TextLayout.getAdvance() for " " returns 0 in some cases / JDKs, which caused an div by 0 -> Infinity problem

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1873494 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/sl/draw/DrawTextParagraph.java

@@ -31,6 +31,7 @@ import java.text.AttributedCharacterIterator;
 import java.text.AttributedCharacterIterator.Attribute;
 import java.text.AttributedString;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
 
@@ -383,7 +384,14 @@ public class DrawTextParagraph implements Drawable {
 
     @Internal
     public String getRenderableText(final TextRun tr) {
-        final String txtSpace = tr.getRawText().replace("\t", tab2space(tr)).replace('\u000b', '\n');
+        String txtSpace = tr.getRawText();
+        if (txtSpace == null) {
+            return null;
+        }
+        if (txtSpace.contains("\t")) {
+            txtSpace = txtSpace.replace("\t", tab2space(tr));
+        }
+        txtSpace = txtSpace.replace('\u000b', '\n');
         final Locale loc = LocaleUtil.getUserLocale();
 
         switch (tr.getTextCap()) {
@@ -414,19 +422,23 @@ public class DrawTextParagraph implements Drawable {
         string.addAttribute(TextAttribute.SIZE, fs.floatValue());
 
         TextLayout l = new TextLayout(string.getIterator(), new FontRenderContext(null, true, true));
+        // some JDK versions return 0 here
         double wspace = l.getAdvance();
 
+        final int numSpaces;
         Double tabSz = paragraph.getDefaultTabSize();
+        if (wspace <= 0) {
+            numSpaces = 4;
+        } else {
             if (tabSz == null) {
                 tabSz = wspace*4;
             }
-
-        int numSpaces = (int)Math.ceil(tabSz / wspace);
-        StringBuilder buf = new StringBuilder();
-        for(int i = 0; i < numSpaces; i++) {
-            buf.append(' ');
+            numSpaces = (int)Math.min(Math.ceil(tabSz / wspace), 20);
         }
-        return buf.toString();
+
+        char[] buf = new char[numSpaces];
+        Arrays.fill(buf, ' ');
+        return new String(buf);
     }