I am impatient enough not to like reading books or tutorials on the stuff i want to learn. That said, i almost always will get the toolchains ready and start firing code off with whatever crazy idea gets on my head.
Scala piqued my interest today and i inmediately setup IDEA with the Scala plugin to get started... now, i got some knowledge about the syntax and why Scala has that much amount of Awesome-Sauce, so i decided to test it out with another technology i didn't know: QT, especially QtJambi. I imported the QtJambi dist into the IDEA project structure and wrote this snippet:
import com.trolltech.qt.gui._
class MyMainWindow extends QWidget {
def showWindow = {
setWindowTitle("Scala Jambi Test")
resize(250, 250)
move(300, 300)
show()
}
}
object MainApp extends QWidget() {
def main(args: Array[String]) {
QApplication.initialize(args)
new MyMainWindow().showWindow
QApplication.exec
}
}
It compiles and runs but i get this on the console:
QWidget: Must construct a QApplication before a QPaintDevice
Any ideas on what i am doing wrong are appreciated.
I might add that the same code on a standard java project with the same libs does work.
The problem is that MainApp is extending QWidget, i removed the extension and the thing worked all out of the blue. If anyone knows why please comment, i'd love to know why that went wrong.
Related
In unity multiplayer the player prefab spawns after the scene loads, what is the best way to declare scripts that are needed and avoid the NullReferenceException error?
I'm not that familiar with multiplayer myself, but I believe this could be done through GameObject.Find("") and GetComponent.
I also stumbled across FindObjectOfType. I'm not sure if that's what you're looking for, but it doesn't hurt to post it. Good luck.
Instead of letting a script look for when the prefabs have spawned why not letting the prefabs tell the script it has spawned?
It's really hard to give any kind of example when the use-case is not specified.
Really basic example (and since you're going to use it for networking you might have to redo this a lot so you don't trust the client too much):
class ScriptA : Monobehaviour () {
List<GameObject> prefabs;
public void AddPrefab (GameObject Prefab) {
prefabs.Add (Prefab)
}
}
class Prefab : Monobehaviour () {
void Start () {
FindObjectOfType(ScriptA).AddPrefab(gameObject);
}
}
It's not the best example but the point is, you might need to rethink the architecture
I've been trying to start with a simple app that retrieves data from a simple HTML page upon clicking a button and stumbled upon a rather helpful tutorial on QT-Project and have been trying to implement it for my own project.
Everything manages to compile until I try to actually try to implement the loadImage function (as found in the tutorial). (I actually had to initialize m_pImgCtrl as Filedownloader * m_pImgCtrl = new FileDownloader(imageUrl, this); and I'm not exactly sure how it's suppose to work without prior object declaration?)
From what I get, m_pImgCtrl isn't actually defined in the loadImage() function since it is initialized outside of the function? Or does the connect() function do something that I'm not too aware of?
Thanks for the help!
The tutorial doesn't tell you the whole story.
The code in section Usage is supposed to be part of a class MainWindow – the controller of your main window (see line 1 of tutorial's last snippet). This class contains a slot loadImaged() called when the NetworkReply has finished. It also has a member FileDownloader * m_pImgCtrl.
For instance, the second Usage snippet could be part of a slot MainWindow::buttonClicked() like
void MainWindow::buttonClicked()
{
QUrl imageUrl("http://qt.digia.com/Documents/1/QtLogo.png");
m_pImgCtrl = new FileDownloader(imageUrl, this);
connect(m_pImgCtrl, SIGNAL(downloaded()), SLOT(loadImage()));
}
I am running FlexUnit tests through Ant. The test test1 fails with the message "Timeout Occurred before expected event" but test2 passes. The only difference between the two tests is that one uses UIImpersonator.addChild() whereas the other uses FlexGlobals.topLevelApplication.addElement().
test1 fails even if I listen for "addedToStage" event. Listening for "added" event, however, makes test1 pass.
[Test(async, ui, description="Fails")]
public function test1():void
{
var c:UIComponent = new UIComponent;
Async.proceedOnEvent(this, c, FlexEvent.CREATION_COMPLETE);
UIImpersonator.addChild(c);
}
[Test(async, ui, description="Passes")]
public function test2():void
{
var c:UIComponent = new UIComponent;
Async.proceedOnEvent(this, c, FlexEvent.CREATION_COMPLETE);
FlexGlobals.topLevelApplication.addElement(c);
}
when adding a child, it will not initiate the flex component lifecycle, because displayobject is flash core element, not flex.
assuming Flex4/spark. addChild adds a MovieClip, not a Flex UIElement, it doesn't even know FlexEvent type as it is a flash.core object. It will only throw addedToStage or added events (Event.added), but in unit test, it is not added to stage, because UIImpersonator is not part of the stage
I ran into this same issue today using the new Apache FlexUnit 4.2.0 release.
When trying to run the sampleCIProject included in the binary distribution, none of the tests that used Async would succeed. The exception was exactly as described above.
After looking at the source code for a while, I noticed that the core FlexUnit libraries have two flavours: flexunit-4.2.0-20140410-as3_4.12.0.swc and flexunit-4.2.0-20140410-flex_4.12.0.swc.
The first of these is intended for pure AS3 projects, while the latter is intended for projects that use Flex. The sampleCIProject included both of these libraries in the library path, and I'm assuming that it was using the UIImpersonator class from the pure AS3 library rather than the Flex-supporting one. I removed flexunit-4.2.0-20140410-as3_4.12.0.swc from the project, and lo and behold, the Async tests started working again.
Probably a bit late for you, but I hope this helps someone else.
I'm trying to prepare QML plugin to play video on embedded device in a way that other developers can use it without much hassle. However the way it is currently proposed requires almost always writing some C++ wrapper around your QML application. I'm refering to this example:
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/qt-gstreamer/html/examples_2qmlplayer_2main_8cpp-example.html
I would like to be able to have plugin and simply write:
import AwesomeVideoPlugin 1.0
Rect
{
AwesomeVideo
{
width: 320
height: 240
url: "./myvideo.avi"
// ... some minor stuff like mouse click handling, controls, etc.
}
}
Currently QtGStreamer requires to provide videoSurface property to VideoItem. The only way to do this is to create and set context for additional property in rootContext(). And to create GraphicsVideoSurface I need QGraphicsView (QDeclarativeView fills this role).
Is it possible to:
Get QDeclarativeView from within QDeclarativeItem (to which I have only access from QML plugin) in a way that it can be later used to feed GraphicsVideoSurface? My guess is no - however I've found path QFraphicsItem::scene() ==> QGraphScene ==> QGraphScene::views() ==> QList of QGraphicsView - it looks like VERY bad programming but maybe somebody got it to work (I'm getting segfault)
Is there other way to provide video sink for QtGStreamer from within QDeclarativeItem ?
Greetz
Yatsa
I had the same question, but haven't come up with an elegant solution.
However, one thought would be to make the videosurface available via an accessor function from a sub-classed QApplication object.
This would, of course, mean that your plug-in depends on the application subclass having a getVideoSurface method, but it does remove the ugliness from the QML code.
class MyApp : public QApplication
{
....
QGst::Ui::GraphicsVideoSurface *getVideoSurface() { return m_videosurface; }
}
...
int MyApp::init()
{
m_viewer = new QDeclarativeView();
m_viewer->setViewport(new QGLWidget(QGLFormat(QGL::SampleBuffers)));
m_videosurface = new QGst::Ui::GraphicsVideoSurface(m_viewer);
}
MyVideoPlugin::MyVideoPlugin(QDeclarativeItem *parent) : QDeclarativeItem(parent)
{
QGst::Ui::GraphicsVideoSurface *surface = ((MyApp*)qApp)->getVideoSurface();
}
...
Now the MyVideoPlugin element may be used without referencing an exported videosurface context item.
this generates a segmentation fault becuase of "QColor colorMap[9]";. If I remove colorMap the segmentation fault goes away. If I put it back. It comes back. If I do a clean all then build all, it goes away. If I increase its arraysize it comes back. On the other hand if I reduce it it doesnt come back. I tired adding this array to another project and
What could be happening. I am really curious to know. I have removed everything else in that class. This widget subclassed is used to promote a widget in a QMainWindow.
class LevelIndicator : public QWidget
{
public:
LevelIndicator(QWidget * parent);
void paintEvent(QPaintEvent * event );
float percent;
QColor colorMap[9];
int NUM_GRADS;
};
the error happens inside ui_mainwindow.h at one of these lines:
hpaFwdPwrLvl->setObjectName(QString::fromUtf8("hpaFwdPwrLvl"));
verticalLayout->addWidget(hpaFwdPwrLvl);
I know i am not providing much but I will give alink to the app. Im trying to see if anyone has a quick answer for this.
If I do a clean all then build all, it goes away.
This makes it sound as though your build system isn't recognizing a dependency and that a change to that class definition isn't triggering a rebuild of something that should be recompiled when the definition changes.
Make sure class LevelIndicator is defined in exactly one place (generally that would be a header file that gets included by whatever modules need to use a LevelIndicator object). Also make sure that any global/static instances of LevelIndicator objects are following the one definition rule.
Firstly it might not be QColor, that may simply be changing the memory layout enough that a buffer overrun somewhere else triggers a segfault - try a different size QColor ..[1] for example.
Can QColor be used as an array like this, does it have the correct default ctor?