QListWidget Drag after scrolling down the list - qt

I am creating A Sortable List in Qt. The Code works perfectly well for Downward Scroll but when i having some issues getting the draggable item after i scroll the list down. I have added some test case screenshot for better understanding
Well this is the test case code
#include <QtGui>
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QListWidget *listWidget = new QListWidget;
for(int i=0;i<100;++i){
listWidget->addItem("SongOne");
listWidget->addItem("SongTwo");
listWidget->addItem("SongThree");
listWidget->addItem("SongFour");
listWidget->addItem("SongFive");
}
listWidget->setDragDropMode(QAbstractItemView::InternalMove);
listWidget->setDragEnabled(true);
listWidget->setAcceptDrops(true);
listWidget->setDropIndicatorShown(true);
listWidget->viewport()->setAcceptDrops(true);
listWidget->setSelectionMode(QAbstractItemView::SingleSelection);
listWidget->show();
app.exec();
delete listWidget;
return 0;
}
Thankz for taking the time in reading my post. Do help me if you have any hint on what i am missing out.I think i am missing setting some property. In the main Program(not the test code), i tried rewriting the dragMoveEvent and few more method, but no use.
the problem here is not the drag and drop but the QRect that is created while doing Drag and Drop. In Figure Two the Qrect is Created but not in Figure Four

Try to remove the lines:
listWidget->setDragEnabled(true);
listWidget->setAcceptDrops(true);
listWidget->setDropIndicatorShown(true);
listWidget->viewport()->setAcceptDrops(true);
They may interfer with the "real" Drag'n'Drop system. Reordering is typically handled in an optimized way.
Another solution could be that you subclass QListWidget and get the element's index in the drag event and the other's element's index in the drop event. So you know what to reorder and where it should be placed (before or after the second element's index). The rest should be easy, just takeItem() and insertItem().
Hope I helped you with these two ways ;)

In win7, i was not able to reproduce the same behavior. It just works(even size hint is tweaked to meet your screen shot requirement. :) )
My test code was...
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QListWidget *listWidget = new QListWidget;
const char* titles[] = {
"SongOne%1",
"SongTwo%1",
"SongThree%1",
"SongFour%1",
"SongFive%1",
};
for(int i=0;i<100;++i){
QString title = QString(titles[i%5]).arg(i);
QListWidgetItem* item = new QListWidgetItem(title);
item->setData(Qt::SizeHintRole, QSize(50,100));
listWidget->addItem(item);
}
listWidget->setDragDropMode(QAbstractItemView::InternalMove);
listWidget->setDragEnabled(true);
listWidget->setAcceptDrops(true);
listWidget->setDropIndicatorShown(true);
listWidget->viewport()->setAcceptDrops(true);
listWidget->setSelectionMode(QAbstractItemView::SingleSelection);
listWidget->show();
app.exec();
delete listWidget;
return 0;
}

Related

Would that be possible to build a particular customized QPushButton?

I was trying to understand if there is a way to build a particular customized QPushButton?
What I am trying to achieve is the following layout and appearance:
The button is shown below, notice the red line (which meas that the button is not clicked). I am not sure how to achieve the red line. I think it could be widget? or a QProgressbar, that when is clicked goes/loads up to green..I am not sure because I don't have enough experience and have been trying to build it. However this seems to be a bit tough:
And below how it should look like right after the click happened (note the green line):
Despite my efforts, I found some useful sources that I could use to get me started: for example this source was great to understand how to start. I studied the fact that in order to achieve that, the button need to be subclassed, and that is great because it lays some sort of route.
Below the code I used:
custombutton.h
#ifndef CUSTOMBUTTON_H
#define CUSTOMBUTTON_H
#include <QPushButton>
class CustomButton : public QPushButton
{
public:
CustomButton( const QString& text, QWidget* parent = 0 );
void writeText();
};
#endif // CUSTOMBUTTON_H
custombutton.cpp
#include "CustomButton.h"
#include "algorithm"
CustomButton::CustomButton( const QString& text, QWidget* parent )
: QPushButton( text, parent )
{
}
void CustomButton::writeText()
{
QString buttonText = text();
setText( buttonText );
}
main
#include <QApplication>
#include "CustomButton.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
CustomButton w( "MyButton" );
w.show();
w.writeText();
a.exec();
return 0;
}
Another useful source I found is this one which also was useful.
The official documentation points to use the styles, but I am trying not to do that because I would like to solve the problem understanding what is the potential of subclassing with Qt.
Unless going in the style direction is the only possible way to solve this problem?
I would like to thank anyone in advance for sharing or pointing to a potential solution on how to do that.
You can set your button as checkable and then set a different icon for the 2 states.
In your case you'd have to set the red icon for the Normal mode and the green one for the Selected mode
Here's an example:
https://www.dropbox.com/s/x40byuyu2ph8m1y/CheckableButton.zip?dl=0
Here someone asked the same thing:
https://forum.qt.io/topic/72363/change-icon-of-pushbutton
Here you can read abouth the modes:
https://doc.qt.io/qt-5/qicon.html#Mode-enum
PS: Of course overriding QAbstractButton::paintEvent(QPaintEvent *event) is a viable option too

How to align two widgets in a QHBoxLayout where one is aligned far left, and one is aligned far right?

I want to have a QHBoxLayout where one QLabel is on the far left, the one QLabel is on the far right.
My Google-fu fails me. :( I cannot find the solution.
Here is a screenshot of the QHBoxLayout with two QLabel widgets:
Whatever I try, I cannot get the second QLabel widget aligned on the far right.
Roughly speaking, I tried something like this:
QHBoxLayout* const hboxLayout = new QHBoxLayout{};
hboxLayout->addWidget(m_leftLabel, 1);
hboxLayout->addStretch(1);
hboxLayout->addWidget(m_rightLabel, 0, Qt::AlignmentFlag::AlignRight);
I tried various large stretch values for the first addWidget() call and addStretch().
I also tried:
m_rightLabel->setAlignment(Qt::AlignmentFlag::AlignRight)
None of these solutions works. I am sure the solution is very simple ( ! ), but I cannot find it.
How can I do this?
My solution is to set a stretch in the middle:
#include <QtWidgets>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget w;
QHBoxLayout *lay = new QHBoxLayout(&w);
lay->addWidget(new QLabel("Left"));
lay->addStretch();
lay->addWidget(new QLabel("Right"));
w.show();
return a.exec();
}

How to make Transparent QT Dock Widget

On Windows ,I am trying to create Qt application with transparent DOCKWIDGETS, where background of dock widget is transparent when it is floated. So we can see through dock widget.
Currently it looks black as below.
Code as below
QDockWidget * dock3 = new QDockWidget(tr("DOCK3 TranslucentBackground"),
textEdit,Qt::FramelessWindowHint);
dock3->setAllowedAreas(Qt::LeftDockWidgetArea | Qt::RightDockWidgetArea);
//dock3->setWindowFlags(dock2->windowFlags()|Qt::FramelessWindowHint);
dock3->setAttribute(Qt::WA_TranslucentBackground);
//dock3->setAttribute(Qt::WA_NoSystemBackground);
{
QWidget* WindowRect = new QWidget(dock3);
QWidget* titleRect = new QLabel ("Title",WindowRect);
titleRect->setFixedSize(QSize(30,60));
titleRect->setStyleSheet("background:rgb(0,0,255);");
QWidget* ContentRect = new QLabel("Content",WindowRect);
ContentRect->setFixedSize(QSize(60,30));
ContentRect->setStyleSheet("background:rgb(0,255,0);");
QVBoxLayout* layout = new QVBoxLayout(WindowRect);
layout->addWidget(titleRect);
layout->addWidget(ContentRect);
dock3->setWidget(WindowRect);
}
One way is to use setWindowOpacity(qreal) of the QDockWidget.
But keep in mind that this will apply the opacity to all children of the QDockWidget.
For reference: https://doc.qt.io/qt-5/qwidget.html#windowOpacity-prop
Another way is to use style sheets:
setStyleSheet("background-color: transparent;");. Unfortunately this doesn't work for top level widgets until you set the attribute WA_TranslucentBackground of the base widget.
For reference:
https://doc.qt.io/qt-5/stylesheet.html
https://doc.qt.io/qt-5/qwidget.html#styleSheet-prop
Try with this article:
Qt tip & Trick: Masking Widgets
You can do it with:
setStyleSheet("background-color: rgba(0,0,0,0)");
You can try to to it in the drawin customisation by changing the style of your widget like:
MyCustomWidget {background-color: none;}
It should work
I understand that you want to see through the docking bar only when it is floating. When it's not (docked), it makes no sense because there's nothing behind to be shown.
Using setAttribute(Qt::WA_TranslucentBackground) does the trick. I'm under Linux, hopefully, it also works for Windows (I found some posts where people additionally set setAttribute(Qt::WA_NoSystemBackground), it made no difference for me under Linux, if Qt::WA_TranslucentBackground is not enough for you, give it a try with both).
#include <QMainWindow>
#include <QApplication>
#include <QDockWidget>
#include <QLabel>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QMainWindow w;
w.setCentralWidget( new QWidget() );
w.centralWidget()->setStyleSheet("background-color: green");
QDockWidget* dock = new QDockWidget();
dock->setWidget( new QLabel("Hello World",dock) );
// make docking bar transparent!
dock->setAttribute(Qt::WA_TranslucentBackground);
w.addDockWidget(Qt::BottomDockWidgetArea,dock, Qt::Horizontal);
w.show();
return a.exec();
}
When docked, it looks like this:
When floating, it looks like this:
You can see the central widget (green), can be visible through the docking bar.
Reference: Make QWidget transparent

How can I get my caret to show up on first double-click action on a QGraphicsTextItem?

I am struggling to get a QGraphicsTextItem to work as a user friendly object.
Since it is very hard to move while being editable, I start it as not editable, and make it editable on double-click. Then turn editing off on losing focus.
My problem is, the caret does not show up on first edit.
I have tried getting the position based on mouse position (as in this question that was trying to solve a different problem), or calling the QGraphicsTextItem::mouseDoubleClickEvent(event);
No matter what I try, the caret is invisible on first action - until I start typing (or if I focus out and back in) - even though it is at the correct location.
After typing, or unselecting and reselecting , the caret shows up in normal location every time.
I have tried to call the QTextCursor in the item constructor, setting its position at 0, made no difference.
What made a difference : one of the 2 situations (neither of which I can do though):
a) start item with Qt::TextEditorInteraction in constructor
b) start item with no moving/focus/selectable flags
I can't do either - because my default state of item must be movable, and that interferes with text editing (as explained at start).
I have tried to disable those flags during editing though... with no effect.
Here is a simple code to demonstrate the problem, I hope somebody can have an idea.
mytextitem.h
#ifndef TEXTITEM_H
#define TEXTITEM_H
#include <QGraphicsTextItem>
class MyTextItem : public QGraphicsTextItem
{
Q_OBJECT
public:
MyTextItem();
protected:
virtual void focusOutEvent (QFocusEvent * event);
virtual void mouseDoubleClickEvent(QGraphicsSceneMouseEvent * event);
};
#endif // TEXTITEM_H
mytextitem.cpp
#include "mytextitem.h"
#include <QTextCursor>
#include <QAbstractTextDocumentLayout>
#include <QGraphicsSceneMouseEvent>
#include <QFont>
MyTextItem::MyTextItem()
{
setHtml("ABCD");
setFont(QFont("Arial", 50));
setTextInteractionFlags(Qt::NoTextInteraction);
setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsFocusable);
}
void MyTextItem::focusOutEvent(QFocusEvent *event)
{
Q_UNUSED(event);
setTextInteractionFlags(Qt::NoTextInteraction);
QTextCursor _cursor = textCursor();
_cursor.clearSelection();
setTextCursor(_cursor);
}
void MyTextItem::mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event)
{
setTextInteractionFlags(Qt::TextEditorInteraction);
QGraphicsTextItem::mouseDoubleClickEvent(event); // or the version in linked question
}
main.cpp
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QGraphicsScene s;
QGraphicsView view(&s);
s.setSceneRect(-20, -100, 800, 600);
view.show();
MyTextItem* t = new MyTextItem();
s.addItem(t);
return app.exec();
}
I have also considered editing text - not sure if that would work but I think it would affect the undo stack which I will have to deal with soon....
How can I get my caret to show up on first double-click action on the text item ?
(As a user, not seeing a caret would make me uncertain if I can type... even though it works... I would not have confidence in the object if I do not have feedback of my action. That's why I care about this problem.)
I can't explain it... after trying EVERYTHING to get the caret to show, the solution was so simple:
I had to change the order of flags being set, in constructor.
The QGraphicsTextItem flag must be set AFTER setting the QGraphicsItem flags.
setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsFocusable);
setTextInteractionFlags(Qt::NoTextInteraction);

QWidget::geometry() vs. QWidget::frameGeometry()

Although Qt's docs indicate that these two functions are different (the first doesn't include the frame) no matter what widget I choose - including the main window of my application - someWidget->frameGeometry().height() always returns the same value as someWidget->geometry.height().
What am I missing here?
I think, you don't give enough time to widget to be painted. There is little example:
#include <QApplication>
#include <QMainWindow>
#include <QDebug>
class MainWindow : public QMainWindow
{
public:
MainWindow() {
startTimer(500);
}
void timerEvent(QTimerEvent *e) {
// Here values are different
qDebug() << geometry().height() << frameGeometry().height();
}
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MainWindow mainWin;
mainWin.show();
// Here values are equals
qDebug() << mainWin.geometry().height() << mainWin.frameGeometry().height();
return app.exec();
}
First debug output will produce the same values for geometry and frameGeometry, but the second (in timerEvent) will produce different.
The QWidget class cannot have a frame. For example, QWidget doesn't have a frame, but QFrame has a frame.
if QWidget is toplevel window then you can see borders and title bar around it. We call it frame or decoration frame and frameGeometry() returns exactly that: window size and position which includes OS decorations.On the other side geometry() returs QWidget inner rect which is available for other child controls or painting.See http://doc.qt.io/qt-4.8/application-windows.html#window-geometry for more details.Toplevel geometry() / frameGeometry() differs if our window is not frameless or fullscreen ... or we are talking about some frameless window manager under x11.
this is an old post, but that could help those searching for the same problem.
Just call
adjustSize();
before prompting for some geometry attributes
As user fasked notes, frameGeometry() may not include the frame margins early in the window creation lifecycle. I have found that the following code works in some situations where calling frameGeometry() does not.
QMargins frameMargins;
QWindow *window = widget->windowHandle();
if (window) {
window->create();
frameMargins = window->frameMargins();
}
QRect myFrameGeometry = widget->geometry().adjusted(
-frameMargins.left(), -frameMargins.top(),
frameMargins.right(), frameMargins.bottom());

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