Add text wrapping to FreeText editors (issue 18191)

Text wrapping is ensured by preventing the FreeText editor from going
out of bounds.

- max-width is a formula of (100% of the parentElement - the left % of the editor element)
- this ensures that clicking on the very right edge of the document does
- not create the editor out of bounds.

src/display/editor/freetext.js

@@ -409,12 +409,56 @@ class FreeTextEditor extends AnnotationEditor {
         // text and one for the br element).
         continue;
       }
-      buffer.push(FreeTextEditor.#getNodeContent(child));
+      if (child.nodeType === Node.TEXT_NODE && child.textContent.trim()) {
+        const visualLines = this.#detectVisualLineBreaks(child);
+        buffer.push(...visualLines);
+      } else {
+        buffer.push(FreeTextEditor.#getNodeContent(child));
+      }
+
       prevChild = child;
     }
     return buffer.join("\n");
   }
 
+  /**
+   * Detects line breaks within a text node.
+   * Algorithm is based on this gist:
+   * https://gist.github.com/bennadel/033e0158f47bff9e066016f99567ebba
+   * @param {Text} textNode
+   * @returns {Array<string>}
+   */
+  #detectVisualLineBreaks(textNode) {
+    const range = document.createRange();
+    const lines = [];
+    let lineCharacters = [];
+
+    const text = textNode.textContent.trim().replaceAll(/\s+/g, " ");
+
+    if (!text) {
+      return [];
+    }
+
+    for (let i = 0; i < text.length; i++) {
+      range.setStart(textNode, 0);
+      range.setEnd(textNode, i + 1);
+
+      const lineIndex = range.getClientRects().length - 1;
+
+      if (!lines[lineIndex]) {
+        lines.push((lineCharacters = []));
+      }
+
+      lineCharacters.push(text.charAt(i));
+    }
+
+    range.detach();
+
+    return lines
+      .map(characters => characters.join("").trim())
+      .filter(line => line.length > 0);
+  }
+
   #setEditorDimensions() {
     const [parentWidth, parentHeight] = this.parentDimensions;
 
@@ -647,6 +691,10 @@ class FreeTextEditor extends AnnotationEditor {
       this.div.setAttribute("annotation-id", this.annotationElementId);
     }
 
+    // Not sure why we need the -16px but it's neccessary to prevent
+    // text shifting when user finishes typing.
+    this.div.style.maxWidth = `calc(100% - ${this.div.style.left} - 16px)`;
+
     return this.div;
   }
 

test/integration/freetext_editor_spec.mjs

@@ -3519,4 +3519,56 @@ describe("FreeText Editor", () => {
       );
     });
   });
+
+  describe("FreeText text wrapping", () => {
+    let pages;
+
+    beforeAll(async () => {
+      pages = await loadAndWait("empty.pdf", ".annotationEditorLayer");
+    });
+
+    afterAll(async () => {
+      await closePages(pages);
+    });
+
+    it("must wrap long text into multiple lines", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          await switchToFreeText(page);
+
+          const rect = await getRect(page, ".annotationEditorLayer");
+          const editorSelector = getEditorSelector(0);
+
+          await page.mouse.click(rect.x + 100, rect.y + 100);
+          await page.waitForSelector(editorSelector, { visible: true });
+
+          const longText =
+            "This is a very long text string that should definitely need to wrap onto multiple lines of text so that it can be displayed properly within the FreeText annotation editor.";
+          await page.type(`${editorSelector} .internal`, longText);
+
+          const hasMultipleLines = await page.evaluate(selector => {
+            const el = document.querySelector(`${selector} .internal`);
+            const style = window.getComputedStyle(el);
+            const lineHeight = parseFloat(style.lineHeight);
+            const totalHeight = el.getBoundingClientRect().height;
+            return totalHeight > lineHeight;
+          }, editorSelector);
+
+          expect(hasMultipleLines).withContext(`In ${browserName}`).toBeTrue();
+
+          await commit(page);
+
+          const maintainsWrapping = await page.evaluate(selector => {
+            const el = document.querySelector(`${selector} .internal`);
+            const style = window.getComputedStyle(el);
+            const lineHeight = parseFloat(style.lineHeight);
+            const totalHeight = el.getBoundingClientRect().height;
+            return totalHeight > lineHeight * 1.5;
+          }, editorSelector);
+
+          expect(maintainsWrapping).withContext(`In ${browserName}`).toBeTrue();
+        })
+      );
+    });
+  });
 });

web/annotation_editor_layer_builder.css

@@ -517,7 +517,8 @@
   border: none;
   inset: 0;
   overflow: visible;
-  white-space: nowrap;
+  white-space: pre-wrap;
+  word-wrap: break-word;
   font: 10px sans-serif;
   line-height: var(--freetext-line-height);
   user-select: none;