Implement option to embed fonts (#45)

* pass around 'embedFonts` and pre-cache charmap

* fix wrong width with some fonts

* font embedding

* Remove demo/test_embedding_size.nim from version control

* `drawTextAsPaths` if not embed

* feat: implement font embedding modes and improve text selectability

- Add FontRenderMode enum with frmDefault, frmEmbed, and frmPathRendering options
- Implement full font embedding with proper Unicode mapping for text extraction
- Fix ToUnicode CMap generation to use correct GID mapping based on render mode
- Update font subsetting logic to handle different rendering modes
- Improve character-to-glyph mapping for embedded vs subset fonts
- Add renderMode parameter to font creation and management functions

* add `frmDefault` example

* add `demo/embed_fonts.pdf`

---------

Co-authored-by: bung87 <crc32@qq.com>

Author: ThomasTJdev

demo/embed_fonts.nim

@@ -0,0 +1,80 @@
+import streams, nimPDF, unittest
+
+proc draw_title(doc: PDF, text: string) =
+  let size = getSizeFromName("A4")
+
+  # Use Helvetica (Base14) for title to avoid affecting KaiTi embedding status
+  doc.setFont("Helvetica", {FS_BOLD}, 12, ENC_STANDARD)
+  let tw = doc.getTextWidth(text)
+  let x = size.width.toMM / 2 - tw / 2
+
+  doc.setFillColor(0, 0, 0)
+  doc.drawText(x, 10.0, text)
+  doc.setStrokeColor(0, 0, 0)
+  doc.drawRect(10, 15, size.width.toMM - 20, size.height.toMM - 25)
+  doc.stroke()
+
+proc createPDF(doc: PDF) =
+  let size = getSizeFromName("A4")
+  let SAMP_TEXT = "The Quick Brown Fox Jump Over The Lazy Dog"
+
+  doc.addPage(size, PGO_PORTRAIT)
+  draw_title(doc, "FONT RENDERING MODES DEMO")
+
+  # Example 1: Font with renderMode=frmEmbed
+  doc.setFillColor(0, 0, 0)  # Set black color for text
+  doc.setFont("Calligrapher", {FS_REGULAR}, 10, ENC_STANDARD, renderMode = frmEmbed)
+  doc.drawText(15, 30, "Calligrapher - renderMode=frmEmbed")
+
+  # Example 2: Korean text with Eunjin font (embedded)
+  doc.setFillColor(0, 0, 0)  # Set black color for text
+  doc.setFont("Eunjin", {FS_REGULAR}, 10, ENC_UTF8, renderMode = frmEmbed)
+  doc.drawText(15, 60, "은진 - 한국어 테스트 (embedded)")
+
+  # Example 3: Path rendering (text drawn as vector paths)
+  doc.setFillColor(0, 0, 0)  # Set black color for text
+  doc.setFont("KaiTi",  {FS_REGULAR}, 10,  enc = ENC_UTF8, renderMode = frmPathRendering)
+  doc.drawText(15, 90, "你好世界 (text drawn as vector paths)")
+
+  # Example 4: Base14 font (embedding flag ignored)
+  doc.setFillColor(0, 0, 0)  # Set black color for text
+  doc.setFont("Times", {FS_REGULAR}, 10, ENC_STANDARD, renderMode = frmEmbed)
+  doc.drawText(15, 120, "Times (Base14 ignores flag)")
+
+  # Example 5: FreeMono with renderMode=frmDefault
+  doc.setFillColor(0, 0, 0)  # Set black color for text
+  doc.setFont("FreeMono", {FS_REGULAR}, 10, ENC_UTF8, renderMode = frmDefault)
+  doc.drawText(15, 150, "FreeMono - The Quick Brown Fox Jump Over The Lazy Dog")
+  
+
+  doc.setInfo(DI_TITLE, "Font Rendering Modes Demo")
+  doc.setInfo(DI_AUTHOR, "Andri Lim")
+  doc.setInfo(DI_SUBJECT, "Demonstrating three font rendering modes: frmDefault, frmEmbed, frmPathRendering")
+
+proc main(): bool {.discardable.} =
+  #echo currentSourcePath()
+  var fileName = "embed_fonts.pdf"
+  var file = newFileStream(fileName, fmWrite)
+
+  if file != nil:
+    var opts = newPDFOptions()
+    opts.addFontsPath("fonts")
+
+    echo "Creating PDF with font rendering modes demonstration..."
+    echo "- frmDefault: No embedding, standard text rendering"
+    echo "- frmEmbed: Text rendering with font embedding"
+    echo "- frmPathRendering: Text drawn as vector paths (not selectable)"
+    echo "- Check text copying/pasting to verify different behaviors"
+
+    var doc = newPDF(opts)
+    doc.createPDF()
+    doc.writePDF(file)
+    file.close()
+    echo "PDF created successfully: ", fileName
+    echo "Try copying text from different lines to see embedding effects"
+    return true
+
+  echo "cannot open: ", fileName
+  result = false
+
+main()

demo/embed_fonts.pdf

@@ -1,8 +1,4 @@
-import
-  std/[streams, strutils],
-  nimPDF,
-  unittest
-
+import streams, nimPDF, unittest, strutils
 proc draw_title(doc: PDF, text:string) =
   let size = getSizeFromName("A4")
 
@@ -46,48 +42,48 @@ proc test(doc: PDF) =
     var tw = doc.getTextWidth(text)
     var th = doc.getTextHeight(text)
     check:
-      tw.formatFloat(ffDecimal, 2) == "11.39"
-      th.formatFloat(ffDecimal, 2) == "3.59"
+      $tw == "11.39"
+      $th == "3.59"
 
   test "getTextWidth and GetTextHeight TTF":
     doc.setFont("FreeMono", {FS_REGULAR}, 5)
     var tw = doc.getTextWidth(text)
     var th = doc.getTextHeight(text)
     check:
-      tw.formatFloat(ffDecimal, 2) == "15.00"
-      th.formatFloat(ffDecimal, 2) == "3.02"
+      $tw.formatFloat(ffDecimal, 2) == "15.00"
+      $th.formatFloat(ffDecimal, 2) == "3.02"
 
   test "getVTextWidth and GetVTextHeight base14":
     doc.setFont("Helvetica", {FS_REGULAR}, 5)
     var tw = doc.getVTextWidth(text)
     var th = doc.getVTextHeight(text)
     check:
-      tw.formatFloat(ffDecimal, 2) == "3.61"
-      th.formatFloat(ffDecimal, 2) == "14.05"
+      $tw.formatFloat(ffDecimal, 2) == "3.61"
+      $th.formatFloat(ffDecimal, 2) == "14.05"
 
   test "getTextWidth and GetTextHeight TTF":
     doc.setFont("FreeMono", {FS_REGULAR}, 5)
     var tw = doc.getVTextWidth(text)
     var th = doc.getVTextHeight(text)
     check:
-      tw.formatFloat(ffDecimal, 2) == "3.00"
-      th.formatFloat(ffDecimal, 3) == "13.325"
+      $tw.formatFloat(ffDecimal, 2) == "3.00"
+      $th.formatFloat(ffDecimal, 3) == "13.325"
 
-proc main() =
+proc main(): bool {.discardable.} =
+  #echo currentSourcePath()
   var fileName = "test.pdf"
   var file = newFileStream(fileName, fmWrite)
 
   if file != nil:
-    var opts = newPDFOptions()
-    opts.addFontsPath("fonts")
-    var doc = newPDF(opts)
+    var doc = newPDF()
     doc.createPDF()
     doc.writePDF(file)
     doc.test()
     file.close()
     echo "OK"
-    return
+    return true
 
   echo "cannot open: ", fileName
+  result = false
 
 main()

demo/test.nim

@@ -9,4 +9,5 @@ import
   link_annot,
   pagelabels,
   test,
-  text_annot
+  text_annot,
+  embed_fonts