This optimizes PlainView to only paint the lines that are necessary, wrt
to the current clip and allocation. This makes JTextArea more snappy
with scrolling. I tested this by copy+pasting Component.java into a
JTextArea (which has around 7000 lines) and once it got around to parse
all the (which takes a while naturally) the actual scrolling/painting
is pretty damn fast. :-D
2006-08-13 Roman Kennke <[EMAIL PROTECTED]>
PR 28028
* javax/swing/text/PlainView.java
(paint): Limit painted area to the lines inside the clip
and allocation.
/Roman
Index: javax/swing/text/PlainView.java
===================================================================
RCS file: /cvsroot/classpath/classpath/javax/swing/text/PlainView.java,v
retrieving revision 1.46
diff -u -1 -2 -r1.46 PlainView.java
--- javax/swing/text/PlainView.java 11 Aug 2006 12:06:59 -0000 1.46
+++ javax/swing/text/PlainView.java 13 Aug 2006 15:15:48 -0000
@@ -271,37 +271,45 @@
selectedColor = textComponent.getSelectedTextColor();
unselectedColor = textComponent.getForeground();
disabledColor = textComponent.getDisabledTextColor();
selectionStart = textComponent.getSelectionStart();
selectionEnd = textComponent.getSelectionEnd();
Rectangle rect = s instanceof Rectangle ? (Rectangle) s : s.getBounds();
tabBase = rect.x;
// FIXME: Text may be scrolled.
Document document = textComponent.getDocument();
Element root = getElement();
- int y = rect.y + metrics.getAscent();
int height = metrics.getHeight();
// For layered highlighters we need to paint the layered highlights
// before painting any text.
LayeredHighlighter hl = null;
Highlighter h = textComponent.getHighlighter();
if (h instanceof LayeredHighlighter)
hl = (LayeredHighlighter) h;
int count = root.getElementCount();
- for (int i = 0; i < count; i++)
+ // Determine first and last line inside the clip.
+ Rectangle clip = g.getClipBounds();
+// SwingUtilities.computeIntersection(rect.x, rect.y, rect.width, rect.height,
+// clip);
+ int line0 = (clip.y - rect.y) / height;
+ line0 = Math.max(0, Math.min(line0, count - 1));
+ int line1 = (clip.y + clip.height - rect.y) / height;
+ line1 = Math.max(0, Math.min(line1, count - 1));
+ int y = rect.y + metrics.getAscent() + height * line0;
+ for (int i = line0; i <= line1; i++)
{
if (hl != null)
{
Element lineEl = root.getElement(i);
// Exclude the trailing newline from beeing highlighted.
if (i == count)
hl.paintLayeredHighlights(g, lineEl.getStartOffset(),
lineEl.getEndOffset(), s, textComponent,
this);
else
hl.paintLayeredHighlights(g, lineEl.getStartOffset(),
lineEl.getEndOffset() - 1, s,
