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Fix glyph width calculation and Remove extra spaces #722

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Merged
MaximPlusov merged 4 commits into from
Feb 9, 2026
Merged

Fix glyph width calculation and Remove extra spaces #722

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6e8cddc
Fix glyph width calculation and Remove extra spaces
LonelyMidoriya Feb 6, 2026
002215e
Create method addSpacesByShift
LonelyMidoriya Feb 9, 2026
30b1bff
Update ChunkParser.java
LonelyMidoriya Feb 9, 2026
c6a0db9
Some refactoring
LonelyMidoriya Feb 9, 2026
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26 changes: 13 additions & 13 deletions wcag-validation/src/main/java/org/verapdf/gf/model/factory/chunks/ChunkParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -832,15 +832,13 @@ private List<Double> parseTextShowArgument(COSBase argument, StringBuilder unico
double shift = - obj.getReal() / 1000 *
graphicsState.getTextState().getTextFontSize() *
graphicsState.getTextState().getHorizontalScaling();
if (-obj.getReal() >= TextChunkUtils.TEXT_CHUNK_SPACE_RATIO && StaticStorages.getIsAddSpacesBetweenTextPieces()) {
textPieces.add(new TextPieces.TextPiece(" ", textPieces.getCurrentX(),
textPieces.getCurrentX() + shift));
} else {
textPieces.shiftCurrentX(shift);
}
textPieces.shiftCurrentX(shift);
}
}
}
double threshold = graphicsState.getTextState().getTextFontSize() * TextChunkUtils.TEXT_LINE_SPACE_RATIO;
textPieces.addSpaces(threshold);
Comment on lines +839 to +840
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⚠️ Potential issue | 🟠 Major

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rg -n "TEXT_LINE_SPACE_RATIO" --type java -C 3

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find . -name "TextPieces.java" -type f

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Threshold for space detection doesn't account for horizontal scaling.

The gap between consecutive text pieces (line 92 in TextPieces.java) is calculated in a coordinate space where both glyph widths (line 873) and character shifts (line 871) are scaled by horizontalScaling. However, the threshold computed on line 839 only uses fontSize * TEXT_LINE_SPACE_RATIO without including horizontalScaling. This causes incorrect space insertion when horizontalScaling deviates from 1.0.

Proposed fix 
-            double threshold = graphicsState.getTextState().getTextFontSize() * TextChunkUtils.TEXT_LINE_SPACE_RATIO;
+            double threshold = graphicsState.getTextState().getTextFontSize() *
+                    graphicsState.getTextState().getHorizontalScaling() * TextChunkUtils.TEXT_LINE_SPACE_RATIO;
🤖 Prompt for AI Agents 
In
`@wcag-validation/src/main/java/org/verapdf/gf/model/factory/chunks/ChunkParser.java`
around lines 839 - 840, The space-detection threshold in ChunkParser currently
uses graphicsState.getTextState().getTextFontSize() *
TextChunkUtils.TEXT_LINE_SPACE_RATIO but ignores horizontal scaling; change the
computation to include the text state's horizontal scaling (e.g., multiply by
graphicsState.getTextState().getHorizontalScaling()) so the threshold becomes
fontSize * horizontalScaling * TextChunkUtils.TEXT_LINE_SPACE_RATIO, then pass
that adjusted threshold into textPieces.addSpaces(threshold) to ensure spaces
are detected correctly when horizontalScaling != 1.0.


unicodeValue.append(textPieces.getValue());
if (!textPieces.isEmpty()) {
textMatrix.concatenate(Matrix.getTranslateInstance(textPieces.getStartX(), 0));
Expand All @@ -867,17 +865,18 @@ private void parseString(COSString string, StringBuilder unicodeValue, TextPiece
" in font" + graphicsState.getTextState().getTextFont().getName());
width = 0.0;
}
double shift = (width *
graphicsState.getTextState().getTextFontSize() / 1000 +
graphicsState.getTextState().getCharacterSpacing() + (code == 32 ?
double shift = (graphicsState.getTextState().getCharacterSpacing() + (code == 32 ?
graphicsState.getTextState().getWordSpacing() : 0)) *
graphicsState.getTextState().getHorizontalScaling();
String value = graphicsState.getTextState().getTextFont().toUnicode(code);
width = width *
graphicsState.getTextState().getTextFontSize() / 1000 *
graphicsState.getTextState().getHorizontalScaling();
String value = graphicsState.getTextState().getTextFont().toUnicode(code);
if (symbolEnds != null) {
if (symbolEnds.isEmpty()) {
TextChunksHelper.updateSymbolEnds(symbolEnds, shift, 0, value != null ? value.length() : 0);
TextChunksHelper.updateSymbolEnds(symbolEnds, shift + width, 0, value != null ? value.length() : 0);
} else {
TextChunksHelper.updateSymbolEnds(symbolEnds, shift, symbolEnds.get(symbolEnds.size() - 1),
TextChunksHelper.updateSymbolEnds(symbolEnds, shift + width, symbolEnds.get(symbolEnds.size() - 1),
value != null ? value.length() : 0);
}
}
Expand All @@ -892,7 +891,8 @@ private void parseString(COSString string, StringBuilder unicodeValue, TextPiece
unicodeValue.append(result);
} else {
textPieces.add(new TextPieces.TextPiece(result, textPieces.getCurrentX(),
textPieces.getCurrentX() + shift));
textPieces.getCurrentX() + width));
textPieces.shiftCurrentX(shift);
}
}
} catch (IOException e) {
Expand Down
24 changes: 24 additions & 0 deletions wcag-validation/src/main/java/org/verapdf/gf/model/factory/chunks/TextPieces.java
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,26 @@ public List<Double> getSymbolEnds() {
return ends;
}

public void addSpaces(double threshold) {
List<TextPiece> spaces = new ArrayList<>();
Iterator<TextPiece> validation = textPieces.iterator();
if (!validation.hasNext()) {
return;
}
TextPiece prev = validation.next();
double previousEnd = prev.getEndX();

while (validation.hasNext()) {
TextPiece piece = validation.next();
double currentStart = piece.getStartX();
if (currentStart - previousEnd > threshold) {
spaces.add(new TextPieces.TextPiece(" ", previousEnd, currentStart));
}
previousEnd = piece.getEndX();
}
textPieces.addAll(spaces);
}

public static class TextPiece {
private final String value;
private final double startX;
Expand All @@ -91,6 +111,10 @@ public TextPiece(String value, double startX, double endX) {
public double getEndX() {
return endX;
}

public double getStartX() {
return startX;
}
}

public static class TextPieceComparator implements Comparator<TextPiece> {
Expand Down