I've been stuck on this for a little while now, I'm trying to set the drag mode of my QGraphicsView to ScrollHandDrag so that I can build a panning feature on my application.
However whenever I try to set the drag mode Qt always complains that DragMode is an undeclared identifier.
I'm also aiming to build a crop functionality (I assume I'd be using rubber band dragging for that?), I'm just wondering why I can't set the drag mode on the View
void MainWindow::on_btnCrop_clicked()
{
cropping = true;
QApplication::setOverrideCursor(Qt::CrossCursor);
// Stuck with this...
ui->imageView->setDragMode(ScrollHandDrag);
}
^ I have tried multiple other workarounds but I've not yet found any solution, any suggestions would be greatly appreciated.
This is not QGraphicsView specific an issue, but generic C++. Your problem is located at this line:
ui->imageView->setDragMode(ScrollHandDrag);
The problem is that you assume that you have visibility to the ScrollHandDrag value, whereas it appears inside the QGraphicsView scope. Therefore, since you are trying to access that value in your MainWindow, you will need add the scope explicitly as follows:
ui->imageView->setDragMode(QGraphicsView::ScrollHandDrag);
Note that how even the documentation specifies the scope for this constant:
QGraphicsView::ScrollHandDrag 1 The cursor changes into a pointing hand, and dragging the mouse around will scroll the scrolbars. This mode works both in interactive and non-interactive mode.
Here is my minimal building code:
#include <QGraphicsView>
int main()
{
QGraphicsView graphicsView;
graphicsView.setDragMode(QGraphicsView::ScrollHandDrag);
return 0;
}
main.pro
TEMPLATE = app
TARGET = main
QT += widgets
SOURCES += main.cpp
Build and Run
qmake && make
Related
I would like to have a button that creates another window. I'm building off the template app you get in VS2019 Preview So far, I've created a new control BlankWindow, just the default one. I can see that in App::OnLaunched, a window is created with:
window = make<MainWindow>();
window.Activate();
So in my MainWindow.xaml.cs in my button click method, I put:
Window bWindow= make<BlankWindow>();
bWindow.Activate();
That doesn't build, I check the BlankWindow.idl file and see that BlankWindow inherits from Controls and not Windows, so I change it. Now it builds, but when I click the button in the MainWindow, I see the window flicker open and instantly close. What's going on?
Work on multi-window applications is ongoing. It's available as a Preview feature.
https://learn.microsoft.com/en-us/windows/apps/winui/winui3/#preview-features
You can find the solution to this problem in the definition of the Window Class for the Windows UI Library (WinUI) under the subtitle "Create a new Window on a new thread". To put the section in context it would help to read the entire webpage. It's not that long.
We were able to include xaml.h for the target subwindow and display the window using the make template function.
Note that the types held in the member variables and the types specified to the make template function are different.
(I am using the translation at DeepL, so the text may be slightly incorrect.)
#include "pch.h"
#include "MainWindow.xaml.h"
#if __has_include("MainWindow.g.cpp")
#include "MainWindow.g.cpp"
#include "Window_Sub.xaml.h"
#endif
winrt::App1::Window_Sub _subWindow{ nullptr };
void MainWindow::ShowSubWindowButton_Clicked(winrt::Windows::Foundation::IInspectable const& sender, winrt::Microsoft::UI::Xaml::RoutedEventArgs const& e)
{
if (_subWindow == nullptr) {
_subWindow = make<App1::implementation::Window_Sub>();
_subWindow.Closed([](winrt::Windows::Foundation::IInspectable const& sender, winrt::Microsoft::UI::Xaml::WindowEventArgs const& e){
_subWindow = nullptr;
});
}
_subWindow.Activate();
}
I'm trying to use QFileDialog as a widget, to use QFileDialog as a widget the final step for my is to disable the cancel button.
Have you an idea of how can i disable this button.
PS : I am using Qt 5.5.0
You should be able to access the various standard buttons via the QDialogButtonBox and, from there, do what you want with the Cancel button.
The following example code appears to works as expected...
QFileDialog fd;
/*
* Find the QDialogButtonBox.
*/
if (auto *button_box = fd.findChild<QDialogButtonBox *>()) {
/*
* Now find the `Cancel' button...
*/
if (auto *cancel_button = button_box->button(QDialogButtonBox::Cancel)) {
/*
* ...and remove it (or disable it if you prefer).
*/
button_box->removeButton(cancel_button);
}
}
fd.show();
The QFileDialog Class doesn't seem to have any option for this.
However, you could make your own file browser using QTreeModel and QTreeView (It's not too difficult).
There is a tutorial on how to do just that here.
It would take a while to type out all the code (sorry, I'm a slow typer), but this tutorial should allow you to have the flexibility you need to do what you want to do.
I understand that this answer isn't exactly what you asked, but I hope it is a good alternative.
EDIT: Accidentally pasted wrong link for QFileDialog Class
Coming from making single-page applications with the visual WYSISWYG editor in JUCE, I'm having a bit of trouble figuring out how to invoke new windows (outside of the main GUI window). I made a test application that just has a small minimal main GUI that I created with the visual editor. It has a button "Make New Window." My goal is to be able to click that button and have a new window pop up and that this new window is a JUCE "GUI component," (AKA, the graphical / visual GUI editor file). Now, I actually have sort of achieved this, however, its throwing errors and assertions, so it would be great to get a very simple, step-by-step tutorial.
I studied the main.cpp file that the Projucer automatically created in order to get a feel for how they are creating a window. Here's what I did.
1) In my project, I added a new GUI Component (which becomes a class) and called it "InvokedWindow."
2) In my main GUI component class header, I added a new scoped pointer of type InvokedWindow: ScopedPointer<InvokedWindow> invokedWindow;
3) I created a new button in the main GUI editor called "Make New Window" and added this to the handler code:
newWindowPtr = new InvokedWindow; so that any time the button is hit, a new object of type InvokedWindow is created.
4) In the InvokedWindow class, in the constructor, on top of the automatically generated code, I added:
setUsingNativeTitleBar (true);
setCentrePosition(400, 400);
setVisible (true);
setResizable(false, false);
Which I sort of got from the main file of the JUCE application.
I also added a slider to this new window just to add functionality to it.
5) I added an overloaded function to let me close the window:
void InvokedWindow::closeButtonPressed()
{
delete this;
}
So, now when I run the app and click the make new window button, a new window does pop up, but I get an assertion:
/* Agh! You shouldn't add components directly to a ResizableWindow - this class
manages its child components automatically, and if you add your own it'll cause
trouble. Instead, use setContentComponent() to give it a component which
will be automatically resized and kept in the right place - then you can add
subcomponents to the content comp. See the notes for the ResizableWindow class
for more info.
If you really know what you're doing and want to avoid this assertion, just call
Component::addAndMakeVisible directly.
*/
Also, I'm able to close the window once and hit the button in the main GUI to create another instance of a newWindow, but closing it a second time leads to an error:
template <typename ObjectType>
struct ContainerDeletePolicy
{
static void destroy (ObjectType* object)
{
// If the line below triggers a compiler error, it means that you are using
// an incomplete type for ObjectType (for example, a type that is declared
// but not defined). This is a problem because then the following delete is
// undefined behaviour. The purpose of the sizeof is to capture this situation.
// If this was caused by a ScopedPointer to a forward-declared type, move the
// implementation of all methods trying to use the ScopedPointer (e.g. the destructor
// of the class owning it) into cpp files where they can see to the definition
// of ObjectType. This should fix the error.
ignoreUnused (sizeof (ObjectType));
delete object;
}
};
This is all a bit over my head. I was figuring it wouldn't be too bad to be able to create a new window, via a button. A new window that I could edit with the graphical GUI editor, but I'm not able to fully figure it out all on my own, through I did try. Could anyone post a step-by-step guide to doing this the correct way? I did post this at the JUCE forums, but due to my lack of GUI programming, I was unable to understand the solutions posted (my own fault), so I'm hoping to get a very simple guide to this. It would be very much appreciated. Thank you.
I figured it out. I needed to create:
A new GUI component (Remember, this is the visual editor in JUCE)
A class (I called it BasicWindow, based on the JUCE demo code) that acts as a shell to run this new window and holds the GUI component.
A JUCE SafePointer that makes a new object of type BasicWindow whenever the button is clicked and sets the attributes to that window.
Here is my code:
Referring to line 3) Inside the handler section of the button to create the new window:
basicWindow = new BasicWindow("Information", Colours::grey, DocumentWindow::allButtons);
basicWindow->setUsingNativeTitleBar(true);
basicWindow->setContentOwned(new InformationComponent(), true);// InformationComponent is my GUI editor component (the visual editor of JUCE)
basicWindow->centreWithSize(basicWindow->getWidth(), basicWindow->getHeight());
basicWindow->setVisible(true);
Referring to line 2) A .cpp file that defines what the BasicWindow is:
#include "../JuceLibraryCode/JuceHeader.h"
class BasicWindow : public DocumentWindow
{
private:
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (BasicWindow)
public:
BasicWindow (const String& name, Colour backgroundColour, int buttonsNeeded)
: DocumentWindow (name, backgroundColour, buttonsNeeded)
{
}
void closeButtonPressed() override
{
delete this;
}
};
And referring to line 1) Make the GUI editor component, which this is easy to do. You just right add a new file in the JUCE file manager. "Add New GUI Component," then visually add all your elements and handler code.
My biggest issue was that I was using a JUCE ScopedPointer, so after deleting the object, the pointer pointing to it wasn't being set back to NULL. The SafePointer does this. If any more explanation is needed, I'm happy to help, as this was terrible for someone with not much GUI development "under his belt."
I have a Application mostly written with the owl-libary.
There I want open new vcl-windows out of the main owl-window.
This works great, though if a dialog-window is opened (even with ShowModal) and I focus another application, then the main-window get's into foreground but is blocked by the window behind it.
I guess the Problem is the missing parent-setting.
However, I can't convert owl's TWindow to vcl's TWinControl.
Is there a trick to set a vcl's parent setting to a owl's TWindow-Object?
Or could this be caused by something entirely different?
EDIT:
I'm using...
void(TWindow* parent){
Form=new TForm((HWND)parent->Handle);
Form->ParentWindow=parent->Handle;
Form->BorderIcons >> biMinimize >> biMaximize << biSystemMenu; //No minimize, no maximize, but close
Form->BorderStyle = bsSingle;
Form->Position = poMainFormCenter;
...
Form->ShowModal();
...now.
However, the new window is locked up and can not be clicked/closed/switched to.
Is there something I missed in using ParentWindow?
EDIT2:
I think it might be a Problem that the parent is a TDecoratedMDIFrame, which is a MDI-Container, so my dialog is treated like a mdi-child instead of a normal dialog...
TWinControl has a ParentWindow property for specifying a non-VCL parent window.
Also, in modern VCL versions, you can specify a ParentWnd when displaying a VCL dialog.
So I am trying to set this window/ mainwindow / application in qt to always be on the bottom (like always bottom window) (so rainmeter somehow does this with their widgets), but I can't even get mac osx to do such things.
I've tried the whole
this->setWindowFlags(Qt::WindowStaysOnBottomHint);
but without any luck. Any hints? Example code is amazing.
Got bad news and good news. The bad news is it's simply not implemented.
The good news is: as Qt is open source, you can crack it open and take a look to know that. And if there's a bug you can submit a fix. Here's the deal, in the generic code for QWidget::setWindowFlags in
qwidget.cpp:9144 you have this:
void QWidget::setWindowFlags(Qt::WindowFlags flags)
{
if (data->window_flags == flags)
return;
Q_D(QWidget);
if ((data->window_flags | flags) & Qt::Window) {
// the old type was a window and/or the new type is a window
QPoint oldPos = pos();
bool visible = isVisible();
setParent(parentWidget(), flags);
// if both types are windows or neither of them are, we restore
// the old position
if (!((data->window_flags ^ flags) & Qt::Window)
&& (visible || testAttribute(Qt::WA_Moved))) {
move(oldPos);
}
// for backward-compatibility we change Qt::WA_QuitOnClose attribute value only when the window was recreated.
d->adjustQuitOnCloseAttribute();
} else {
data->window_flags = flags;
}
}
So essentially it just sets window_flags. The mac behavior of QWidget is in qwidget_mac.mm.
And you will find no reference to Qt::WindowStaysOnBottomHint in that file. (You'll find Qt::WindowStaysOnTopHint though...)
I'll stop at saying "not possible unless you either patch Qt, or otherwise go beneath Qt".
Patching qwidget_mac.mm is left as an exercise to the reader. :-)