I have application which has MainWindow that is divided in three main parts:
Thing is, all three parts need to communicate between themselves. For example, there is a QListView in left section where you select items, and depending on the selected item options change in the right section.
I have come up with three solutions:
draw everything within the MainWindow which would make MainWindow one big superclass:
This solution solves all problems with communication between widgets because all of them are part of MainWindow::ui but then I get one big (potentially messy) class.
put each section in it's own class and make MainWindow a singleton:
This solution is... well a singleton. And I don't really like singletons. I will have access to MainWindow from everywhere (essentially I am creating a global variable) and I would still have to expose MainWindow::ui (and ::uis of other sections) via getter which would mean that everything will have access to ::uis.
put each section in it's own class and connect everything via signals and slots:
This would probably be the best solution but with this solution I need to create getter for each widget from EachSection::ui (to be able to connect it in MainWindow with it's counterparts), I would need a lot of calls to connect() and I also have a problem if two slots react to same signal but they need to react in specific order.
So what would be the best approach?
The best approach would be to define messaging (protocol) between views, so that views is not tightly coupled (all views isolated and dont know about each other) one instance class (main window) know all three and connects them. Imagine a button line edit and label, when you press button label gets value of line edit, button implementation does not depend on lineedit implementation, lineedit does not depend on label and so on, all three classes can be extended or changed and it doesnot affect two other, so you can focus on one of them at the time.
Related
I have 2 custom widgets inheriting from QGLWidget and I aim to show the same scene from 2 different views using these widgets. For this I share the first widget with the second widget. However this requires a custom constructor than the compiled UI file provides.
Such as
// The line I mention from Compiled UI file
widget_2 = new SideGlWidget(widget);
// What I actually want this line to be
widget_2 = new SideGlWidget(widget, MainScreen);
Some suggests to set such additional parameters later using an init function. Then how do I set shareWidget member of QGLWidget?
here is the contructor of SideGlWidget
SideGlWidget::SideGlWidget(QWidget *parent,QGLWidget * shareWidget)
: QGLWidget(parent,shareWidget)
{
}
Any comments and edits are welcome.
When dealing with Qt widgets generated through a UI file, you can't change how the constructor of your custom widget is called.
You have two options then :
Make a default second parameter to the SideGlWidget
Add a init( sharedWidget) method to your widget and call it after setupUi() (most likely in your main window's constructor). You can thus pass your parameter to the side widget before it is shown.
This forum post explains it in detail.
Looking at your problem at a higher level, I would suggest using some kind of shared object that holds common data to the two widgets and use either inheritance or composition instead of defining one widget to use another.
Here is the official and latest solution to this problem from http://doc.qt.io/qt-5/qopenglwidget.html:
When multiple QOpenGLWidgets are added as children to the same
top-level widget, their contexts will share with each other. This does
not apply for QOpenGLWidget instances that belong to different
windows.
Therefore by inheriting from QOpenglWidget instead of QGlWidget you dont have to deal with context sharing at all. Beware that updategl function is replaced with update function.
I have two QSlider-s/QSpinBox-es. Got those working but not sure about the best way of adding the two together to output the total.
Here is a picture of what I got:
You need to connect signals form the sliders and spinboxes to slots in your main widget (or some other QObject derived class). Doing this allows your main widget to be informed whenever they are changed, do the addition, and output the result where you want. Check out some of the tutorials included with Qt for more info.
In our application, we have a variable number of dockwidgets because some of them are added by plugins that are loaded at runtime. Not all dockwidgets need to be visible at the same time necessarily. This depends strongly on what the user is working on and what plugins are active.
However, if too many dockwidgets are added programmatically with addDockWidget(...), they start to overlap each other (not in terms of tabs, but in terms of content of one being painted on the area of a different one, which obviously looks broken).
The user can move the dockwidgets to dockareas that still have space left, but the layout/main window successfully prevents (untabbed) re-addition to the "crowded" dockarea.
We do allow tabbed docks to allow the user to arrange the dockwidgets a required, but we don't want to enable QMainWindow::ForceTabbedDocks since this would constrain the number of simultaneously visible dockwidgets too much (one per dock area).
How can I prevent this or better control how dockwidgets are added?
Not answering your question directly but it might be worthwhile to actually forget about Qt and actually think of how the whole interaction should work. What are the user expectations? What should actually happen if 10 different plugins become active? Should they be docked or should they be floating or should they become pin-able docking windows with initial state as a small button on the MainWindow edges? I think once you do that ground work and come up with user interface mock-ups, you can then start looking at Qt and figure out if Qt provides a direct way to develop that interface and if not what additional components you will need to develop to get that interface working.
From my own experience, I had developed a similar interface long back but in MFC. The way we did it was that some of the docked windows were deemed to be must have and they would come up as docked. Then there were a set of windows that didnt need to be visible always but should be quickly available and their initial state was as hidden pin-able dock window which meant they came up as buttons on the MainWindow edge. Finally there was a third set that was not required by the user always and could be called in from File->View Menu. Once the user made it visible, the user typically would assign it to one of the first two groups or keep it afloat. This whole configuration was saved in a config file and from there onwards whenever the plugin was loaded/became active the last used state of the associated docking window was used. It though involved quite a bit of extra work but the end result was to the satisfaction of all users.
Have you tryed setDockOptions(QMainWindow::AllowNestedDocks)? I can't test it now but it may help.
By default, QMainWindow::dockOptions is set to AnimatedDocks | AllowTabbedDocks so you would want something like
setDockOptions(QMainWindow::AllowNestedDocks | QMainWindow::AnimatedDocks | QMainWindow::AllowTabbedDocks)
EDIT:
If you are having too many problems, you may be going about this the wrong way. Instead of using docks, you may want to try using QMdiArea with QMdiWindow. This may not work for your program, but its something to think about.
This is the solution I tried:
I created in QTCreator an empty project with a window, a minimalistic menu labelled "New Dock" and a DockWidget named dockWidget
This is the triggered() handler for my menu item:
void MainWindow::on_actionNew_Dock_triggered()
{
QDockWidget* w = new QDockWidget("Demo", ui->dockWidget);
this->addDockWidget(Qt::LeftDockWidgetArea,w);
this->tabifyDockWidget(ui->dockWidget,w);
}
tabifyDockWidget(QDockWidget* first, QDockWidget* second) is a QMainWindow method that stacks the second dockwidget upon the first one. Hope it helps...
I am creating a GUI to manipulate a robot arm. The location of the arm can be described by 6 floats (describing the positions of the various arm joints.
The interface consists of a QGraphicsView with a diagram of the arm (which can be clicked to change the arm position - adjusting the 6 floats). The interface also has 6 lineEdit boxes, to also adjust those values separately.
When the graphics view is clicked, and when the line edit boxes are changed, I'd like the line edit boxes / graphics view to stay in synchronisation.
This brings me to confusion about how to store the 6 floats, and trigger events when they're updated. My current idea is this:
The robot arm's location should be represented by a class, RobotArmLocation. Objects of this class then have methods such as obj.ShoulderRotation() and obj.SetShoulderRotation().
The MainWindow has a single instance of RobotArmLocation.
Next is the bit I'm more confused about, how to join everything up. I am thinking:
The MainWindow has a ArmLocationChanged slot. This is signalled whenever the location object is changed.
The diagram class will have a SetRobotArmLocation(RobotArmLocation &loc). When the diagram is changed, it's free to change the location object, and fire a signal to the ArmLocationChanged slot.
Likewise, changing any of the text boxes will fire a signal to that ArmLocationChanged slot. The slot then has code to synchronise all the elements.
This kind of seems like a mess to me, does anyone have any other suggestions? I've also thought of the following, does it have any merrit?
The RobotArmLocation class has a ValueChanged slot, the diagram and textboxes can use that directly, and bypass the MainWindow directly (seems cleaner?)
thanks for any wisdom!
Except for really simple cases (e.g. a label that shows the value of a slider) my experience has been to stay away from inter-component signal/slot connections inside Qt Designer. Rather, have the component firing the signal of interest connect to a slog defined in the top level QWidget class you're subclassing (i.e. QMainWidow, etc... let's just call it the Form class). You can also go the other way: if you have a custom signal in the Form class, you can connect it with Qt Designer to one of the public widget slots.
To be specific using your example:
I'm going to assume that you have subclassed QMainWindow and QGraphicsView. Let's call the subclasses RobotMainWindow and RobotView.
RobotMainWindow contains the QLineEdit fields and RobotView. The way you specify RobotView in Qt Designer is to insert a QWidget and use the Promote to... feature to tell Qt that the QWidget should be replaced at compile time with your custom RobotView.
Name the QLineEdit fields edit1, edit2...edit6.
In the Qt Designer signal/slot editor define slots in RobotMainWindow to be called when the value in a QLineEdit changes. There are some more elegant ways of doing this, but for simplicity let's say you define 6 slots named setValue1(float), setValue2(float), etc.
In the source code for RobotMainWindow, go declare and define these slots, such that they update your arm, shoulder, whatever.
Also in the source code, define a signal valueChanged() (or multiple for each field, your choice). Have the slots you defined emit valueChanged().
Back in Qt Designer you can now link the appropriate signal from each QLineEdit to the corresponding slot in RobotMainWindow.
Back in the signal/slot editor add the valueChanged() signal to the RobotMainWindow (so Qt Designer knows about it). Connect this signal to a new slot in RobotView, using the procedure above, so it can update the rendering.
Repeat all of this for handling changes from RobotView to the editing fields (via RobotMainWindow.
In short, I think you'll find everything more straight-forward if your route the signals through your Form subclass (which I think of as the Controller in MVC parlance).
I am currently writing a wizard-style application using Qt4. I am not using the wizard class however, since going next/back does not make sense from every step in the process.
The user starts off at a "hub"-window with five buttons, each of which take him to another window at a different stage of the process. At the beginning all but the first button of the hub are disabled. After clearing each stage, the user will be directed back to the hub and one new button/stage will get enabled.
Since every stage has significantly differing objectives, I coded every single stage as a single QWidget that gets instantiated in the main() function. To switch between the widgets, I simply hide() the one I am leaving and show() the one I am going to.
However, this leads to problems if the user resized or moved one widget, since the next widget will always show up at its default position instead of the new one.
Is there a way to synchronize the widgets' sizes and positions?
Or, better yet, is there a more elegant way to deal with those different windows than switching between several hidden widgets?
Thank you in advance!
Create one top-level widget that holds the others.
I suggest that you either use QStackedWidget, or, if you want more control, create your own widget and use QStackedLayout directly.
Why not just have one main QWidget as a container for your pages? That way if the user moves the main QWidget and then goes to the next page, it will still open in the new position inside the main widget.
Generally, I've never had occasion to create multiple widgets inside my main method. Don't quite see the point.
I'm beginning on something similar - with different views (perspectives) for different tasks along the way. Using toolbar icons and file menu, not buttons, to move between views. Similar to how MS Outlook allows you to have the window display email, or a calendar, or contacts, etc.
My intent (haven't started yet) is to have one QMainWindow as the application window, containing my various QWidgets that offer the various views. Depending on what task the user is doing, one composite widget will be visible, and the others hidden.