Fix XLSX Indic script rendering (#87)

shps951023 · shps951023 · commit 51e265550711 · 2026-07-23T10:01:05.000+08:00
diff --git a/src/MiniPdf/ExcelToPdfConverter.cs b/src/MiniPdf/ExcelToPdfConverter.cs
@@ -1,3 +1,7 @@
+using System.Drawing;
+using System.Drawing.Drawing2D;
+using System.Drawing.Imaging;
+using System.Drawing.Text;
 using System.Globalization;
 
 namespace MiniSoftware;
@@ -1525,7 +1529,7 @@ float RenderPrintTitleRows()
                                 var tw = (float)MeasureHelveticaWidth(titleCellLines[i][lineIdx], cellFs, bold: titleIsBold);
                                 textX = titleContentX + (titleContentWidth - tw) / 2f;
                             }
-                            currentPage!.AddText(titleCellLines[i][lineIdx], textX, cellY, cellFs, cell?.Color,
+                            AddExcelText(currentPage!, titleCellLines[i][lineIdx], textX, cellY, cellFs, cell?.Color,
                                 maxWidth: lineMaxWidth,
                                 bold: titleIsBold,
                                 underline: cell?.Underline ?? false,
@@ -1945,7 +1949,7 @@ float RenderPrintTitleRows()
                                     var tw = (float)MeasureHelveticaWidth(lines[lineIdx], options.FontSize, bold: mpIsBold);
                                     textX = mpContentX + (mpContentWidth - tw) / 2f;
                                 }
-                                currentPage!.AddText(lines[lineIdx], textX, cellY, options.FontSize, color,
+                                AddExcelText(currentPage!, lines[lineIdx], textX, cellY, options.FontSize, color,
                                     bold: mpIsBold,
                                     underline: cell?.Underline ?? false,
                                     strikethrough: cell?.Strikethrough ?? false,
@@ -2176,7 +2180,7 @@ float RenderPrintTitleRows()
                             // overlap with the normal text.
                             var boldWidth = (float)MeasureFontWidth(boldPart, cellFontSize, bold: true, cell?.FontName);
 
-                            currentPage!.AddText(boldPart, textX, cellY, cellFontSize, color,
+                            AddExcelText(currentPage!, boldPart, textX, cellY, cellFontSize, color,
                                 maxWidth: boldWidth,
                                 bold: true,
                                 underline: cell?.Underline ?? false,
@@ -2187,7 +2191,7 @@ float RenderPrintTitleRows()
                             {
                                 var normalX = textX + boldWidth + spaceGap;
                                 var normalMax = lineMaxWidth > 0 ? lineMaxWidth - boldWidth - spaceGap : 0f;
-                                currentPage!.AddText(normalPart, normalX, cellY, cellFontSize, color,
+                                AddExcelText(currentPage!, normalPart, normalX, cellY, cellFontSize, color,
                                     maxWidth: normalMax > 0 ? normalMax : 0f,
                                     bold: false,
                                     underline: cell?.Underline ?? false,
@@ -2198,7 +2202,7 @@ float RenderPrintTitleRows()
                         }
                         else
                         {
-                            currentPage!.AddText(lines[lineIdx], textX, cellY, cellFontSize, color,
+                            AddExcelText(currentPage!, lines[lineIdx], textX, cellY, cellFontSize, color,
                                 maxWidth: lineMaxWidth,
                                 bold: isBold,
                                 underline: cell?.Underline ?? false,
@@ -3693,6 +3697,121 @@ private static string[] WrapCellText(string text, float widthPts, float fontSize
         return lines.ToArray();
     }
 
+    private static void AddExcelText(PdfPage page, string text, float x, float y, float fontSize, PdfColor? color = null, (float, float, float, float)? clipRect = null, float? maxWidth = null, bool bold = false, bool italic = false, bool underline = false, float charSpacing = 0, float wordSpacing = 0, string? preferredFontName = null, float? underlineWidth = null, bool strikethrough = false)
+    {
+        if (!ContainsIndicText(text) || !TryRenderComplexScriptText(text, fontSize, color ?? PdfColor.Black, bold, italic, preferredFontName, maxWidth, out var png, out var widthPt, out var heightPt, out var baselineFromBottomPt))
+        {
+            page.AddText(text, x, y, fontSize, color, clipRect, maxWidth, bold, italic, underline, charSpacing, wordSpacing, preferredFontName, underlineWidth, strikethrough);
+            return;
+        }
+
+        var imageY = y - baselineFromBottomPt;
+        page.AddImage(png, "png", x, imageY, widthPt, heightPt);
+        page.AddText(text, x, y, fontSize, color, clipRect, maxWidth, bold, italic, underline: false, charSpacing, wordSpacing, preferredFontName, underlineWidth: null, strikethrough: false, hidden: true);
+    }
+
+    private static bool ContainsIndicText(string text)
+    {
+        foreach (var ch in text)
+        {
+            if (ch is >= '\u0900' and <= '\u0D7F')
+                return true;
+        }
+        return false;
+    }
+
+    private static bool TryRenderComplexScriptText(string text, float fontSize, PdfColor pdfColor, bool bold, bool italic, string? preferredFontName, float? maxWidth, out byte[] png, out float widthPt, out float heightPt, out float baselineFromBottomPt)
+    {
+        png = [];
+        widthPt = 0;
+        heightPt = 0;
+        baselineFromBottomPt = 0;
+
+        try
+        {
+            const float dpiScale = 3f;
+            var fontStyle = (bold ? FontStyle.Bold : FontStyle.Regular) | (italic ? FontStyle.Italic : FontStyle.Regular);
+            using var font = CreateComplexScriptFont(preferredFontName, fontSize, fontStyle);
+            using var probe = new Bitmap(1, 1, PixelFormat.Format32bppArgb);
+            probe.SetResolution(72f * dpiScale, 72f * dpiScale);
+            using var probeGraphics = Graphics.FromImage(probe);
+            probeGraphics.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;
+            var format = StringFormat.GenericTypographic;
+            format.FormatFlags |= StringFormatFlags.MeasureTrailingSpaces | StringFormatFlags.NoClip;
+            var measured = probeGraphics.MeasureString(text, font, int.MaxValue, format);
+
+            var naturalWidthPt = Math.Max(1f, measured.Width / dpiScale);
+            widthPt = Math.Max(1f, Math.Min(maxWidth ?? naturalWidthPt, naturalWidthPt));
+
+            var family = font.FontFamily;
+            var em = family.GetEmHeight(font.Style);
+            var ascent = family.GetCellAscent(font.Style);
+            var lineSpacing = family.GetLineSpacing(font.Style);
+            var baselineFromTopPt = fontSize * ascent / em;
+            heightPt = Math.Max(fontSize * 1.35f, fontSize * lineSpacing / em);
+            baselineFromBottomPt = Math.Max(0.1f, heightPt - baselineFromTopPt);
+
+            var widthPx = Math.Max(1, (int)Math.Ceiling(widthPt * dpiScale));
+            var heightPx = Math.Max(1, (int)Math.Ceiling(heightPt * dpiScale));
+            using var bmp = new Bitmap(widthPx, heightPx, PixelFormat.Format32bppArgb);
+            bmp.SetResolution(72f * dpiScale, 72f * dpiScale);
+            using (var graphics = Graphics.FromImage(bmp))
+            {
+                graphics.Clear(System.Drawing.Color.Transparent);
+                graphics.SmoothingMode = SmoothingMode.AntiAlias;
+                graphics.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;
+                graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
+                using var brush = new SolidBrush(ToDrawingColor(pdfColor));
+                graphics.SetClip(new RectangleF(0, 0, widthPx, heightPx));
+                graphics.DrawString(text, font, brush, 0, 0, format);
+            }
+
+            using var ms = new MemoryStream();
+            bmp.Save(ms, ImageFormat.Png);
+            png = ms.ToArray();
+            return png.Length > 0;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    private static Font CreateComplexScriptFont(string? preferredFontName, float fontSize, FontStyle style)
+    {
+        foreach (var name in ComplexScriptFontCandidates(preferredFontName))
+        {
+            try
+            {
+                if (FontFamily.Families.Any(f => string.Equals(f.Name, name, StringComparison.OrdinalIgnoreCase)))
+                    return new Font(name, fontSize, style, GraphicsUnit.Point);
+            }
+            catch
+            {
+            }
+        }
+
+        return new Font(FontFamily.GenericSansSerif, fontSize, style, GraphicsUnit.Point);
+    }
+
+    private static IEnumerable<string> ComplexScriptFontCandidates(string? preferredFontName)
+    {
+        if (!string.IsNullOrWhiteSpace(preferredFontName))
+            yield return preferredFontName!;
+        yield return "Nirmala UI";
+        yield return "Mangal";
+        yield return "Latha";
+        yield return "Vrinda";
+        yield return "Gautami";
+        yield return "Shruti";
+    }
+
+    private static System.Drawing.Color ToDrawingColor(PdfColor color)
+    {
+        static int Component(float value) => Math.Max(0, Math.Min(255, (int)Math.Round(value * 255f)));
+        return System.Drawing.Color.FromArgb(255, Component(color.R), Component(color.G), Component(color.B));
+    }
+
     /// <summary>
     /// Checks if a sheet name is a generic default like Sheet1, Sheet2, etc.
     /// </summary>
diff --git a/src/MiniPdf/PdfPage.cs b/src/MiniPdf/PdfPage.cs
@@ -160,10 +160,11 @@ internal PdfPage(float width, float height)
     /// <param name="preferredFontName">Optional preferred Unicode font family hint.</param>
     /// <param name="underlineWidth">Optional explicit underline width override in points.</param>
     /// <param name="strikethrough">Whether to draw a line through the text.</param>
+    /// <param name="hidden">Whether to keep text extractable without visibly painting it.</param>
     /// <returns>The current page for chaining.</returns>
-    public PdfPage AddText(string text, float x, float y, float fontSize = 12, PdfColor? color = null, (float, float, float, float)? clipRect = null, float? maxWidth = null, bool bold = false, bool italic = false, bool underline = false, float charSpacing = 0, float wordSpacing = 0, string? preferredFontName = null, float? underlineWidth = null, bool strikethrough = false)
+    public PdfPage AddText(string text, float x, float y, float fontSize = 12, PdfColor? color = null, (float, float, float, float)? clipRect = null, float? maxWidth = null, bool bold = false, bool italic = false, bool underline = false, float charSpacing = 0, float wordSpacing = 0, string? preferredFontName = null, float? underlineWidth = null, bool strikethrough = false, bool hidden = false)
     {
-        _textBlocks.Add(new PdfTextBlock(text, x, y, fontSize, color, clipRect, maxWidth, bold, italic, underline, charSpacing, wordSpacing, preferredFontName, underlineWidth, strikethrough));
+        _textBlocks.Add(new PdfTextBlock(text, x, y, fontSize, color, clipRect, maxWidth, bold, italic, underline, charSpacing, wordSpacing, preferredFontName, underlineWidth, strikethrough, hidden));
         return this;
     }
 
diff --git a/src/MiniPdf/PdfTextBlock.cs b/src/MiniPdf/PdfTextBlock.cs
@@ -67,6 +67,11 @@ internal sealed class PdfTextBlock
     /// </summary>
     public bool Strikethrough { get; }
 
+    /// <summary>
+    /// Whether to keep this text for extraction without painting visible glyphs.
+    /// </summary>
+    public bool Hidden { get; }
+
     /// <summary>
     /// Character spacing in points (PDF Tc operator). 0 means default.
     /// </summary>
@@ -91,7 +96,7 @@ internal sealed class PdfTextBlock
     /// </summary>
     public float? UnderlineWidth { get; }
 
-    internal PdfTextBlock(string text, float x, float y, float fontSize, PdfColor? color = null, (float, float, float, float)? clipRect = null, float? maxWidth = null, bool bold = false, bool italic = false, bool underline = false, float charSpacing = 0, float wordSpacing = 0, string? preferredFontName = null, float? underlineWidth = null, bool strikethrough = false)
+    internal PdfTextBlock(string text, float x, float y, float fontSize, PdfColor? color = null, (float, float, float, float)? clipRect = null, float? maxWidth = null, bool bold = false, bool italic = false, bool underline = false, float charSpacing = 0, float wordSpacing = 0, string? preferredFontName = null, float? underlineWidth = null, bool strikethrough = false, bool hidden = false)
     {
         Text = text;
         X = x;
@@ -108,5 +113,6 @@ internal PdfTextBlock(string text, float x, float y, float fontSize, PdfColor? c
         WordSpacing = wordSpacing;
         PreferredFontName = preferredFontName;
         UnderlineWidth = underlineWidth;
+        Hidden = hidden;
     }
 }
diff --git a/src/MiniPdf/PdfWriter.cs b/src/MiniPdf/PdfWriter.cs
@@ -1044,6 +1044,8 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict
                 sb.Append("BT\n");
                 sb.Append(colorCmd);
                 sb.Append($"/{fontName} {fontSize} Tf\n");
+                if (block.Hidden)
+                    sb.Append("3 Tr\n");
                 // For justified text, the caller's wordSpacing was derived from a
                 // wrap-time width estimate. Recompute it using the actual measured
                 // natural width so the rendered line fills (not exceeds) MaxWidth.
@@ -1097,6 +1099,8 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict
                 }
                 sb.Append($"{x} {y} Td\n");
                 sb.Append($"({escapedText}) Tj\n");
+                if (block.Hidden)
+                    sb.Append("0 Tr\n");
                 sb.Append("ET\n");
             }
             else
@@ -1123,6 +1127,8 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict
                     sb.Append("\n");
                     sb.Append("2 Tr\n");               // rendering mode: fill + stroke
                 }
+                if (block.Hidden)
+                    sb.Append("3 Tr\n");
                 // Determine the block's preferred font slot for font-aware
                 // width computation and Tz scaling.
                 var blockPrefSlot = -1;
@@ -1318,7 +1324,7 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict
                     }
                 }
 
-                if (block.Bold)
+                if (block.Bold || block.Hidden)
                     sb.Append("0 Tr\n"); // reset rendering mode
                 sb.Append("ET\n");
             }
@@ -1328,7 +1334,7 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict
                 sb.Append("Q\n");
 
             // Render underline as a line below the text
-            if (block.Underline)
+            if (!block.Hidden && block.Underline)
             {
                 var textWidth = block.UnderlineWidth ?? MeasureTextWidth(block.Text, block.FontSize, block.CharSpacing, bold: block.Bold);
                 if (!block.UnderlineWidth.HasValue && block.MaxWidth.HasValue && textWidth > block.MaxWidth.Value)
@@ -1346,7 +1352,7 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict
                 sb.Append($"{x1} {y1} m {x2} {y1} l S\n");
             }
 
-            if (block.Strikethrough)
+            if (!block.Hidden && block.Strikethrough)
             {
                 var textWidth = MeasureTextWidth(block.Text, block.FontSize, block.CharSpacing, bold: block.Bold);
                 if (block.MaxWidth.HasValue && textWidth > block.MaxWidth.Value)
diff --git a/tests/MiniPdf.Benchmark/reports/comparison_report.json b/tests/MiniPdf.Benchmark/reports/comparison_report.json
@@ -10058,7 +10058,7 @@
     "name": "classic164_indic_scripts",
     "minipdf_exists": true,
     "reference_exists": true,
-    "minipdf_size": 71613,
+    "minipdf_size": 77409,
     "reference_size": 53352,
     "pdf_valid": true,
     "minipdf_pages": 1,
@@ -10068,36 +10068,17 @@
     "word_text_similarity": 1.0,
     "text_diff": "(identical)",
     "visual_scores": [
-      0.9903
+      0.9947
     ],
-    "visual_avg": 0.9903,
+    "visual_avg": 0.9947,
     "diff_images": [
       {
         "page": 1,
         "minipdf_img": "classic164_indic_scripts_p1_minipdf.png",
-        "reference_img": "classic164_indic_scripts_p1_reference.png",
-        "heatmap_img": "classic164_indic_scripts_p1_heatmap.png",
-        "heatmap_metrics": {
-          "size_px": [
-            1241,
-            1650
-          ],
-          "difference_bbox_px": [
-            113,
-            147,
-            427,
-            335
-          ],
-          "changed_pixels": 10718,
-          "changed_fraction": 0.005234,
-          "mean_abs_rgb": 0.826,
-          "rmse_rgb": 12.8411,
-          "threshold": 12,
-          "gain": 5.0
-        }
+        "reference_img": "classic164_indic_scripts_p1_reference.png"
       }
     ],
-    "overall_score": 0.9961
+    "overall_score": 0.9979
   },
   {
     "name": "classic165_southeast_asian",
diff --git a/tests/MiniPdf.Benchmark/reports/comparison_report.md b/tests/MiniPdf.Benchmark/reports/comparison_report.md
@@ -1,6 +1,6 @@
 # MiniPdf vs Reference PDF Comparison Report
 
-Generated: 2026-07-19T19:49:12.102818
+Generated: 2026-07-23T09:55:09.574001
 
 ## Summary
 
@@ -169,7 +169,7 @@ Generated: 2026-07-19T19:49:12.102818
 | 161 | 🟢 classic161_box_drawing | ✅ | 0.9976 | 0.9867 | 1/1 | **0.9937** |
 | 162 | 🟢 classic162_cjk_emoji_styled | ✅ | 1.0 | 0.9872 | 1/1 | **0.9949** |
 | 163 | 🟢 classic163_cyrillic_alphabets | ✅ | 0.9519 | 0.9849 | 1/1 | **0.9747** |
-| 164 | 🟢 classic164_indic_scripts | ✅ | 1.0 | 0.9903 | 1/1 | **0.9961** |
+| 164 | 🟢 classic164_indic_scripts | ✅ | 1.0 | 0.9947 | 1/1 | **0.9979** |
 | 165 | 🟢 classic165_southeast_asian | ✅ | 0.9672 | 0.8185 | 1/1 | **0.9143** |
 | 166 | 🟢 classic166_emoji_progress | ✅ | 1.0 | 0.9761 | 1/1 | **0.9904** |
 | 167 | 🟢 classic167_musical_symbols | ✅ | 1.0 | 0.9843 | 1/1 | **0.9937** |
@@ -1561,11 +1561,6 @@ Blue areas are below the configured difference threshold; red areas have stronge
   <td><img src="images/classic163_cyrillic_alphabets_p1_heatmap.png" width="760" alt="classic163_cyrillic_alphabets page 1 difference heatmap"></td>
   <td>changed: 33058 px (1.61%)<br>bbox: [114, 147, 908, 336]<br>mean abs RGB: 2.3605<br>RMSE RGB: 21.0512<br>threshold: 12, gain: 5.0</td>
 </tr>
-<tr>
-  <td><b>classic164_indic_scripts</b><br>Page 1</td>
-  <td><img src="images/classic164_indic_scripts_p1_heatmap.png" width="760" alt="classic164_indic_scripts page 1 difference heatmap"></td>
-  <td>changed: 10718 px (0.52%)<br>bbox: [113, 147, 427, 335]<br>mean abs RGB: 0.826<br>RMSE RGB: 12.8411<br>threshold: 12, gain: 5.0</td>
-</tr>
 <tr>
   <td><b>classic165_southeast_asian</b><br>Page 1</td>
   <td><img src="images/classic165_southeast_asian_p1_heatmap.png" width="760" alt="classic165_southeast_asian page 1 difference heatmap"></td>
@@ -3520,7 +3515,7 @@ Blue areas are below the configured difference threshold; red areas have stronge
 </tr>
 <tr>
   <td><b>classic164_indic_scripts</b></td>
-  <td colspan="1">classic164_indic_scripts <span style="color:#3fb950">⬤</span> 99.6%</td>
+  <td colspan="1">classic164_indic_scripts <span style="color:#3fb950">⬤</span> 99.8%</td>
 </tr>
 <tr>
   <td><img src="images/classic164_indic_scripts_p1_minipdf.png" width="340" alt="MiniPdf"></td>
@@ -9230,10 +9225,10 @@ Text content: ✅ Identical
 ### classic164_indic_scripts
 
 - **Text Similarity:** 1.0
-- **Visual Average:** 0.9903
-- **Overall Score:** 0.9961
+- **Visual Average:** 0.9947
+- **Overall Score:** 0.9979
 - **Pages:** MiniPdf=1, Reference=1
-- **File Size:** MiniPdf=71613 bytes, Reference=53352 bytes
+- **File Size:** MiniPdf=77409 bytes, Reference=53352 bytes
 
 Text content: ✅ Identical
 
diff --git a/tests/MiniPdf.Benchmark/reports/images/classic164_indic_scripts_p1_heatmap.png b/tests/MiniPdf.Benchmark/reports/images/classic164_indic_scripts_p1_heatmap.png
diff --git a/tests/MiniPdf.Benchmark/reports/images/classic164_indic_scripts_p1_minipdf.png b/tests/MiniPdf.Benchmark/reports/images/classic164_indic_scripts_p1_minipdf.png

Original file line number	Diff line number	Diff line change
`@@ -160,10 +160,11 @@ internal PdfPage(float width, float height)`
`160`	`160`	`/// <param name="preferredFontName">Optional preferred Unicode font family hint.</param>`
`161`	`161`	`/// <param name="underlineWidth">Optional explicit underline width override in points.</param>`
`162`	`162`	`/// <param name="strikethrough">Whether to draw a line through the text.</param>`
	`163`	`+ /// <param name="hidden">Whether to keep text extractable without visibly painting it.</param>`
`163`	`164`	`/// <returns>The current page for chaining.</returns>`
`164`		`- public PdfPage AddText(string text, float x, float y, float fontSize = 12, PdfColor? color = null, (float, float, float, float)? clipRect = null, float? maxWidth = null, bool bold = false, bool italic = false, bool underline = false, float charSpacing = 0, float wordSpacing = 0, string? preferredFontName = null, float? underlineWidth = null, bool strikethrough = false)`
	`165`	`+ public PdfPage AddText(string text, float x, float y, float fontSize = 12, PdfColor? color = null, (float, float, float, float)? clipRect = null, float? maxWidth = null, bool bold = false, bool italic = false, bool underline = false, float charSpacing = 0, float wordSpacing = 0, string? preferredFontName = null, float? underlineWidth = null, bool strikethrough = false, bool hidden = false)`
`165`	`166`	`{`
`166`		`- _textBlocks.Add(new PdfTextBlock(text, x, y, fontSize, color, clipRect, maxWidth, bold, italic, underline, charSpacing, wordSpacing, preferredFontName, underlineWidth, strikethrough));`
	`167`	`+ _textBlocks.Add(new PdfTextBlock(text, x, y, fontSize, color, clipRect, maxWidth, bold, italic, underline, charSpacing, wordSpacing, preferredFontName, underlineWidth, strikethrough, hidden));`
`167`	`168`	`return this;`
`168`	`169`	`}`
`169`	`170`
Original file line number	Diff line number	Diff line change
`@@ -1044,6 +1044,8 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict`
`1044`	`1044`	`sb.Append("BT\n");`
`1045`	`1045`	`sb.Append(colorCmd);`
`1046`	`1046`	`sb.Append($"/{fontName} {fontSize} Tf\n");`
	`1047`	`+ if (block.Hidden)`
	`1048`	`+ sb.Append("3 Tr\n");`
`1047`	`1049`	`// For justified text, the caller's wordSpacing was derived from a`
`1048`	`1050`	`// wrap-time width estimate. Recompute it using the actual measured`
`1049`	`1051`	`// natural width so the rendered line fills (not exceeds) MaxWidth.`
`@@ -1097,6 +1099,8 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict`
`1097`	`1099`	`}`
`1098`	`1100`	`sb.Append($"{x} {y} Td\n");`
`1099`	`1101`	`sb.Append($"({escapedText}) Tj\n");`
	`1102`	`+ if (block.Hidden)`
	`1103`	`+ sb.Append("0 Tr\n");`
`1100`	`1104`	`sb.Append("ET\n");`
`1101`	`1105`	`}`
`1102`	`1106`	`else`
`@@ -1123,6 +1127,8 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict`
`1123`	`1127`	`sb.Append("\n");`
`1124`	`1128`	`sb.Append("2 Tr\n"); // rendering mode: fill + stroke`
`1125`	`1129`	`}`
	`1130`	`+ if (block.Hidden)`
	`1131`	`+ sb.Append("3 Tr\n");`
`1126`	`1132`	`// Determine the block's preferred font slot for font-aware`
`1127`	`1133`	`// width computation and Tz scaling.`
`1128`	`1134`	`var blockPrefSlot = -1;`
`@@ -1318,7 +1324,7 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict`
`1318`	`1324`	`}`
`1319`	`1325`	`}`
`1320`	`1326`
`1321`		`- if (block.Bold)`
	`1327`	`+ if (block.Bold \|\| block.Hidden)`
`1322`	`1328`	`sb.Append("0 Tr\n"); // reset rendering mode`
`1323`	`1329`	`sb.Append("ET\n");`
`1324`	`1330`	`}`
`@@ -1328,7 +1334,7 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict`
`1328`	`1334`	`sb.Append("Q\n");`
`1329`	`1335`
`1330`	`1336`	`// Render underline as a line below the text`
`1331`		`- if (block.Underline)`
	`1337`	`+ if (!block.Hidden && block.Underline)`
`1332`	`1338`	`{`
`1333`	`1339`	`var textWidth = block.UnderlineWidth ?? MeasureTextWidth(block.Text, block.FontSize, block.CharSpacing, bold: block.Bold);`
`1334`	`1340`	`if (!block.UnderlineWidth.HasValue && block.MaxWidth.HasValue && textWidth > block.MaxWidth.Value)`
`@@ -1346,7 +1352,7 @@ private static string BuildContentStream(PdfPage page, bool hasUnicodeFont, Dict`
`1346`	`1352`	`sb.Append($"{x1} {y1} m {x2} {y1} l S\n");`
`1347`	`1353`	`}`
`1348`	`1354`
`1349`		`- if (block.Strikethrough)`
	`1355`	`+ if (!block.Hidden && block.Strikethrough)`
`1350`	`1356`	`{`
`1351`	`1357`	`var textWidth = MeasureTextWidth(block.Text, block.FontSize, block.CharSpacing, bold: block.Bold);`
`1352`	`1358`	`if (block.MaxWidth.HasValue && textWidth > block.MaxWidth.Value)`