I have a problem with qRubberBand not painting continuous rectangles in some cases. I used exact example from Qt documentation:
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();
}
my problem is shown in this video:
https://imgur.com/a/TMpUz0l
as you can see, if I am painting the rectangle from left top to right bottom, the rectangle is painted smoothly. But otherwise the painting is not continuous.
Here are some events of my code:
void Graph::onMousePress(QMouseEvent* event){
if ((event->buttons() & Qt::RightButton) == Qt::RightButton) {
m_RMBPressed = true;
m_globalOrigin = QPoint(event->globalPos().x(), event->globalPos().y());
if (!m_rubberBand) {
m_rubberBand = new QRubberBand(QRubberBand::Rectangle, qobject_cast<QWidget*>(this));
}
m_rubberBand->setGeometry(QRect(m_globalOrigin, QSize()));
m_rubberBand->show();
}
}
void Graph::onMouseRelease(QMouseEvent* event){
m_RMBPressed = false;
if (m_rubberBand) {
m_rubberBand->hide();
}
}
void Graph::onMouseMove(QMouseEvent* event){
if (m_RMBPressed) {
auto rectangle = QRect(QPoint(event->globalPos().x(), event->globalPos().y()), m_globalOrigin).normalized();
m_rubberBand->setGeometry(rectangle);
m_rubberBand->update();
}
}
I tried to swap the coordinates of the QRect, remove the .normalized() function and then correct the rectangle coordinates but none of it worked. Any help is appreciated.
Related
I'm wondering if there's any way to get all widgets (QLabel specifically) inside a QRubberBand area.
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());
//...do something with the widgets inside
}
void Widget::mouseReleaseEvent(QMouseEvent *event)
{
rubberBand->hide();
}
I want to make an implementation of chart selection based on QChart and QChartView.
The family of the classes have a big advantage - easy use of openGL and animations, for example:
QLineSeries *series = new QLineSeries();
series->setUseOpenGL(true); // <==
QChart *chart = new QChart();
chart->addSeries(series);
chart->setAnimationOptions(QChart::AllAnimations); // <==
QChartView *chartView = new QChartView(chart);
chartView->setRenderHint(QPainter::Antialiasing);
The QChartView class provides the useful zoom feature - QChartView::setRubberBand():
chartView->setRubberBand(QChartView::RectangleRubberBand);
The main problem is that the rubber band can be used only for zoom, but I need to implement it for horizontal selection without zoom, as the feature usually implemented in audio editors:
Now, when I have inherit QChartView, I can disable zoom after selection:
class ChartView : public QChartView
...
bool m_drawRubberBand;
QRubberBand m_rubberBand;
...
ChartView::ChartView(QChart *chart, QWidget *parent)
: QChartView(chart, parent)
{
setRubberBand(QChartView::HorizontalRubberBand);
}
...
// Just copy-paste from the Qt 5 sources - file \Src\qtcharts\src\charts\qchartview.cpp:
/*!
If the rubber band rectangle is displayed in the press event specified by
\a event, the event data is used to update the rubber band geometry.
Otherwise, the default QGraphicsView::mouseMoveEvent() implementation is called.
*/
void ChartView::mouseMoveEvent(QMouseEvent *event)
{
if (m_drawRubberBand && m_rubberBand.isVisible())
{
QRect rect = chart()->plotArea().toRect();
int width = event->pos().x() - m_rubberBandOrigin.x();
int height = event->pos().y() - m_rubberBandOrigin.y();
if (!rubberBand().testFlag(VerticalRubberBand))
{
m_rubberBandOrigin.setY(rect.top());
height = rect.height();
}
if (!rubberBand().testFlag(HorizontalRubberBand))
{
m_rubberBandOrigin.setX(rect.left());
width = rect.width();
}
m_rubberBand.setGeometry(QRect(m_rubberBandOrigin.x(), m_rubberBandOrigin.y(), width, height).normalized());
}
else
{
QGraphicsView::mouseMoveEvent(event);
}
}
Then I can just don't implement the zoom action on the mouse key release event:
void ChartView::mouseReleaseEvent(QMouseEvent *event)
{
if (m_rubberBand.isVisible())
{
if (event->button() == Qt::LeftButton)
{
m_drawRubberBand = false;
do_nothing(); // <==
}
}
}
So, my questions now:
How borders of the the visual rubber band can be mapped to real chart's coordinates. I.e., how can the selection be mapped into a line series on the chart? Now I receive same wrong coordinates:
void MyView::resizeEvent(QResizeEvent *event)
{
QChartView::resizeEvent(event);
QRect rct(QPoint(10, 10), QPoint(20, 20));
qDebug() << mapToScene(rct); <==
}
Output:
QPolygonF(QPointF(10,10)QPointF(21,10)QPointF(21,21)QPointF(10,21))
QPolygonF(QPointF(10,10)QPointF(21,10)QPointF(21,21)QPointF(10,21))
QPolygonF(QPointF(10,10)QPointF(21,10)QPointF(21,21)QPointF(10,21))
QPolygonF(QPointF(10,10)QPointF(21,10)QPointF(21,21)QPointF(10,21))
...
How can an existing rubber selection be proportionally resized together with the view?
Edit: May be it is a useful keyword - QGraphicsScene::setSelectionArea().
The Qt 5 chip example which provides nice rubber band selection, but the example based on QGraphicsView, not on QChartView.
The question is resolved thanks to the reply to this answer: Get mouse coordinates in QChartView's axis system
The key moment: it was necessary to invoke QChart::mapToValue() for a correct coordinates transform:
QPointF ChartView::point_to_chart(const QPoint &pnt)
{
QPointF scene_point = mapToScene(pnt);
QPointF chart_point = chart()->mapToValue(scene_point);
return chart_point;
}
And the inverse transformation:
QPoint ChartView::chart_to_view_point(QPointF char_coord)
{
QPointF scene_point = chart()->mapToPosition(char_coord);
QPoint view_point = mapFromScene(scene_point);
return view_point;
}
That's how I have implemented resize of the rubber band on the resizeEvent.
Firstly, I save the current rubber band on mouse release event:
void ChartView::mouseReleaseEvent(QMouseEvent *event)
{
if (m_rubberBand.isVisible())
{
update_rubber_band(event);
m_drawRubberBand = false;
save_current_rubber_band(); <==
}
}
Where:
void ChartView::update_rubber_band(QMouseEvent * event)
{
QRect rect = chart()->plotArea().toRect();
int width = event->pos().x() - m_rubberBandOrigin.x();
int height = event->pos().y() - m_rubberBandOrigin.y();
if (!rubberBand().testFlag(VerticalRubberBand))
{
m_rubberBandOrigin.setY(rect.top());
height = rect.height();
}
if (!rubberBand().testFlag(HorizontalRubberBand))
{
m_rubberBandOrigin.setX(rect.left());
width = rect.width();
}
m_rubberBand.setGeometry(QRect(m_rubberBandOrigin.x(), m_rubberBandOrigin.y(), width, height).normalized());
}
And:
void ChartView::save_current_rubber_band()
{
QRect rect = m_rubberBand.geometry();
QPointF chart_top_left = point_to_chart(rect.topLeft());
m_chartRectF.setTopLeft(chart_top_left);
QPointF chart_bottom_right = point_to_chart(rect.bottomRight());
m_chartRectF.setBottomRight(chart_bottom_right);
}
And how I repaint the rubber on the resize event:
void ChartView::resizeEvent(QResizeEvent *event)
{
QChartView::resizeEvent(event);
if (m_rubberBand.isVisible())
{
restore_rubber_band();
}
apply_nice_numbers();
}
Where:
void ChartView::restore_rubber_band()
{
QPoint view_top_left = chart_to_view_point(m_chartRectF.topLeft());
QPoint view_bottom_right = chart_to_view_point(m_chartRectF.bottomRight());
m_rubberBandOrigin = view_top_left;
m_rubberBand.setGeometry(QRect(view_top_left, view_bottom_right));
}
And don't forget about the "nice numbers":
void ChartView::apply_nice_numbers()
{
QList<QAbstractAxis*> axes_list = chart()->axes();
for each(QAbstractAxis* abstract_axis in axes_list)
{
QValueAxis* value_axis = qobject_cast<QValueAxis*>(abstract_axis);
if (value_axis)
{
value_axis->applyNiceNumbers();
}
}
}
This logic in action.
Before resize:
After resize:
I am stuck with this weird behavior where, if I enable rubberband drag, the wheel event doesn't zoom under mouse anymore. It does zooming but irrespective of mouse position. And if I disable other events, then wheelEvent works properly.
I have a custom class inheriting QGraphicsView as :
class MyGraphics : public QGraphicsView{
public :
MyGraphics(QWidget *parent = NULL);
public slots:
void zoomIn() { scale(1.2, 1.2); }
void zoomOut() { scale(1 / 1.2, 1 / 1.2); }
protected :
QRubberBand *rubberBand;
QPoint origin;
QPointF InitialCenterPoint;
QPointF CurrentCenterPoint;
QPoint rubberBandOrigin;
bool rubberBandActive;
QPoint LastPanPoint;
int _numScheduledScalings;
//if I uncomment these three event handlers, the wheelevent doesnt zoom properly!
// virtual void mousePressEvent(QMouseEvent *event);
// virtual void mouseMoveEvent(QMouseEvent *event);
// virtual void mouseReleaseEvent(QMouseEvent *event);
virtual void wheelEvent(QWheelEvent *);
virtual void resizeEvent(QResizeEvent *event);
};
The constructor :
MyGraphics::MyGraphics(QWidget *parent) : QGraphicsView(parent){
setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
this->installEventFilter(this);
this->setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
this->setResizeAnchor( QGraphicsView::AnchorUnderMouse );
QGraphicsScene *graphScene = new QGraphicsScene(this);
this->setScene(graphScene);
QGraphicsItem* pEllipse = graphScene->addEllipse(0,100,50,50);
QGraphicsItem* pRect = graphScene->addRect(200,100,50,50);
pEllipse->setFlag(QGraphicsItem::ItemIsSelectable, true);
pRect->setFlag(QGraphicsItem::ItemIsSelectable, true);
setSceneRect(0, 0, 1000, 1000);
rubberBandOrigin = QPoint(0,0);
}
Event handlers :
void MyGraphics::wheelEvent(QWheelEvent *event){
if(event->delta() > 0){
//Zoom in
this->zoomIn();
} else {
this->zoomOut();
}
}
/*
void MyGraphics::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::MiddleButton) {
rubberBandOrigin = event->pos();
rubberBand = new QRubberBand(QRubberBand::Rectangle, this);
rubberBand->setGeometry(event->x(),event->y(),0, 0);
rubberBand->show();
rubberBandActive = true;
}
if(event->button() == Qt::LeftButton){
LastPanPoint = event->pos();
}
}
void MyGraphics::mouseMoveEvent(QMouseEvent *event)
{
if (event->buttons() == Qt::MiddleButton && rubberBandActive == true){
rubberBand->resize( event->x()-rubberBandOrigin.x(), event->y()-rubberBandOrigin.y() );
}
else{
if(!LastPanPoint.isNull()) {
//Get how much we panned
QGraphicsView * view = static_cast<QGraphicsView *>(this);
QPointF delta = view->mapToScene(LastPanPoint) - view->mapToScene(event->pos());
LastPanPoint = event->pos();
}
}
}
void MyGraphics::mouseReleaseEvent(QMouseEvent *event)
{
if (event->button() == Qt::MiddleButton){
QGraphicsView * view = static_cast<QGraphicsView *>(this);
QPoint rubberBandEnd = event->pos();
QRectF zoomRectInScene = QRectF(view->mapToScene(rubberBandOrigin), view->mapToScene(rubberBandEnd));
QPointF center = zoomRectInScene.center();
view->fitInView(zoomRectInScene, Qt::KeepAspectRatio);
rubberBandActive = false;
delete rubberBand;
}
else{
LastPanPoint = QPoint();
}
}
*/
Any idea where I am doing wrong or how do I fix it ?
QGraphicsView::scale function's behaviour depends on the mouse position. It's performing automatically and internally by QGraphicsView. Since you don't pass mouse position to the scale function, I think QGraphicsView tracks the mouse and remembers the last position on its own.
By reimplementing mouse event handlers you have taken this ability from it. The view can't determine the mouse position anymore because its original handlers aren't called.
Luckily this issue can be easily fixed. You need to call base class implementation before your own:
void MyGraphics::mousePressEvent(QMouseEvent *event) {
QGraphicsView::mousePressEvent(event);
// your implementation goes here
}
It's an example for mousePressEvent but you should add similar statements to all your event handlers unless you need to disable some part of default behavior.
I have a QGraphicsView widget with lots of items on scene. I am panning the view on ctr+left mouse click and zooming it to rectangle of rubber band created with left mouse button drag. I am not able to see rubber band selection rectangle (dotted lines) whereas rubberband selection functionality works fine. Can anybody help me understand this?.I use these flags in my view:
setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
setViewportUpdateMode(QGraphicsView::SmartViewportUpdate);
setRenderHints(QPainter::HighQualityAntialiasing | QPainter::SmoothPixmapTransform);
setOptimizationFlag(QGraphicsView::DontSavePainterState,true);
setCacheMode(QGraphicsView::CacheBackground);
setOptimizationFlag(QGraphicsView::DontAdjustForAntialiasing);
setViewport(new QGLWidget);
below are my event handlers.
Mouse press event handler:
void MyView::mousePressEvent(QMouseEvent* event)
{
if(event->button()==Qt::LeftButton)
{
if(event->modifiers()==Qt::ControlModifier)
{
setDragMode(QGraphicsView::NoDrag);
m_rubberBandActive = false;
mousepressed=true;
m_lastDragPos = event->pos();
return;
}
else
{
setDragMode(QGraphicsView::RubberBandDrag);
m_rubberBandOrigin = event->pos();
m_rubberBandActive = true;
}
}
event->accept();
}
else
{
QWidget::mousePressEvent(event);
}
}
Mouse move event:
void MyView::mouseMoveEvent(QMouseEvent* event)
{
if(mousepressed)
{
QPointF delta = mapToScene(event->pos()) - mapToScene(m_lastDragPos);
this->panView(delta);
m_lastDragPos = event->pos();
return;
}
event->accept();
}
Mouse release event Handler:
void MyView::mouseReleaseEvent(QMouseEvent *event)
{
if (m_rubberBandActive)
{
QPoint rubberBandEnd = event->pos();
QRectF zoomRectInScene = QRectF(mapToScene(m_rubberBandOrigin),mapToScene(rubberBandEnd));
fitInView(zoomRectInScene, Qt::KeepAspectRatio);
m_rubberBandActive = false;
}
mousepressed=false;
event->accept();
}
Pan view:
void MyView::panView(QPointF delta)
{
QPoint viewCenter(viewport()->width() / 2 + delta.x(), viewport()->height() / 2 + delta.y());
QPointF newCenter = mapToScene(viewCenter);
centerOn(newCenter);
}
so I am trying to draw a line between two points. Left mouse click starts the line then I would like the line to by dynamically drawn as the mouse moves (almost like a preview of the line). Left mouse click again and the line will be permanently drawn. I know there are a lot of other posts about QPaintEvents and I have combined some of the techniques used, but for some reason nothing is being drawn to the canvas. Below is the code:
void Main::mousePressEvent(QMouseEvent * event)
{
if (event->button() == Qt::LeftButton) {
QPointF pos = event->pos();
if( mStartPoint.isNull() ) {
if(josh.contains(pos))
mStartPoint = pos;
} else {
canvas.addLine(mStartPoint.x(),mStartPoint.y(),pos.x(),pos.y());
mStartPoint = QPointF();
}
}
}
bool Main::eventFilter(QObject *obj, QEvent *event)
{
if (event->type() == QEvent::MouseMove)
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
if (!mStartPoint.isNull()) {
m_targetImage = QImage(canvas.width(),canvas.height(),QImage::Format_ARGB32);
QPainter p;
p.begin(&m_targetImage);
p.drawLine(mStartPoint, mouseEvent->pos());
p.end();
}
statusBar()->showMessage(QString("Mouse move (%1,%2)").arg(mouseEvent->pos().x()).arg(mouseEvent->pos().y()));
}
return false;
}
void Main::paintEvent(QPaintEvent *pe)
{
QPainter painter(this);
QPen pen(Qt::red);
pen.setWidth(10);
painter.setPen(pen);
painter.drawImage(0, 0, m_targetImage);
}
Any help is appreciated! Thanks! Josh
I think this is what you want. Change parameters according to your requirements.
//In your constructor
m_nInitialX = 0;
m_nInitialY = 0;
m_nFinalX = 0;
m_nFinalY = 0;
m_nPTargetPixmap = 0;
m_nPTargetPixmap = new QPixmap(400,400);
m_nbMousePressed = false;
void Main::mousePressEvent(QMouseEvent* event)
{
m_nbMousePressed = true;
m_nInitialX = event->pos().x();
m_nInitialY = event->pos().y();
}
void Main::mouseReleaseEvent(QMouseEvent *event)
{
m_nbMousePressed = false;
}
void Main::paintEvent(QPaintEvent *e)
{
if(m_nbMousePressed)
{
QPainter PixmapPainter(m_nPTargetPixmap);
QPen pen(Qt::green);
PixmapPainter.setPen(pen);
PixmapPainter.drawLine(m_nInitialX, m_nInitialY, m_nFinalX, m_nFinalY);
}
QPainter painter(this);
painter.drawPixmap(0, 0, *m_nPTargetPixmap);
}
void Main::mouseMoveEvent(QMouseEvent *event)
{
if (event->type() == QEvent::MouseMove)
{
QPainter PixmapPainter(m_nPTargetPixmap);
QPen pen(Qt::black);
PixmapPainter.setPen(pen);
PixmapPainter.drawLine(m_nInitialX, m_nInitialY, m_nFinalX, m_nFinalY);
update(); // update your view
m_nFinalX = event->pos().x();
m_nFinalY = event->pos().y();
}
update(); // update your view
}
This piece of code will draw a 2 point line that you want.
Here's my example of how to paint lines in your way directly on the widget.
Declaration:
private:
void drawLines(QPainter *p);
QPoint startPos;
QPoint endPos;
bool inDrawing;
QVector<QLine> lines;
Setting initial values in constructor:
Widget::Widget(QWidget *parent)
: QWidget(parent)
{
startPos = QPoint();
endPos = QPoint();
inDrawing = false;
setMouseTracking(true);
}
Starting or ending the line drawing:
void Widget::mousePressEvent(QMouseEvent *event)
{
if (event->buttons() & Qt::LeftButton)
{
if (!inDrawing)
{
startPos = event->pos();
}
else
{
endPos = event->pos();
QLine line = QLine(startPos, event->pos());
lines.append(line);
}
inDrawing = !inDrawing;
}
}
void Widget::mouseMoveEvent(QMouseEvent *event)
{
if (inDrawing)
{
endPos = event->pos();
update();
}
}
Drawing current and saved lines:
void Widget::drawLines(QPainter *p)
{
if (!startPos.isNull() && !endPos.isNull())
{
p->drawLine(startPos, endPos);
}
p->drawLines(lines);
}
Drawing:
void Widget::paintEvent(QPaintEvent *event)
{
QPainter p(this);
QPen pen;
pen.setColor(Qt::red);
pen.setWidth(4);
p.setPen(pen);
drawLines(&p);
}