hey want to drag this bezier curve when mouse button is pressed and moved..
I did this:
void MainWindow::mouseMoveEvent(QMouseEvent *e)
{
qDebug()<<"in mouse move - outside if";
if((e->buttons() & Qt::RightButton) && isStart && enableDrag)
{
qDebug()<<"mouse dragging happening";
xc2=e->pos().x();
yc2=e->pos().y();
drawDragBezier(xc2,yc2);
}
}
this starts dragging when i press right button and start moving mouse in whole main window..but I want to start dragging only when I press mouse button and move mouse inside the QGraphicsScene.
how to solve this?
EDIT:
void mySubClass1::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
if(event->button() == Qt::LeftButton)
{
qDebug()<<"in musubclass mouse press event: "<<event->pos().x()<<" "
<<event- >pos().y();
if(shape().contains(event->pos()))
{
currPosX=event->pos().x();
currPosY=event->pos().y();
qDebug()<<"currPosX currPosY: "<<currPosX<<" "<<currPosY;
}
}
}
And the mainwindow class is:
{
myGPath=new mySubClass1();
myScene=new QGraphicsScene;
myScene->addItem(myGPath);
ui->graphicsView->setScene(myScene);
QPointF *startPoint=new QPointF(50,50);
myPaintPath=new QPainterPath(*startPoint);
myPaintPath->quadTo(100,25,200,200);
myGPath->setPath(*myPaintPath);
}
is this the right way?
Personally, to solve this issue I'd take a different approach.
Create a class inherited from QGraphicsItem (or QGraphicsObject if you want signals and slots) to represent the bezier curve. Then implement the mouseMoveEvent of the object in this class.
class MyBezierCurve : public QGraphicsItem
{
protected:
void mousePressEvent(QGraphicsSceneMouseEvent*);
void mouseMoveEvent(QGraphicsSceneMouseEvent*);
void mouseReleaseEvent(QGraphicsSceneMouseEvent*);
};
This way, the object can detect in its mousePressEvent when the mouse is directly over one of its control points and update the control points with mouse move events until the release event occurs.
Handling the mouse events in the QGraphicsView will work, but if you introduce more bezier curves, or other objects you'll find you'll need to check which of them you need to be interacting with. Handling it in the object itself will take care of that for you.
You should subclass QGraphicsView and detect mouseMoveEvent over there.
class MyGraphicsView : public QGraphicsView
{
Q_OBJECT
...
protected:
void mouseMoveEvent(QMouseEvent *event);
...
};
Related
I would like to change my mouse cursor when it is in a graphics item (MyCircle inherits from QObject and QGraphicsItem).
Had my class inherited from QWidget, I would have reimplemented enterEvent() and leaveEvent() and use it as follows :
MyCircle::MyCircle(QObject *parent)
: QWidget(parent), QGraphicsItem() // But I can't
{
rect = QRect(-100,-100,200,200);
connect(this,SIGNAL(mouseEntered()),this,SLOT(in()));
connect(this,SIGNAL(mouseLeft()),this,SLOT(out()));
}
void MyCircle::in()
{
QApplication::setOverrideCursor(Qt::PointingHandCursor);
}
void MyCircle::out()
{
QApplication::setOverrideCursor(Qt::ArrowCursor);
}
void MyCircle::enterEvent(QEvent *)
{
emit mouseEntered();
}
void MyCircle::leaveEvent(QEvent *)
{
emit mouseLeft();
}
Unfortunately, I need to animate that circle (it's a button actually), so I need QObject, is there an easy way to change the cursor ?
QGraphicsItem already has a method for changing the cursor, so you don't need to manually play around with hover events:
QGraphicsItem::setCursor(const QCursor &cursor)
http://doc.qt.io/qt-5/qgraphicsitem.html#setCursor
PS: The dual inheritance of QWidget and QGraphicsItem you do is also a bad idea, only inherit from QGraphicsItem.
You can probably use hover events.
In your class constructor make sure you do...
setAcceptHoverEvents(true);
Then override hoverEnterEvent and hoverLeaveEvent.
virtual void hoverEnterEvent (QGraphicsSceneHoverEvent *event) override
{
QGraphicsItem::hoverEnterEvent(event);
QApplication::setOverrideCursor(Qt::PointingHandCursor);
}
virtual void hoverLeaveEvent (QGraphicsSceneHoverEvent *event) override
{
QGraphicsItem::hoverLeaveEvent(event);
QApplication::setOverrideCursor(Qt::ArrowCursor);
}
As a side note: do you actually inherit from both QObject and QGraphicsItem? If so, you could probably achieve the same goal by simply inheriting from QGraphicsObject.
Edit 1: In answer to...
I have the pointing hand icone in my whole bounding rect, how can I
reduce the area only to my drawing (in this case a circle) ?
Override QGraphicsItem::shape to return a QPainterPath representing the actual shape...
virtual QPainterPath shape () const override
{
QPainterPath path;
/*
* Update path to represent the area in which you want
* the mouse pointer to change. This will probably be
* based on the code in your 'paint' method.
*/
return(path);
}
Now override QGraphicsItem::hoverMoveEvent to make use of the shape method...
virtual void hoverMoveEvent (QGraphicsSceneHoverEvent *event) override
{
QGraphicsItem::hoverMoveEvent(event);
if (shape().contains(event->pos())) {
QApplication::setOverrideCursor(Qt::PointingHandCursor);
} else {
QApplication::setOverrideCursor(Qt::ArrowCursor);
}
}
The above could, obviously, have an impact on performance depending on the complexity of the shape drawn and, hence, the QPainterPath.
(Note: rather than using QGraphicsItem::shape you could do a similar thing with QGraphicsItem::opaque instead.)
I have a QGraphicsView with a bigger QGraphicsScene that can be dragged.
In the QGraphicsScene I have a subclassed QGraphicsItem (TestItem) that displays a QGraphicsPixmapItem, which can have random shapes.
(I don't use QGraphicsPixmapItem directly because of extra functionality to be implemented in the future)
I want this item to be movable, but only if the user presses within the shape of the item. If outside the shape, but still inside the boundingRectangle, I want the scene behind it to be dragged. This because the boundingRectangle can be much bigger than the shape and the user doesn't see it, so it would be weird trying to drag the scene near the Pixmap and it not working.
This is my subclassed item:
TestItem::TestItem(QPointF position, QPixmap testImage, double width,
double length, QGraphicsItem * parent):
QGraphicsItem(parent),
m_boundingRect(QRectF(0,0,5, 5)),
m_dragValid(false),
m_path(QPainterPath()),
mp_image(new QGraphicsPixmapItem(this))
{
setBoundingRect(QRectF(0,0,width,length));
setPos(position - boundingRect().center());
setFlag(QGraphicsItem::ItemIsMovable);
mp_image->setPixmap(testImage.scaled(width, length));
m_path = mp_image->shape();
}
QPainterPath TestItem::shape()
{
return m_path;
}
QRectF TestItem::boundingRect() const
{
return m_boundingRect;
}
void TestItem::setBoundingRect(QRectF newRect)
{
prepareGeometryChange();
m_boundingRect = newRect;
}
I've tried overriding the mouse events like this, but all it brings me is no functionality at all when outside the shape but inside the bounding rectangle
void TestItem::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
if(shape().contains(event->pos()))
{
QGraphicsItem::mousePressEvent(event);
m_dragValid = true;
}
}
void TestItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
if(m_dragValid)
QGraphicsItem::mouseMoveEvent(event);
}
void TestItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
if(m_dragValid)
QGraphicsItem::mouseReleaseEvent(event);
m_dragValid = false;
}
which of course makes sense, but I wouldn't know how to implement the dragging of the scene, since it's the scene itself that sends the mouse events to the graphics item.
(My QGraphicsView is setup to DragMode QGraphicsView::ScrollHandDrag)
Anyone have ideas?
I figured it out. I only needed to add a event->ignore(); to my mouse events.
void TestItem::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
if(shape().contains(event->pos()))
{
QGraphicsItem::mousePressEvent(event);
m_dragValid = true;
}
else
event->ignore();
}
void TestItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
if(m_dragValid)
QGraphicsItem::mouseMoveEvent(event);
else
event->ignore();
}
void TestItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
if(m_dragValid)
QGraphicsItem::mouseReleaseEvent(event);
else
event->ignore();
m_dragValid = false;
}
You just need to enable QGraphicsItem::ItemClipsToShape flag:
The item clips to its own shape. The item cannot draw or receive mouse, tablet, drag and drop or hover events outside its shape. It is disabled by default.
I am using QRubberBand to draw a selection box on my QWidget that displays a QImage.
I am using the code exactly as it is shown in the documentation, but it doesn't work. I get no errors, but it does act strange. Instead of displaying a selection box when I hold my left button down and drag it across my QWidget which is painted with the QImage it just makes one of my buttons on my interface disappear and reappear based on my left button click. I should also add that the button that disappears isn't apart of the QWidget, or even apart of the parent QObject that creates the QWidget.
void Widget::mousePressEvent(QMouseEvent *event)
{
origin = event->pos();
if (!rubberBand)
rubberBand = new QRubberBand(QRubberBand::Rectangle, this);
rubberBand->setGeometry(QRect(origin, QSize()));
rubberBand->show();
}
void Widget::mouseMoveEvent(QMouseEvent *event)
{
rubberBand->setGeometry(QRect(origin, event->pos()).normalized());
}
void Widget::mouseReleaseEvent(QMouseEvent *event)
{
rubberBand->hide();
// determine selection, for example using QRect::intersects()
// and QRect::contains().
}
Any help is appreciated.
Thanks
It is totally my fault. I failed to set my pointer as NULL in my header.
Instead of this :
QRubberBand *rubberBand {rubberBand = NULL};
I just did :
QRubberBand *rubberBand;
I would like to open a window when I click on a QSpinBox. The problem is that there is no such signal "clicked" for this widget.
Does someone has an idea how to do that?
A QSpinBox is just a QLineEdit with two buttons, input validation and event handling. It doesn't have clicked signal because it's supposed to handle the mouse even itself.
The problem is that even making a custom widget derived from QSpinBox won't be enough since it doesn't receive the mouse events itself, they are handled by its children widgets. You could install an event filter on the QSpinBox children in order to catch the click event, but that's not the neatest way.
If you just want to display a numpad when the user select the box, you can use directly a QLineEdit. You will lose the QSpinBox buttons (but you can add your own ones if you need them) and the validation (but you can add you own using QValidator).
Then you just have to derive it in order to catch the focus event, trigger a custom signal which would show your keyboard :
class MySpinBox: public QLineEdit
{
Q_OBJECT
public:
MySpinBox(QWidget *parent = 0);
~MySpinBox();
signals:
needNumpad(bool hasFocus);
protected:
virtual void focusInEvent(QFocusEvent *e) {
QLineEdit::focusInEvent(e);
emit(needNumpad(true));
}
virtual void focusOutEvent(QFocusEvent *e) {
QLineEdit::focusInEvent(e);
emit(needNumpad(false));
}
}
You can use an event filter and do something like this:
ui->spinBox->installEventFilter(this);
QObjectList o_list = ui->spinBox->children();
for(int i = 0; i < o_list.length(); i++)
{
QLineEdit *cast = qobject_cast<QLineEdit*>(o_list[i]);
if(cast)
cast->installEventFilter(this);
}
And in the event filter you check for a mouse click (in this example its triggered by all mouse buttons, left click, right click, scroll wheel click etc.).
bool MainWindow::eventFilter(QObject *obj, QEvent *event)
{
if(event->type() == QEvent::MouseButtonPress)
{
showNumpadDialog();
}
return false;
}
You do not need to create your own QSpinBox with QLineEdit and two buttons.
Since QLineEdit is the child of QSpinBox. You can create an event filter for QLineEdit and check whether its parent is a spinbox. Then so, you would get a click event for spin box.
if(event->type() == QEvent::MouseButtonPress && dynamic_cast<QSpinBox *>(dynamic_cast<QLineEdit *>(obj)->parent()) )
I want to implement a widget (with some edit boxes and sliders) that would open beneath or next to a button ("Opener") when I hover it. The key is it's a temporary widget - as soon as it loses focus, I want it gone. Also, I want it to pop up right next to the Opener, ideally pointing an arrow to Opener.
So, it's basically a tooltip. But it needs to be a widget with buttons and sliders and stuff like that. Is there a clever way to implement it without making a custom widget and writing handlers for all the mouse and focus events and recomputing its ideal position every time I open it or the Opener moves?
class OpenerButton : public QPushButton
{
public:
OpenerButton(QWidget * parent = 0);
protected:
void enterEvent(QEvent *e);
void leaveEvent(QEvent *e);
};
OpenerButton::OpenerButton(QWidget * parent)
: QPushButton(parent)
{
//Do necessary initializations For ex:set a menu for opener button
}
void OpenerButton::leaveEvent(QEvent * e)
{
//hide the popup_menu
}
void OpenerButton::enterEvent(QEvent * e)
{
//Show the menu
//You can use animation for ex:
Popup_menu=new Popup_Dialog(this);//Popup_Dialog is a dialog containing all your widgets
QPropertyAnimation *animation = new QPropertyAnimation(Popup_menu,"geometry");
animation->setDuration(500);
animation->setDirection(QAbstractAnimation::Forward);
QRect startRect(Rect_Relative_to_Opener_Button);
QRect endRect(Shifted_Rect_Relative_to_Opener_Button);
animation->setStartValue(startRect);
animation->setEndValue(endRect);
animation->start();
}
Enterevent is called when the mouse cursor enters the widget. Similarly leaveevent when mouse cursor leaves the widget.