[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/core/evaluator.js

@@ -2042,7 +2042,7 @@ class PartialEvaluator {
     resources = resources || Dict.empty;
     stateManager = stateManager || new StateManager(new TextState());
 
-    var WhitespaceRegexp = /\s/g;
+    const WhitespaceRegexp = /\s/g;
 
     var textContent = {
       items: [],
@@ -2051,26 +2051,43 @@ class PartialEvaluator {
     var textContentItem = {
       initialized: false,
       str: [],
+      totalWidth: 0,
+      totalHeight: 0,
       width: 0,
       height: 0,
       vertical: false,
-      lastAdvanceWidth: 0,
-      lastAdvanceHeight: 0,
+      lastCharSize: 0,
+      prevTransform: null,
       textAdvanceScale: 0,
       spaceWidth: 0,
-      fakeSpaceMin: Infinity,
-      fakeMultiSpaceMin: Infinity,
-      fakeMultiSpaceMax: -0,
-      textRunBreakAllowed: false,
+      spaceInFlowMin: 0,
+      spaceInFlowMax: 0,
+      trackingSpaceMin: Infinity,
       transform: null,
       fontName: null,
+      hasEOL: false,
+      isLastCharWhiteSpace: false,
     };
-    var SPACE_FACTOR = 0.3;
-    var MULTI_SPACE_FACTOR = 1.5;
-    var MULTI_SPACE_FACTOR_MAX = 4;
+
+    // Used in addFakeSpaces.
+    // wsw stands for whitespace width.
+
+    // A white <= wsw * TRACKING_SPACE_FACTOR is a tracking space
+    // so it doesn't count as a space.
+    const TRACKING_SPACE_FACTOR = 0.3;
+
+    // A white with a width in [wsw * MIN_FACTOR; wsw * MAX_FACTOR]
+    // is a space which will be inserted in the current flow of words.
+    // If the width is outside of this range then the flow is broken
+    // (which means a new span in the text layer).
+    // It's useful to adjust the best as possible the span in the layer
+    // to what is displayed in the canvas.
+    const SPACE_IN_FLOW_MIN_FACTOR = 0.3;
+    const SPACE_IN_FLOW_MAX_FACTOR = 1.3;
 
     var self = this;
     var xref = this.xref;
+    const showSpacedTextBuffer = [];
 
     // The xobj is parsed iff it's needed, e.g. if there is a `DO` cmd.
     var xobjs = null;
@@ -2081,26 +2098,10 @@ class PartialEvaluator {
 
     var textState;
 
-    function ensureTextContentItem() {
-      if (textContentItem.initialized) {
-        return textContentItem;
-      }
-      const font = textState.font,
-        loadedName = font.loadedName;
-      if (!seenStyles.has(loadedName)) {
-        seenStyles.add(loadedName);
-
-        textContent.styles[loadedName] = {
-          fontFamily: font.fallbackName,
-          ascent: font.ascent,
-          descent: font.descent,
-          vertical: font.vertical,
-        };
-      }
-      textContentItem.fontName = loadedName;
-
+    function getCurrentTextTransform() {
       // 9.4.4 Text Space Details
-      var tsm = [
+      const font = textState.font;
+      const tsm = [
         textState.fontSize * textState.textHScale,
         0,
         0,
@@ -2120,18 +2121,44 @@ class PartialEvaluator {
         }
       }
 
-      var trm = Util.transform(
+      return Util.transform(
         textState.ctm,
         Util.transform(textState.textMatrix, tsm)
       );
-      textContentItem.transform = trm;
+    }
+
+    function ensureTextContentItem() {
+      if (textContentItem.initialized) {
+        return textContentItem;
+      }
+      const font = textState.font,
+        loadedName = font.loadedName;
+      if (!seenStyles.has(loadedName)) {
+        seenStyles.add(loadedName);
+
+        textContent.styles[loadedName] = {
+          fontFamily: font.fallbackName,
+          ascent: font.ascent,
+          descent: font.descent,
+          vertical: font.vertical,
+        };
+      }
+      textContentItem.fontName = loadedName;
+
+      const trm = (textContentItem.transform = getCurrentTextTransform());
       if (!font.vertical) {
-        textContentItem.width = 0;
-        textContentItem.height = Math.hypot(trm[2], trm[3]);
+        textContentItem.width = textContentItem.totalWidth = 0;
+        textContentItem.height = textContentItem.totalHeight = Math.hypot(
+          trm[2],
+          trm[3]
+        );
         textContentItem.vertical = false;
       } else {
-        textContentItem.width = Math.hypot(trm[0], trm[1]);
-        textContentItem.height = 0;
+        textContentItem.width = textContentItem.totalWidth = Math.hypot(
+          trm[0],
+          trm[1]
+        );
+        textContentItem.height = textContentItem.totalHeight = 0;
         textContentItem.vertical = true;
       }
 
@@ -2141,29 +2168,53 @@ class PartialEvaluator {
       );
       const scaleCtmX = Math.hypot(textState.ctm[0], textState.ctm[1]);
       textContentItem.textAdvanceScale = scaleCtmX * scaleLineX;
-      textContentItem.lastAdvanceWidth = 0;
-      textContentItem.lastAdvanceHeight = 0;
+      textContentItem.lastCharSize = textContentItem.lastCharSize || 0;
 
       var spaceWidth = (font.spaceWidth / 1000) * textState.fontSize;
       if (spaceWidth) {
         textContentItem.spaceWidth = spaceWidth;
-        textContentItem.fakeSpaceMin = spaceWidth * SPACE_FACTOR;
-        textContentItem.fakeMultiSpaceMin = spaceWidth * MULTI_SPACE_FACTOR;
-        textContentItem.fakeMultiSpaceMax = spaceWidth * MULTI_SPACE_FACTOR_MAX;
-        // It's okay for monospace fonts to fake as much space as needed.
-        textContentItem.textRunBreakAllowed = !font.isMonospace;
+        textContentItem.trackingSpaceMin = spaceWidth * TRACKING_SPACE_FACTOR;
+        textContentItem.spaceInFlowMin = spaceWidth * SPACE_IN_FLOW_MIN_FACTOR;
+        textContentItem.spaceInFlowMax = spaceWidth * SPACE_IN_FLOW_MAX_FACTOR;
       } else {
         textContentItem.spaceWidth = 0;
-        textContentItem.fakeSpaceMin = Infinity;
-        textContentItem.fakeMultiSpaceMin = Infinity;
-        textContentItem.fakeMultiSpaceMax = 0;
-        textContentItem.textRunBreakAllowed = false;
+        textContentItem.trackingSpaceMin = Infinity;
       }
 
+      textContentItem.hasEOL = false;
+
       textContentItem.initialized = true;
       return textContentItem;
     }
 
+    function updateAdvanceScale() {
+      if (!textContentItem.initialized) {
+        return;
+      }
+
+      const scaleLineX = Math.hypot(
+        textState.textLineMatrix[0],
+        textState.textLineMatrix[1]
+      );
+      const scaleCtmX = Math.hypot(textState.ctm[0], textState.ctm[1]);
+      const scaleFactor = scaleCtmX * scaleLineX;
+      if (scaleFactor === textContentItem.textAdvanceScale) {
+        return;
+      }
+
+      if (!textContentItem.vertical) {
+        textContentItem.totalWidth +=
+          textContentItem.width * textContentItem.textAdvanceScale;
+        textContentItem.width = 0;
+      } else {
+        textContentItem.totalHeight +=
+          textContentItem.height * textContentItem.textAdvanceScale;
+        textContentItem.height = 0;
+      }
+
+      textContentItem.textAdvanceScale = scaleFactor;
+    }
+
     function replaceWhitespace(str) {
       // Replaces all whitespaces with standard spaces (0x20), to avoid
       // alignment issues between the textLayer and the canvas if the text
@@ -2178,17 +2229,19 @@ class PartialEvaluator {
     }
 
     function runBidiTransform(textChunk) {
-      var str = textChunk.str.join("");
-      var bidiResult = bidi(str, -1, textChunk.vertical);
+      const text = textChunk.str.join("");
+      const bidiResult = bidi(text, -1, textChunk.vertical);
+      const str = normalizeWhitespace
+        ? replaceWhitespace(bidiResult.str)
+        : bidiResult.str;
       return {
-        str: normalizeWhitespace
-          ? replaceWhitespace(bidiResult.str)
-          : bidiResult.str,
+        str,
         dir: bidiResult.dir,
-        width: textChunk.width,
-        height: textChunk.height,
+        width: textChunk.totalWidth,
+        height: textChunk.totalHeight,
         transform: textChunk.transform,
         fontName: textChunk.fontName,
+        hasEOL: textChunk.hasEOL,
       };
     }
 
@@ -2202,91 +2255,276 @@ class PartialEvaluator {
         });
     }
 
-    function buildTextContentItem(chars) {
-      var font = textState.font;
-      var textChunk = ensureTextContentItem();
-      var width = 0;
-      var height = 0;
-      var glyphs = font.charsToGlyphs(chars);
-      for (var i = 0; i < glyphs.length; i++) {
-        var glyph = glyphs[i];
-        var glyphWidth = null;
-        if (font.vertical && glyph.vmetric) {
-          glyphWidth = glyph.vmetric[0];
-        } else {
-          glyphWidth = glyph.width;
+    function compareWithLastPosition(fontSize) {
+      if (
+        !combineTextItems ||
+        !textState.font ||
+        !textContentItem.prevTransform
+      ) {
+        return;
+      }
+
+      const currentTransform = getCurrentTextTransform();
+      const posX = currentTransform[4];
+      const posY = currentTransform[5];
+      const lastPosX = textContentItem.prevTransform[4];
+      const lastPosY = textContentItem.prevTransform[5];
+
+      if (lastPosX === posX && lastPosY === posY) {
+        return;
+      }
+
+      const advanceX = (posX - lastPosX) / textContentItem.textAdvanceScale;
+      const advanceY = (posY - lastPosY) / textContentItem.textAdvanceScale;
+      const HALF_LAST_CHAR = -0.5 * textContentItem.lastCharSize;
+
+      if (textState.font.vertical) {
+        if (
+          Math.abs(advanceX) >
+          textContentItem.width /
+            textContentItem.textAdvanceScale /* not the same column */
+        ) {
+          appendEOL();
+          return;
         }
 
-        var glyphUnicode = glyph.unicode;
-        var NormalizedUnicodes = getNormalizedUnicodes();
-        if (NormalizedUnicodes[glyphUnicode] !== undefined) {
-          glyphUnicode = NormalizedUnicodes[glyphUnicode];
+        if (HALF_LAST_CHAR > advanceY) {
+          return;
         }
-        glyphUnicode = reverseIfRtl(glyphUnicode);
 
-        var charSpacing = textState.charSpacing;
-        if (glyph.isSpace) {
-          var wordSpacing = textState.wordSpacing;
-          charSpacing += wordSpacing;
-          if (wordSpacing > 0) {
-            addFakeSpaces(wordSpacing, textChunk.str);
+        if (advanceY > textContentItem.trackingSpaceMin) {
+          textContentItem.height += advanceY;
+        } else if (!addFakeSpaces(advanceY, 0, textContentItem.prevTransform)) {
+          if (textContentItem.str.length === 0) {
+            textContent.items.push({
+              str: " ",
+              dir: "ltr",
+              width: 0,
+              height: advanceY,
+              transform: textContentItem.prevTransform,
+              fontName: textContentItem.fontName,
+              hasEOL: false,
+            });
+            textContentItem.isLastCharWhiteSpace = true;
+          } else {
+            textContentItem.height += advanceY;
           }
         }
 
-        var tx = 0;
-        var ty = 0;
-        if (!font.vertical) {
-          var w0 = glyphWidth * textState.fontMatrix[0];
-          tx = (w0 * textState.fontSize + charSpacing) * textState.textHScale;
-          width += tx;
+        return;
+      }
+
+      if (
+        Math.abs(advanceY) >
+        textContentItem.height /
+          textContentItem.textAdvanceScale /* not the same line */
+      ) {
+        appendEOL();
+        return;
+      }
+
+      if (HALF_LAST_CHAR > advanceX) {
+        return;
+      }
+
+      if (advanceX <= textContentItem.trackingSpaceMin) {
+        textContentItem.width += advanceX;
+      } else if (!addFakeSpaces(advanceX, 0, textContentItem.prevTransform)) {
+        if (textContentItem.str.length === 0) {
+          textContent.items.push({
+            str: " ",
+            dir: "ltr",
+            width: advanceX,
+            height: 0,
+            transform: textContentItem.prevTransform,
+            fontName: textContentItem.fontName,
+            hasEOL: false,
+          });
+          textContentItem.isLastCharWhiteSpace = true;
         } else {
-          var w1 = glyphWidth * textState.fontMatrix[0];
-          ty = w1 * textState.fontSize + charSpacing;
-          height += ty;
+          textContentItem.width += advanceX;
         }
-        textState.translateTextMatrix(tx, ty);
-
-        textChunk.str.push(glyphUnicode);
       }
-
-      if (!font.vertical) {
-        textChunk.lastAdvanceWidth = width;
-        textChunk.width += width;
-      } else {
-        textChunk.lastAdvanceHeight = height;
-        textChunk.height += Math.abs(height);
-      }
-
-      return textChunk;
     }
 
-    function addFakeSpaces(width, strBuf) {
-      if (width < textContentItem.fakeSpaceMin) {
+    function buildTextContentItem({ chars, extraSpacing, isFirstChunk }) {
+      const font = textState.font;
+      if (!chars) {
+        // Just move according to the space we have.
+        const charSpacing = textState.charSpacing + extraSpacing;
+        if (charSpacing) {
+          if (!font.vertical) {
+            textState.translateTextMatrix(
+              charSpacing * textState.textHScale,
+              0
+            );
+          } else {
+            textState.translateTextMatrix(0, charSpacing);
+          }
+        }
+
         return;
       }
-      if (width < textContentItem.fakeMultiSpaceMin) {
-        strBuf.push(" ");
-        return;
+
+      const NormalizedUnicodes = getNormalizedUnicodes();
+      const glyphs = font.charsToGlyphs(chars);
+      const scale = textState.fontMatrix[0] * textState.fontSize;
+      if (isFirstChunk) {
+        compareWithLastPosition(scale);
       }
-      var fakeSpaces = Math.round(width / textContentItem.spaceWidth);
-      while (fakeSpaces-- > 0) {
-        strBuf.push(" ");
+
+      let textChunk = ensureTextContentItem();
+      let size = 0;
+      let lastCharSize = 0;
+
+      for (let i = 0, ii = glyphs.length; i < ii; i++) {
+        const glyph = glyphs[i];
+        let charSpacing =
+          textState.charSpacing + (i === ii - 1 ? extraSpacing : 0);
+
+        let glyphUnicode = glyph.unicode;
+        if (glyph.isSpace) {
+          charSpacing += textState.wordSpacing;
+          textChunk.isLastCharWhiteSpace = true;
+        } else {
+          glyphUnicode = NormalizedUnicodes[glyphUnicode] || glyphUnicode;
+          glyphUnicode = reverseIfRtl(glyphUnicode);
+          textChunk.isLastCharWhiteSpace = false;
+        }
+        textChunk.str.push(glyphUnicode);
+
+        const glyphWidth =
+          font.vertical && glyph.vmetric ? glyph.vmetric[0] : glyph.width;
+
+        let scaledDim = glyphWidth * scale;
+        if (!font.vertical) {
+          scaledDim *= textState.textHScale;
+          textState.translateTextMatrix(scaledDim, 0);
+        } else {
+          textState.translateTextMatrix(0, scaledDim);
+          scaledDim = Math.abs(scaledDim);
+        }
+        size += scaledDim;
+
+        if (charSpacing) {
+          if (!font.vertical) {
+            charSpacing *= textState.textHScale;
+          }
+
+          scaledDim += charSpacing;
+          const wasSplit =
+            charSpacing > textContentItem.trackingSpaceMin &&
+            addFakeSpaces(charSpacing, size);
+          if (!font.vertical) {
+            textState.translateTextMatrix(charSpacing, 0);
+          } else {
+            textState.translateTextMatrix(0, charSpacing);
+          }
+
+          if (wasSplit) {
+            textChunk = ensureTextContentItem();
+            size = 0;
+          } else {
+            size += charSpacing;
+          }
+        }
+
+        lastCharSize = scaledDim;
       }
+
+      textChunk.lastCharSize = lastCharSize;
+      if (!font.vertical) {
+        textChunk.width += size;
+      } else {
+        textChunk.height += size;
+      }
+
+      textChunk.prevTransform = getCurrentTextTransform();
+    }
+
+    function appendEOL() {
+      if (textContentItem.initialized) {
+        textContentItem.hasEOL = true;
+        flushTextContentItem();
+      } else if (textContent.items.length > 0) {
+        textContent.items[textContent.items.length - 1].hasEOL = true;
+      } else {
+        textContent.items.push({
+          str: "",
+          dir: "ltr",
+          width: 0,
+          height: 0,
+          transform: getCurrentTextTransform(),
+          fontName: textState.font.loadedName,
+          hasEOL: true,
+        });
+      }
+
+      textContentItem.isLastCharWhiteSpace = false;
+      textContentItem.lastCharSize = 0;
+    }
+
+    function addFakeSpaces(width, size, transf = null) {
+      if (
+        textContentItem.spaceInFlowMin <= width &&
+        width <= textContentItem.spaceInFlowMax
+      ) {
+        if (textContentItem.initialized) {
+          textContentItem.str.push(" ");
+          textContentItem.isLastCharWhiteSpace = true;
+        }
+        return false;
+      }
+
+      const fontName = textContentItem.fontName;
+
+      let height = 0;
+      width *= textContentItem.textAdvanceScale;
+      if (!textContentItem.vertical) {
+        textContentItem.width += size;
+      } else {
+        textContentItem.height += size;
+        height = width;
+        width = 0;
+      }
+
+      flushTextContentItem();
+
+      if (textContentItem.isLastCharWhiteSpace) {
+        return true;
+      }
+
+      textContentItem.isLastCharWhiteSpace = true;
+      textContent.items.push({
+        str: " ",
+        // TODO: check if using the orientation from last chunk is
+        // better or not.
+        dir: "ltr",
+        width,
+        height,
+        transform: transf ? transf : getCurrentTextTransform(),
+        fontName,
+        hasEOL: false,
+      });
+
+      return true;
     }
 
     function flushTextContentItem() {
-      if (!textContentItem.initialized) {
+      if (!textContentItem.initialized || !textContentItem.str) {
         return;
       }
 
       // Do final text scaling.
       if (!textContentItem.vertical) {
-        textContentItem.width *= textContentItem.textAdvanceScale;
+        textContentItem.totalWidth +=
+          textContentItem.width * textContentItem.textAdvanceScale;
       } else {
-        textContentItem.height *= textContentItem.textAdvanceScale;
+        textContentItem.totalHeight +=
+          textContentItem.height * textContentItem.textAdvanceScale;
       }
-      textContent.items.push(runBidiTransform(textContentItem));
 
+      textContent.items.push(runBidiTransform(textContentItem));
       textContentItem.initialized = false;
       textContentItem.str.length = 0;
     }
@@ -2330,7 +2568,6 @@ class PartialEvaluator {
         textState = stateManager.state;
         var fn = operation.fn;
         args = operation.args;
-        var advance, diff;
 
         switch (fn | 0) {
           case OPS.setFont:
@@ -2363,32 +2600,6 @@ class PartialEvaluator {
             textState.leading = args[0];
             break;
           case OPS.moveText:
-            // Optimization to treat same line movement as advance
-            var isSameTextLine = !textState.font
-              ? false
-              : (textState.font.vertical ? args[0] : args[1]) === 0;
-            advance = args[0] - args[1];
-            if (
-              combineTextItems &&
-              isSameTextLine &&
-              textContentItem.initialized &&
-              advance > 0 &&
-              advance <= textContentItem.fakeMultiSpaceMax
-            ) {
-              textState.translateTextLineMatrix(args[0], args[1]);
-              textContentItem.width +=
-                args[0] - textContentItem.lastAdvanceWidth;
-              textContentItem.height +=
-                args[1] - textContentItem.lastAdvanceHeight;
-              diff =
-                args[0] -
-                textContentItem.lastAdvanceWidth -
-                (args[1] - textContentItem.lastAdvanceHeight);
-              addFakeSpaces(diff, textContentItem.str);
-              break;
-            }
-
-            flushTextContentItem();
             textState.translateTextLineMatrix(args[0], args[1]);
             textState.textMatrix = textState.textLineMatrix.slice();
             break;
@@ -2399,40 +2610,10 @@ class PartialEvaluator {
             textState.textMatrix = textState.textLineMatrix.slice();
             break;
           case OPS.nextLine:
-            flushTextContentItem();
+            appendEOL();
             textState.carriageReturn();
             break;
           case OPS.setTextMatrix:
-            // Optimization to treat same line movement as advance.
-            advance = textState.calcTextLineMatrixAdvance(
-              args[0],
-              args[1],
-              args[2],
-              args[3],
-              args[4],
-              args[5]
-            );
-            if (
-              combineTextItems &&
-              advance !== null &&
-              textContentItem.initialized &&
-              advance.value > 0 &&
-              advance.value <= textContentItem.fakeMultiSpaceMax
-            ) {
-              textState.translateTextLineMatrix(advance.width, advance.height);
-              textContentItem.width +=
-                advance.width - textContentItem.lastAdvanceWidth;
-              textContentItem.height +=
-                advance.height - textContentItem.lastAdvanceHeight;
-              diff =
-                advance.width -
-                textContentItem.lastAdvanceWidth -
-                (advance.height - textContentItem.lastAdvanceHeight);
-              addFakeSpaces(diff, textContentItem.str);
-              break;
-            }
-
-            flushTextContentItem();
             textState.setTextMatrix(
               args[0],
               args[1],
@@ -2449,6 +2630,7 @@ class PartialEvaluator {
               args[4],
               args[5]
             );
+            updateAdvanceScale();
             break;
           case OPS.setCharSpacing:
             textState.charSpacing = args[0];
@@ -2466,14 +2648,16 @@ class PartialEvaluator {
               self.ensureStateFont(stateManager.state);
               continue;
             }
-            var items = args[0];
-            var offset;
-            for (var j = 0, jj = items.length; j < jj; j++) {
-              if (typeof items[j] === "string") {
-                buildTextContentItem(items[j]);
-              } else if (isNum(items[j])) {
-                ensureTextContentItem();
 
+            const spaceFactor =
+              ((textState.font.vertical ? 1 : -1) * textState.fontSize) / 1000;
+            const elements = args[0];
+            let isFirstChunk = true;
+            for (let i = 0, ii = elements.length; i < ii - 1; i++) {
+              const item = elements[i];
+              if (typeof item === "string") {
+                showSpacedTextBuffer.push(item);
+              } else if (typeof item === "number" && item !== 0) {
                 // PDF Specification 5.3.2 states:
                 // The number is expressed in thousandths of a unit of text
                 // space.
@@ -2482,64 +2666,75 @@ class PartialEvaluator {
                 // In the default coordinate system, a positive adjustment
                 // has the effect of moving the next glyph painted either to
                 // the left or down by the given amount.
-                advance = (items[j] * textState.fontSize) / 1000;
-                var breakTextRun = false;
-                if (textState.font.vertical) {
-                  offset = advance;
-                  textState.translateTextMatrix(0, offset);
-                  breakTextRun =
-                    textContentItem.textRunBreakAllowed &&
-                    advance > textContentItem.fakeMultiSpaceMax;
-                  if (!breakTextRun) {
-                    // Value needs to be added to height to paint down.
-                    textContentItem.height += offset;
-                  }
-                } else {
-                  advance = -advance;
-                  offset = advance * textState.textHScale;
-                  textState.translateTextMatrix(offset, 0);
-                  breakTextRun =
-                    textContentItem.textRunBreakAllowed &&
-                    advance > textContentItem.fakeMultiSpaceMax;
-                  if (!breakTextRun) {
-                    // Value needs to be subtracted from width to paint left.
-                    textContentItem.width += offset;
-                  }
-                }
-                if (breakTextRun) {
-                  flushTextContentItem();
-                } else if (advance > 0) {
-                  addFakeSpaces(advance, textContentItem.str);
+                const str = showSpacedTextBuffer.join("");
+                showSpacedTextBuffer.length = 0;
+                buildTextContentItem({
+                  chars: str,
+                  extraSpacing: item * spaceFactor,
+                  isFirstChunk,
+                });
+                if (str && isFirstChunk) {
+                  isFirstChunk = false;
                 }
               }
             }
+
+            const item = elements[elements.length - 1];
+            if (typeof item === "string") {
+              showSpacedTextBuffer.push(item);
+            }
+
+            if (showSpacedTextBuffer.length > 0) {
+              const str = showSpacedTextBuffer.join("");
+              showSpacedTextBuffer.length = 0;
+              buildTextContentItem({
+                chars: str,
+                extraSpacing: 0,
+                isFirstChunk,
+              });
+            }
             break;
           case OPS.showText:
             if (!stateManager.state.font) {
               self.ensureStateFont(stateManager.state);
               continue;
             }
-            buildTextContentItem(args[0]);
+
+            buildTextContentItem({
+              chars: args[0],
+              extraSpacing: 0,
+              isFirstChunk: true,
+            });
             break;
           case OPS.nextLineShowText:
             if (!stateManager.state.font) {
               self.ensureStateFont(stateManager.state);
               continue;
             }
+            textContentItem.hasEOL = true;
             flushTextContentItem();
             textState.carriageReturn();
-            buildTextContentItem(args[0]);
+            buildTextContentItem({
+              chars: args[0],
+              extraSpacing: 0,
+              isFirstChunk: true,
+            });
             break;
           case OPS.nextLineSetSpacingShowText:
             if (!stateManager.state.font) {
               self.ensureStateFont(stateManager.state);
               continue;
             }
+            textContentItem.hasEOL = true;
             flushTextContentItem();
             textState.wordSpacing = args[0];
             textState.charSpacing = args[1];
             textState.carriageReturn();
-            buildTextContentItem(args[2]);
+            buildTextContentItem({
+              chars: args[2],
+              extraSpacing: 0,
+              isFirstChunk: true,
+            });
             break;
           case OPS.paintXObject:
             flushTextContentItem();
@@ -3887,46 +4082,6 @@ class TextState {
     m[5] = m[1] * x + m[3] * y + m[5];
   }
 
-  calcTextLineMatrixAdvance(a, b, c, d, e, f) {
-    var font = this.font;
-    if (!font) {
-      return null;
-    }
-    var m = this.textLineMatrix;
-    if (!(a === m[0] && b === m[1] && c === m[2] && d === m[3])) {
-      return null;
-    }
-    var txDiff = e - m[4],
-      tyDiff = f - m[5];
-    if ((font.vertical && txDiff !== 0) || (!font.vertical && tyDiff !== 0)) {
-      return null;
-    }
-    var tx,
-      ty,
-      denominator = a * d - b * c;
-    if (font.vertical) {
-      tx = (-tyDiff * c) / denominator;
-      ty = (tyDiff * a) / denominator;
-    } else {
-      tx = (txDiff * d) / denominator;
-      ty = (-txDiff * b) / denominator;
-    }
-    return { width: tx, height: ty, value: font.vertical ? ty : tx };
-  }
-
-  calcRenderMatrix(ctm) {
-    // 9.4.4 Text Space Details
-    var tsm = [
-      this.fontSize * this.textHScale,
-      0,
-      0,
-      this.fontSize,
-      0,
-      this.textRise,
-    ];
-    return Util.transform(ctm, Util.transform(this.textMatrix, tsm));
-  }
-
   carriageReturn() {
     this.translateTextLineMatrix(0, -this.leading);
     this.textMatrix = this.textLineMatrix.slice();

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) {