On Roman's advice, I changed the 2 methods to use binary searching
rather than sequential searching. This is now committed.
2005-09-27 Anthony Balkissoon <[EMAIL PROTECTED]>
* javax/swing/text/Utilities.java:
(getRowEnd): New method.
(getRowStart): New method.
--Tony
On Mon, 2005-09-26 at 16:34 -0400, Anthony Balkissoon wrote:
> I implemented getRowStart and getRowEnd in javax.swing.text.Utilities.
> This is RFC because of the issue raised in the large comment in each of
> this methods (namely, performance). Some comments would be appreciated.
>
>
> 2005-09-26 Anthony Balkissoon <[EMAIL PROTECTED]>
>
> * javax/swing/text/Utilities.java:
> (getRowEnd): New method.
> (getRowStart): New method.
>
> --Tony
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> Classpath-patches mailing list
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Index: javax/swing/text/Utilities.java
===================================================================
RCS file: /cvsroot/classpath/classpath/javax/swing/text/Utilities.java,v
retrieving revision 1.11
diff -u -r1.11 Utilities.java
--- javax/swing/text/Utilities.java 22 Sep 2005 20:17:08 -0000 1.11
+++ javax/swing/text/Utilities.java 27 Sep 2005 16:39:55 -0000
@@ -394,4 +394,95 @@
wb.setText(text);
return wb.following(offs);
}
+
+ /**
+ * Get the model position of the end of the row that contains the
+ * specified model position. Return null if the given JTextComponent
+ * does not have a size.
+ * @param c the JTextComponent
+ * @param offs the model position
+ * @return the model position of the end of the row containing the given
+ * offset
+ * @throws BadLocationException if the offset is invalid
+ */
+ public static final int getRowEnd(JTextComponent c, int offs)
+ throws BadLocationException
+ {
+ Element root = c.getDocument().getDefaultRootElement();
+ Element rowElement = root.getElement(root.getElementIndex(offs));
+ String text = c.getText(rowElement.getStartOffset(),
+ rowElement.getEndOffset());
+ if (text == null)
+ return -1;
+
+ // Do a binary search for the smallest position X > offs
+ // such that that character at positino X is not on the same
+ // line as the character at position offs
+ int high = offs + ((text.length() - 1 - offs) / 2);
+ int low = offs;
+ int oldHigh = text.length();
+ while (true)
+ {
+ if (c.modelToView(high).y != c.modelToView(offs).y)
+ {
+ oldHigh = high;
+ high = low + ((high + 1 - low) / 2);
+ if (oldHigh == high)
+ return high - 1;
+ }
+ else
+ {
+ low = high;
+ high += ((oldHigh - high) / 2);
+ if (low == high)
+ return low;
+ }
+ }
+ }
+
+ /**
+ * Get the model position of the start of the row that contains the specified
+ * model position. Return null if the given JTextComponent does not have a
+ * size.
+ *
+ * @param c the JTextComponent
+ * @param offs the model position
+ * @return the model position of the start of the row containing the given
+ * offset
+ * @throws BadLocationException if the offset is invalid
+ */
+ public static final int getRowStart(JTextComponent c, int offs)
+ throws BadLocationException
+ {
+ Element root = c.getDocument().getDefaultRootElement();
+ Element rowElement = root.getElement(root.getElementIndex(offs));
+ String text = c.getText(rowElement.getStartOffset(),
+ rowElement.getEndOffset());
+ if (text == null)
+ return -1;
+
+ // Do a binary search for the greatest position X < offs
+ // such that the character at position X is not on the same
+ // row as the character at position offs
+ int high = offs;
+ int low = 0;
+ int oldLow = 0;
+ while (true)
+ {
+ if (c.modelToView(low).y != c.modelToView(offs).y)
+ {
+ oldLow = low;
+ low = high - ((high + 1 - low) / 2);
+ if (oldLow == low)
+ return low + 1;
+ }
+ else
+ {
+ high = low;
+ low -= ((low - oldLow) / 2);
+ if (low == high)
+ return low;
+ }
+ }
+ }
}
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