[edition] Add a FreeText editor (#14970)

- add a basic UI to edit some text in a pdf;
- an editor can be moved, suppressed, cut, copied, pasted, selected;
- add an undo/redo manager.

web/app.js

@@ -525,6 +525,7 @@ const PDFViewerApplication = {
       l10n: this.l10n,
       textLayerMode: AppOptions.get("textLayerMode"),
       annotationMode: AppOptions.get("annotationMode"),
+      annotationEditorEnabled: AppOptions.get("annotationEditorEnabled"),
       imageResourcesPath: AppOptions.get("imageResourcesPath"),
       enablePrintAutoRotate: AppOptions.get("enablePrintAutoRotate"),
       useOnlyCssZoom: AppOptions.get("useOnlyCssZoom"),
@@ -560,6 +561,10 @@ const PDFViewerApplication = {
       this.findBar = new PDFFindBar(appConfig.findBar, eventBus, this.l10n);
     }
 
+    if (AppOptions.get("annotationEditorEnabled")) {
+      document.getElementById("editorModeButtons").classList.remove("hidden");
+    }
+
     this.pdfDocumentProperties = new PDFDocumentProperties(
       appConfig.documentProperties,
       this.overlayManager,
@@ -1878,6 +1883,10 @@ const PDFViewerApplication = {
     eventBus._on("namedaction", webViewerNamedAction);
     eventBus._on("presentationmodechanged", webViewerPresentationModeChanged);
     eventBus._on("presentationmode", webViewerPresentationMode);
+    eventBus._on(
+      "switchannotationeditormode",
+      webViewerSwitchAnnotationEditorMode
+    );
     eventBus._on("print", webViewerPrint);
     eventBus._on("download", webViewerDownload);
     eventBus._on("firstpage", webViewerFirstPage);
@@ -2459,6 +2468,13 @@ if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
 function webViewerPresentationMode() {
   PDFViewerApplication.requestPresentationMode();
 }
+function webViewerSwitchAnnotationEditorMode(evt) {
+  if (evt.toggle) {
+    PDFViewerApplication.pdfViewer.annotionEditorEnabled = true;
+  } else {
+    PDFViewerApplication.pdfViewer.annotationEditorMode = evt.mode;
+  }
+}
 function webViewerPrint() {
   PDFViewerApplication.triggerPrinting();
 }