[Annotations] charLimit === 0 means unlimited (bug 1782564)

Changing the charLimit in JS had no impact, so this patch aims to fix
that and add an integration test for it.

src/core/annotation.js

@@ -2255,7 +2255,7 @@ class TextWidgetAnnotation extends WidgetAnnotation {
     // Determine the maximum length of text in the field.
     let maximumLength = getInheritableProperty({ dict, key: "MaxLen" });
     if (!Number.isInteger(maximumLength) || maximumLength < 0) {
-      maximumLength = null;
+      maximumLength = 0;
     }
     this.data.maxLen = maximumLength;
 
@@ -2266,7 +2266,7 @@ class TextWidgetAnnotation extends WidgetAnnotation {
       !this.hasFieldFlag(AnnotationFieldFlag.MULTILINE) &&
       !this.hasFieldFlag(AnnotationFieldFlag.PASSWORD) &&
       !this.hasFieldFlag(AnnotationFieldFlag.FILESELECT) &&
-      this.data.maxLen !== null;
+      this.data.maxLen !== 0;
     this.data.doNotScroll = this.hasFieldFlag(AnnotationFieldFlag.DONOTSCROLL);
   }
 

src/display/annotation_layer.js

@@ -1000,7 +1000,14 @@ class TextWidgetAnnotationElement extends WidgetAnnotationElement {
       const storedData = storage.getValue(id, {
         value: this.data.fieldValue,
       });
-      const textContent = storedData.formattedValue || storedData.value || "";
+      let textContent = storedData.formattedValue || storedData.value || "";
+      const maxLen = storage.getValue(id, {
+        charLimit: this.data.maxLen,
+      }).charLimit;
+      if (maxLen && textContent.length > maxLen) {
+        textContent = textContent.slice(0, maxLen);
+      }
+
       const elementData = {
         userValue: textContent,
         formattedValue: null,
@@ -1030,6 +1037,10 @@ class TextWidgetAnnotationElement extends WidgetAnnotationElement {
 
       this._setRequired(element, this.data.required);
 
+      if (maxLen) {
+        element.maxLength = maxLen;
+      }
+
       element.addEventListener("input", event => {
         storage.setValue(id, { value: event.target.value });
         this.setPropertyOnSiblings(
@@ -1088,6 +1099,36 @@ class TextWidgetAnnotationElement extends WidgetAnnotationElement {
             selRange(event) {
               event.target.setSelectionRange(...event.detail.selRange);
             },
+            charLimit: event => {
+              const { charLimit } = event.detail;
+              const { target } = event;
+              if (charLimit === 0) {
+                target.removeAttribute("maxLength");
+                return;
+              }
+
+              target.setAttribute("maxLength", charLimit);
+              let value = elementData.userValue;
+              if (!value || value.length <= charLimit) {
+                return;
+              }
+              value = value.slice(0, charLimit);
+              target.value = elementData.userValue = value;
+              storage.setValue(id, { value });
+
+              this.linkService.eventBus?.dispatch("dispatcheventinsandbox", {
+                source: this,
+                detail: {
+                  id,
+                  name: "Keystroke",
+                  value,
+                  willCommit: true,
+                  commitKey: 1,
+                  selStart: target.selectionStart,
+                  selEnd: target.selectionEnd,
+                },
+              });
+            },
           };
           this._dispatchEventFromSandbox(actions, jsEvent);
         });
@@ -1225,13 +1266,9 @@ class TextWidgetAnnotationElement extends WidgetAnnotationElement {
         element.addEventListener("blur", blurListener);
       }
 
-      if (this.data.maxLen !== null) {
-        element.maxLength = this.data.maxLen;
-      }
-
       if (this.data.comb) {
         const fieldWidth = this.data.rect[2] - this.data.rect[0];
-        const combWidth = fieldWidth / this.data.maxLen;
+        const combWidth = fieldWidth / maxLen;
 
         element.classList.add("comb");
         element.style.letterSpacing = `calc(${combWidth}px * var(--scale-factor) - 1ch)`;

src/scripting_api/field.js

@@ -29,7 +29,6 @@ class Field extends PDFObject {
     this.buttonScaleHow = data.buttonScaleHow;
     this.ButtonScaleWhen = data.buttonScaleWhen;
     this.calcOrderIndex = data.calcOrderIndex;
-    this.charLimit = data.charLimit;
     this.comb = data.comb;
     this.commitOnSelChange = data.commitOnSelChange;
     this.currentValueIndices = data.currentValueIndices;
@@ -69,6 +68,7 @@ class Field extends PDFObject {
     this._browseForFileToSubmit = data.browseForFileToSubmit || null;
     this._buttonCaption = null;
     this._buttonIcon = null;
+    this._charLimit = data.charLimit;
     this._children = null;
     this._currentValueIndices = data.currentValueIndices || 0;
     this._document = data.doc;
@@ -151,6 +151,17 @@ class Field extends PDFObject {
     this.fillColor = color;
   }
 
+  get charLimit() {
+    return this._charLimit;
+  }
+
+  set charLimit(limit) {
+    if (typeof limit !== "number") {
+      throw new Error("Invalid argument value");
+    }
+    this._charLimit = Math.max(0, Math.floor(limit));
+  }
+
   get numItems() {
     if (!this._isChoice) {
       throw new Error("Not a choice widget");