How do I pass QML events to C++ code? I want to manage these events by passing them to a VTK interactor.
In QML code:
// some shape
Rectangle {
signal signalEvent333
onYourEvent: {
signalEvent333();
}
And in C++ code:
auto* qqView = new QQuickView(); // don't forget to delete sometimes
qqView->setSource(QUrl(QStringLiteral("qrc:///res/qml/myQmlForm.qml"))); // if that qml form in the app resource
QQuickItem* root = qqView->rootObject();
connect((QObject*)root, SIGNAL(signalEvent333()), this, SLOT(onSignalEvent333()));
We assume we have onSignalEvent333 slot for 'this' object.
P.S. And this question should be marked Qt as well. And I don't know what VTK is.
Related
I have registered an action in the EditorPopupMenu (this is right click menu). I also have a bunch of components inside a ToolWindow (that I designed using the GUI Designer plugin) that I want to update the values of.
There have been some posts on the IntelliJ forums about this, and the typical answer seems to advice using the ToolWindow's ContentManager, and obtain the JPanel containing all your components. E.g. the following:
Project p = e.getProject();
ToolWindow toolWindow;
toolWindow = ToolWindowManager.getInstance(p).getToolWindow("My ToolWindow ID");
ContentManager contentManager = toolWindow.getContentManager();
JPanel jp = (JPanel) contentManager.getContent(0).getComponent();
This feels counterintuitive... Having to navigate inside JPanel's to find a bunch of components. What if I decided to put my components inside a different container? Suddenly the way I navigate to my components would break down.
Is it really the most practical way to constrain myself to the way my GUI is built? Can't I access these components in a different way?
I found a way to access my custom myToolWindow. This should help quite some people.
Make sure that your custom MyToolWindow extends the class SimpleToolWindowPanel.
In your custom myToolWindowFactory class, pass your custom MyToolWindow to ContentFactory.createContent() as the first argument. NOT one of the JPanel's inside MyToolWindow as is done in the ToolWindow examples given in the official IntelliJ documentation...
In your MyToolWindow constructor, call the method setContent(<YourJPanelContainingYourComponents>).
I found the answer by experimenting on example 5 from this link:
public JBTabbedTerminalWidget getTerminalWidget(ToolWindow window) {
window.show(null);
if (myTerminalWidget == null) {
JComponent parentPanel = window.getContentManager().getContents()[0].getComponent();
if (parentPanel instanceof SimpleToolWindowPanel) {
SimpleToolWindowPanel panel = (SimpleToolWindowPanel) parentPanel;
JPanel jPanel = (JPanel) panel.getComponents()[0];
myTerminalWidget = (JBTabbedTerminalWidget) jPanel.getComponents()[0];
} else {
NotificationUtils.infoNotification("Wait for Freeline to initialize");
}
}
return myTerminalWidget;
}
I run often into many problems which leads to refactoring my code...
That is why I want to ask for some recommendations.
The problems I'm running into are:
1) Providing data to XAML
Providing simple data to control value instead of using a value converter. For instance I have a color string like "#FF234243" which is stored in a class. The value for the string is provided by a web application so I can only specify it at runtime.
2) UI for every resolution
In the beginnings of my learning I got told that you can create a UI for every possible resolution, which is stupid.
So I've written a ValueConverter which I bind on an element and as ConverterParameter I give a value like '300' which gets calculated for every possible resolution... But this leads to code like this...
<TextBlock
Height={Binding Converter={StaticResource SizeValue}, ConverterParameter='300'}
/>
3) DependencyProperties vs. NotifyProperties(Properties which implement INotifyPropertyChanged) vs. Properties
I have written a control which takes a list of value and converts them into Buttons which are clickable in the UI. So I did it like this I created a variable which I set as DataContext for this specific Control and validate my data with DataContextChanged but my coworker mentioned that for this reason DependencyProperties where introduced. So I created a DependecyProperty which takes the list of items BUT when the property gets a value I have to render the buttons... So I would have to do something like
public List<string> Buttons
{
get { return (List<string>)GetValue(ButtonsProperty); }
set
{
SetValue(ButtonsProperty, value);
RenderButtons();
}
}
// Using a DependencyProperty as the backing store for Buttons. This enables animation, styling, binding, etc...
public static readonly DependencyProperty ButtonsProperty =
DependencyProperty.Register("Buttons", typeof(List<string>), typeof(MainPage), new PropertyMetadata(""));
private void RenderButtons()
{
ButtonBar.Children.Clear();
ButtonBar.ColumnDefinitions.Clear();
if(Buttons != null)
{
int added = 0;
foreach (var item in Buttons)
{
var cd = new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star) };
var btn = new Button() { Content = item };
ButtonBar.ColumnDefinitions.Add(cd);
ButtonBar.Children.Add(btn);
Grid.SetColumn(btn, added);
}
}
}
And have to use it like this:
<Controls:MyControl
x:Name="ButtonBar" Button="{Binding MyButtons}">
</Controls:MyControl>
Since these are a lot of topics I could seperate those but I think that this is a pretty common topic for beginners and I have not found a got explanation or anything else
1. Providing data to XAML
There are two options: prepare data in the ViewModel or to use converter.
To my mind using converter is better since you can have crossplatform viewModel with color like you mentioned in your example and converter will create platform dependent color. We had similar problem with image. On android it should be converted to Bitmap class, while on UWP it's converted to BitmapImage class. In the viewModel we have byte[].
2. UI for every resolution
You don't need to use converter, since Height is specified in effective pixels which will suit all the required resolutions automatically for you. More info can be found at the following link:
https://learn.microsoft.com/en-us/windows/uwp/design/layout/layouts-with-xaml
There are two options how to deal with textblock sizes:
a) Use predefined textblock styles and don't invent the wheel (which is the recommended option):
https://learn.microsoft.com/en-us/windows/uwp/design/style/typography#type-ramp
Or
b) Specify font size in pixels. They are not pixels, but effective pixels. They will be automatically scaled on different devices:
https://learn.microsoft.com/en-us/windows/uwp/design/style/typography#size-and-scaling
Furthermore, use adaptive layout to have different Layout for different screen sizes.
3) DependencyProperties vs. NotifyProperties(Properties which implement INotifyPropertyChanged) vs. Properties
As per your code you can try to use ListView or ItemsControl and define custom item template.
DependencyProperties are created in DependencyObject and are accessible in xaml. All controls are inherited from DependencyObjects. Usually you create them when you want to set them in xaml. They are not stored directly in the objects, but in the global dictionary and resolved at runtime.
DependencyProperties were created long time ago and you can find lots of links which explain them in details:
http://www.wpftutorial.net/dependencyproperties.html
https://techpunch.wordpress.com/2008/09/25/wpf-wf-what-is-a-dependency-property/
When should I use dependency properties in WPF?
What is a dependency property? What is its use?
What is a dependency property?
INotifyPropertyChanged INPC are the central part of MVVM. You bind your view to viewModel which implements INPC and when you change value of the property control is notified and rereads the new value.
Download the following video in high resolution which explains MVVM in details (by Laurent Bugnion):
https://channel9.msdn.com/Events/MIX/MIX11/OPN03
MVVM: Tutorial from start to finish?
Normal properties are used in model classes or when there is no need to notify UI regarding changes.
I don't know who is setting a width property in a Rectangle.
I'ts possible to know who is calling the width property?
For example:
Rectangle
{
onWidthChanged: console.log ("who is calling me: ", sender())
}
Find where the signal is emitted in C++ (git grep on a clone of Qt's source), set a breakpoint there, and then debug the application. In your case it's probably here:
http://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/quick/items/qquickitem.cpp#n3794
I am coding a program combining QML and C++. The TableView shows a column of a table. I can add or delete the record correctly, but I can not update the TableView, which always shows the content before adding or deleting.
How to update theTableView?
PS: I do not know whether it is good choice to code with QML and C++ instead of QWidget directly.
main()
{
//other code
......
MySqlModel *model = new MySqlModel;//class MySqlModel : public QSqlTableModel
model->QSqlQueryModel::setQuery("SELECT FieldName1 FROM Table");
QQmlApplicationEngine engine;
engine.rootContext()->setContextProperty ("SQQL", model);
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
//other code
......
}
In the qml:
TableView{
//other code
......
model: SQQL
//other code
......
}
QWidget-based has more default feature built-in, I would suggest you start from there.
how to enable edit
override flags function to enable edit on items, see
http://www.qtcentre.org/threads/38338-Can-t-edit-my-QTableView-cells
http://doc.qt.io/qt-4.8/qabstractitemview.html#EditTrigger-enum
how to sync changes back to db
you could manual commit the change per edit, or manually batch all changes in a db transaction, or you could just use sqltablemodel
http://doc.qt.io/qt-4.8/qsqltablemodel.html#EditStrategy-enum
However, if you need more flexible ui, or it is for a multi-touch device, you should go QML approach
make a qabstractview model
have qml view that bind to this qabstracttableview model. or using qt control tool kits
I'm newbie in using ogre3D and I need help on a certain point!
I'm trying a library mixing ogre3D engine and qtml :
http://advancingusability.wordpress.com/2013/08/14/qmlogre-is-now-a-library/
this library works fine when you want to draw some object and rotate or translate these objects already initialise in a first step.
void initialize(){
// we only want to initialize once
disconnect(this, &ExampleApp::beforeRendering, this, &ExampleApp::initializeOgre);
// start up Ogre
m_ogreEngine = new OgreEngine(this);
m_root = m_ogreEngine->startEngine();
m_ogreEngine->setupResources();
m_ogreEngine->activateOgreContext();
//draw a small cube
new DebugDrawer(m_sceneManager, 0.5f);
DrawCube(100,100,100);
DebugDrawer::getSingleton().build();
m_ogreEngine->doneOgreContext();
emit(ogreInitialized());
}
but If you want to draw or change the scene after this initialisation step it is problematic!
In fact in Ogre3D only (without the qtogre library), you have to use a frameListener
which will connect the rendering thread and allow a repaint of your scene.
But here, we have two ContextOpengl: one for qt and the other one for Ogre.
So If you try to put the common part of code :
createScene();
createFrameListener();
// La Boucle de rendu
m_root->startRendering();
//createScene();
while(true)
{
Ogre::WindowEventUtilities::messagePump();
if(pRenderWindow->isClosed())
std::cout<<"pRenderWindow close"<<std::endl;
if(!m_root->renderOneFrame())
std::cout<<"root renderOneFrame"<<std::endl;
}
the app will freeze! I know that startRendering is a render loop itself, so the loop below never gets executed.
But I don't know where to put those line or how to correct this part!
I've also try to add a background buffer and to swap them :
void OgreEngine::updateOgreContext()
{
glPopAttrib();
glPopClientAttrib();
m_qtContext->functions()->glUseProgram(0);
m_qtContext->doneCurrent();
delete m_qtContext;
m_BackgroundContext= QOpenGLContext::currentContext();
// create a new shared OpenGL context to be used exclusively by Ogre
m_BackgroundContext = new QOpenGLContext();
m_BackgroundContext->setFormat(m_quickWindow->requestedFormat());
m_BackgroundContext->setShareContext(m_qtContext);
m_BackgroundContext->create();
m_BackgroundContext->swapBuffers(m_quickWindow);
//m_ogreContext->makeCurrent(m_quickWindow);
}
but i've also the same error:
OGRE EXCEPTION(7:InternalErrorException): Cannot create GL vertex buffer in GLHardwareVertexBuffer::GLHardwareVertexBuffer at Bureau/bibliotheques/ogre_src_v1-8-1/RenderSystems/GL/src/OgreGLHardwareVertexBuffer.cpp (line 46)
I'm very stuck!
I don't know what to do?
Thanks!