParameters,
+  // Single-step settings component for Automate
+  settingsComponentPath: 'components/tools/adjustContrast/AdjustContrastSingleStepSettings',
 } as const;
 
 export const useAdjustContrastOperation = () => {

frontend/src/tools/AdjustContrast.tsx

@@ -1,4 +1,5 @@
 import { useTranslation } from 'react-i18next';
+import React, { useEffect, useMemo, useState } from 'react';
 import { createToolFlow } from '../components/tools/shared/createToolFlow';
 import { BaseToolProps, ToolComponent } from '../types/tool';
 import { useBaseTool } from '../hooks/tools/shared/useBaseTool';
@@ -8,6 +9,7 @@ import AdjustContrastBasicSettings from '../components/tools/adjustContrast/Adju
 import AdjustContrastColorSettings from '../components/tools/adjustContrast/AdjustContrastColorSettings';
 import AdjustContrastPreview from '../components/tools/adjustContrast/AdjustContrastPreview';
 import { useAccordionSteps } from '../hooks/tools/shared/useAccordionSteps';
+import NavigationArrows from '../components/shared/filePreview/NavigationArrows';
 
 const AdjustContrast = (props: BaseToolProps) => {
   const { t } = useTranslation();
@@ -27,6 +29,23 @@ const AdjustContrast = (props: BaseToolProps) => {
     afterResults: base.handleSettingsReset
   });
 
+  // Track which selected file is being previewed. Clamp when selection changes.
+  const [previewIndex, setPreviewIndex] = useState(0);
+  const totalSelected = base.selectedFiles.length;
+
+  useEffect(() => {
+    if (previewIndex >= totalSelected) {
+      setPreviewIndex(Math.max(0, totalSelected - 1));
+    }
+  }, [totalSelected, previewIndex]);
+
+  const currentFile = useMemo(() => {
+    return totalSelected > 0 ? base.selectedFiles[previewIndex] : null;
+  }, [base.selectedFiles, previewIndex, totalSelected]);
+
+  const handlePrev = () => setPreviewIndex((i) => Math.max(0, i - 1));
+  const handleNext = () => setPreviewIndex((i) => Math.min(totalSelected - 1, i + 1));
+
   return createToolFlow({
     files: {
       selectedFiles: base.selectedFiles,
@@ -59,10 +78,25 @@ const AdjustContrast = (props: BaseToolProps) => {
       },
     ],
     preview: (
-      <AdjustContrastPreview
-        file={base.selectedFiles[0] || null}
-        parameters={base.params.parameters}
-      />
+      <div>
+        <NavigationArrows
+          onPrevious={handlePrev}
+          onNext={handleNext}
+          disabled={totalSelected <= 1}
+        >
+          <div style={{ width: '100%' }}>
+            <AdjustContrastPreview
+              file={currentFile || null}
+              parameters={base.params.parameters}
+            />
+          </div>
+        </NavigationArrows>
+        {totalSelected > 1 && (
+          <div style={{ textAlign: 'center', marginTop: 8, fontSize: 12, color: 'var(--text-color-muted)' }}>
+            {`${previewIndex + 1} of ${totalSelected}`}
+          </div>
+        )}
+      </div>
     ),
     executeButton: {
       text: t('adjustContrast.confirm', 'Confirm'),