Marked a needle on the speedometer.
// 이미지 출력
QPixmap pix("C:\\Users\\WORK002\\Desktop\\speedmeter.png");
QPixmap pix2("C:\\Users\\WORK002\\Desktop\\pointer.png");
QPixmap pointer = pix2.scaled(300, 300);
scene.addPixmap(pix);
scene.addPixmap(pointer);
ui-> graphicsView ->setScene(&scene);
ui-> graphicsView ->show();
I want rotate and reposition.
How can i do this?
You don't have to mess with the QPixmap, you can manipulate the QGraphicsPixmapItem returned by QGraphicsScene::addPixmap:
QGraphicsPixmapItem *pixmap_item = scene.addPixmap(pix);
To set the position, you can use QGraphicsItem::setPos.
To set the rotation, first set the transform origin point with QGraphicsItem::setTransformOriginPoint,(this will set the point around which your item will be rotated) and then set the rotation with QGraphicsItem::setRotation:
pixmap_item->setPos(50, 0);
pixmap_item->setTransformOriginPoint(pixmap_item->boundingRect().center());
pixmap_item->setRotation(90);
You will have to set the correct values yourself, but this should lead you in the right way.
You can look into QPixmap::transformed()
QPixmap QPixmap::transformed(const QTransform &transform, Qt::TransformationMode mode = Qt::FastTransformation) const
The specification can be given through the QTransform object:
rotate() for rotation
translate() for reposition
may this one can help:
//Please note this method takes 2 mseg to finish for a 20x20 pixmap.
QPixmap rotatedPixmap(m_pixOriginal.size());
rotatedPixmap.fill(QColor::fromRgb(0, 0, 0, 0)); //the new pixmap must be transparent.
QPainter* p = new QPainter(&rotatedPixmap);
QSize size = m_pxOriginal.size();
p->translate(size.height()/2,size.height()/2);
p->rotate(m_iAngle);
p->translate(-size.height()/2,-size.height()/2);
p->drawPixmap(0, 0, m_pxOriginal);
p->end();
delete p;
m_pxItem->setPixmap(rotatedPixmap);
copied from:
Read this forum thread
Related
I am trying to implement the same functionality in my widget as it is in cv:: namedWindow.
The goal is to enable zooming and to make the overlay with the grid and the values of pixel's colors directly over the original pixmap. Here is the example: сv picture zoomed:
I inherited the QGraphicsView widget, added to QGraphicsScene the QGraphicsPixmapItem and reimplemented the QWheelEvent so that zooming in and out works correctly now. The problem starts with creating an overlay.
Instead of creating a pack of QGraphicsLineItems and adding them to the scene in order to make the grid, I inherit the QGraphicsRectItem and draw the whole grid on it.
void QGraphicsOverlayItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QPen pen(Qt::black);
pen.setWidthF(0.02);
painter->setPen(pen);
painter->setBrush(Qt::BrushStyle::NoBrush);
QVector<QLineF> crossLines = createCrossLines();
painter->drawLines(crossLines);
}
This works very fast. But when I try to drawText with the QPainter and set the QFont:: pointSizeF() as small as possible, it works incorrectly (symbols change their size from small to huge during zooming or even disappear at all). Nevertheless, the best result that I get this way is the following:
the QPainter's drawText() result:
QFont font(painter->font());
font.setPointSizeF(0.1);
font.setLetterSpacing(QFont::SpacingType::AbsoluteSpacing,0.01);
painter->setFont(font);
painter->drawText(432,195,"123");
The easiest way is to add to scene a lot of QGraphicsTextItems and scale them to correct size, but it is too slow.
So the question is how can I subscribe the pixel's color value in the QGraphicsScene directly over the QPixmapItem?
I finally watched through the openCV source code and found what I looked for.
The answer for me was the QTransform matrix. OpenCV developers show the image not by using the scene in the QGraphicsView, but actually painting the image directly on the viewport in the paintEvent.
The QTransform matrix is stored in the class and is passed to QPainter in the beginning of the paintEvent.
void DefaultViewPort::paintEvent(QPaintEvent *event)
{
QPainter painter(viewport());
painter.setWorldTransform(param_matrixWorld);
painter.drawImage(QRect(0,0,viewport()->width(),viewport()->height()),image2Draw,QRect(0,0,image2Draw.width(),image2Draw.height()));
If you know the ratio of the image's size to the widget's size, and you also know the scale of QTransform matrix used to paint the image, it is easy to calculate how much area does the single source pixel take on the screen:
qreal ratioX = width() / float(image2Draw.width());
qreal ratioY = height() / float(image2Draw.height());
double pixel_width = qtransform_matrixWorld.m11()*ratioX;
double pixel_height = qtransform_matrixWorld.m11()*ratioY;
If we know the pixel_height, we can just set the QFont::pixelSize like this:
QFont font = painter->font();
font.setPixelSize(pixel_height/5);
painter->setFont(font);
I'm trying to save a chart to a file, in a QTextDocument in this example :
QTextDocument doc("Frame rate test\n");
QTextCursor cursor(&doc);
cursor.movePosition(QTextCursor::End);
if (getTestFinishedStatus())
{
QPixmap pix = _pFrameRateChart->grab(); //_pFrameRateChart is QChartView
cursor.insertImage(pix.toImage());
}
QTextDocumentWriter docWriter;
docWriter.setFileName("framerate.odf");
docWriter.setFormat("ODF");
docWriter.write(&doc);
The problem is the result isn't same if I'm displaying the chart in an ui.
Here is the result when not displayed :
Here is the result when displayed :
Obviously I would like to have the second result even when I don't add the ChartView to a widget to display it on an ui.
I've tried resizing the QChartView, resizing the QChart, adding the Chart to a temporarly widget and QVBoxLayout then saving it, showing temporarly the QChartView before saving it etc... but didn't managed to get a good result.
I use the following code to render a QGraphivsView on a Pixmap, since QtCharts is based on QGraphivsView, I think this will also work.
Try to render the image instead of trying to grab the pixmap.
void Printer::putProfileImage(QRect profilePlaceholder, QRect viewPort, QPainter *painter, QGraphivsView* profile)
{
int x = profilePlaceholder.x() - viewPort.x();
int y = profilePlaceholder.y() - viewPort.y();
QRect pos(x, y, profilePlaceholder.width(), profilePlaceholder.height());
profile->render(painter, pos);
}
I didn't find any easy way to this, so here's my solution, which is more like a workaround though :
QPixmap ChartView::getChartPixmap()
{
QWidget* w = new QWidget; //creating a temporary widget, which will enable to display the chart
w->resize(REPORT_IMAGE_WIDTH, REPORT_IMAGE_HEIGHT);
QVBoxLayout *vl;
vl = new QVBoxLayout(w);
vl->addWidget(this); //'this' being the QChartView
w->show(); //showing the widget so it is resized and can be grabbed with the correct dimensions
QTest::qWait(500); //we need to wait for a little for the graph to be drawn otherwise you'll still have the same size problem
QPixmap pixmap = w->grab(); //retrieve the pixmap
w->hide(); //hiding the widget
return pixmap;
}
It's working but you'll have a small window opened with the graph for 500 ms.
I have a QPushButton to which I want to add an icon (that I add to the button by using QPushButton::setIcon()) with rounded corners. However I have a pixmap which is a square image. Is it possible to adapt the pixmap in such a way that it becomes rounded?
I have found the setMask() function on the QPixmap, which I can maybe use. But how would I make a bitmap that masks the edges of my QPixmap?
Or is there a better way for this?
This is how you can prepare a QPixmap with rounded corners:
const QPixmap orig = QPixmap("path to your image");
// getting size if the original picture is not square
int size = qMax(orig.width(), orig.height());
// creating a new transparent pixmap with equal sides
QPixmap rounded = QPixmap(size, size);
rounded.fill(Qt::transparent);
// creating circle clip area
QPainterPath path;
path.addEllipse(rounded.rect());
QPainter painter(&rounded);
painter.setClipPath(path);
// filling rounded area if needed
painter.fillRect(rounded.rect(), Qt::black);
// getting offsets if the original picture is not square
int x = qAbs(orig.width() - size) / 2;
int y = qAbs(orig.height() - size) / 2;
painter.drawPixmap(x, y, orig.width(), orig.height(), orig);
Then you can use the resulting pixmap to set a QPushButton icon:
QPushButton *button = new QPushButton(this);
button->setText("My button");
button->setIcon(QIcon(rounded));
And of course you have a second option to use some image editor to prepare images with rounded corners beforehand.
I know that every item has own coordinates relative to scene. I am adding an ellipse in the scene. Each of them returns the following from boundingRect(): QRect(0, 0, 50, 50). I don't know how to map coordinates to another QGraphicsItem which is a line. The line supposed to connect this two ellipses. I have correct coordinates of ellipses and I am passing them to a custom QGraphicsLineItem constructor. However the line is in a wrong place. How should I use mapFromItem() or other method to get the result?
I get each ellipse's coordinates as follows:
selfCoords = ellipse->mapFromScene(QPointF(0.0,0.0));
You should map the coordinates from each ellipse to some common coordinate system that you can then map to the line's parent. The common coordinate system can be the scene's coordinate system.
For example, to connect the centers of the ellipses:
QGraphicsScene scene;
QGraphicsEllipseItem e1, e2;
scene.addItem(&e1);
scene.addItem(&e2);
... // set the ellipse rects/sizes
auto start = e1.mapToScene(e1.boundingRect().center());
auto end = e2.mapToScene(e2.boundingRect().center());
QGraphicsLineItem l(QLineF(start, end));
scene.addItem(&l);
You can do this because the line's parent is the scene. Now assume that we had some other parent for the line - you'd need to map the coordinates to that parent instead.
...
QGraphicsItem p;
p(20, 20);
scene.addItem(&p);
auto start = e1.mapToItem(&p, e1.boundingRect().center());
auto end = e2.mapToItem(&p, e2.boundingRect().center());
QGraphicsLineItem l(QLineF(start, end), &p);
If I want to add new ellipse on mouse position, how to map coords to ellipse item to get right position on scene ? For example from contextMenuEvent I get
QPointF coords = event->scenePos(); and there I want to create ellipse. I have custom QGraphicsScene MyScene where I have pointer to QGraphicsView* view.
I use event form void MyScene::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
QPointF coords = event->scenePos();
QPointF ellpiseCoords = view->mapToScene(coords .x(), coords .y())
I always get wrong transform.
I want to draw colored tiles as background for a QGraphicsscene and provide pan and zoom functionality for the scene using a QGraphicsView. First I used QGraphicItems to draw each tile. Since I have many tiles this was quite a performance problem when panning or zooming but since I do not need to modify any part of the tiles afterwards I switched to generating a QPixmap using the following code:
void plotGrid(){
Plotable::GraphicItems items;
append(items,mParticleFilter.createGridGraphics());
append(items,mParticleFilter.getRoi().mRectangle.createGraphics(greenPen()));
scaleItems(items,1.0,-1.0);
QGraphicsScene scene;
showItemsOnScene(items,&scene);
QRectF boundingRect = scene.itemsBoundingRect();
double cScale = ceil(1920.0/boundingRect.size().width());
QSize size(boundingRect.size().toSize()*cScale);
QPixmap pixmap(size);
pixmap.fill(Qt::transparent);
QPainter p(&pixmap);
//p.setRenderHint(QPainter::Antialiasing);
scene.render(&p);
p.end();
QGraphicsPixmapItem* item = new QGraphicsPixmapItem(pixmap);
item->setOffset(boundingRect.topLeft()*cScale);
item->scale(1/cScale,1/cScale);
mpView->showOnScene(item);
}
While this solves the zoom and pan problem, the time to generate the pixmap introduces some significant delay, probably because I first create a scene and then render it. Is there a faster way of producing a QPixmap on the fly starting from QGraphicItems ?
Just for completeness an image of the tiles:
So I finally got at least past using an intermediary scene. The following code only relies on a QPainter for rendering the pixmap. My main problem was to get all transformations right. Otherwise it is quite straight forward....
This version halves the processing time to 500ms in my scenario. 450ms are spent on painting the items. If someone has more suggestions for more improvement it would be most welcome (cahnging the resolution does not help much by the way)
void SceneWidget::showAsPixmap(Plotable::GraphicItems const& items){
QRectF boundingRect;
boostForeach(QGraphicsItem* pItem,items) {
boundingRect = boundingRect.united(pItem->boundingRect());
}
QSize size(boundingRect.size().toSize());
double const cMaxRes =1920;
double const scale = cMaxRes/boundingRect.size().width();
QPixmap pixmap(size*scale);
pixmap.fill(Qt::transparent);
QPainter p(&pixmap);
//p.setCompositionMode( QPainter::CompositionMode_Source );
p.translate(-boundingRect.topLeft()*scale);
p.scale(scale,scale);
QStyleOptionGraphicsItem opt;
boostForeach(QGraphicsItem* item,items) {
item->paint(&p, &opt, 0);
}
p.end();
QGraphicsPixmapItem* item = new QGraphicsPixmapItem(pixmap);
item->scale(1.0/scale,-1.0/scale);
item->setOffset(boundingRect.topLeft()*scale);
showOnScene(item);
}