im adding QGraphicsLayoutItem in a QGraphicsWidget in run time using QGraphicsLinearLayout.
i have to add more items to the layout that exceeds the height of the viewport height and items shown outside the viewport area.so is it possible to pan or scroll in QGraphicsWidget like QGraphicsView. QGraphicsView i can pan using centerOn and showing only a visible rect.
the normal view
and when more item added
Related
I have a QTabWidget and second page containing a QGraphicsView with scene. The scene canvas is larger than the QGraphicsView's viewport and I'm using QScrollBar to move objects on the scene.
On the scene I place a lot of QGraphicsItem objects. I have a horizontal and a vertical scroll bar, and some items can move only horizontally, another objects on scene can move only vertically.
My QGraphicsview coordinates start at the top left corner of QGraphicsview. After moving objects on the scene, if I change the page of the QTabWidget from second page to first and then back again, the start of coordinates is moved to the center of QGraphicsView, and all objects on the scene are moved to new positions automatically.
This happens only when I'm using a QTabWidget, if I change the parent of QGraphicsView to QWidget, all works well.
I found a solution. Just need to calculate rect of the scene, and set obviously using QGraphicsScene::setSceneRect() method. Otherwise, position of my scene in the QGraphicsView may surprise.
I am using QCustomPlot to plot a bar graph. There are two such bar graphs horizontally arranged inside a QSplitter (which can be dragged). On dragging the splitter horizontally, the bar graphs resize and scale to the point that the axes labels start to overlap. I have a parent QWidget which contains a QScrollArea which ultimately contains the plot. This widget is added to the QSplitter.
QWidget* topLeftParent = new QWidget;
topLeftParent->setLayout(new QVBoxLayout);
QScrollArea *topLeftScrollArea = new QScrollArea(this);
topLeftScrollArea->setWidget(energyGraph->GetPlot());
topLeftScrollArea->setWidgetResizable(true);
topLeftScrollArea->setFrameShape(QFrame::NoFrame);
topLeftParent->layout()->addWidget(topLeftScrollArea);
m_pTopLeftHorizontalSplitter->setMinimumWidth(500);
m_pTopLeftHorizontalSplitter->addWidget(topLeftParent);
Existing Behaviour:
On dragging the splitter horizontally, the bar graphs expand/shrink horizontally till the axes tick labels overlap and ultimately at a very small value of width, the horizontal scrollbar appears, which is useless. Same is the case for resizing the window as well.
Required Behavior
However, I seek a different behavior. I want the bar graphs to be horizontally scrollable without them resizing on dragging the splitter i.e. dragging the splitter left/right should reveal more/less of the graphs, and not resize them
Queries
How do I specify that the bar graph should have a minimum size and expand from that depending on the number of ticks on x-axis?
How do I stop the plot from automatically expanding/shrinking?
What I have tried so far
I have tried setting minimum size for the plot, but it does not work.
I have also tried specifying the stretch factor for the splitter to 0, but that also has no effect i.e. the behavior is auto resizing bar graphs in both the cases with scrollbar appearing too late.
To achieve the required behavior you can use the QTableWidget widget. You need to:
Create a QTableWidget widget with two columns and and one row.
Set the QScrollArea widget as the parent of the QTableWidget widget.
Hide the horizontal and vertical headers. To do so set horizontalHeaderVisible and verticalHeaderVisible to false.
Add QCustomPlot widgets into the table using the setCellWidget(int row, int column, QWidget * widget) method.
This is how it was solved: I just had to call the setWidgetResizable with false for the scroll area and now I have a permanent scrollbar and the custom plot does not resize while dragging the splitter.
Find if you have this line:
ui->my_plot->setInteractions(QCP::iRangeZoom | QCP::iRangeDrag);
And edit it to whatever you want, for example just range zoom:
ui->my_plot->setInteractions(QCP::iRangeZoom);
in Qt 4.8 i have create a QGraphicsView and a DynamicRadarScene(derived from QGraphicsScene):
QGraphicsView* view = new QGraphicsView;
view->setMinimumSize(800, 600);
DynamicRadarScene* _scene = new DynamicRadarScene(mode, channel_types, this);
view->setScene(_scene);
What is the coordinate system of QGraphicsScene? (0,0) is from upper left corner?
How can i draw an item in the upper right corner of the scene (i have set it 800x600: view->setMinimumSize(800, 600);)?
If i resize the widget and so i resize the QGraphicsView, how can move the item i have drawn before to remain in the upper left corner?
Yes, the upper left corner is generally the coordinate of (0,0) in a graphics scene. What you need to consider is that a QGraphicsView is like a window looking into a world (the QGraphicsScene). You set the view to look at an area or the scene, which may be all or just part of the scene.
Once the scene and view are setup, you can then add QGraphicsItems / QGraphicsObjects or instances of classes derived from those by using functions such as QGraphicsScene::addItem. These items are positioned in the scene and draw themselves.
i (sic) resize the widget and so i resize the QGraphicsView
You can change the QGraphicsView position and dimensions, but then the items in the scene will remain in the same place within the scene. Usually you would set up the scene and view and then move / resize the graphics items / objects within the scene, often with the setPos function: QGraphicsItem::setPos(). This sets the position of the item, relative to its parent. If the item has no parent, it sets the position of the item in the scene.
QGraphicsScene has property sceneRect. If it is not set then it is auto adjusted depending on scene content. This can give a filling that origin of coordinating is in some strange place or even that it is mobile.
Set this property. See also this.
I've got a QGraphicsView with a vertical Scrollbar, but the problem is that when I run my app, the scrollbar position is set to the center of the QGraphicsView.
How can I set it to the top by default ?
I tried to use :
view->verticalScrollBar()->setValue(0);
But it doesn't change a thing. However, I tried this too :
view->verticalScrollBar()->setValue(1);
And it does change the Scrollbar Position to the top, but not at its minimum.
I am trying to show a picture in it's full view using QGraphicsScene. But when ever I put the QgraphicsScene inside the QGraphicsView, I am getting a scroll bar. I tried so many ways But all are went to veins. So can anybody tell me how to obtain the full view without the scrollbar.
You might be getting scrollbars because the scene is larger than the usable area within the graphics view. By default, a QGraphicsView comes with a 1-pixel margin. To fix this, you can try:
QRect rcontent = graphicsView.contentsRect();
graphicsView.setSceneRect(0, 0, rcontent.width(), rcontent.height());
I had been getting scrollbars because I was manually setting the scene rect to the size of the graphics item I was adding -- which was as large as the QGraphicsView widget. I wasn't taking into account the margin.
QGraphicsView v;
v.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
v.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
To adjust the scrolling programmatically once these have been hidden, use one of the overloads of v.ensureVisible().