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  • Custom QGraphicsItems not compiling and give object is is private error

    - by bahree
    Hi, I am trying to create a Custom QGraphicsItem button as shown by Fred here. The code which he posted can be found here. The problem is when I try and compile the code I get the following two errors: /usr/include/qt4/QtGui/qgraphicsitem.h ‘QGraphicsItem::QGraphicsItem(const QGraphicsItem&)’ is private /usr/include/qt4/QtCore/qobject.h ‘QObject::QObject(const QObject&)’ is private Here is the code snippet which essentially is the same as that in the sample above. The error is on the class deceleration. class MyButton : public QObject, public QGraphicsItem { Q_OBJECT Q_INTERFACES(QGraphicsItem) public: MyButton(QGraphicsItem *parent = 0); MyButton(const QString normal, const QString pressed = "", QGraphicsItem *parent = 0); .... } Interestingly the other sample as shown here works fine. The sample code for that can be found here. Any idea what is wrong? Thanks in advance.

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  • Container item implementation

    - by onurozcelik
    Hi, I am working in Train Traffic Controller software project. My responsibility in this project is to develop the visual railroad GUI. We are implementing the project with Qt. By now I am using QGraphicsLinearLayout to hold my items. I am using the layout because I do not want to calculate coordinates of each item. So far I wrote item classes to add the layout. For instance SwitchItem class symbolizes railroad switch in real world. Each item class is responsible for its own painting and events. So far so good. Now I need a composite item that can contain two or more item. This class is going to be responsible for painting the items contained in it. I need this class because I have to put two or more items inside same layout cell. If I don' t put them in same cell I can' t use layout. See the image below. BlockSegmentItem and SignalItem inside same cell. Here is my compositeitem implementation. #include "compositeitem.h" CompositeItem::CompositeItem(QString id,QList<FieldItem *> _children) { children = _children; } CompositeItem::~CompositeItem() { } QRectF CompositeItem::boundingRect() const { FieldItem *child; QRectF rect(0,0,0,0); foreach(child,children) { rect = rect.united(child->boundingRect()); } return rect; } void CompositeItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget ) { FieldItem *child; foreach(child,children) { child->paint(painter,option,widget); } } QSizeF CompositeItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const { QSizeF itsSize(0,0); FieldItem *child; foreach(child,children) { // if its size empty set first child size to itsSize if(itsSize.isEmpty()) itsSize = child->sizeHint(Qt::PreferredSize); else { QSizeF childSize = child->sizeHint(Qt::PreferredSize); if(itsSize.width() < childSize.width()) itsSize.setWidth(childSize.width()); itsSize.setHeight(itsSize.height() + childSize.height()); } } return itsSize; } void CompositeItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event) { qDebug()<<"Test"; } This code works good with painting but when it comes to item events it is problematic. QGraphicsScene treats the composite item like a single item which is right for layout but not for events. Because each item has its own event implementation.(e.g. SignalItem has its special context menu event.) I have to handle item events seperately. Also I need a composite item implementation for the layout. How can I overcome this dilemma?

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  • Qt - invalid conversion to child class

    - by David Davidson
    I'm drawing polygons using the Graphics View framework. I added a polygon to the scene with this: QGraphicsPolygonItem *poly = scene->addPolygon(QPolygonF(vector_of_QPointF)); poly->setPos(some_point); But I need to implement some custom behaviour like selection, mouse over indicator, and other similar stuff on the graphics item. So I declared a class that inherits QGraphicsPolygonItem: #include <QGraphicsPolygonItem> class GridHex : public QGraphicsPolygonItem { public: GridHex(QGraphicsItem* parent = 0); }; GridHex::GridHex(QGraphicsItem* parent) : QGraphicsPolygonItem(parent) { } Not doing much with that class so far, as you can see. But shouldn't replacing QGraphicsPolygonItem with my GridHex class? This is throwing a " invalid conversion from 'QGraphicsPolygonItem*' to 'GridHex*' " error: GridHex* poly = scene->addPolygon(QPolygonF(vector_of_QPointF)); What am I doing wrong?

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  • Qt Qbrush issue

    - by Solitaire
    What is the difference in the following code, QGraphicsScene * scence = new QGraphicsScene(); QBrush *brush = new QBrush((QColor(60,20,20))); scence->setBackgroundBrush(*brush); QGraphicsView *view = new QGraphicsView(); view->setScene(scence); //view->setBackgroundBrush(*brush); //view->setCacheMode(QGraphicsView::CacheBackground); view->showFullScreen(); gives black color background QGraphicsScene * scence = new QGraphicsScene(); QBrush *brush = new QBrush(); brush->setColor(QColor(60,20,20)); scence->setBackgroundBrush(*brush); QGraphicsView *view = new QGraphicsView(); view->setScene(scence); //view->setBackgroundBrush(*brush); //view->setCacheMode(QGraphicsView::CacheBackground); view->showFullScreen(); it gives nothing.

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  • How to draw QGraphicsItem in a MFC view

    - by user336969
    I'm starting using Qt in my application. My application is MFC based. I want to draw some QGraphicsItems in my currect MFC view, is it possible? You may say that it could be done by hosting QGraphicsView with QWinWidget in the MFC view, that don't work, however. Because my Canvas (MFC view) supports zooming and rotating while the QGraphicsView itself don't. When I zooming the QGraphicsItem, the QGraphicsView shows scroll bar instead of enlarging itself. Any suggestion? Thanks!

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  • how to use drawItems() in PyQt?

    - by DSblizzard
    I have these two code fragments in program: class TGraphicsView(QGraphicsView): def __init__(self, parent = None): print("__init__") QGraphicsView.__init__(self, parent) def drawItems(self, Painter, ItemCount, Items, StyleOptions): print("drawItems") Brush = QBrush(Qt.red, Qt.SolidPattern) Painter.setBrush(Brush) Painter.drawEllipse(0, 0, 100, 100) ... Mw.gvNavigation = TGraphicsView(Mw) # Mw - main window Mw.gvNavigation.setGeometry(0, 0, Size1, Size1) Mw.gvNavigation.setScene(Mw.Scene) Mw.gvNavigation.setSceneRect(0, 0, Size2, Size2) Mw.gvNavigation.show() _init_ works, Mw.gvNavigation is displayed and there are Mw.Scene items in it, but drawItems() isn't called. Please explain, what I'm doing wrong.

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  • Using custom coordinates with QGraphicsScene

    - by Rob
    I am experimenting with a WYSIWYG editor that allows a user to draw shapes on a page and the Qt graphics scene support seems perfect for this. However, instead of working in pixels I want all my QGraphicsItem objects to work in tenths of a millimetre but I don't know how to achieve this. For example: // Create a scene that is the size if an A4 page (2100 = 21cm, 2970 = 29.7cm) QGraphicsScene* scene = new QGraphicsScene(0, 0, 2100, 2970); // Add a rectangle located 1cm across, 1cm down, 5cm wide and 2cm high QGraphicsItem* item = scene->addRect(100, 100, 500, 200); ... QGraphicsView* view = new QGraphicsView(scene); setCentralWidget(view); Now, when I display the scene above I want the shapes to appear at correct size for the screen DPI. Is this simply a case of using QGraphicsView::scale or do I have to do something more complicated? Note that if I was using a custom QWidget instead then I would use QPainter::setWindow and QPainter::setViewport to create a custom mapping mode but I can't see how to do this using the graphics scene support.

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  • How to use custom drawing in QGraphicsViews in PyQt?

    - by DSblizzard
    I need to view QGraphicsScene in 2 QGraphicsViews with condition that they have different scale factors for items in scene. Closest function which I found is drawItems(), but as far I can understand, it must be called manually. How to repaint views automatically? I have these two code fragments in program: class TGraphicsView(QGraphicsView): def __init__(self, parent = None): print("__init__") QGraphicsView.__init__(self, parent) def drawItems(self, Painter, ItemCount, Items, StyleOptions): print("drawItems") Brush = QBrush(Qt.red, Qt.SolidPattern) Painter.setBrush(Brush) Painter.drawEllipse(0, 0, 100, 100) ... Mw.gvNavigation = TGraphicsView(Mw) # Mw - main window Mw.gvNavigation.setGeometry(0, 0, Size1, Size1) Mw.gvNavigation.setScene(Mw.Scene) Mw.gvNavigation.setSceneRect(0, 0, Size2, Size2) Mw.gvNavigation.show() _init_ works, Mw.gvNavigation is displayed and there are Mw.Scene items in it, but drawItems() isn't called.

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  • How set opacity on QGraphicsItem

    - by La Chamelle
    Hello, i have a inherited from QGraphicsScene and QGraphicsItem to create my own classes. I use Qt 4.6. I want to set a specific opacity on each items of my scene. I use setOpacity : setOpacity method, but its not the result i hope. I want to have for example one item opaque and an other transparent (to see the desktop, or the other application). But if i dont set the opacity of the QGraphicsView to 0.5, i have not the transparancy. And if the QGraphicsView is set to 0.5, the item is not real opaque. What should i do ? Thanks you.

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  • A pointer member variable having different values

    - by Rohan Prabhu
    Ok, to begin with, this is my code: HyperSprite::HyperSprite() { _view = 0; } void HyperSprite::publish(QGraphicsView* view) { _view = view; } void HyperSprite::getKFrame() { if(_view != 0) { qDebug()<<(void*)_view; } } Now, if I call HyperSprite::getKFrame() from within main(), I get the output: 0xbf8ffb84 I have a TCP server, which requires this QGraphicsView* variable. So whenever a new connection is made, HyperSprite::getKFrame() is called. However, whenever I make a connection to my server, this is the output: 0x1e425ff I honestly don't understand this. Shouldn't the value of a member remain same throughout? Why is the pointer value changing? As is obvious, whenever I try to use the _view pointer to access any of its members, a Segmentation Fault occurs. I tried using QSharedPointer, but it also results in the same problem. The data of the QSharedPointer automatically changes. Why is this happening?

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  • OpenGL dans Qt5, tour d'horizon des nouveautés de l'intégration d'OpenGL dans Qt, un billet de Guillaume Belz

    Bonjour, En attendant un article plus détaillé sur Qt5, voici une présentation des classes et des modules utilisant OpenGL dans Qt5. Je rappelle également comment activer l'accélération matérielle dans Qt4 (QGLWidget, QGraphicsView, QDeclarativeView) et explique comment installer les binaires de Qt5 dans Ubuntu en utilisant les dépôts ppa. L'article du blog : OpenGL dans Qt5. Prochainement, j'aborderai en détail dans ce blog le nouveau module Qt3D de Qt5, avec des projets d'exemple. Que pensez-vous de cette réorgan...

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  • What is the most efficient way to display decoded video frames in Qt?

    - by Jason
    What is the fastest way to display images to a Qt widget? I have decoded the video using libavformat and libavcodec, so I already have raw RGB or YCbCr 4:2:0 frames. I am currently using a QGraphicsView with a QGraphicsScene object containing a QGraphicsPixmapItem. I am currently getting the frame data into a QPixmap by using the QImage constructor from a memory buffer and converting it to QPixmap using QPixmap::fromImage(). I like the results of this and it seems relatively fast, but I can't help but think that there must be a more efficient way. I've also heard that the QImage to QPixmap conversion is expensive. I have implemented a solution that uses an SDL overlay on a widget, but I'd like to stay with just Qt since I am able to easily capture clicks and other user interaction with the video display using the QGraphicsView. I am doing any required video scaling or colorspace conversions with libswscale so I would just like to know if anyone has a more efficient way to display the image data after all processing has been performed. Thanks.

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  • How to display a QGraphicsScene?

    - by Chris
    I've got the following code and I'm not sure how to add the QGraphicsScene to my layout.. class MainForm(QDialog): def __init__(self, parent=None): super(MainForm, self).__init__(parent) self.scene = QGraphicsScene(self) self.scene.setSceneRect(0, 0, 500, 500) self.view = QGraphicsView() self.view.setRenderHint(QPainter.Antialiasing) self.view.setScene(self.scene) self.view.setFocusPolicy(Qt.NoFocus) zoomSlider = QSlider(Qt.Horizontal) zoomSlider.setRange(5, 200) zoomSlider.setValue(100) self.pauseButton = QPushButton("Pause") quitButton = QPushButton("Quit") layout = QVBoxLayout() layout.addWidget(zoomSlider) self.setLayout(layout) self.startTimer(10) How can I get my QGraphicsScene running? I'm new to Qt. Am I even supposed to be adding a QGraphicsScene to a layout/

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  • How create widget with clickable text in QT/PyQt?

    - by serge
    Hi everyone, i'm trying to realize non-editable QTableView with widgets in cells that should contain clickable listed text. With following code i'm setting widget in definite cell: view = QTableView() label = QLabel( <some html text> ) ... view.setIndexWidget(index, label) I used html to make label's text clickable, but links became blue with underline and moreover by clicking on it with right mouse button appears popup menu with "Copy Link Locaion" option, where i wanted to place some hidden information instead of url and of course do not let user see this info. I'm looking for light-weight widget, i thought that insertion of QGraphicsView in each cell will lead to big computer loads, but can't think of any other solution. Can you advice what should i use for this purpose? Thank you in advance Serge

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  • How to create widget with clickable text in QT/PyQt?

    - by serge
    Hi everyone, i'm trying to realize non-editable QTableView with widgets in cells that should contain clickable listed text. With following code i'm setting widget in definite cell: view = QTableView() label = QLabel( <some html text> ) ... view.setIndexWidget(index, label) I used html to make label's text clickable, but links became blue with underline and moreover by clicking on it with right mouse button appears popup menu with "Copy Link Locaion" option, where i wanted to place some hidden information instead of url and of course do not let user see this info. I'm looking for light-weight widget, i thought that insertion of QGraphicsView in each cell will lead to big computer loads, but can't think of any other solution. Can you advice what should i use for this purpose? Thank you in advance Serge

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  • Qt/C++, Problems with large QImage

    - by David Günzel
    I'm pretty new to C++/Qt and I'm trying to create an application with Visual Studio C++ and Qt (4.8.3). The application displays images using a QGraphicsView, I need to change the images at pixel level. The basic code is (simplified): QImage* img = new QImage(img_width,img_height,QImage::Format_RGB32); while(do_some_stuff) { img->setPixel(x,y,color); } QGraphicsPixmapItem* pm = new QGraphicsPixmapItem(QPixmap::fromImage(*img)); QGraphicsScene* sc = new QGraphicsScene; sc->setSceneRect(0,0,img->width(),img->height()); sc->addItem(pm); ui.graphicsView->setScene(sc); This works well for images up to around 12000x6000 pixel. The weird thing happens beyond this size. When I set img_width=16000 and img_height=8000, for example, the line img = new QImage(...) returns a null image. The image data should be around 512,000,000 bytes, so it shouldn't be too large, even on a 32 bit system. Also, my machine (Win 7 64bit, 8 GB RAM) should be capable of holding the data. I've also tried this version: uchar* imgbuf = (uchar*) malloc(img_width*img_height*4); QImage* img = new QImage(imgbuf,img_width,img_height,QImage::Format_RGB32); At first, this works. The img pointer is valid and calling img-width() for example returns the correct image width (instead of 0, in case the image pointer is null). But as soon as I call img-setPixel(), the pointer becomes null and img-width() returns 0. So what am I doing wrong? Or is there a better way of modifying large images on pixel level? Regards, David

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  • How do I controll clipping with non-opaque graphics-item's in Qt?

    - by JJacobsson
    I have a bunch of QGraphicsSvgItem's in a QGraphicsScene that are drawn connected by QGraphicsLineItem's. This show's a graph of a tree-structure. What I want to do is provide a feature where everything but a selected sub-tree becomes transparent. A kind of "highlight this sub-tree" feature. That part was easy, but the results are ugly because now the lines can be seen through the semi-transparent svg's. I am looking for some way to still clip other QGraphicsItem's in the scene to the svg item's, giving the effect that the svg's are semi-transparent windows to the background. I know this code does not use svg's but I figure you can replace that yourself if you are so inclined. int main(int argc, char *argv[]) { QApplication app(argc, argv); QGraphicsScene scene; for( int i = 0; i < 10; ++i ) { QGraphicsLineItem* line = new QGraphicsLineItem; line->setLine( i * 25.0 + 1.0, 0, i * 25.0 + 23.0, 0 ); scene.addItem( line ); } for( int i = 0; i < 11; ++i ) { QGraphicsEllipseItem* ellipse = new QGraphicsEllipseItem; ellipse->setRect( (i * 25.0) - 9.0, -9.0, 18.0, 18.0f ); ellipse->setBrush( QBrush( Qt::green, Qt::SolidPattern ) ); ellipse->setOpacity( 0.5 ); scene.addItem( ellipse ); } QGraphicsView view( &scene ); view.show(); return app.exec(); } I would like the line's to not be seen behind the circle's. I have tried fiddling with the depth-buffer and the stencil buffer using opengl rendering to no avail. How do I get the QGraphicsSvgItem's (or QGraphicsEllipseItem's in the example code) to still clip the lines even though they are semi-transparent?

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  • Qt/C++ - confused about caller/callee, object ownership

    - by Isabel
    I am creating a GUI to manipulate a robot arm. The location of the arm can be described by 6 floats (describing the positions of the various arm joints. The interface consists of a QGraphicsView with a diagram of the arm (which can be clicked to change the arm position - adjusting the 6 floats). The interface also has 6 lineEdit boxes, to also adjust those values separately. When the graphics view is clicked, and when the line edit boxes are changed, I'd like the line edit boxes / graphics view to stay in synchronisation. This brings me to confusion about how to store the 6 floats, and trigger events when they're updated. My current idea is this: The robot arm's location should be represented by a class, RobotArmLocation. Objects of this class then have methods such as obj.ShoulderRotation() and obj.SetShoulderRotation(). The MainWindow has a single instance of RobotArmLocation. Next is the bit I'm more confused about, how to join everything up. I am thinking: The MainWindow has a ArmLocationChanged slot. This is signalled whenever the location object is changed. The diagram class will have a SetRobotArmLocation(RobotArmLocation &loc). When the diagram is changed, it's free to change the location object, and fire a signal to the ArmLocationChanged slot. Likewise, changing any of the text boxes will fire a signal to that ArmLocationChanged slot. The slot then has code to synchronise all the elements. This kind of seems like a mess to me, does anyone have any other suggestions? I've also thought of the following, does it have any merrit? The RobotArmLocation class has a ValueChanged slot, the diagram and textboxes can use that directly, and bypass the MainWindow directly (seems cleaner?) thanks for any wisdom!

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