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Move the PagesMapper class into its own file

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The `PagesMapper` class currently makes up one third of the `src/display/display_utils.js` file size, and since its introduction it's grown (a fair bit) in size.
Note that the intention with files such as `src/display/display_utils.js` was to have somewhere to place functionality too small/simple to deserve its own file.
This commit is contained in:
Jonas Jenwald 2026-03-11 12:19:42 +01:00
parent 79df166e06
commit 9aa1ce8f14
3 changed files with 477 additions and 461 deletions
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2
src/display/api.js
View File

@ -47,7 +47,6 @@ import {
deprecated,
isDataScheme,
isValidFetchUrl,
PagesMapper,
PageViewport,
RenderingCancelledException,
StatTimer,
@ -82,6 +81,7 @@ import { DOMWasmFactory } from "display-wasm_factory";
import { GlobalWorkerOptions } from "./worker_options.js";
import { Metadata } from "./metadata.js";
import { OptionalContentConfig } from "./optional_content_config.js";
import { PagesMapper } from "./pages_mapper.js";
import { PDFDataTransportStream } from "./transport_stream.js";
import { PDFFetchStream } from "display-fetch_stream";
import { PDFNetworkStream } from "display-network";

460
src/display/display_utils.js
View File

@ -17,7 +17,6 @@ import {
BaseException,
DrawOPS,
FeatureTest,
makeArr,
MathClamp,
shadow,
stripPath,
@ -1033,464 +1032,6 @@ function makePathFromDrawOPS(data) {
return path;
}
/**
* Maps between page IDs and page numbers, allowing bidirectional conversion
* between the two representations. This is useful when the page numbering
* in the PDF document doesn't match the default sequential ordering.
*/
class PagesMapper {
/**
* Maps page IDs to their corresponding page numbers.
* @type {Map<number, Array<number>>|null}
*/
#idToPageNumber = null;
/**
* Maps page numbers to their corresponding page IDs.
* @type {Uint32Array|null}
*/
#pageNumberToId = null;
/**
* Previous mapping of page IDs to page numbers.
* @type {Int32Array|null}
*/
#prevPageNumbers = null;
/**
* The total number of pages.
* @type {number}
*/
#pagesNumber = 0;
/**
* Listeners for page changes.
* @type {Array<function>}
*/
#listeners = [];
/**
* Maps page numbers to their corresponding page IDs (used in copy
* operations).
* @type {Uint32Array|null}
*/
#copiedPageIds = null;
/**
* Maps page IDs to their corresponding page numbers, used in copy operations.
* @type {Uint32Array|null}
*/
#copiedPageNumbers = null;
#savedData = null;
/**
* Gets the total number of pages.
* @returns {number} The number of pages.
*/
get pagesNumber() {
return this.#pagesNumber;
}
/**
* Sets the total number of pages and initializes default mappings
* where page IDs equal page numbers (1-indexed).
* @param {number} n - The total number of pages.
*/
set pagesNumber(n) {
if (this.#pagesNumber === n) {
return;
}
this.#pagesNumber = n;
this.#reset();
}
/**
* Resets the page mappings to their default state, where page IDs equal page
* numbers (1-indexed). This is called when the number of pages changes, or
* when the current mapping matches the default mapping after a move
* operation.
*/
#reset() {
this.#pageNumberToId = null;
this.#idToPageNumber = null;
}
/**
* Adds a listener function that will be called whenever the page mappings
* are updated.
* @param {function} listener
*/
addListener(listener) {
this.#listeners.push(listener);
}
/**
* Removes a previously added listener function.
* @param {function} listener
*/
removeListener(listener) {
const index = this.#listeners.indexOf(listener);
if (index >= 0) {
this.#listeners.splice(index, 1);
}
}
/**
* Calls all registered listener functions to notify them of changes to the
* page mappings.
* @param {Object} data - An object containing information about the update.
*/
#updateListeners(data) {
for (const listener of this.#listeners) {
listener(data);
}
}
/**
* Initializes the page mappings if they haven't been initialized yet.
* @param {boolean} mustInit
*/
#init(mustInit) {
if (this.#pageNumberToId) {
return;
}
const n = this.#pagesNumber;
const pageNumberToId = (this.#pageNumberToId = new Uint32Array(n));
this.#prevPageNumbers = new Int32Array(pageNumberToId);
const idToPageNumber = (this.#idToPageNumber = new Map());
if (mustInit) {
for (let i = 1; i <= n; i++) {
pageNumberToId[i - 1] = i;
idToPageNumber.set(i, [i]);
}
}
}
/**
* Updates the mapping from page IDs to page numbers based on the current
* mapping from page numbers to page IDs. This should be called after any
* changes to the page-number-to-ID mapping to keep the two mappings in sync.
*/
#updateIdToPageNumber() {
const idToPageNumber = this.#idToPageNumber;
const pageNumberToId = this.#pageNumberToId;
idToPageNumber.clear();
for (let i = 0, ii = this.#pagesNumber; i < ii; i++) {
const id = pageNumberToId[i];
const pageNumbers = idToPageNumber.get(id);
if (pageNumbers) {
pageNumbers.push(i + 1);
} else {
idToPageNumber.set(id, [i + 1]);
}
}
}
/**
* Move a set of pages to a new position while keeping ID→number mappings in
* sync.
*
* @param {Set<number>} selectedPages - Page numbers being moved (1-indexed).
* @param {number[]} pagesToMove - Ordered list of page numbers to move.
* @param {number} index - Zero-based insertion index in the page-number list.
*/
movePages(selectedPages, pagesToMove, index) {
this.#init(true);
const pageNumberToId = this.#pageNumberToId;
const idToPageNumber = this.#idToPageNumber;
const movedCount = pagesToMove.length;
const mappedPagesToMove = new Uint32Array(movedCount);
let removedBeforeTarget = 0;
for (let i = 0; i < movedCount; i++) {
const pageIndex = pagesToMove[i] - 1;
mappedPagesToMove[i] = pageNumberToId[pageIndex];
if (pageIndex < index) {
removedBeforeTarget += 1;
}
}
const pagesNumber = this.#pagesNumber;
// target index after removing elements that were before it
let adjustedTarget = index - removedBeforeTarget;
const remainingLen = pagesNumber - movedCount;
adjustedTarget = MathClamp(adjustedTarget, 0, remainingLen);
// Create the new mapping.
// First copy over the pages that are not being moved.
// Then insert the moved pages at the target position.
for (let i = 0, r = 0; i < pagesNumber; i++) {
if (!selectedPages.has(i + 1)) {
pageNumberToId[r++] = pageNumberToId[i];
}
}
// Shift the pages after the target position.
pageNumberToId.copyWithin(
adjustedTarget + movedCount,
adjustedTarget,
remainingLen
);
// Finally insert the moved pages.
pageNumberToId.set(mappedPagesToMove, adjustedTarget);
this.#setPrevPageNumbers(idToPageNumber, null);
this.#updateIdToPageNumber();
this.#updateListeners({ type: "move" });
if (pageNumberToId.every((id, i) => id === i + 1)) {
this.#reset();
}
}
/**
* Deletes a set of pages while keeping ID→number mappings in sync.
* @param {Array<number>} pagesToDelete - Page numbers to delete (1-indexed).
* These must be unique and sorted in ascending order.
*/
deletePages(pagesToDelete) {
this.#init(true);
const pageNumberToId = this.#pageNumberToId;
const prevIdToPageNumber = this.#idToPageNumber;
this.#savedData = {
pageNumberToId: pageNumberToId.slice(),
idToPageNumber: new Map(prevIdToPageNumber),
pageNumber: this.#pagesNumber,
prevPageNumbers: this.#prevPageNumbers.slice(),
};
this.pagesNumber -= pagesToDelete.length;
this.#init(false);
const newPageNumberToId = this.#pageNumberToId;
let sourceIndex = 0;
let destIndex = 0;
for (const pageNumber of pagesToDelete) {
const pageIndex = pageNumber - 1;
if (pageIndex !== sourceIndex) {
newPageNumberToId.set(
pageNumberToId.subarray(sourceIndex, pageIndex),
destIndex
);
destIndex += pageIndex - sourceIndex;
}
sourceIndex = pageIndex + 1;
}
if (sourceIndex < pageNumberToId.length) {
newPageNumberToId.set(pageNumberToId.subarray(sourceIndex), destIndex);
}
this.#setPrevPageNumbers(prevIdToPageNumber, null);
this.#updateIdToPageNumber();
this.#updateListeners({ type: "delete", pageNumbers: pagesToDelete });
}
cancelDelete() {
if (this.#savedData) {
this.#pageNumberToId = this.#savedData.pageNumberToId;
this.#idToPageNumber = this.#savedData.idToPageNumber;
this.pagesNumber = this.#savedData.pageNumber;
this.#prevPageNumbers = this.#savedData.prevPageNumbers;
this.#savedData = null;
this.#updateListeners({ type: "cancelDelete" });
}
}
cleanSavedData() {
this.#savedData = null;
this.#updateListeners({ type: "cleanSavedData" });
}
/**
* Copies a set of pages while keeping ID→number mappings in sync.
* @param {Uint32Array} pagesToCopy - Page numbers to copy (1-indexed).
*/
copyPages(pagesToCopy) {
this.#init(true);
this.#copiedPageNumbers = pagesToCopy;
this.#copiedPageIds = pagesToCopy.map(
pageNumber => this.#pageNumberToId[pageNumber - 1]
);
this.#updateListeners({ type: "copy", pageNumbers: pagesToCopy });
}
cancelCopy() {
this.#copiedPageIds = null;
this.#copiedPageNumbers = null;
this.#updateListeners({ type: "cancelCopy" });
}
/**
* Pastes a set of pages while keeping ID→number mappings in sync.
* @param {number} index - Zero-based insertion index in the page-number list.
*/
pastePages(index) {
this.#init(true);
const pageNumberToId = this.#pageNumberToId;
const prevIdToPageNumber = this.#idToPageNumber;
const copiedPageNumbers = this.#copiedPageNumbers;
const copiedPageMapping = new Map();
let base = index;
for (const pageNumber of copiedPageNumbers) {
copiedPageMapping.set(++base, pageNumber);
}
this.pagesNumber += copiedPageNumbers.length;
this.#init(false);
const newPageNumberToId = this.#pageNumberToId;
newPageNumberToId.set(pageNumberToId.subarray(0, index), 0);
newPageNumberToId.set(this.#copiedPageIds, index);
newPageNumberToId.set(
pageNumberToId.subarray(index),
index + copiedPageNumbers.length
);
this.#setPrevPageNumbers(prevIdToPageNumber, copiedPageMapping);
this.#updateIdToPageNumber();
this.#updateListeners({ type: "paste" });
this.#copiedPageIds = null;
this.#copiedPageNumbers = null;
}
/**
* Updates the previous page numbers based on the current page-number-to-ID
* mapping and the provided previous ID-to-page-number mapping.
* This is used to keep track of the original page numbers for each page ID.
* @param {Map<number, Array<number>} prevIdToPageNumber
* @param {Map<number, number>|null} copiedPageMapping
*/
#setPrevPageNumbers(prevIdToPageNumber, copiedPageMapping) {
const prevPageNumbers = this.#prevPageNumbers;
const newPageNumberToId = this.#pageNumberToId;
const idsIndices = new Map();
for (let i = 0, ii = this.#pagesNumber; i < ii; i++) {
const oldPageNumber = copiedPageMapping?.get(i + 1);
if (oldPageNumber) {
prevPageNumbers[i] = -oldPageNumber;
continue;
}
const id = newPageNumberToId[i];
const j = idsIndices.get(id) || 0;
prevPageNumbers[i] = prevIdToPageNumber.get(id)?.[j];
idsIndices.set(id, j + 1);
}
}
/**
* Checks if the page mappings have been altered from their initial state.
* @returns {boolean} True if the mappings have been altered, false otherwise.
*/
hasBeenAltered() {
return this.#pageNumberToId !== null;
}
/**
* Gets the current page mapping suitable for saving.
* @returns {Object} An object containing the page indices.
*/
getPageMappingForSaving(idToPageNumber = this.#idToPageNumber) {
// idToPageNumber maps used 1-based IDs to 1-based page numbers.
// For example if the final pdf contains page 3 twice and they are moved at
// page 1 and 4, then it contains:
// pageNumberToId = [3, ., ., 3, ...,]
// idToPageNumber = {3: [1, 4], ...}
// In such a case we need to take a page 3 from the original pdf and take
// page 3 from a "copy".
// So we need to pass to the api something like:
// [ {
// document: null // this pdf
// includePages: [ 2, ... ], // page 3 is at index 2
// pageIndices: [0, ...], // page 3 will be at index 0 in the new pdf
// }, {
// document: null // this pdf
// includePages: [ 2, ... ], // page 3 is at index 2
// pageIndices: [3, ...], // page 3 will be at index 3 in the new pdf
// }
// ]
let nCopy = 0;
for (const pageNumbers of idToPageNumber.values()) {
nCopy = Math.max(nCopy, pageNumbers.length);
}
const extractParams = new Array(nCopy);
for (let i = 0; i < nCopy; i++) {
extractParams[i] = {
document: null,
pageIndices: [],
includePages: [],
};
}
for (const [id, pageNumbers] of idToPageNumber) {
for (let i = 0, ii = pageNumbers.length; i < ii; i++) {
extractParams[i].includePages.push([id - 1, pageNumbers[i] - 1]);
}
}
for (const { includePages, pageIndices } of extractParams) {
includePages.sort((a, b) => a[0] - b[0]);
for (let i = 0, ii = includePages.length; i < ii; i++) {
pageIndices.push(includePages[i][1]);
includePages[i] = includePages[i][0];
}
}
return extractParams;
}
extractPages(extractedPageNumbers) {
extractedPageNumbers = Array.from(extractedPageNumbers).sort(
(a, b) => a - b
);
const usedIds = new Map();
for (let i = 0, ii = extractedPageNumbers.length; i < ii; i++) {
const id = this.getPageId(extractedPageNumbers[i]);
const usedPageNumbers = usedIds.getOrInsertComputed(id, makeArr);
usedPageNumbers.push(i + 1);
}
return this.getPageMappingForSaving(usedIds);
}
/**
* Gets the previous page number for a given page number.
* @param {number} pageNumber
* @returns {number} The previous page number for the given page number, or 0
* if no mapping exists.
*/
getPrevPageNumber(pageNumber) {
return this.#prevPageNumbers[pageNumber - 1] ?? 0;
}
/**
* Gets the page number for a given page ID.
* @param {number} id - The page ID (1-indexed).
* @returns {number} The page number, or 0 if no mapping exists.
*/
getPageNumber(id) {
return this.#idToPageNumber ? (this.#idToPageNumber.get(id)?.[0] ?? 0) : id;
}
/**
* Gets the page ID for a given page number.
* @param {number} pageNumber - The page number (1-indexed).
* @returns {number} The page ID, or the page number itself if no mapping
* exists.
*/
getPageId(pageNumber) {
return this.#pageNumberToId?.[pageNumber - 1] ?? pageNumber;
}
getMapping() {
return this.#pageNumberToId?.subarray(0, this.pagesNumber);
}
}
export {
applyOpacity,
ColorScheme,
@ -1511,7 +1052,6 @@ export {
makePathFromDrawOPS,
noContextMenu,
OutputScale,
PagesMapper,
PageViewport,
PDFDateString,
PixelsPerInch,

476
src/display/pages_mapper.js Normal file
View File

@ -0,0 +1,476 @@
/* Copyright 2026 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { makeArr, MathClamp } from "../shared/util.js";
/**
* Maps between page IDs and page numbers, allowing bidirectional conversion
* between the two representations. This is useful when the page numbering
* in the PDF document doesn't match the default sequential ordering.
*/
class PagesMapper {
/**
* Maps page IDs to their corresponding page numbers.
* @type {Map<number, Array<number>>|null}
*/
#idToPageNumber = null;
/**
* Maps page numbers to their corresponding page IDs.
* @type {Uint32Array|null}
*/
#pageNumberToId = null;
/**
* Previous mapping of page IDs to page numbers.
* @type {Int32Array|null}
*/
#prevPageNumbers = null;
/**
* The total number of pages.
* @type {number}
*/
#pagesNumber = 0;
/**
* Listeners for page changes.
* @type {Array<function>}
*/
#listeners = [];
/**
* Maps page numbers to their corresponding page IDs (used in copy
* operations).
* @type {Uint32Array|null}
*/
#copiedPageIds = null;
/**
* Maps page IDs to their corresponding page numbers, used in copy operations.
* @type {Uint32Array|null}
*/
#copiedPageNumbers = null;
#savedData = null;
/**
* Gets the total number of pages.
* @returns {number} The number of pages.
*/
get pagesNumber() {
return this.#pagesNumber;
}
/**
* Sets the total number of pages and initializes default mappings
* where page IDs equal page numbers (1-indexed).
* @param {number} n - The total number of pages.
*/
set pagesNumber(n) {
if (this.#pagesNumber === n) {
return;
}
this.#pagesNumber = n;
this.#reset();
}
/**
* Resets the page mappings to their default state, where page IDs equal page
* numbers (1-indexed). This is called when the number of pages changes, or
* when the current mapping matches the default mapping after a move
* operation.
*/
#reset() {
this.#pageNumberToId = null;
this.#idToPageNumber = null;
}
/**
* Adds a listener function that will be called whenever the page mappings
* are updated.
* @param {function} listener
*/
addListener(listener) {
this.#listeners.push(listener);
}
/**
* Removes a previously added listener function.
* @param {function} listener
*/
removeListener(listener) {
const index = this.#listeners.indexOf(listener);
if (index >= 0) {
this.#listeners.splice(index, 1);
}
}
/**
* Calls all registered listener functions to notify them of changes to the
* page mappings.
* @param {Object} data - An object containing information about the update.
*/
#updateListeners(data) {
for (const listener of this.#listeners) {
listener(data);
}
}
/**
* Initializes the page mappings if they haven't been initialized yet.
* @param {boolean} mustInit
*/
#init(mustInit) {
if (this.#pageNumberToId) {
return;
}
const n = this.#pagesNumber;
const pageNumberToId = (this.#pageNumberToId = new Uint32Array(n));
this.#prevPageNumbers = new Int32Array(pageNumberToId);
const idToPageNumber = (this.#idToPageNumber = new Map());
if (mustInit) {
for (let i = 1; i <= n; i++) {
pageNumberToId[i - 1] = i;
idToPageNumber.set(i, [i]);
}
}
}
/**
* Updates the mapping from page IDs to page numbers based on the current
* mapping from page numbers to page IDs. This should be called after any
* changes to the page-number-to-ID mapping to keep the two mappings in sync.
*/
#updateIdToPageNumber() {
const idToPageNumber = this.#idToPageNumber;
const pageNumberToId = this.#pageNumberToId;
idToPageNumber.clear();
for (let i = 0, ii = this.#pagesNumber; i < ii; i++) {
const id = pageNumberToId[i];
const pageNumbers = idToPageNumber.get(id);
if (pageNumbers) {
pageNumbers.push(i + 1);
} else {
idToPageNumber.set(id, [i + 1]);
}
}
}
/**
* Move a set of pages to a new position while keeping ID→number mappings in
* sync.
*
* @param {Set<number>} selectedPages - Page numbers being moved (1-indexed).
* @param {number[]} pagesToMove - Ordered list of page numbers to move.
* @param {number} index - Zero-based insertion index in the page-number list.
*/
movePages(selectedPages, pagesToMove, index) {
this.#init(true);
const pageNumberToId = this.#pageNumberToId;
const idToPageNumber = this.#idToPageNumber;
const movedCount = pagesToMove.length;
const mappedPagesToMove = new Uint32Array(movedCount);
let removedBeforeTarget = 0;
for (let i = 0; i < movedCount; i++) {
const pageIndex = pagesToMove[i] - 1;
mappedPagesToMove[i] = pageNumberToId[pageIndex];
if (pageIndex < index) {
removedBeforeTarget += 1;
}
}
const pagesNumber = this.#pagesNumber;
// target index after removing elements that were before it
let adjustedTarget = index - removedBeforeTarget;
const remainingLen = pagesNumber - movedCount;
adjustedTarget = MathClamp(adjustedTarget, 0, remainingLen);
// Create the new mapping.
// First copy over the pages that are not being moved.
// Then insert the moved pages at the target position.
for (let i = 0, r = 0; i < pagesNumber; i++) {
if (!selectedPages.has(i + 1)) {
pageNumberToId[r++] = pageNumberToId[i];
}
}
// Shift the pages after the target position.
pageNumberToId.copyWithin(
adjustedTarget + movedCount,
adjustedTarget,
remainingLen
);
// Finally insert the moved pages.
pageNumberToId.set(mappedPagesToMove, adjustedTarget);
this.#setPrevPageNumbers(idToPageNumber, null);
this.#updateIdToPageNumber();
this.#updateListeners({ type: "move" });
if (pageNumberToId.every((id, i) => id === i + 1)) {
this.#reset();
}
}
/**
* Deletes a set of pages while keeping ID→number mappings in sync.
* @param {Array<number>} pagesToDelete - Page numbers to delete (1-indexed).
* These must be unique and sorted in ascending order.
*/
deletePages(pagesToDelete) {
this.#init(true);
const pageNumberToId = this.#pageNumberToId;
const prevIdToPageNumber = this.#idToPageNumber;
this.#savedData = {
pageNumberToId: pageNumberToId.slice(),
idToPageNumber: new Map(prevIdToPageNumber),
pageNumber: this.#pagesNumber,
prevPageNumbers: this.#prevPageNumbers.slice(),
};
this.pagesNumber -= pagesToDelete.length;
this.#init(false);
const newPageNumberToId = this.#pageNumberToId;
let sourceIndex = 0;
let destIndex = 0;
for (const pageNumber of pagesToDelete) {
const pageIndex = pageNumber - 1;
if (pageIndex !== sourceIndex) {
newPageNumberToId.set(
pageNumberToId.subarray(sourceIndex, pageIndex),
destIndex
);
destIndex += pageIndex - sourceIndex;
}
sourceIndex = pageIndex + 1;
}
if (sourceIndex < pageNumberToId.length) {
newPageNumberToId.set(pageNumberToId.subarray(sourceIndex), destIndex);
}
this.#setPrevPageNumbers(prevIdToPageNumber, null);
this.#updateIdToPageNumber();
this.#updateListeners({ type: "delete", pageNumbers: pagesToDelete });
}
cancelDelete() {
if (this.#savedData) {
this.#pageNumberToId = this.#savedData.pageNumberToId;
this.#idToPageNumber = this.#savedData.idToPageNumber;
this.pagesNumber = this.#savedData.pageNumber;
this.#prevPageNumbers = this.#savedData.prevPageNumbers;
this.#savedData = null;
this.#updateListeners({ type: "cancelDelete" });
}
}
cleanSavedData() {
this.#savedData = null;
this.#updateListeners({ type: "cleanSavedData" });
}
/**
* Copies a set of pages while keeping ID→number mappings in sync.
* @param {Uint32Array} pagesToCopy - Page numbers to copy (1-indexed).
*/
copyPages(pagesToCopy) {
this.#init(true);
this.#copiedPageNumbers = pagesToCopy;
this.#copiedPageIds = pagesToCopy.map(
pageNumber => this.#pageNumberToId[pageNumber - 1]
);
this.#updateListeners({ type: "copy", pageNumbers: pagesToCopy });
}
cancelCopy() {
this.#copiedPageIds = null;
this.#copiedPageNumbers = null;
this.#updateListeners({ type: "cancelCopy" });
}
/**
* Pastes a set of pages while keeping ID→number mappings in sync.
* @param {number} index - Zero-based insertion index in the page-number list.
*/
pastePages(index) {
this.#init(true);
const pageNumberToId = this.#pageNumberToId;
const prevIdToPageNumber = this.#idToPageNumber;
const copiedPageNumbers = this.#copiedPageNumbers;
const copiedPageMapping = new Map();
let base = index;
for (const pageNumber of copiedPageNumbers) {
copiedPageMapping.set(++base, pageNumber);
}
this.pagesNumber += copiedPageNumbers.length;
this.#init(false);
const newPageNumberToId = this.#pageNumberToId;
newPageNumberToId.set(pageNumberToId.subarray(0, index), 0);
newPageNumberToId.set(this.#copiedPageIds, index);
newPageNumberToId.set(
pageNumberToId.subarray(index),
index + copiedPageNumbers.length
);
this.#setPrevPageNumbers(prevIdToPageNumber, copiedPageMapping);
this.#updateIdToPageNumber();
this.#updateListeners({ type: "paste" });
this.#copiedPageIds = null;
this.#copiedPageNumbers = null;
}
/**
* Updates the previous page numbers based on the current page-number-to-ID
* mapping and the provided previous ID-to-page-number mapping.
* This is used to keep track of the original page numbers for each page ID.
* @param {Map<number, Array<number>} prevIdToPageNumber
* @param {Map<number, number>|null} copiedPageMapping
*/
#setPrevPageNumbers(prevIdToPageNumber, copiedPageMapping) {
const prevPageNumbers = this.#prevPageNumbers;
const newPageNumberToId = this.#pageNumberToId;
const idsIndices = new Map();
for (let i = 0, ii = this.#pagesNumber; i < ii; i++) {
const oldPageNumber = copiedPageMapping?.get(i + 1);
if (oldPageNumber) {
prevPageNumbers[i] = -oldPageNumber;
continue;
}
const id = newPageNumberToId[i];
const j = idsIndices.get(id) || 0;
prevPageNumbers[i] = prevIdToPageNumber.get(id)?.[j];
idsIndices.set(id, j + 1);
}
}
/**
* Checks if the page mappings have been altered from their initial state.
* @returns {boolean} True if the mappings have been altered, false otherwise.
*/
hasBeenAltered() {
return this.#pageNumberToId !== null;
}
/**
* Gets the current page mapping suitable for saving.
* @returns {Object} An object containing the page indices.
*/
getPageMappingForSaving(idToPageNumber = this.#idToPageNumber) {
// idToPageNumber maps used 1-based IDs to 1-based page numbers.
// For example if the final pdf contains page 3 twice and they are moved at
// page 1 and 4, then it contains:
// pageNumberToId = [3, ., ., 3, ...,]
// idToPageNumber = {3: [1, 4], ...}
// In such a case we need to take a page 3 from the original pdf and take
// page 3 from a "copy".
// So we need to pass to the api something like:
// [ {
// document: null // this pdf
// includePages: [ 2, ... ], // page 3 is at index 2
// pageIndices: [0, ...], // page 3 will be at index 0 in the new pdf
// }, {
// document: null // this pdf
// includePages: [ 2, ... ], // page 3 is at index 2
// pageIndices: [3, ...], // page 3 will be at index 3 in the new pdf
// }
// ]
let nCopy = 0;
for (const pageNumbers of idToPageNumber.values()) {
nCopy = Math.max(nCopy, pageNumbers.length);
}
const extractParams = new Array(nCopy);
for (let i = 0; i < nCopy; i++) {
extractParams[i] = {
document: null,
pageIndices: [],
includePages: [],
};
}
for (const [id, pageNumbers] of idToPageNumber) {
for (let i = 0, ii = pageNumbers.length; i < ii; i++) {
extractParams[i].includePages.push([id - 1, pageNumbers[i] - 1]);
}
}
for (const { includePages, pageIndices } of extractParams) {
includePages.sort((a, b) => a[0] - b[0]);
for (let i = 0, ii = includePages.length; i < ii; i++) {
pageIndices.push(includePages[i][1]);
includePages[i] = includePages[i][0];
}
}
return extractParams;
}
extractPages(extractedPageNumbers) {
extractedPageNumbers = Array.from(extractedPageNumbers).sort(
(a, b) => a - b
);
const usedIds = new Map();
for (let i = 0, ii = extractedPageNumbers.length; i < ii; i++) {
const id = this.getPageId(extractedPageNumbers[i]);
const usedPageNumbers = usedIds.getOrInsertComputed(id, makeArr);
usedPageNumbers.push(i + 1);
}
return this.getPageMappingForSaving(usedIds);
}
/**
* Gets the previous page number for a given page number.
* @param {number} pageNumber
* @returns {number} The previous page number for the given page number, or 0
* if no mapping exists.
*/
getPrevPageNumber(pageNumber) {
return this.#prevPageNumbers[pageNumber - 1] ?? 0;
}
/**
* Gets the page number for a given page ID.
* @param {number} id - The page ID (1-indexed).
* @returns {number} The page number, or 0 if no mapping exists.
*/
getPageNumber(id) {
return this.#idToPageNumber ? (this.#idToPageNumber.get(id)?.[0] ?? 0) : id;
}
/**
* Gets the page ID for a given page number.
* @param {number} pageNumber - The page number (1-indexed).
* @returns {number} The page ID, or the page number itself if no mapping
* exists.
*/
getPageId(pageNumber) {
return this.#pageNumberToId?.[pageNumber - 1] ?? pageNumber;
}
getMapping() {
return this.#pageNumberToId?.subarray(0, this.pagesNumber);
}
}
export { PagesMapper };