I have subclassed a qgraphicsscene and trying to get the mouse coords inside a "normal" function. I only get it working on "mouse involved" function. Sorry I'm amateur programmer.
For exmample here scenePos() works:
void mousePressEvent(QGraphicsSceneMouseEvent *event)
{
// qDebug() << "Custom scene clicked.";
if(event->modifiers() == Qt::ControlModifier) {
if(event->button() == Qt::LeftButton) {
QPointF pos = {event->scenePos().x(), 70};
addChordnueve(pos); // crea 1 item at mouse x e y = 70
// } if(event->modifiers() == Qt::ControlModifier & event->modifiers() == Qt::ShiftModifier) {
qDebug() << "Control!!!";}}
Here it doesn't works at all, but got QCursor::pos() giving "weird" positions:
void preaddExtChord()
{
auto *hellos = scenePos(); //<- It doesn't works
int xplace = QCursor::pos().x()-620;
int yplace = QCursor::pos().y()-380;
QGraphicsSimpleTextItem *item = new QGraphicsSimpleTextItem("n");
item->setFont(QFont ("omheads", 20));
item->setPos(xplace, yplace);
addItem(item);
}
I searched a lot during months but couldn't find a solution,...
maybe I'm doing a wrong approach, or either there is some easier possibilitie to get the mouse coords inside this type of functions?
Thanks! :-)
If you want to obtain the position with respect to the cursor scene you must first obtain that QGraphicsView is below the cursor (a QGraphicsScene can be part of QGraphicsView), for this we must iterate and verify if it is inside the viewport, then calculate the position with respect to the scene using the mapToScene method of QGraphicsView:
QPoint p = QCursor::pos();
for(QGraphicsView *view: views()){
QWidget *viewport = view->viewport();
QRect vr = viewport->rect();
QPoint vp = viewport->mapFromGlobal(p);
if(vr.contains(vp)){
QPointF sp = view->mapToScene(vp);
QGraphicsSimpleTextItem *item = new QGraphicsSimpleTextItem("n");
item->setFont(QFont("omheads", 20));
item->setPos(sp);
addItem(item);
}
}
Related
I'm working on a Qt/Qml application.
I'm currently trying to emulate drag behavior through Qt on drag QML elements (Listview, Flickable...) for tests purpose.
I have a specific issue that I wanted to solve with the most generic solution possible, my component is a non-interactive ListView, nested by an interactive ListView, nested itself with a MouseArea :
ListView {
anchors.fill: parent
interactive: false
ListView {
anchors.fill: parent
MouseArea {
...
}
}
}
So. My idea was : take a QML object, local coordinates (x, y) where the movement starts, find it's most nested child at position and apply the movement (dx, dy) to this child. If I'm understanding correctly how QT/QML works, it should send the event to parent if not used by the child, and Flickable components should be able to detect drags and catch them.
void xx::touchAndDrag(QObject *object, const int x, const int y, const int dx, const int dy)
{
timer = new QTimer(this);
timerIteration = 0;
deltaPoint = new QPointF(dx, dy);
parentItem = qobject_cast<QQuickItem *>(object);
item = parentItem;
startPoint = QPointF(x, y);
QPointF tempPoint = startPoint;
for( ;; ) {
//Find the most nested child at coordinate
QQuickItem* child = item->childAt(tempPoint.x(), tempPoint.y());
if(child) {
item = child;
tempPoint = child->mapFromItem(parentItem, tempPoint);
qDebug() << "child found " << item;
} else {
break;
}
}
timer->setInterval(movementDuration / nbIteration);
qDebug() << "interval " << timer->interval();
timer->setSingleShot(false);
connect(timer, SIGNAL(timeout()), this, SLOT(mouseMove()));
// Send press event at starting point
QMouseEvent *e = new QMouseEvent(QEvent::MouseButtonPress, item->mapFromItem(parentItem, startPoint), Qt::LeftButton, Qt::LeftButton, Qt::NoModifier );
qDebug() << "press " << e;
qApp->postEvent(item, e);
timer->start();
}
void xx::mouseMove()
{
timerIteration++;
QMouseEvent *e;
if(timerIteration < nbIteration) {
int x = startPoint.x() + deltaPoint->x() * timerIteration / nbIteration;
int y = startPoint.y() + deltaPoint->y() * timerIteration / nbIteration;
QPointF point = QPointF(x, y);
// Send moveEvent
e = new QMouseEvent(QEvent::MouseMove, item->mapFromItem(parentItem, point), Qt::LeftButton, Qt::LeftButton, Qt::NoModifier );
qDebug() << "move! " << e ;
}else {
//End reached, send end event
QPointF point = QPointF(startPoint.x() + deltaPoint->x(), startPoint.y() + deltaPoint->y());
e = new QMouseEvent(QEvent::MouseButtonRelease, item->mapFromItem(parentItem, point), Qt::LeftButton, Qt::LeftButton, Qt::NoModifier );
timer->stop();
qDebug() << "end! " << e ;
}
qApp->postEvent(item, e);
}
So... It is not working. What happens? From my tests:
-If I remove the nested child part, and give directly the interactive (to drag) QML Component (here the nested ListView), the result is good. But this is not a good solution for me, since I would have exactly to know which component should react. However, this seems to override the "interactive: false" of a component, which is a bad idea when the purpose is... to test the component.
-The mouse area receives all events. The mouseX property is updated. This is an issue. With non simulated event, MouseArea should receive the press event, some move event, then events should captured by the ListView / Flickable. Even worst, even if positions are way different (400px) between mousePress and mouseRelease events, Qt detects a MouseClicked event and triggers it on QML side...
So, not sure where to go from there. I could do some crappy child detection (checks the type of the nested child, and only accepts the good one), but I'm not very happy with it. Any idea?
Ok, so I went a bit deeper in QT code, and I understood my mistake:
To use sendEvent correctly, you have to pass them to the root view (on my project it is a QQuickView, but it can also be a QWindow). If you do not send the event on the root, it won't filter the mouseEvent as expected (through childMouseEventFilter() method)
I also discover than the MouseRelease event needs a NoButton parameter. So my code works now and looks like this:
//Set mouse timer
mouseTimer = new QTimer(this);
mouseTimer->setInterval(m_movementDuration / m_nbIteration);
mouseTimer->setSingleShot(false);
connect(mouseTimer, SIGNAL(timeout()), this, SLOT(mouseMove()));
}
void xx::pressAndDrag(QObject *object, const int x, const int y, const int dx, const int dy)
{
m_pressAndDragCompleted = false;
//Reset timer iteration
m_timerIteration = 0;
//Keep all coordinates
startPoint = ((QQuickItem *) object)->mapToScene(QPointF(x, y));
deltaPoint = new QPointF(dx, dy);
QMouseEvent *e = new QMouseEvent(QEvent::MouseButtonPress, startPoint, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier );
qApp->postEvent(parent(), e);
//Start timer
mouseTimer->start();
}
void xx::mouseMove()
{
m_timerIteration++;
if (m_timerIteration < m_nbIteration + 2) {
//Move mouse
int x = startPoint.x() + deltaPoint->x() * m_timerIteration / m_nbIteration;
int y = startPoint.y() + deltaPoint->y() * m_timerIteration / m_nbIteration;
QMouseEvent *e = new QMouseEvent(QEvent::MouseMove, QPointF(x, y), Qt::LeftButton, Qt::LeftButton, Qt::NoModifier );
qApp->postEvent(parent(), e);
// Let some time to not trigger a flick
} else if (m_timerIteration - m_nbIteration >= 400 / mouseTimer->interval()) {
//End movement
QPointF point = QPointF(startPoint.x() + deltaPoint->x(), startPoint.y() + deltaPoint->y());
QMouseEvent *e = new QMouseEvent(QEvent::MouseButtonRelease, point, Qt::NoButton, Qt::NoButton, Qt::NoModifier );
qApp->postEvent(parent(), e);
//Stop timer
mouseTimer->stop();
m_pressAndDragCompleted = true;
}
}
If it can help. :)
I would like to programmatically scroll a scene to the left / right, but I am not sure how to do that properly. Note that I do not want to have (visible) scroll bars.
I use a standard QGraphicsView + QGraphicsScene + QGraphicsItem setup. I have downsized it to the minimum, with one single QGraphicsItem (a QGraphicsRectItem) in the scene.
I have managed to achieve programmatic scrolling by setting my view like this:
// view setup
view->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
view->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
and then, in another part of the code:
// programmatic scrolling
QScrollBar* const sb = view->horizontalScrollBar();
sb->setRange(0, 1000); // some values for experimenting
sb->setValue(sb->value() + 100 or -100); // some increment for experimenting
This works, but... scrolling through invisible scrollbars doesn't feel right.
I tried this more straightforward approach:
// programmatic scrolling - doesn't quite work
view->viewport()->scroll(100 or -100, 0); // some increment for experimenting
This code does scroll, but when the rectangle goes off the left edge of the view, and I reverse the scrolling direction (increment changed from 100 to -100 in the call to scroll()), the uncovered part of the rectangle is not repainted. The reason is that QGraphicsRectItem::paint() is not called in that case (it is called when using the scrollbar method).
So, is there a way to get viewport()->scroll() work? Or some other simple way to achieve programmatic scrolling? Or is the artificial scrollbar method just the way to go?
Moving the view assumes that it's smaller than its scene. If they're the same size, it won't move.
QGraphicsView can be set to centerOn any position in scene coordinates. Use a timer to call centerOn to move the view one frame at a time.
Here's a working example: -
#include <QApplication>
#include <QGraphicsScene>
#include <QGraphicsView>
#include <QGraphicsRectItem>
#include <QTimer>
class MyView : public QGraphicsView
{
private:
public:
MyView(QGraphicsScene* pScene)
: QGraphicsView(pScene, NULL)
{}
void AnimateBy(int x)
{
float updateFrequency = (1000/30.0); // ~30 frames per second
QPointF currScenePos = sceneRect().center();
int curX = currScenePos.x();
int endPos = curX + x;
int distanceToAnimate = (endPos - curX);
// speed = dist / time
float updatePosInterval = (float)distanceToAnimate / updateFrequency;
printf("updatePosInterval: %f \n", updatePosInterval);
static float newXPos = sceneRect().center().x();
QTimer* pTimer = new QTimer;
QObject::connect(pTimer, &QTimer::timeout, [=](){
newXPos += updatePosInterval;
centerOn(newXPos, sceneRect().center().y());
// check for end position or time, then....
if(newXPos >= endPos)
{
pTimer->stop();
pTimer->deleteLater();
}
});
pTimer->start(updateFrequency);
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QGraphicsScene scene(0, 0, 10000, 20000);
MyView* view = new MyView(&scene);
QGraphicsRectItem* pRect = new QGraphicsRectItem(0, 0, 100, 100);
pRect->setPos(scene.width()/2, scene.height()/2);
scene.addItem(pRect);
// timer to wait for the window to appear, before starting to move
QTimer* pTimer = new QTimer;
pTimer->setSingleShot(true);
QObject::connect(pTimer, &QTimer::timeout,[=](){
view->centerOn(pRect); // centre on the rectangle
view->AnimateBy(100);
pTimer->deleteLater();
});
pTimer->start(1000);
view->show();
return a.exec();
}
So, we create the animation by moving the view frame-by-frame using the call to centerOn.
For simplicity, the code just deals with moving in one axis. To move in 2 axis, use 2D vector maths to calculate the interval position.
Try to change the view transformation with the QGraphicsView::translate() or QGraphicsView::setTransform().
But keep in mind that you can't move the viewport "outside" the scene, so make sure that your scene rectangle is large enough.
If I got your question correctly, there is a dojo classes library with such class as PanWebView that allow QWebView to scroll smoothly with mouse without any scrollbars. Take a look at sources. It supports panning and can be suitable for mobile apps, but maybe it'll help you too.
PanWebView class looks like this
#include <QWebView>
#include <QWebFrame>
#include <QMouseEvent>
#include <QApplication>
class PanWebView : public QWebView
{
Q_OBJECT
private:
bool pressed;
bool scrolling;
QPoint position;
QPoint offset;
QList<QEvent*> ignored;
public:
PanWebView(QWidget *parent = 0): QWebView(parent), pressed(false), scrolling(false) {
QWebFrame *frame = page()->mainFrame();
frame->setScrollBarPolicy(Qt::Vertical, Qt::ScrollBarAlwaysOff);
frame->setScrollBarPolicy(Qt::Horizontal, Qt::ScrollBarAlwaysOff);
}
protected:
void mousePressEvent(QMouseEvent *mouseEvent) {
if (ignored.removeAll(mouseEvent))
return QWebView::mousePressEvent(mouseEvent);
if (!pressed && !scrolling && mouseEvent->modifiers() == Qt::NoModifier)
if (mouseEvent->buttons() == Qt::LeftButton) {
pressed = true;
scrolling = false;
position = mouseEvent->pos();
QWebFrame *frame = page()->mainFrame();
int x = frame->evaluateJavaScript("window.scrollX").toInt();
int y = frame->evaluateJavaScript("window.scrollY").toInt();
offset = QPoint(x, y);
QApplication::setOverrideCursor(Qt::OpenHandCursor);
return;
}
return QWebView::mousePressEvent(mouseEvent);
}
void mouseReleaseEvent(QMouseEvent *mouseEvent) {
if (ignored.removeAll(mouseEvent))
return QWebView::mouseReleaseEvent(mouseEvent);
if (scrolling) {
pressed = false;
scrolling = false;
QApplication::restoreOverrideCursor();
return;
}
if (pressed) {
pressed = false;
scrolling = false;
QMouseEvent *event1 = new QMouseEvent(QEvent::MouseButtonPress,
position, Qt::LeftButton,
Qt::LeftButton, Qt::NoModifier);
QMouseEvent *event2 = new QMouseEvent(*mouseEvent);
ignored << event1;
ignored << event2;
QApplication::postEvent(this, event1);
QApplication::postEvent(this, event2);
QApplication::restoreOverrideCursor();
return;
}
return QWebView::mouseReleaseEvent(mouseEvent);
}
void mouseMoveEvent(QMouseEvent *mouseEvent) {
if (scrolling) {
QPoint delta = mouseEvent->pos() - position;
QPoint p = offset - delta;
QWebFrame *frame = page()->mainFrame();
frame- >evaluateJavaScript(QString("window.scrollTo(%1,%2);").arg(p.x()).arg(p.y()));
return;
}
if (pressed) {
pressed = false;
scrolling = true;
return;
}
return QWebView::mouseMoveEvent(mouseEvent);
}
};
And usage:
PanWebView web;
web.setUrl(QUrl("http://news.google.com"));
web.setWindowTitle("Web View - use mouse to drag and pan around");
web.show();
Also did you check this and this topics? I think it can be usefull.
In Qt5, I have a main window with a scene:
MyWindow::MyWindow(QWidget *parent) : QMainWindow(parent)
{
view = new QGraphicsView();
scene = new QGraphicsScene();
scene->installEventFilter(this);
view->setScene(scene);
...
setCentralWidget(view);
}
view and scene are both private members of MyWindow. I want to know, in the MyWindow class, the mouse position when I click on the scene. That's why I use installEventFilter above. And I have tried to catch the event with this:
bool MyWindow::eventFilter(QObject *target, QEvent *event)
{
if (target == scene)
{
if (event->type() == QEvent::GraphicsSceneMousePress)
{
const QGraphicsSceneMouseEvent* const me = static_cast<const QGraphicsSceneMouseEvent*>(event);
const QPointF position = me->pos();
cout << position.x() << "," << position.y() << endl;
}
}
return QMainWindow::eventFilter(target, event);
}
This code does not work as expected: The position it prints when I click on the scene is always 0,0. Any clue about what is wrong?
QGraphicsSceneMouseEvent.pos() returns position in coordinates of item on which you clicked. Your scene has no items so it returns (0,0). If you want to get position in scene coordinates use scenePos().
const QPointF position = me->scenePos();
I am trying to get the positions of the graphicsitems in the scene.
But their QPointF value always remains (0,0).
I am painting when mouse-click event occurs. On debugging scene->items(), I get
(QGraphicsItem(this =0x22edff0, parent =0x0, pos =QPointF(0, 0) , z = 0 , flags = ( ) ) )
for each graphics item in scene but with different memory address.
This is my mainwindow.cpp code:
#include "mainwindow.h"
#include <QDebug>
MainWindow::MainWindow()
{
scene = new QGraphicsScene;
view = new QGraphicsView;
view->setScene(scene);
button = new QPushButton("Item");
QGridLayout *layout = new QGridLayout;
layout->addWidget(button);
layout->addWidget(view);
setLayout(layout);
connect(button, SIGNAL(clicked()), this, SLOT(createItem()));
}
void MainWindow::createItem()
{
myEntity = new Item;
scene->addItem(myEntity);
count_items();
}
void MainWindow::count_items()
{
qDebug() << scene->items().count();
qDebug() << scene->items();
}
MainWindow::~MainWindow()
{}
This is my item.cpp code:
#include "item.h"
Item::Item()
{
ClickFlag = true;
PaintFlag = false;
}
Item::~Item(){}
QRectF Item::boundingRect() const
{
// outer most edges
return QRectF(0,0,1450,1400);
}
void Item::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
if(event->button()==Qt::LeftButton){
if(ClickFlag){
x = event->pos().x();
y = event->pos().y();
PaintFlag = true;
ClickFlag = false;
}
}
}
void Item::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
QWidget *widget)
{
if(PaintFlag){
QPen paintPen;
paintPen.setWidth(4);
pt.setX(x);
pt.setY(y);
painter->setPen(paintPen);
painter->drawPoint(x,y);
update();
}
}
I can't seem to find the position of these items correctly.
This task is supposed to be implemented in another way. For example:
Use QGraphicsScene::addEllipse to add small ellipse (which will look like a point) to the scene. Save the pointer to it in a class variable. The ellipse itself should be at the center, e.g. (-1, -1, 2, 2).
Reimplement QGraphicsScene::mousePressEvent, detect mouse clicks and call setPos for the ellipse item (or add new ellipse each time and immediately call setPos if you need multiple points).
Use QGraphicsItem::pos to get previously set positions.
Reimplementing QGraphicsItem::paint is usually an over-complication. Qt have plenty of item classes for all common needs. Just build your scene from geometric primitives, pixmaps, etc.
I have a list of objects that I use to add objects into a QGraphicsScene:
for(int i = 0; i < levelObjects.length(); i++)
{
QRect objRect;
objRect = spriteSheetLocations.value(levelObjects.at(i).value("frame_name"));
//Q_ASSERT_X(objRect != QRect(0,0,0,0), "MainWindow::loadFile()", "Could not find sprite location!");
QImage img = spriteSheet.copy(objRect);
int height = levelObjects.at(i).value("height").toInt();
int width = levelObjects.at(i).value("width").toInt();
int x = levelObjects.at(i).value("x").toInt();
int y = levelObjects.at(i).value("y").toInt();
img = img.scaled(QSize(width, height), Qt::IgnoreAspectRatio);
item = scene->addPixmap(QPixmap::fromImage(img));
int xPos = x - width/2;
int yPos = levelPlist.value("level_height").toInt() - (y + height/2);
item->setPos(xPos, yPos);
}
Later on, in the GraphicsScene class, I detect when the user clicks on an item and drags it to move it:
void LevelGraphicsView::mousePressEvent(QMouseEvent *event)
{
if (QGraphicsItem *item = itemAt(event->pos())) {
qDebug() << "You clicked on item" << item;
draggedItem = item;
int mouseX = draggedItem->pos().x() - mapToScene(event->pos()).x();
int mouseY = draggedItem->pos().y() - mapToScene(event->pos()).y();
mouseOffset = QPointF(mouseX, mouseY);
} else {
qDebug() << "You didn't click on an item.";
draggedItem = NULL;
mouseOffset = QPointF(0,0);
}
}
void LevelGraphicsView::mouseMoveEvent(QMouseEvent *event)
{
if(!draggedItem) // no item selected
return;
QPointF pos = mapToScene(event->pos()) + mouseOffset;
draggedItem->setPos(pos);
}
This works fine for moving the items in the graphics view, but I'm having trouble tracing the QGraphicsItem back to the list item that created it.
What's the best way to link the QGraphicsItem with the list item from which it was made so that the list item can be changed to reflect the change of position?
You could assign each item in your domain object a QUuid property and pass this along to a property in your QGraphicsItem. I have used this on a project and it works quite well. I added a QHash lookup table to my domain model to make it more efficient, but this would not be necessary for shorter lists.
The best way would be a way that does not require to manualy sync items from your list and items on the scene.
The best way to do that depends on your design - may be your items can become pointers to the items on the scene or they can hold ones.