[api-minor] Fix the way to chunk the strings (#13257)

- Improve chunking in order to fix some bugs where the spaces aren't here:
    * track the last position where a glyph has been drawn;
    * when a new glyph (first glyph in a chunk) is added then compare its position with the last saved one and add a space or break:
      - there are multiple ways to move the glyphs and to avoid to have to deal with all the different possibilities it's a way easier to just compare positions;
      - and so there is now one function (i.e. "compareWithLastPosition") where all the job is done.
  - Add some breaks in order to get lines;
  - Remove the multiple whites spaces:
    * some spaces were filled with several whites spaces and so it makes harder to find some sequences of words using the search tool;
    * other pdf readers replace spaces by one white space.

Update src/core/evaluator.js

Co-authored-by: Jonas Jenwald <jonas.jenwald@gmail.com>

Co-authored-by: Jonas Jenwald <jonas.jenwald@gmail.com>

src/display/text_layer.js

@@ -57,12 +57,7 @@ const renderTextLayer = (function renderTextLayerClosure() {
   const DEFAULT_FONT_SIZE = 30;
   const DEFAULT_FONT_ASCENT = 0.8;
   const ascentCache = new Map();
-
-  const NonWhitespaceRegexp = /\S/;
-
-  function isAllWhitespace(str) {
-    return !NonWhitespaceRegexp.test(str);
-  }
+  const AllWhitespaceRegexp = /^\s+$/g;
 
   function getAscent(fontFamily, ctx) {
     const cachedAscent = ascentCache.get(fontFamily);
@@ -133,7 +128,8 @@ const renderTextLayer = (function renderTextLayerClosure() {
     const textDivProperties = {
       angle: 0,
       canvasWidth: 0,
-      isWhitespace: false,
+      hasText: geom.str !== "",
+      hasEOL: geom.hasEOL,
       originalTransform: null,
       paddingBottom: 0,
       paddingLeft: 0,
@@ -142,12 +138,8 @@ const renderTextLayer = (function renderTextLayerClosure() {
       scale: 1,
     };
 
+    textDiv.textContent = geom.str;
     task._textDivs.push(textDiv);
-    if (isAllWhitespace(geom.str)) {
-      textDivProperties.isWhitespace = true;
-      task._textDivProperties.set(textDiv, textDivProperties);
-      return;
-    }
 
     const tx = Util.transform(task._viewport.transform, geom.transform);
     let angle = Math.atan2(tx[1], tx[0]);
@@ -176,7 +168,6 @@ const renderTextLayer = (function renderTextLayerClosure() {
     // Keeps screen readers from pausing on every new text span.
     textDiv.setAttribute("role", "presentation");
 
-    textDiv.textContent = geom.str;
     // geom.dir may be 'ttb' for vertical texts.
     textDiv.dir = geom.dir;
 
@@ -192,7 +183,10 @@ const renderTextLayer = (function renderTextLayerClosure() {
     // little effect on text highlighting. This makes scrolling on docs with
     // lots of such divs a lot faster.
     let shouldScaleText = false;
-    if (geom.str.length > 1) {
+    if (
+      geom.str.length > 1 ||
+      (task._enhanceTextSelection && AllWhitespaceRegexp.test(geom.str))
+    ) {
       shouldScaleText = true;
     } else if (geom.transform[0] !== geom.transform[3]) {
       const absScaleX = Math.abs(geom.transform[0]),
@@ -218,7 +212,7 @@ const renderTextLayer = (function renderTextLayerClosure() {
       task._layoutText(textDiv);
     }
 
-    if (task._enhanceTextSelection) {
+    if (task._enhanceTextSelection && textDivProperties.hasText) {
       let angleCos = 1,
         angleSin = 0;
       if (angle !== 0) {
@@ -666,12 +660,9 @@ const renderTextLayer = (function renderTextLayerClosure() {
 
     _layoutText(textDiv) {
       const textDivProperties = this._textDivProperties.get(textDiv);
-      if (textDivProperties.isWhitespace) {
-        return;
-      }
 
       let transform = "";
-      if (textDivProperties.canvasWidth !== 0) {
+      if (textDivProperties.canvasWidth !== 0 && textDivProperties.hasText) {
         const { fontSize, fontFamily } = textDiv.style;
 
         // Only build font string and set to context if different from last.
@@ -700,8 +691,15 @@ const renderTextLayer = (function renderTextLayerClosure() {
         }
         textDiv.style.transform = transform;
       }
-      this._textDivProperties.set(textDiv, textDivProperties);
-      this._container.appendChild(textDiv);
+
+      if (textDivProperties.hasText) {
+        this._container.appendChild(textDiv);
+      }
+      if (textDivProperties.hasEOL) {
+        const br = document.createElement("br");
+        br.setAttribute("role", "presentation");
+        this._container.appendChild(br);
+      }
     },
 
     _render: function TextLayer_render(timeout) {
@@ -778,7 +776,7 @@ const renderTextLayer = (function renderTextLayerClosure() {
         const div = this._textDivs[i];
         const divProps = this._textDivProperties.get(div);
 
-        if (divProps.isWhitespace) {
+        if (!divProps.hasText) {
           continue;
         }
         if (expandDivs) {