Created a floating button to move around lines/equations in a pdf. Also added a feature to move back to a internal link.

README.md

@@ -6,6 +6,9 @@ PDF.js is community-driven and supported by Mozilla. Our goal is to
 create a general-purpose, web standards-based platform for parsing and
 rendering PDFs.
 
+## One difference from Mozilla repo 
+This fork of pdf.js has one single extra feature and that is to go back and forth (Use the Key B) to any link inside the pdf and come back. And we can create marked positions (Mark aline using M) and move between those positions in the pdf using a shortcut key "C"
+
 ## Contributing
 
 PDF.js is an open source project and always looking for more contributors. To

l10n/en-US/viewer.ftl

@@ -574,6 +574,37 @@ pdfjs-editor-undo-bar-close-button =
     .title = Close
 pdfjs-editor-undo-bar-close-button-label = Close
 
+## Jump history (marks, and returning from links)
+
+# Variables:
+#   $page (Number) - the page number of the position to return to
+pdfjs-jump-history-back-button =
+    .title = Return to page { $page } (B)
+    .aria-label = Return to page { $page }
+pdfjs-jump-history-back-button-empty =
+    .title = Nothing to return to yet; follow a link, or use the outline, first (B)
+    .aria-label = Nothing to return to yet
+pdfjs-jump-history-list-button =
+    .title = Show marks (C / Shift+C to cycle)
+    .aria-label = Show marks
+pdfjs-jump-history-panel-title = Marks
+pdfjs-jump-history-save-button = Save to file
+pdfjs-jump-history-max-entries-label = Marks to remember
+# Variables:
+#   $page (Number) - the page number of the mark
+pdfjs-jump-history-entry-page = Page { $page }
+pdfjs-jump-history-entry-empty = No marks yet. Press M, or select text and use the mark button.
+pdfjs-jump-history-clear-button = Clear all
+pdfjs-jump-history-clear-button-confirm = Confirm clear
+pdfjs-jump-history-mark-floating-button =
+    .title = Mark this line (M)
+pdfjs-jump-history-mark-floating-button-label = Mark this line
+pdfjs-jump-history-list-floating-button =
+    .title = Show marks
+pdfjs-jump-history-list-floating-button-label = Show marks
+pdfjs-jump-history-entry-loading = Loading…
+pdfjs-jump-history-entry-no-text = (no text on this line)
+
 ## Add a signature dialog
 
 pdfjs-editor-add-signature-dialog-label = This modal allows the user to create a signature to add to a PDF document. The user can edit the name (which also serves as the alt text), and optionally save the signature for repeated use.

src/core/document.js

@@ -2275,17 +2275,18 @@ class PDFDocument {
   }
 
   get calculationOrderIds() {
-    const co = this.catalog.acroForm?.get("CO");
-    let ids = null;
+    const calculationOrder = this.catalog.acroForm?.get("CO");
+    if (!Array.isArray(calculationOrder) || calculationOrder.length === 0) {
+      return shadow(this, "calculationOrderIds", null);
+    }
 
-    if (Array.isArray(co)) {
-      for (const id of co) {
-        if (id instanceof Ref) {
-          (ids ??= []).push(id.toString());
-        }
+    const ids = [];
+    for (const id of calculationOrder) {
+      if (id instanceof Ref) {
+        ids.push(id.toString());
       }
     }
-    return shadow(this, "calculationOrderIds", ids);
+    return shadow(this, "calculationOrderIds", ids.length ? ids : null);
   }
 
   get annotationGlobals() {

src/core/evaluator.js

@@ -3020,7 +3020,7 @@ class PartialEvaluator {
 
       for (let i = 0, ii = glyphs.length; i < ii; i++) {
         const glyph = glyphs[i];
-        const { category } = glyph;
+        const { category, originalCharCode } = glyph;
 
         if (category.isInvisibleFormatMark) {
           continue;
@@ -3030,7 +3030,7 @@ class PartialEvaluator {
         const glyphWidth = font.vertical ? glyph.vmetric[0] : glyph.width;
         let scaledDim = glyphWidth * scale;
 
-        if (glyph.isSpace) {
+        if (originalCharCode === 0x20) {
           charSpacing += textState.wordSpacing;
         }
 

src/core/fonts.js

@@ -242,7 +242,6 @@ function amendFallbackToUnicode(properties) {
 
 class Glyph {
   constructor(
-    fontExtraProperties,
     originalCharCode,
     fontChar,
     unicode,
@@ -254,9 +253,7 @@ class Glyph {
     isInFont,
     isRotated
   ) {
-    if (fontExtraProperties) {
-      this.originalCharCode = originalCharCode;
-    }
+    this.originalCharCode = originalCharCode;
     this.fontChar = fontChar;
     this.unicode = unicode;
     this.accent = accent;
@@ -3675,7 +3672,6 @@ class Font {
     }
 
     glyph = new Glyph(
-      this.fontExtraProperties,
       charcode,
       fontChar,
       unicode,

src/display/editor/toolbar.js

@@ -316,6 +316,11 @@ class FloatingToolbar {
       }
     );
 
+    for (const { className, l10nId, labelL10nId, onClick } of this.#uiManager
+      .floatingToolbarButtons) {
+      this.#makeButton(className, l10nId, labelL10nId, onClick);
+    }
+
     return editToolbar;
   }
 

src/display/editor/tools.js

@@ -779,6 +779,8 @@ class AnnotationEditorUIManager {
 
   #floatingToolbar = null;
 
+  #floatingToolbarButtons = [];
+
   #idManager = new IdManager();
 
   #isEnabled = false;
@@ -1218,6 +1220,26 @@ class AnnotationEditorUIManager {
     return !!this.#commentManager;
   }
 
+  /**
+   * Add a button to the floating toolbar shown when selecting text, after the
+   * built-in ones; the selection is still available when it's clicked.
+   * @param {object} button
+   * @param {string} button.className - Used to style the button, e.g. its icon.
+   * @param {string} button.l10nId - For the title of the button.
+   * @param {string} button.labelL10nId - For the label of the button.
+   * @param {Function} button.onClick
+   */
+  addFloatingToolbarButton(button) {
+    this.#floatingToolbarButtons.push(button);
+    // Re-create the toolbar, if already used, to include the new button.
+    this.#floatingToolbar?.hide();
+    this.#floatingToolbar = null;
+  }
+
+  get floatingToolbarButtons() {
+    return this.#floatingToolbarButtons;
+  }
+
   editComment(editor, posX, posY, options) {
     this.#commentManager?.showDialog(this, editor, posX, posY, options);
   }

web/annotation_editor_layer_builder.css

@@ -268,6 +268,14 @@
         &.deleteButton::before {
           mask-image: var(--editor-toolbar-delete-image);
         }
+
+        &.jumpHistoryMarkButton::before {
+          mask-image: url(images/toolbarButton-bookmark.svg);
+        }
+
+        &.jumpHistoryListButton::before {
+          mask-image: url(images/toolbarButton-viewOutline.svg);
+        }
       }
 
       > * {

web/app.js

@@ -84,6 +84,7 @@ import { PDFDocumentProperties } from "web-pdf_document_properties";
 import { PDFFindBar } from "web-pdf_find_bar";
 import { PDFFindController } from "./pdf_find_controller.js";
 import { PDFHistory } from "./pdf_history.js";
+import { PDFJumpHistory } from "./pdf_jump_history.js";
 import { PDFLayerViewer } from "web-pdf_layer_viewer";
 import { PDFOutlineViewer } from "web-pdf_outline_viewer";
 import { PDFPresentationMode } from "web-pdf_presentation_mode";
@@ -138,6 +139,8 @@ const PDFViewerApplication = {
   pdfTextExtractor: null,
   /** @type {PDFHistory} */
   pdfHistory: null,
+  /** @type {PDFJumpHistory} */
+  pdfJumpHistory: null,
   /** @type {ViewsManager} */
   viewsManager: null,
   /** @type {PDFOutlineViewer} */
@@ -767,6 +770,14 @@ const PDFViewerApplication = {
       linkService.setHistory(this.pdfHistory);
     }
 
+    if (appConfig.jumpHistory) {
+      this.pdfJumpHistory = new PDFJumpHistory(
+        appConfig.jumpHistory,
+        eventBus,
+        pdfViewer
+      );
+    }
+
     if (!this.supportsIntegratedFind && appConfig.findBar) {
       this.findBar = new PDFFindBar(
         appConfig.findBar,
@@ -1379,6 +1390,7 @@ const PDFViewerApplication = {
     this.pdfLayerViewer?.reset();
 
     this.pdfHistory?.reset();
+    this.pdfJumpHistory?.reset();
     this.findBar?.reset();
     this.toolbar?.reset();
     this.secondaryToolbar?.reset();
@@ -2259,6 +2271,8 @@ const PDFViewerApplication = {
     // Scale was not initialized: invalid bookmark or scale was not specified.
     // Setting the default one.
     this.pdfViewer.currentScaleValue ||= DEFAULT_SCALE_VALUE;
+
+    this.pdfJumpHistory?.initialize(this.store, this._docFilename);
   },
 
   /**
@@ -3530,6 +3544,25 @@ function onKeyDown(evt) {
         this.rotatePages(90);
         break;
 
+      case 66: // 'b'
+        if (this.pdfJumpHistory?.canReturn) {
+          this.pdfJumpHistory.toggleReturn();
+          handled = true;
+        }
+        break;
+      case 77: // 'm'
+        if (this.pdfJumpHistory) {
+          this.pdfJumpHistory.markCurrentPosition();
+          handled = true;
+        }
+        break;
+      case 67: // 'c'
+        if (this.pdfJumpHistory?.hasMarks) {
+          this.pdfJumpHistory.cycleBack();
+          handled = true;
+        }
+        break;
+
       case 115: // F4
         this.viewsManager?.toggle();
         break;
@@ -3574,6 +3607,12 @@ function onKeyDown(evt) {
       case 82: // 'r'
         this.rotatePages(-90);
         break;
+      case 67: // 'c'
+        if (this.pdfJumpHistory?.hasMarks) {
+          this.pdfJumpHistory.cycleForward();
+          handled = true;
+        }
+        break;
     }
   }