Hi Sean,
Hi Pavel ,
I'm sorry I didn't make update for this bug for a long time, and
here is some
recent investigation. The scenario is as follows:
Suppose we are dragging "abcde" over TextField tf, which have "hello
dragging" as
its content. When we are dragging from start to end, there is a cursor
moving from
"h" to "g", which means the place to insert "abcde" if we drop it.
When we dragging "abcde" exit tf, there will be a dragExit event, the
tf needs to
restore its original status after we drag out. Eg. if its cursor is
between "h" and
"e" in "hello", which appears like "h|ello", when we are dragging over
it, it may like
"hello dr|agging", and when drag exit, it needs to be "h|ello" again.
So in dragExit handler, it calls
javax.swing.TransferHandler.cleanup(false), which
means only to restore the original state. cleanup calls
javax.swing.text.JTextComponent.setDropLocation to set the cursor to
original
position. And setDropLocation calls DefaultCaret.setDot
and DefaultCaret.moveDot
to set the state.
The problem is moveDot doesn't know this is just to restore the
original state,
it treats the invocation as an action to select something. And it
calls updateSystemSelection
which will call java.awt.datatransfer.Clipboard.setContent. And the
selected content
is changed from "abcde" to the original selected part of "hello
dragging", then
the drop operation finds it is not the string dragged and nothing is
dropped.
So I made a simple patch(attached) . It just check if the textField
owns focus
before updateSystemSelection, if it is not focused, it does not treat
the moveDot as
a selection action and does not call Clipboard.setContent. This works
on Linux,
however, DefaultCaret is shared by Linux and Windows while windows
doesn't have
this problem. So I don't think this is a correct patch, but it brings
my question.
I think it is strange for DefaultCaret to use setDot and moveDot to
restore
original state, especially moveDot will cause an updateSystemSelection
operation,
which makes moveDot much like an action from user instead of just
restoring state.
I'm not sure why it works well on windows, but I don't think it is
right to call
updateSystemSelection or it is not right to use setDot and moveDot to
restore
the original state. Is there any reason for that ?
Thanks for the patch! I believe you are right and we shouldn't update
system selection clipboard when the component doesn't have focus. I'd
like to modify your fix and move checking into the
DefaultCaret#updateSystemSelection method:
if (this.dot != this.mark && component != null && component.hasFocus()) {
We also must write regression tests for fixes if possible, so an
automatic test is needed as well. Could you please write a test for the fix?
> I'm not sure why it works well on windows,
That's because Windows doesn't have system selection clipboard...
> Is there any reason for that ?
No, that's a just bug...
Regards, Pavel
2011/6/6 Pavel Porvatov <[email protected]
<mailto:[email protected]>>
Hi Sean,
Hi,
I reported, but the system doesn't reply me a bug number. It says
"will give me email",
but I haven't got one yet. Is this the right process, or I might
make a problem when
reporting?
I don't know why the system didn't report bug ID, but your bug was
filed successfully. You can find it here:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7049024
Regards, Pavel
2011/5/27 Pavel Porvatov <[email protected]
<mailto:[email protected]>>
Hi Sean,
Hi all,
I have a testcase related to DnD failure with JTextArea
and JTextField on linux. The
testcase is as follows:
/*
* DnDTest.java
*/
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JTextArea;
import javax.swing.JTextField;
public class DnDTest extends Frame {
Component c;
public DnDTest() {
super("Single Frame --- AWT Frame");
super.setBackground(Color.gray);
// set layout here.
setLayout(new FlowLayout());
c = new JTextArea("JTextArea component");
c.setPreferredSize(new Dimension(400, 100));
add(c);
c = new JTextField("JTextField component(No IM)");
c.setPreferredSize(new Dimension(400, 20));
add(c);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent event) {
System.exit(0);
}
});
setSize(850, 360);
setVisible(true);
}
public static void main(String[] args) {
new DnDTest();
}
}
Reproduce steps:
1. Run the testcase with b143
2. Open a new file with gedit and input some words like "abcde"
3. Drag "abcde" into JTextField and drop it there.
4. Once more, drag "abcde" into JTextField and then move out
of the Frame (keep draging) and drag into JTextField again
and drop it.
Expectation:
The second DnD inputs another "abcde" into JTextField.
Result:
The second DnD inputs nothing into JTextField.
Yes, looks like a bug. The test case works on Windows as
expected.
Investigation:
The JTextArea as well has this problem, and in step 4, if we
drag "abcde" over JTextField and then drop into JTextArea,
nothing
is input into JTextArea either. However, if "abcde" is drag
into JTextField or JTextArea directly or when
JTextArea/Field are
empty as in step 2, it works.
Are there any comments? And can anyone file a bug for it
please ?
Anybody can file a bug, http://bugreport.sun.com/bugreport/
Regards, Pavel
--
Best Regards,
Sean Chou
--
Best Regards,
Sean Chou
