Part of PIVOT-696: Add support for viewing tab characters in TextArea.

Already the TerraTextAreaSkin has a "tabWidth" style, and supports
Ctrl-Tab entering a "tab" which is a number of spaces up to the tab
width.

The previous change added conversion of tab to spaces in "setText".
This change extends that to "insertText", so that (in particular)
"paste" looks right too.


git-svn-id: https://svn.apache.org/repos/asf/pivot/trunk@1410555 13f79535-47bb-0310-9956-ffa450edef68

wtk/src/org/apache/pivot/wtk/TextArea.java

@@ -735,8 +735,8 @@ public void setText(Reader textReader) throws IOException {
                         throw new IllegalArgumentException("Text length is greater than maximum length.");
                     }
                     paragraph.append(' ');
-                    tabPosition++;
                 }
+                tabPosition += spaces;
             } else {
                 paragraph.append((char)c);
                 tabPosition++;
@@ -775,6 +775,8 @@ private void insertText(CharSequence text, int index, boolean addToEditHistory)
             Paragraph paragraph = paragraphs.get(paragraphIndex);
 
             int characterOffset = index - paragraph.offset;
+            int tabPosition = characterOffset;
+            int tabWidth = ((TextArea.Skin)getSkin()).getTabWidth();
 
             StringBuilder textBuilder = new StringBuilder();
 
@@ -793,11 +795,19 @@ private void insertText(CharSequence text, int index, boolean addToEditHistory)
                     paragraph.insertText(trailingCharacters, 0);
                     paragraphSequence.insert(paragraph, ++paragraphIndex);
                     characterOffset = 0;
+                    tabPosition = 0;
 
                     textBuilder = new StringBuilder();
+                } else if (c == '\t') {
+                    int spaces = tabWidth - (tabPosition % tabWidth);
+                    for (int j = 0; j < spaces; j++) {
+                        textBuilder.append(' ');
+                    }
+                    tabPosition += spaces;
                 } else {
                     // Append character
                     textBuilder.append(c);
+                    tabPosition++;
                 }
             }