In Stringray grid, there is the ability to use a transparent background which allows the background of the dialog to be shown through the grid.
In the documentation it states:
But be careful; you should disable scrolling or you have to redraw the grid each time it is scrolled (by overriding DoScroll).
I have a scrollable gird and override the DoScroll and make sure I call Redraw and also tried Invalidate, however the grid is still not completely erasing and redrawing.
I also tried using the old drawing method by setting m_bForceOldDrawing to TRUE.
How can I create a grid that has a transparent background that paint correctly after a scroll without leaving artifacts?
Yes you have to redraw the grid by overriding DoScroll because it is no longer using ScrollWindow to scroll contents because the background is transparent.
However you now have artifacts of the grid over your background.
This is because the background behind the grid is not getting redrawn.
Do you have clipchildren set for the parent?
Another potential problem is that the background is not being drawn because it doesn't realize it has been exposed.
Try calling the parent with the following.
Parent.Invalidate();
Parent.UpdateWindow();
before calling...
Invalidate();
Related
In my project, I have a window that has been masked with setMask(QRect()). It works fine, but the shadow that the Window Manager leaves is gone. I definitely want that drop shadow effect on my program.
At first, I moved all of my objects into a single widget and had that widget cast a box shadow onto the MainWindow. Then I made the MainWindow transparent with setAttribute(Qt::WA_TranslucentBackground, true) and setWindowFlags(Qt::FramelessWindowHint). This did the job, however, having a frameless window caused many issue that I can't seem to fix. Namely, this: https://stackoverflow.com/questions/31418494/qtframelesswindowhint-window-cant-be-recorded-with-obs
If I just do setAttribute(Qt::WA_TranslucentBackground, true) or set the style sheet, the background becomes black, not transparent.
So my question is, how do I make the MainWindow transparent without removing the frame? Or how do I cast a shadow when using setMask?
Thanks for your time.
I have a drawing that is built inside a QGraphicsScene with several layers of QGraphicsItem derived objects.
I am repositioning the QGraphicsItem objects based on some parameters and have noticed that there are some "ghost" trails left unless I call graphicsArea->viewport()->update(). I am repositioning the QGraphicsItem objects quite frequently (i.e. when a slider is moved) and updating the viewport only works if I call it manually some time after drawing is finished (e.g. on a button click).
One possible solution that I found was to fill the background of each QGraphicsItem to be a neutral colour. This doesn't work when I have overlapping items though, as the underlying items can get overwritten.
Does anyone have any suggestions?
Thanks,
Alan
I am writing a scheduling-type application using Qt/C++ and want to display weekly schedules in one part of the window, and have this rendering scale as the window size increases. The renders will be composed of rectangles with text in them, and as the display area increases the rectangles should scale nicely while the text should remain the same size.
I have experimented with QGraphicsScene and QGraphicsView and I can make rectangles and text scale; however, the rectangle scaling seems ugly (stretches the outline) and I don't want text to scale at all.
I suspect that I might want to resize the scene to the display area and re-draw the rectangles and text; however, I am not sure how to do this - QGraphicsScene doesn't seem to respond to resizeEvent. Is this even the right approach?
I'm not sure what the ugly rectangle scaling is about (a screenshot might help me understand better what you meant there), but if you don't want the text parts to scale, you can accomplish that by calling setFlag(ItemIgnoresTransformations, true) on your QTextGraphicItem objects.
As far as automatically rescaling the rectangles in response to a window resize, you might take a look at the documentation of the QGraphicsView::fitInView() method:
Scales the view matrix and scrolls the scroll bars to ensure that the
scene rectangle rect fits inside the viewport [...] It's common to
call fitInView() from inside a reimplementation of resizeEvent(), to
ensure that the whole scene, or parts of the scene, scales
automatically to fit the new size of the viewport as the view is
resized. Note though, that calling fitInView() from inside
resizeEvent() can lead to unwanted resize recursion, if the new
transformation toggles the automatic state of the scrollbars. You can
toggle the scrollbar policies to always on or always off to prevent
this (see horizontalScrollBarPolicy() and verticalScrollBarPolicy()).
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().
I've got a long horizontal QLabel displaying a png (the image shows a signal/time graph). Under that, I've got a QTableWidget. Both of these are in a QScrollArea because I want them to stay vertically aligned (the cells in the table correspond with the signal seen directly above them). I'm trying to add a handler to the QLabel such that the user can use the picture itself to scroll the scrollarea, rather than having to use the scrollbar. Is there a tried-and-tested way to do this? Directly setting the scrollarea's sliderPosition inside the QLabel's dragMoveEvent doesn't seem smart, because when the scrollarea scrolls it also leads to another dragMoveEvent on the (moving) QLabel.
I would suggest wrapping the combination (including the scroll area) in their own widget, and overriding the dragMoveEvent() on that widget. The dragMoveEvent() shouldn't be triggered when you change the scroll position if you are doing it this way, I wouldn't think, although I haven't actually tested it.