<Swing Dev> How to resolve image tearing

[Walter Laan]

> We didn't change JComponent.repaint() to make it "no longer thread
safe"
> and I don't see why someone may think about it

The bug report https://netbeans.org/bugzilla/show_bug.cgi?id=192548
shows the stack:
-
With the latest changes to jdk7 and jdk6 update 22 it's no longer true
due to
repaint()'s call to getLocationOnScreen() which acquires AWT tree lock:

java.awt.Component.getLocationOnScreen(Component.java:1995)
javax.swing.SwingUtilities.convertPointToScreen(SwingUtilities.java:380)
javax.swing.SwingUtilities.convertPoint(SwingUtilities.java:182)
javax.swing.SwingUtilities.convertRectangle(SwingUtilities.java:219)
javax.swing.RepaintManager.addDirtyRegion(RepaintManager.java:455)
javax.swing.JComponent.repaint(JComponent.java:4791)
java.awt.Component.repaint(Component.java:3264)

This causes deadlocks. Even in JDK's code itself - the
JEditorPane.PageLoader
may get deadlocked in the same way.
-

I see that code path in the JDK7-ea but not in 6u23 or 6u25 (I don't
have 6u22 installed). Neither version of JComponent#repaint() are
documented to be thread-safe though, although this blog
http://weblogs.java.net/blog/kschaefe/archive/2011/01/19/repaintmanager-
and-dirty-reads says so based on
http://java.sun.com/products/jfc/tsc/articles/threads/threads1.html

HTH,
Walter.