Refactor TextRenderInfo#splitString using PdfFont#decodeIntoGlyphLine

Consider separately cases of one-to-one byte <-> character mapping and many bytes to one character.
Get rid of inconsistency of glyph widths in PdfType0Font#decodeIntoGlyphLine vs PdfType0Font#getContentWidth

DEVSIX-1058

Author: Snipx

kernel/src/main/java/com/itextpdf/kernel/font/PdfType0Font.java

@@ -528,24 +528,18 @@ public GlyphLine decodeIntoGlyphLine(PdfString content) {
             if (glyph != null && glyph.getChars() != null) {
                 glyphs.add(glyph);
             } else {
-                glyphs.add(new Glyph(0, -1));
+                glyphs.add(new Glyph(0, fontProgram.getGlyphByCode(0).getWidth(), -1));
             }
         }
         return new GlyphLine(glyphs);
     }
 
     @Override
     public float getContentWidth(PdfString content) {
-        Glyph notdef = fontProgram.getGlyphByCode(0);
         float width = 0;
         GlyphLine glyphLine = decodeIntoGlyphLine(content);
         for (int i = glyphLine.start; i < glyphLine.end; i++) {
-            Glyph glyph = glyphLine.get(i);
-            if (glyph.getCode() >= 0) {
-                width += glyph.getWidth();
-            } else {
-                width += notdef.getWidth();
-            }
+            width += glyphLine.get(i).getWidth();
         }
         return width;
     }

kernel/src/main/java/com/itextpdf/kernel/pdf/canvas/parser/data/TextRenderInfo.java

@@ -46,6 +46,7 @@ This file is part of the iText (R) project.
 import com.itextpdf.io.font.otf.GlyphLine;
 import com.itextpdf.kernel.colors.Color;
 import com.itextpdf.kernel.font.PdfFont;
+import com.itextpdf.kernel.font.PdfType0Font;
 import com.itextpdf.kernel.geom.LineSegment;
 import com.itextpdf.kernel.geom.Matrix;
 import com.itextpdf.kernel.geom.Vector;
@@ -546,24 +547,28 @@ private int getCharCode(String string) {
     /**
      * Split PDF string into array of single character PDF strings.
      *
-     * @param string PDF string to be splitted.
-     * @return splitted PDF string.
+     * @param string PDF string to be split.
+     * @return split PDF string.
      */
     private PdfString[] splitString(PdfString string) {
         checkGraphicsState();
-        List<PdfString> strings = new ArrayList<>();
-        String stringValue = string.getValue();
-        for (int i = 0; i < stringValue.length(); i++) {
-            PdfString newString = new PdfString(stringValue.substring(i, i + 1), string.getEncoding());
-
-            String text = gs.getFont().decode(newString);
-            if (text.length() == 0 && i < stringValue.length() - 1) {
-                newString = new PdfString(stringValue.substring(i, i + 2), string.getEncoding());
-                i++;
+        PdfFont font = gs.getFont();
+        if (font instanceof PdfType0Font) {
+            // Number of bytes forming one glyph can be arbitrary from [1; 4] range
+            List<PdfString> strings = new ArrayList<>();
+            GlyphLine glyphLine = gs.getFont().decodeIntoGlyphLine(string);
+            for (int i = glyphLine.start; i < glyphLine.end; i++) {
+                strings.add(new PdfString(gs.getFont().convertToBytes(glyphLine.get(i))));
             }
-            strings.add(newString);
+            return strings.toArray(new PdfString[strings.size()]);
+        } else {
+            // One byte corresponds to one character
+            PdfString[] strings = new PdfString[string.getValue().length()];
+            for (int i = 0; i < string.getValue().length(); i++) {
+                strings[i] = new PdfString(string.getValue().substring(i, i + 1), string.getEncoding());
+            }
+            return strings;
         }
-        return strings.toArray(new PdfString[strings.size()]);
     }
 
     private float[] getAscentDescent() {