I'm trying to creat a Dicom GUI Toolkit where the user selects some dicom images and the image of first dicom image from the selected ones will be shown. Then the user clicks on the image and the image pops out with bigger image window. In this shown bigger image, the image will consist of a red colored rectangle that contains necessary regions of the Dicom image while the unnecessary region is outside the rectangle. The user should then have the option to change the rectangle by mouse.
Until now, I have been able to show the big dicom image with the rectangle in it using QLabel which is by the following code snippets.
void MainWindow::showBigImage()
{
QPixmap bigimage;
bigimage.load(imageName.c_str());
QPainter painter(&bigimage);
painter.setPen(Qt::red);
QRectF rect(xmin, ymin, xmax, ymax);
painter.drawRect(rect);
QSize bigsize = ui->bigImageLabel->size();
ui->bigImageLabel->setPixmap(bigimage.scaled(bigsize, Qt::IgnoreAspectRatio, Qt::FastTransformation));
ui->bigImageLabel->show();
}
and the big image on the app looks like the following:
Can you please suggest me how I should now make the rectangle editable by the user where the user can set the existing red rectangle as per his or her wish?
I also tried similar thing using QGraphicsView and QGraphicsScene with the following code:
void MainWindow::showBigImage()
{
QGraphicsScene* scene = new QGraphicsScene;
scene->addPixmap(bigimage);
ui->bigImageView->setScene(scene);
ui->bigImageView->show();
}
And this code gives me the following look:
As you can see, I could not fit the image to the boundaries of QGraphicsView, could you suggest me how to do it? Could you also suggest me how to add the red rectangle(that I showed in the example using QLabel) on the QGraphicsView without adding the rectangle on the QPixmap?
In order to get the red selection rectangle, Qt provides the class QRubberBand. The docs state:
The QRubberBand class provides a rectangle or line that can indicate a selection or a boundary.
By subclassing the image object and implementing the mouse handling functions, to create the rubber band on mousePressEvent, update its position on mouseMoveEvent and grab its final rect on mouseReleaseEvent, the QRubberBand will simplify the problem.
If you want the QRubberBand to show all the time, just create it when you display the enlarged image and don't hide it on releasing the mouse button.
As for displaying the image in the QGraphicsView, the code you displayed doesn't set the geometry of the QGraphicsScene and QGraphicsView, so you're seeing a border. If you don't want that, you should set them accordingly. Also note that QGraphicsView has a function fitInView, which you could use, after having retrieved an area from the QRubberBand, in order to zoom into the selected area.
Related
Actually I set an image on a QProgressBar and want to change the color of image according to selected part of QProgressBar.
I tried covering my image with QProgressBar color but that fills the image, but as my image is not a rectangle it color the whole QProgressBar and not just the image.
Is it possible to change color of image only using qt (with C++)
You are looking for Qt Style Sheet Documentation. You can customize your own QProgressBar, and add your own setProgress() function which should update the value property. You could modify the image background, the border, margins... depending of the value of the current value.
See QSS examples for more detail: Example Style Sheet
I want to inform user when cursor hover on the particular rectangle. I have many 20x20 rectangles. Below you can see how I draw the rectangles.
QRect rec(horizontalScan,verticalScan,20,20);
QPen framepen(Qt::black);
framepen.setWidth(1);
QBrush brush(colors[randColorNo],Qt::SolidPattern);
painter.fillRect(rec,brush);
painter.setPen(framepen);
painter.drawRect(rec);
Please consider that I am not so good on Qt so try to explain exactly what should I do.
If you want interactivity - better use QGraphicsScene. QGraphicsItems has tooltip attribute.
If you want to stick with QPainter - you should do it manually by detecting mouse position with mouseMoveEvent() and showing tooltip with QToolTip::showText().
I am trying to develop very simple image viewer using QT. I am using the following code to show the image on QGraphicsScene widget:
QImage image(fileName);
firstPicture = new QGraphicsScene();
firstPicture->addPixmap(QPixmap::fromImage(image));
ui->graphicsView->setScene(firstPicture);
ui->graphicsView->fitInView(firstPicture->sceneRect() ,Qt::KeepAspectRatio);
I am getting the following output:
How can I fit the image into the GraphicsScene?
This approach works only when view showed your scene. In your case you did not call show(). Solution:
Use your approach when scene already shown.
You can reimplement showEvent and use your approach here.
You can scale image by yourself and set this scaled image to scene.
Also you can try to use: Qt::IgnoreAspectRatio instead of Qt::KeepAspectRatio.
You can make your custom class which inherits from QGraphicsView. You should reimplement resizeEvent( QResizeEvent *event ) in your custom QGraphicsView like:
void MyView::resizeEvent(QResizeEvent *event)
{
fitInView(firstPicture->sceneRect(), Qt::KeepAspectRatio);
QGraphicsView::resizeEvent(event);
}
This way the view will always display the whole scene. I.e. if the window size is changed and the graphicsView is resized, The scene gets scaled and you can see everything appropriately.
I guess there are lots of ways to achieve this. I have an application in which a video stream is shown over a custom QWidget that I have subclasses from QLabel, and painting frames using QPainter. Given that, is it possible to let the user to drag a rectangle over the image and retrieve the coordinates? The requirement is that the rectangle must be visible during the dragging.
Thanks in advance,
Have a look at QRubberBand. It allows you to place such a rect on top of e.g. a QLabel. The documentation also contains an example how to move and resize the rubberband using the mouse.
the QGraphicsView has the void setRubberBandSelectionMode ( Qt::ItemSelectionMode mode ) but i dont know if the QLabel has some similar feature ...
maybe you have to draw your own rectangle while the user drags the rectangle and catch it on mouserelease
soo long zai
In you widget you could track mouse pressed and released events and track where on the widget the corners of the selection rect are. For drawing the rectangle, I'd take a look at QStyle::drawFocusRect. I think the intent of that is to draw a rect you'd be able to see regardless of what's behind it.
Or perhaps try this:
QStylePainter painter(this);
QStyleOptionFocusRect option;
option.initFrom(this);
option.backgroundColor = palette().color(QPalette::Background);
painter.drawPrimitive(QStyle::PE_FrameFocusRect, option);
I'm new to Qt. I searched for my question on multiple sites, but I couldn't find an answer. How can I add an image to centralWidget?
I tried:
MainWindow w;
w.centralWidget()->setStyleSheet("image: url(image)");
it worked fine but the image isn't stretched for the entire window/widget. How can I resize the image through setStyleSheet?
I want to display an image in the background and not the gray color, when the application opens. I tried changing the color. That worked, but it doesn't look good with buttons and labels.
If you want it to stretch for the entire widget use background-image, but I'm guessing what you probably want is an image that expands in one direction, either vertically or horizontally, in that case use background-position to fix it to one of the borders of your widget:
image: url(:/path/to/image);
background-position: bottom left;