[Qt-jambi-interest] Overriding itemChange() crashes the VM in 4.4.0_01
Hi,
this is probably related to
http://trolltech.com/developer/task-tracker/index_html?method=entryid=215908,
but I though I'd give additional information about this.
I have VertexItems (based on QGraphicsItem) and PolygonItems (based on
QGraphicsPolygonItem). PolygonItems should have VertexItems as children,
so when I move a polygon it's vertices would also move.
I'm setting up the PolygonItem from my own Polygon class like this:
public void setMyPolygon(Polygon poly) {
this.polygon = poly;
this.color = new QColor(poly.getColor().getRed(),
poly.getColor().getGreen(), poly.getColor().getBlue(),
poly.getColor().getAlpha());
setBrush(new QBrush(color));
setPen(VertexItem.blackPen);
// Create the Qt polygon
QPolygonF qPoly = new QPolygonF();
// Add the vertices
for (Vertex v : poly.getVertices()) {
qPoly.add(v.position.x, v.position.y);
// Add them as children VertexItems
VertexItem vItem = new VertexItem(v);
vItem.setParentItem(this); / --- CRASHES HERE!
}
setPolygon(qPoly);
}
The line vItem.setParentItem(this) causes the crash. That occurs only
when either VertexItem and/or PolygonItem have overridden itemChange().
Even when I just supply the default implementation, it will crash. For
example, on VertexItem:
@Override
public Object itemChange(GraphicsItemChange change, Object value) {
return super.itemChange(change, value);
}
So the bottom line is, itemChange() can be overridden when the items are
not in any kind of parent/child relationship.
Unfortunately, I cannot continue my project too far without this being
fixed. :( Hopefully you get it resolved for the next Qt Jambi update. Is
there any work arounds for this? I'd really need to know when the
Vertex/Polygon item positions change..
Anyways, thanks for the great work on Qt + Qt Jambi! :)
--
Mika
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Re: [Qt-jambi-interest] Jambi and JNI Integration
Adam Batkin wrote: Anyway, I've now set out to write my own JNI code to do what I want, instead of using the Jambi Generator. Everything was working nicely until trying to transfer a QImage from C++ to a Java/Jambi QImage. Back in February, Gunnar suggested stealing some logic from the generated Jambi code, in particular QPixmap::toImage(): jobject jimg = qtjambi_from_object(env, image, QImage, com/trolltech/qt/gui/, true); This works -- almost. I get back a valid Java QImage object (System.err.println(image) prints something like [EMAIL PROTECTED]) but when I try to do anything with it (like call image.width()), the JVM crashes. Hi, Adam. Has Qt Jambi been properly initialized at this point? I.e. you need to initialize each of the libraries you use before they can be used, otherwise Qt Jambi won't know e.g. that it has to copy the QImage into a new object before linking it into a Java object, and you will get a Java object with a pointer into the stack. The initialization of Qt Jambi libraries is done the first time a class from the library is loaded by the virtual machine. In your case, I think you are calling the conversion code before loading any Jambi GUI classes. The conversion code itself will resolve and load the QImage class, thus initializing the GUI library, but unfortunately this is too late for the first conversion, and the first Java object you retrieve will contain a pointer to the object you allocated on stack. This is why you can fix the problem by manually loading the class using the resolveClass() call, or by calling another method which causes the library to be initialized. We can easily fix this particular problem by moving some code around, and I'll make a suggestion to do so. However, I'm not convinced that we'll be able to fix all related issues, so I recommend you initialize the library prior to using Qt Jambi. For instance, we don't support having Qt Jambi application that have not called QApplication.initialize() or QCoreApplication.initialize() (the former in your case.) If you call QApplication.initialize() in the beginning of your application, this should cause the GUI library to be initialized. -- Eskil ___ Qt-jambi-interest mailing list Qt-jambi-interest@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-jambi-interest
[Qt-jambi-interest] Using .jui files with custom widget needing personal library crashes Eclipse
Hi people, I developed my own library called dgl (pure java, no jambi here). Once this library packaged into a jar, I used it to develop my own jambi widget called Plotter. Until then all is working fine. The first problem arise when I want to include this widget into the jambi designer integrated in Eclipse. The plugin refuse to load as long as the Plotter constructor included a dgl object. To workaround this, I create an empty constructor and also create other functions to manage dgl objects. OK, then I can see my newly created Qt designer plugin in project properties panel. But at this point when I tried to open a .jui file, Eclipse crashes systematically. Here is the beginning of the error log : Exception in thread main java.lang.NoClassDefFoundError: org/lgmt/dgl/Curve at java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2427) at java.lang.Class.getDeclaredMethods(Class.java:1791) at com.trolltech.qt.internal.MetaObjectTools.buildMetaData(MetaObjectTools.java:405) at com.trolltech.qt.gui.QWidget.__qt_QWidget_QWidget_WindowFlags(Native Method) at com.trolltech.qt.gui.QWidget.init(QWidget.java:77) at com.trolltech.qt.gui.QWidget.init(QWidget.java:69) at org.lgmt.jasp.plotter.Plotter.init(Plotter.java:45) snip I precise that of course my dgl.jar file including not found Curve object is in libraries build path. So my question is : is there special requirements to make a qt designer plugin ? How to make a plugin that can deal with an external object ? How to modify my own library to avoid this crash ? Thanks for any help... jMax ___ Qt-jambi-interest mailing list Qt-jambi-interest@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-jambi-interest
Re: [Qt-jambi-interest] Jambi and JNI Integration
Initializing my QApplication first does in fact solve the problem. I'm not sure how I missed that (*smacks forehead*). Mostly because I was doing this in a 4-line test harness and not an actual program (which would of course have initialized QT since using QT Jambi is the whole point of this exercise!) You mentioned being able to move some code around to fix this particular issue but that wouldn't be a general fix; I would say that even better (if possible) would be to warn that you have to initialize QT first. I mention this because some classes do in fact print warnings if you try to use them without initializing QT first (for example when I was testing and I created an empty QPixmap, it yelled at me). In other words, what I did was wrong, but it would have been helpful to get a warning or something (since JVM crashes aren't the easiest things to debug) Anyway, thanks for the help! -Adam Batkin Eskil Abrahamsen Blomfeldt wrote: Adam Batkin wrote: Anyway, I've now set out to write my own JNI code to do what I want, instead of using the Jambi Generator. Everything was working nicely until trying to transfer a QImage from C++ to a Java/Jambi QImage. Back in February, Gunnar suggested stealing some logic from the generated Jambi code, in particular QPixmap::toImage(): jobject jimg = qtjambi_from_object(env, image, QImage, com/trolltech/qt/gui/, true); This works -- almost. I get back a valid Java QImage object (System.err.println(image) prints something like [EMAIL PROTECTED]) but when I try to do anything with it (like call image.width()), the JVM crashes. Hi, Adam. Has Qt Jambi been properly initialized at this point? I.e. you need to initialize each of the libraries you use before they can be used, otherwise Qt Jambi won't know e.g. that it has to copy the QImage into a new object before linking it into a Java object, and you will get a Java object with a pointer into the stack. The initialization of Qt Jambi libraries is done the first time a class from the library is loaded by the virtual machine. In your case, I think you are calling the conversion code before loading any Jambi GUI classes. The conversion code itself will resolve and load the QImage class, thus initializing the GUI library, but unfortunately this is too late for the first conversion, and the first Java object you retrieve will contain a pointer to the object you allocated on stack. This is why you can fix the problem by manually loading the class using the resolveClass() call, or by calling another method which causes the library to be initialized. We can easily fix this particular problem by moving some code around, and I'll make a suggestion to do so. However, I'm not convinced that we'll be able to fix all related issues, so I recommend you initialize the library prior to using Qt Jambi. For instance, we don't support having Qt Jambi application that have not called QApplication.initialize() or QCoreApplication.initialize() (the former in your case.) If you call QApplication.initialize() in the beginning of your application, this should cause the GUI library to be initialized. -- Eskil ___ Qt-jambi-interest mailing list Qt-jambi-interest@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-jambi-interest
[Qt-jambi-interest] [Bug] JUIC broken with ScrollArea
Hi
I found a bug in the JUIC. The problem is when you try to use a scroll
area in a form. The preview is ok, but when you exec the app with the
Ui file, the scroll area is empty. After a few research I encounter
the problem, look at this code:
/
** Form generated from reading ui file 'MainWindow.jui'
**
** Created: mi jul 9 00:24:23 2008
** by: Qt User Interface Compiler version 4.4.0
**
** WARNING! All changes made in this file will be lost when recompiling ui file!
/
import com.trolltech.qt.core.*;
import com.trolltech.qt.gui.*;
public class Ui_MainWindow
{
public QWidget centralwidget;
public QGridLayout gridLayout;
public QScrollArea scrollArea;
public QWidget scrollAreaWidgetContents;
public QPushButton pushButton;
public QMenuBar menubar;
public QStatusBar statusbar;
public Ui_MainWindow() { super(); }
public void setupUi(QMainWindow Ui_MainWindow)
{
Ui_MainWindow.setObjectName(Ui_MainWindow);
Ui_MainWindow.resize(new QSize(800,
600).expandedTo(Ui_MainWindow.minimumSizeHint()));
centralwidget = new QWidget(Ui_MainWindow);
centralwidget.setObjectName(centralwidget);
centralwidget.setGeometry(new QRect(0, 30, 800, 547));
gridLayout = new QGridLayout(centralwidget);
gridLayout.setObjectName(gridLayout);
scrollArea = new QScrollArea(centralwidget);
scrollArea.setObjectName(scrollArea);
scrollArea.setWidgetResizable(true);
scrollAreaWidgetContents = new QWidget();
scrollAreaWidgetContents.setObjectName(scrollAreaWidgetContents);
scrollAreaWidgetContents.setGeometry(new QRect(0, 0, 778, 525));
pushButton = new QPushButton(scrollAreaWidgetContents);
pushButton.setObjectName(pushButton);
pushButton.setGeometry(new QRect(200, 160, 75, 28));
pushButton.setFocusPolicy(com.trolltech.qt.core.Qt.FocusPolicy.StrongFocus);
gridLayout.addWidget(scrollArea, 0, 0, 1, 1);
Ui_MainWindow.setCentralWidget(centralwidget);
menubar = new QMenuBar(Ui_MainWindow);
menubar.setObjectName(menubar);
menubar.setGeometry(new QRect(0, 0, 800, 30));
Ui_MainWindow.setMenuBar(menubar);
statusbar = new QStatusBar(Ui_MainWindow);
statusbar.setObjectName(statusbar);
statusbar.setGeometry(new QRect(0, 577, 800, 23));
Ui_MainWindow.setStatusBar(statusbar);
retranslateUi(Ui_MainWindow);
Ui_MainWindow.connectSlotsByName();
} // setupUi
void retranslateUi(QMainWindow Ui_MainWindow)
{
Ui_MainWindow.setWindowTitle(com.trolltech.qt.core.QCoreApplication.translate(Ui_MainWindow,
MainWindow));
pushButton.setText(com.trolltech.qt.core.QCoreApplication.translate(Ui_MainWindow,
PushButton));
} // retranslateUi
}
The problem is that the scrollAreaWidgetContents is never set the
widget of scrollArea.
For now Im using this workaround in the MainWindow class:
/*main class*/
import com.trolltech.qt.gui.*;
public class MainWindow extends QMainWindow {
Ui_MainWindow ui = new Ui_MainWindow();
public static void main(String[] args) {
QApplication.initialize(args);
MainWindow testMainWindow = new MainWindow();
testMainWindow.ui.scrollArea.setWidget(testMainWindow.ui.scrollAreaWidgetContents);
testMainWindow.show();
QApplication.exec();
}
public MainWindow() {
ui.setupUi(this);
}
}
This problem is experiment in windows and linux using the lastest qt
eclipse integration and the lastest QT jambi (4.4.0).
Thanks for your good work.
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