My main.cpp
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QSurfaceFormat format;
format.setDepthBufferSize(24);
format.setStencilBufferSize(8);
format.setVersion(3, 2);
format.setProfile(QSurfaceFormat::CoreProfile);
format.setSamples(4);
QSurfaceFormat::setDefaultFormat(format);
MyGLWidget w;
w.setFormat(format);
QGraphicsScene scene;
QGraphicsProxyWidget* proxy = scene.addWidget(&w);
scene.addText("Hello");
QGraphicsView view(&scene);
view.show();
return a.exec();
}
My MyGLWidget.h
class MyGLWidget :
public QOpenGLWidget
, protected QOpenGLFunctions
{
public:
MyGLWidget(QWidget* parent = nullptr);
protected:
void initializeGL() override;
void resizeGL(int w, int h) override;
void paintGL() override;
};
MyGLWidget.cpp
MyGLWidget::MyGLWidget(QWidget* parent) : QOpenGLWidget(parent)
{
}
void MyGLWidget::initializeGL()
{
initializeOpenGLFunctions();
glClearColor(1.0f, 0.0f, 1.0f, 1.0f);
}
void MyGLWidget::resizeGL(int w, int h)
{
glViewport(0, 0, w, h);
}
void MyGLWidget::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT);
QPainter p(this);
p.drawText(rect(), Qt::AlignCenter, "Testing");
p.drawEllipse(100, 100, 100, 100);
}
Output image.
It seems that void MyGLWidget::paintGL() wasnt called. How do I call paintGL? Can I set it to auto update rendering?
Also, I get weird exception.
If I made changes like this,
MyGLWidget w;
w.setFormat(format);
w.show();
//QGraphicsScene scene;
//QGraphicsProxyWidget* proxy = scene.addWidget(&w);
//scene.addText("Hello");
//QGraphicsView view(&scene);
//view.show();
I get this. Which means that OpenGL rendering works fine.
Related
I'm trying to create a program in which you can connect points together with lines. I instantiate QGraphicsEllipseItem into a QGraphicsScene and I use HoverEnterEvent and HoverLeaveEvent to change the color and the size of the ellipses when the mouse is over them. To draw a temporary line between the point clicked and the mouse cursor I have to use MouseMoveEvent into the scene. However, when I do that, the HoverEvents of the items don't work anymore ! How can I use both MouseMoveEvent of the scene and HoverEvents of the items ?
void GraphicsScene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
for (int i = 0; i < pointList.size(); ++i) {
if (pointList[i]->over == 1){
pointList[i]->press();
lineActivated=true;
tempLine.setLine(pointList[i]->x(),pointList[i]->y(),pointList[i]->x(),pointList[i]->y());
}
}
}
void GraphicsScene::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
if(lineActivated){
const QPointF pos = event->scenePos();
tempLine.setP2(pos);
}
}
void Point::hoverEnterEvent(QGraphicsSceneHoverEvent *event)
{
pen.setColor(Qt::green);
pen.setWidth(2);
this->setPen(pen);
over=true;
qDebug("enter");
update();
}
void Point::hoverLeaveEvent(QGraphicsSceneHoverEvent *event)
{
if(isClicked==false){
pen.setColor(Qt::lightGray);
pen.setWidth(1);
over=false;
this->setPen(pen);
qDebug("leave");
update();
}
}
By default QGraphicsScene::mouseMoveEvent sends the necessary information to handle the hover event of the items but override that method you eliminate that behavior. The solution is to call the parent method.
#include <QtWidgets>
class GraphicsScene: public QGraphicsScene{
public:
using QGraphicsScene::QGraphicsScene;
protected:
void mousePressEvent(QGraphicsSceneMouseEvent *event){
if(!m_lineitem){
m_lineitem = new QGraphicsLineItem;
addItem(m_lineitem);
}
QLineF l(event->scenePos(), event->scenePos());
m_lineitem->setLine(l);
QGraphicsScene::mousePressEvent(event);
}
void mouseMoveEvent(QGraphicsSceneMouseEvent *event){
if(m_lineitem){
QLineF l(m_lineitem->line().p1(), event->scenePos());
m_lineitem->setLine(l);
}
QGraphicsScene::mouseMoveEvent(event);
}
private:
QGraphicsLineItem *m_lineitem = nullptr;
};
class Point: public QGraphicsEllipseItem{
public:
Point(QGraphicsItem *parent=nullptr): QGraphicsEllipseItem(parent){
setRect(QRectF(-5, -5, 10, 10));
QPen pen;
pen.setColor(Qt::lightGray);
pen.setWidth(1);
setPen(pen);
setAcceptHoverEvents(true);
}
protected:
void hoverEnterEvent(QGraphicsSceneHoverEvent *event){
QPen pen;
pen.setColor(Qt::green);
pen.setWidth(2);
setPen(pen);
QGraphicsEllipseItem::hoverEnterEvent(event);
}
void hoverLeaveEvent(QGraphicsSceneHoverEvent *event){
QPen pen;
pen.setColor(Qt::lightGray);
pen.setWidth(1);
setPen(pen);
QGraphicsEllipseItem::hoverLeaveEvent(event);
}
};
int main(int argc, char *argv[]){
QApplication a(argc, argv);
GraphicsScene *scene = new GraphicsScene;
QGraphicsView w(scene);
w.setRenderHint(QPainter::Antialiasing, true);
w.fitInView(QRectF(0, 0, 100, 100), Qt::KeepAspectRatio);
for(const QPointF & p: {QPointF(10.0, 10.0), QPointF(90.0, 20.0), QPointF(30.0, 40.0)}){
Point *it = new Point();
scene->addItem(it);
it->setPos(p);
}
w.resize(640, 480);
w.show();
return a.exec();
}
i have graphic view(QGraphics view) setted scene(QGraphic scene) i am dropping objects on scene its working fine, i have to assign parameter for dropped object by dragging parameter from parameter list .i have implemented drag drop events of object.but when i am dragging parameter from param list non- acceptance symbol on object.how to assign param to object by dropping ? Any other suggestions and examples are welcome where i can get ideas to implementation.
image of gui
speedometer.cpp
#include <QMimeData>
SpeedoMeter::SpeedoMeter( QWidget *parent ):
QwtDial( parent ),
d_label( "km/h" )
{
setAcceptDrops(true);
}
void SpeedoMeter::dragEnterEvent(QDragEnterEvent *event)
{
if (event->mimeData()->hasFormat(paramlistMimeType()))
{
qDebug()<<"dragenter event in speedo" ;
event->accept();
}
}
void SpeedoMeter::dragMoveEvent(QDragMoveEvent *event)
{
if (event->mimeData()->hasFormat(paramlistMimeType()))
{
qDebug()<<"dragmove event in speedo" ;
event->acceptProposedAction();
}
}
void SpeedoMeter::dropEvent(QDropEvent *event)
{
if (event->mimeData()->hasFormat(paramlistMimeType()))
{
qDebug()<<"dragmove event in speedo" ;
event->accept();
}
}
The following example shows how to implement the logic to accept the drag-and-drop:
speedometer.h
#ifndef SPEEDOMETER_H
#define SPEEDOMETER_H
#include <qwt_dial.h>
class SpeedoMeter : public QwtDial
{
public:
SpeedoMeter(QWidget *parent=nullptr);
protected:
void dragEnterEvent(QDragEnterEvent *event);
void dropEvent(QDropEvent *event);
void dragMoveEvent(QDragMoveEvent *event);
void paintEvent(QPaintEvent *event);
private:
QString d_label;
};
#endif // SPEEDOMETER_H
speedometer.cpp
#include "speedometer.h"
#include <qwt_dial_needle.h>
#include <QDragEnterEvent>
#include <QMimeData>
#include <QPainter>
SpeedoMeter::SpeedoMeter(QWidget *parent):
QwtDial(parent),
d_label( "km/h" )
{
setAcceptDrops(true);
QwtDialSimpleNeedle *nd = new QwtDialSimpleNeedle(QwtDialSimpleNeedle::Arrow, Qt::white, Qt::red);
setNeedle(nd);
setValue(80);
}
void SpeedoMeter::dragEnterEvent(QDragEnterEvent *event)
{
if(event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist"))
event->acceptProposedAction();
}
void SpeedoMeter::dropEvent(QDropEvent *event)
{
const QMimeData *mimedata = event->mimeData();
if(mimedata->hasFormat("application/x-qabstractitemmodeldatalist")){
QString text;
// https://stackoverflow.com/questions/1723989/how-to-decode-application-x-qabstractitemmodeldatalist-in-qt-for-drag-and-drop
QByteArray encoded = mimedata->data("application/x-qabstractitemmodeldatalist");
QDataStream stream(&encoded, QIODevice::ReadOnly);
while (!stream.atEnd()) {
int row, col;
QMap<int, QVariant> roleDataMap;
stream >> row >> col >> roleDataMap;
if(roleDataMap.contains(Qt::DisplayRole)){
text = roleDataMap[Qt::DisplayRole].toString();
break;
}
}
// your text
d_label = text;
update();
}
}
void SpeedoMeter::dragMoveEvent(QDragMoveEvent *event)
{
if(event->mimeData()->hasFormat("application/x-qabstractitemmodeldatalist"))
event->accept();
}
void SpeedoMeter::paintEvent(QPaintEvent *event)
{
// https://stackoverflow.com/questions/43904204/qwt-dial-show-unit
QwtDial::paintEvent(event);
QPainter painter(this);
painter.setPen(Qt::black);
QFont font;
font.setPointSize(11);
painter.setFont(font);
QString text = QString("%1 %2").arg(value()).arg(d_label);
QPoint c = rect().center();
QSize Size = painter.fontMetrics().size(Qt::TextSingleLine, text);
painter.drawText(QPointF(c.x() -Size.width()/2, c.y() + 2.5*Size.height()), text);
}
main.cpp
#include "speedometer.h"
#include <QApplication>
#include <QGraphicsView>
#include <QHBoxLayout>
#include <QListWidget>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget w;
QHBoxLayout *layout = new QHBoxLayout(&w);
QListWidget listWidget;
listWidget.setDragDropMode(QAbstractItemView::DragOnly);
listWidget.addItems({"km/h", "ft/s", "m/s", "miles/h"});
QGraphicsView view;
QGraphicsScene scene;
view.setScene(&scene);
SpeedoMeter speed;
scene.addWidget(&speed);
layout->addWidget(&listWidget);
layout->addWidget(&view);
w.show();
return a.exec();
}
In the following link you can find the complete example.
I have tried this method (Answer of NikitaFeodonit) for offscreen rendering and creating a QImage and saving to disk. Everything is working fine, except when using a QColor with Alpha-Channel for QPen.
QPainter.drawEllipse without ALPHA in Pen-Color
QPainter.drawEllipse with ALPHA in Pen-Color
Here is my source:
Using OpenGlOffscreenSurface from this method:
Header ExamplePaintSurface.h:
#ifndef EXAMPLEPAINTSURFACE_H
#define EXAMPLEPAINTSURFACE_H
#include <QPainter>
#include "OpenGlOffscreenSurface.h"
class ExamplePaintSurface
: public OpenGlOffscreenSurface
{
public:
explicit ExamplePaintSurface(
QScreen* targetScreen = nullptr,
const QSize& size = QSize (1, 1));
void renderImage(bool useAlpha);
virtual ~ExamplePaintSurface() override;
protected:
virtual void initializeGL() override;
virtual void resizeGL(
int width,
int height) override;
virtual void paintGL() override;
private:
bool m_useAlpha;
};
#endif // EXAMPLEPAINTSURFACE_H
Source ExamplePaintSurface.cpp:
#include "ExamplePaintSurface.h"
ExamplePaintSurface::ExamplePaintSurface(
QScreen* targetScreen,
const QSize& size)
: OpenGlOffscreenSurface(targetScreen, size) {}
void ExamplePaintSurface::renderImage(bool useAlpha)
{
m_useAlpha = useAlpha;
this->paintGL();
}
ExamplePaintSurface::~ExamplePaintSurface() {}
void ExamplePaintSurface::initializeGL() {}
void ExamplePaintSurface::resizeGL(int width, int height) {}
void ExamplePaintSurface::paintGL()
{
QPainter painter(getPaintDevice());
painter.eraseRect(0,0,200,200);
painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);
painter.setCompositionMode (QPainter::CompositionMode_Source);
painter.fillRect(0,0,200,200, Qt::transparent);
painter.setCompositionMode (QPainter::CompositionMode_SourceOver);
QPen pen;
if(m_useAlpha == true)
pen.setColor(QColor(255, 0, 0, 150));
else
pen.setColor(QColor(255, 0, 0, 255));
QBrush brush(Qt::yellow);
brush.setStyle(Qt::SolidPattern);
pen.setWidth(8);
painter.setPen(pen);
painter.setBrush(brush);
painter.drawEllipse(50,50,100,100);
//painter.drawText(20, 40, "Test"); // <-- drawing here
painter.end();
}
Source main.cpp:
#include <QApplication>
#include "ExamplePaintSurface.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
ExamplePaintSurface paintSurface;
paintSurface.resize(200, 200);
paintSurface.renderImage(false);
paintSurface.render();
QImage image = paintSurface.grabFramebuffer();
image.save("Ellipse_noAlpha.png");
paintSurface.renderImage(true);
paintSurface.render();
image = paintSurface.grabFramebuffer();
image.save("Ellipse_alpha.png");
return a.exec();
}
I have a QDialog for beginning of my game.in this class I have a QGraphicsTextItem. I want to it is clickable. When user clicked play game start. I do this but not work.
class Mydialog_start:public QDialog
{
Q_OBJECT
public:
explicit Mydialog_start(QWidget *parent = 0);
signals:
public slots:
void on_play_clicked();
void on_exit_clicked();
private:
QGraphicsScene* scene;
QGraphicsView* view;
QPixmap image;
QBrush brush;
QGraphicsTextItem* text;
QFont font;
const int x_size;
const int y_size;
};
Mydialog_start::Mydialog_start(QWidget *parent) :
QDialog(parent),x_size(400),y_size(400)
{
scene=new QGraphicsScene(this);
view=new QGraphicsView(this);
view->setScene(scene);
scene->setSceneRect(0,0,x_size,y_size);
image.load(":picture/image/background.jpg");
image=image.scaled(x_size,y_size);
brush.setTexture(image);
scene->setBackgroundBrush(brush);
font.setBold(true);
font.setPointSize(40);
font.setItalic(true);
text=scene->addText("play",font);
text->setDefaultTextColor(QColor("red"));
text->setPos(100,300);
this->setFixedSize(400,400);
connect(text,SIGNAL(linkActivated(QString("play"))),this,SLOT(on_play_clicked()));
}
void Mydialog_start::on_play_clicked()
{
accept();
}
void Mydialog_start::on_exit_clicked()
{
reject();
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
Mydialog_start dialog;
dialog.exec();
if( dialog.exec()==QDialog::Accepted)
{
w.show();
}
else
{
w.close();
}
}
Not quite sure whether you needed your text item to be "editable" - see Mitch's comment...
It seems that you need your item to be "clickable" - then all you need are some flags:
text->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable);
I coded a small QT program using QGLWidget. The goal is to display a simple triangle in permanent rotation. The problem is that there is no animation because just the first frame is rendered.
Here's my main C++ source code :
#include "qtapplication.h"
#include <QtWidgets/QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QtApplication w;
w.show();
return a.exec();
}
My qtapplication.h file :
include <QtWidgets/QMainWindow>
#include "ui_qtapplication.h"
#include "HSGLWidget.hpp"
class QtApplication : public QMainWindow
{
Q_OBJECT
public:
QtApplication(QWidget *parent = 0);
~QtApplication();
private:
Ui::QtApplicationClass ui;
HSGLWidget *_glwidget;
};
My qtapplication.cpp file :
#include "qtapplication.h"
QtApplication::QtApplication(QWidget *parent)
: QMainWindow(parent)
{
ui.setupUi(this);
this->_glwidget = NULL;
if (this->_glwidget == NULL)
this->_glwidget = new HSGLWidget();
this->_glwidget->setVisible(true);
setCentralWidget(this->_glwidget);
}
QtApplication::~QtApplication()
{
}
My HSGLWidjet.h file:
#include <QGLWidget>
class HSGLWidget : public QGLWidget {
Q_OBJECT
public:
explicit HSGLWidget(QWidget *parent = 0);
virtual ~HSGLWidget();
protected:
virtual void initializeGL();
virtual void resizeGL(int width, int height);
virtual void paintGL();
virtual void keyPressEvent(QKeyEvent *keyEvent);
private:
void _onSetup();
private:
QTimer *_timer;
};
And my HSGLWidjet.cpp file:
#include <iostream>
#include "HSGLWidget.hpp"
float toto_angle = 0.0f;
HSGLWidget::HSGLWidget(QWidget *parent)
: QGLWidget(parent)
{
this->_onSetup();
}
HSGLWidget::~HSGLWidget(void)
{
}
void HSGLWidget::initializeGL()
{
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.20f, 0.0f, 0.0f);
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
}
void HSGLWidget::resizeGL(int width, int height)
{
if (height == 0)
height = 1;
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 100.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void HSGLWidget::paintGL(void)
{
std::cout << "PAINTGL" << std::endl;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glTranslatef(-1.5f, 0.0f, -6.0f);
glEnable(GL_MODELVIEW);
glPushMatrix();
glTranslatef(0.0f, 0.0f, 0.0f);
glRotatef(toto_angle, 1.0f, 1.0f, 1.0f);
glScalef(1.0f, 1.0f, 1.0f);
glBegin(GL_TRIANGLES);
glColor3ub(255, 0, 0);
glVertex3f(0.0f, 0.75f, 0.0f);
glColor3ub(0, 255, 0);
glVertex3f(-0.75f, 0.0f, 0.0f);
glColor3ub(0, 0, 255);
glVertex3f(0.75f, 0.0f, 0.0f);
glEnd();
toto_angle+=1.0f;
glPopMatrix();
}
void HSGLWidget::keyPressEvent(QKeyEvent *keyEvent)
{
}
void HSGLWidget::_onSetup()
{
}
The string 'PAINTGL' is written just for the first frame. Normally, paintGL is called automatically. I'm really lost in front of this situation. Does anyone can help me, please ? Thanks a lot in advance for your help.
There's no problem at all, that's the standard behavior.
You see, paint() and paintGL() are called only when the window needs to be draw. That is: when your application is created, when the window is resized, or moved around. Only then paintGL() is triggered. That's it!
If you want it to be called more than once, you will need to add a timer to execute update(), which is a method that forces the window to be redraw, which in turn triggers paintGL(). Do not call paintGL() directly!
QTimer can help you achieve what you are looking for!