I'm working on a music/MIDI editor using C++ and Qt.
The develop was smooth until I met an issue that QGraphicsView is rendering weirdly with its child widget's child widget.
(wow, that's confusing)
This is the code I used to add my sub widgets to a QGraphicsView
pianoPlain = new QawPianoPlain();
keyBoard = new QawPianoKeyBoard();
scene->addWidget(pianoPlain);
scene->addWidget(keyBoard);
keyBoard->setGeometry(0,0,100,540);
keyBoard->setKeyNum(36);
pianoPlain->setGeometry(100,0,500,540);
pianoPlain->setStriptNum(36);
The code makes something like this.
pianoRoll -> keyBoard -> key
...............|-> pianoPlaom -> noteStript
Where pianoPlain and keyBoard are classes I inherit from GraphicsView and key and noteStript are both inherit from QWidget.
Here is a picture of what happens:
https://drive.google.com/file/d/0BzYLJIsbhhuVZ0RMdzRqV01Cd2M/view?usp=sharing
And this is picture of a normal keyBoard which is placed directy in MainWindow(left) and a screwed up one placed in QGraphicsView(right)
(I have disable back/while key in this picture)
https://drive.google.com/file/d/0BzYLJIsbhhuVSDFhSXRVM0dHWnM/view?usp=sharing
It seems that whenever pianoPlain and keyBoard are placed in a QGtraphicsView, it will be screwed.
Anyone know what's happening? How can I fix this?
Qt : 5.4.1
OS : KUubutu 15.04 AMD64
Compiler : clang 3.6.0/ GCC 4.9.2
I would suggest pianoPlain and keyBoard should use a class that inherits QGraphicsItem - for example QGraphicsPixmapItem or QGraphicsProxyWidget.
You then would add these to the scene using your scene->addWidget() method.
The scene itself should then be part of a QGraphicsView.
For example:
QGraphicsView *view = new QGraphicsView();
QGraphicsScene* scene = new QGraphicsScene(view);
view->setScene(scene_);
// No need to parent these
pianoPlain = new QawPianoPlain();
keyBoard = new QawPianoKeyBoard();
// This will work if QawPianoPlain and QawPianoKeyBoard inherit QWidget
QGraphicsProxyWidget* pianoProxy = scene_->addWidget(pianoPlain);
QGraphicsProxyWidget* keyBoardProxy = scene_->addWidget(keyBoard );
Use the proxy widget for any transformations/animations.
Related
I'm trying to write a circuit designer software in QT on Linux. I'm using KDE 5 Plasma desktop and QTCreator as an IDE.
I tried to use QFrame paintEvent to paint on it, and it worked, but when im grabbed the window inside QFrame it moved.
I know about QGraphicsView, but i cant make a custom class and promote it based on that(it's not listed).
How can i create a custom class from a container(QFrame, QGraphicsView or anything) where i can override paint event and also it doesn't move window if i grab it?
Sorry for my poor english.
QGraphicsView inherits from QAbstractScrollArea which inherits from QFrame itself.
So you can keep the QFrame in the form, and keep it promoted to your canvas class, but simply make you canvas class inherit QGraphicsView instead.
Although, my Qt has two differences in behavior from the OP (but I don't use KDE):
Clicking on a QFrame and moving the mouse doesn't move the whole window for me. I guess this behavior for the OP could be changed by reimplementing void mousePressEvent ( QMouseEvent * event ) in the canvas class and giving it an empty code instead. (doc)
I can put QGraphicsView in my ui files, and I can right click on them to promote them to another custom-defined class.
Edit: Found the reason why the window moves on KDE!
My problem:
I want to customize the way the title bar works and looks for my application.
My idea:
I created a new QWidget form in Qt Designer and added a QWidget to it. I added the following code in constructor:
setAttribute(Qt::WA_TranslucentBackground);
setWindowFlags(Qt::FramelessWindowHint);
QGraphicsDropShadowEffect* effect = new QGraphicsDropShadowEffect();
effect->setBlurRadius(20);
effect->setXOffset(0);
effect->setYOffset(0);
setGraphicsEffect(effect);
which makes the outer widget transparent and adds shadow to my inner widget. From this on I can create a custom title bar widget which I can implement however I want.
This is the result:
My issue
I want to make this usable from the designer as a main window and the QWidget doesn't allow me to add FROM THE DESIGNER tool bars, menu bar and status bar.
What I thought about was adding a QMainWindow widget as a child widget for the outer QWidget(which is transparent and acts as support for my shadow(the shadow is drawn on it)). I did this successfully but only from code:
QMainWindow *centralwidget = new QMainWindow();
centralwidget->setStyleSheet("background-color: lightgray;");
centralwidget->setGeometry(0, 0, 50, 20);
centralwidget->setWindowFlags(Qt::Widget);
this->layout()->addWidget(centralwidget);
QMenuBar *menuBar = new QMenuBar(centralwidget);
menuBar->addAction("Action");
QStatusBar *statusBar = new QStatusBar;
statusBar->showMessage("Status bar here");
centralwidget->addToolBar("tool bar");
centralwidget->setMenuBar(menuBar);
centralwidget->setStatusBar(statusBar);
This is the result:
My question:
How can I achieve this result from Qt Designer? Is it possible to promote a QWidget to QMainWindow? I cannot think to another way of doing it... It is really important for me to make it usable from Qt Designer because I intend to make it a template widget and be able to create e.g. a new QCustomMainWindow form Qt Creator just like you can create a QWidget or a QMainWindow.
Please help!
Here is another SO question similar to yours: Qt4: Placing QMainWindow instance inside other QWidget/QMainWindow
Just adding on to my original comment:
Start with a QMainWindow, and then apply the appropriate flags to it. QMainWindow is a subclass of QWidget. If it can't be done easily in the designer, it is pretty painless to do in code. Do it in your constructor right after the ui->setup() call.
Start with QMainWindow
Customize Window Flags
So in the constructor in mainwindow.cpp, you put
http://qt-project.org/doc/qt-5/qt.html#WindowType-enum
this->setWindowFlags(Qt::Widget);
This is the default type for QWidget. Widgets of this type are child
widgets if they have a parent, and independent windows if they have no
parent. See also Qt::Window and Qt::SubWindow.
// or if you want to apply more than one you, "or" it together, like so:
this->setWindowFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint | Qt::Tool);
Try out a couple of those and see what you like.
Customize Widget Attributes
There are also Widget Attributes, that give you strong control over how your widgets look like and behave.
http://qt-project.org/doc/qt-5/qt.html#WidgetAttribute-enum
Qt Style Sheets
In addition to all the flags and attributes above, you can also modify a ton of it with stylesheets:
http://qt-project.org/doc/qt-5/stylesheet-reference.html
this->setStyleSheet("background: #000000;");
Qt Designer Custom Widgets
And also if you are interested in making this a reusable thing in Qt Designer, you can make it into a Qt Designer plugin, or custom widgets.
http://qt-project.org/doc/qt-4.8/designer-using-custom-widgets.html
http://qt-project.org/doc/qt-4.8/designer-creating-custom-widgets.html
QMdiArea and QMdiWindow
Another path to look into besides using QMainWindow is QMdiSubWindow
http://qt-project.org/doc/qt-5/QMdiSubWindow.html
I have a QMainWindow whose central widget has been set to a QGraphicsView viewing a black scene (for test purposes). Note that in the code below, I use my class derived from QGraphicsView, called CQtGlView, which reimplements only the resizeEvent function.
Regardless of whether I add the view directly,
CQtMainWindow::CQtMainWindow() {
m_glView = new CQtGlView();
setCentralWidget(m_glView);
}
or stick it in a layout with margins of 0 in a dummy widget,
CQtMainWindow::CQtMainWindow() {
m_glView = new CQtGlView();
QWidget* dummy = new QWidget();
QHBoxLayout* l = new QHBoxLayout();
l->setContentsMargins(0,0,0,0);
l->addWidget(m_glView);
dummy->setLayout(l);
setCentralWidget(dummy);
}
I get an unwanted grey border around the widget.
The screenshot below illustrates the problem, visible between my scene and the windows aero border.
This would not be a problem if my application did not allow switching to full screen. The border is very obvious once the rest of the screen is black.
It's possible this area represents the DockWidgetAreas around the outside of the central widget.
Is there anything I can do to solve this other than not use QMainWindow? (Undesirable due to my use of menuBar, tool bars, and statusBar.)
It turns out that QGraphicsView derives from QFrame, where I assumed it was only a QWidget.
The solution to this problem was to call setFrameStyle(QFrame::NoFrame); in the constructor of my QGraphicsView subclass. Or if it was not a subclass,
m_glView->setFrameStyle(QFrame::NoFrame);
Have you tried setFrameShape(QFrame::NoFrame) on the QGraphicsView?
I'm creating an application using Qt which consists of a widget that is used as the background of the application, and a user control interface that is floating above.
A similar example is google maps, where the map is on the background and the controls are on top of the background.
But the thing is that the background widget can be changed to a different widget (there's a widget that displays a map, another widget that displays video feed, ...)
And the same thing happens for the buttons in the user control interface, they are not directly related to the current background and can be change dinamically.
I've tried using a QStackedLayout, using two layers, the background widget and the user control interface. But you cannot interact with the background layer because all the clicks are blocked by the widget in the front.
Any suggestions?
You could place a filter on the event stream to your interface widgets using the QObject::installEventFilter() function, and intercept all the incoming mouse-click events. Once you have captured these events, use the filter function to delegate them to either the background widget, or deliver them to the front interface buttons. You would most likely have to use the (x,y) coordinates of the mouse-click to determine if an event should go to the background widget, or one of the foreground button widgets.
Another option is to create a derived class from QAbstractButton (or whatever QWidget you're using for your buttons), and re-implement the event functions for mouse-clicks on that widget (i.e., QAbstractButton::mousePressEvent(), etc.). When a mouse-click arrives, check to see if the mouse was over the button, and if it wasn't, send the event to the background widget via a signal or QCoreApplication::sendEvent().
Your question is too generic to give you a especific answer, but the most obvious solution is to implement classes that inherits from QWidget for each possible component of you system. In your example I can visualize 2 distinct components: Background and Controls. Background would store all the image data, like maps and videos, while the Controls would have the buttons to interact with the system. You can even break the Background into different classes to manage image or video. I recommend using a central GUIController class that inherits from QObject to manage all the interface interactions, like connecting the signals/slots or implementing any animations, this way you can add/manage multiple widgets without going trough different .cpp's.
EDIT: With your comment, seems that your main problem is that your mouse events are not propagating to your widgets as you expected. Probably the reason for this is that you are not setting the parent/children relationships between the components. Make sure that you are calling the default QWidget constructor in your custom widgets classes like above:
CustoWidget(QWidget *parent = 0, Qt::WFlags flags = 0) : QWidget(parent, flags)
{
//your code here
}
When creating the Controller class, sets the right relationships between the components. In the context of your system, seens to me that all components will be added as Background children, so it would looks like below:
class Controller : public QObject
{
public:
Controller(QObject *parent = 0, Qt::WFlags flags = 0) : QObject(parent, flags)
{
wdg_back_= new BackWidget(this);
wdg_control_ = new Controls(wdg_back);
wdg_1_ = new GenericWidget(wdg_back);
//connect your signals/slots, etc
}
private:
BackWidget *wdg_back_;
Controls *wdg_control_;
GenericWidget *wdg_1_;
}
Ok I've finally found a solution for my issue.
My approach of using QStackedWidget was wrong, widget on the background are not meant to be clickable, and even though it might be done, it's not what I was looking for.
In the end, this is what I've done:
QWidget *centralWidget = new QWidget(this);
setCentralWidget(centralWidget);
MapView *backgroundWidget = new MapView(centralWidget);
backgroundWidget->setMinimumSize(1024,600);
QGridLayout *controlsLayout = new QGridLayout(centralWidget);
MyControlWidget *control1 = new MyControlWidget(centralWidget);
control1->setMinimumSize(140,140);
control1->show();
controlsLayout->addWidget(control1,2,0);
So I create a QWidget, centralWidget which will be the parent of the background and the foreground. Set the background to full screen, and organize the controls in a QGridLayout, which doesn't affect the backgroundWidget.
If I click on a control, the event is processed by this control, but clicking on an empty space will trigger a mouse event on the backgroundWidget, which is what I needed.
I'll test this for some time and if it works fine I'll close the question.
In GTK, I used to have a window to which I gtk_container_add()'d a GtkVBox. Then I could pack widgets I wanted to the GtkVBox to have them appear in the window.
Now I've decided to try out Qt, but I can't seem to figure out how to do this in Qt.
Right now what I've done is create a QMainWindow, but I found that you can only pack one main widget into it, which is obviously quite limiting. So I wanted to create something like the GtkVBox and use that as the main widget and then add other widgets to this box.
What I've found by Googling are however only the Q3VBox widget, which seems to be what I want, but is deprecated, and the QVBoxLayout.
I tried to use the QVBoxLayout, but it tells me that I cannot change the layout of my QMainWindow since it already has a layout.
Edit: Here is how I do it (this is in the constructor):
box = new QVBoxLayout;
setLayout(box)
It compiles fine, but during runtime, it prints on the console:
QWidget::setLayout: Attempting to set QLayout "" on HCGWindow "", which already has a layout
(HCGWindow is my app's window, which is a subclass of QMainWindow)
So, how can I create something similar to a GtkVBox in Qt, and if the solution is the Q3VBox, why is it deprecated and what other thing should I use?
Thanks
In fact, here is the recommended solution provided by the Qt documentation.
You should create a QVBoxLayout and add the widgets you want in it. After that, you set the layout on another empty widget and then you set this widget as the central widget of the QMainWindow subclass. Here is an example in code:
QWidget* widget1 = new QWidget(); // This could be anything subclassing QWidget.
QWidget* widget2 = new QWidget();
QVBoxLayout* layout = new QVBoxLayout();
layout->addWidget(widget1);
layout->addWidget(widget2);
QWidget* central = new QWidget(); // Only a containing QWidget.
central->setLayout(layout);
this->setCentralWidget(central);
Now, you QMainWindow subclass should have the two QWidgets in it, arranged in a QVBoxLayout.
Note here that I did not give any parent to anyone. You could have done it, but when you call addWidget or setCentralWidget, the ownership of the widget (and the layout) is given to the containing class.
If you read a bit about Qt, you'll know that this allows the parent to destroy his children when he is about to be destroyed itself.
Finally, note that QMainWindow is an exception and, from what I know, is the only class with setCentralWidget as a method. If you attempt to create a QWidget subclass, you will be able to use setLayout (as shown in the example above).
Hope this helps.
Try to create QVBoxLayout instance, add your widgets to it and add (not replace) this layout to main window's layout.
Note, QLayout class has no member addLayout, but subclasses has one.
Firstly you must get and remember classname of main window's layout:
qDebug(this.layout()->objectName);
Then add your QVBoxLayout to window's layout:
dynamic_cast<YourWindowLayoutClass>(
this.layout())->addLayout(your_qvboxlayout_object);
I hope it will work.