I would like to draw inside a Qt QFrame, however the QFrame will have a border. As far as I understand, the paintEvent receives a QPainter which is associated to the whole frameRect, so I will have to offset my paint operations of the border. Is this correct? Is there a way of getting a QPainter already associated to the inner part of the widget, without the (variable in size) border?
you have to consider the contentsRect contentsRect()-> Returns the area inside the widget's margins.using the return value rect of contensRect() you can restrict to draw anything inside the rect.
One way to do this would be to embed a QWidget inside the QFrame, place it in a simple QVBoxLayout layout or QStackedLayout layout with no margins and paint the QWidget instead. You'll probably get better performance if you simply offset your painting, though.
Related
So, I have a QFrame with its layout set as a QGridLayout.
Within this layout I have tiles in rows of 16 which represent something of a palette.
I want this grid of tiles to be separated by lines, like a grid should be. I can do this easily with the tiles' paintEvents.
However, the obvious problem is that between the tiles, the lines are doubled up. When I scale this up for other applications, the difference becomes even more noticeable.
So, is there a way to create a gridline overlay for my QFrame? I have considered converting the whole thing to a view/scene solution, and using drawForeground, however this seems like a completely inappropriate use of the paradigm.
Thanks for any assistance!
Put the QFrame into a QGridLayout, then put a custom QWidget with transparent background and paintEvent that paints the grid on top of it (same QGridLayout position).
Or since you already have a QGridLayout, just put the custom QWidget in that, above the tiles, filling the entire grid.
A side note, are you sure you want QFrame there, or if just QWidget would do? Just saying, because with QFrame you get that 1990's look into your UI... If you do want that then go ahead, just saying.
What I want to do:
In PySide, one could override the paintEvent() method of a QWidget to draw a custom widget. The bounding rect can be customized by overriding the boundingRect() method.
How does one do this in JavaFX? My goal is to create a custom Rectangle object, that draws itself smaller than it's bounding rect.
In context:
I'm creating an MS Paint clone in JavaFX. I'm working on the selection box that you use to select/move pixels around. I want the cursor to change to the appropriate resizing cursor when it is near the outside of the selection box.
However, the bounding rect is the same size as the selection box drawn on the screen, so the cursor only changes when it is on top of the box, but not when near. My solution is to set the bounding rect to larger than the actual selection box is, so the cursor change will occur. Then, override it's paintEvent() equivalent to draw a smaller selection box.
Thanks for your help.
I have a similar use case to you, and asked a similiar question here : Drawing transform independent layout bounds in JavaFX.
The JavaFX API is much higher level though than Java2D or PySide (I am assuming from your snippets, because I actually never heard of it ;) ), it does not allow you to override painting of Nodes, nor can you stop a Node from inheriting its parents transform.
This means that you need a seperate Group parallel to your content where you create the selection box and update it according to your needs (content changes etc.).
Example SceneGraph:
Scene
contentGroup
someShapeFromUser
selectionBoxGroup
selectionBoxOfSomeShapeFromUser
I have a QGLWidget and I like to attach on top of it a QLabel for some measurement visualization (fps, number of object, etc).
I'd like to keep QGLWidget as clean as possible for further re-using and not use QGLWidget::renderText inside of it but use an external debug interface with those measurement.
For now I have:
QVBoxLayout *l = new QVBoxLayout;
this->gl = new MyGLWidget;
l->addWidget(gl);
QLabel *fps = new QLabel;
fps->setText(QString("FPS"));
fps->setStyleSheet("QLabel { background-color : red; color : blue; }");
fps->setParent(gl);
this->setLayout(l);
But nothing appears.. of course if I add the QLabel to the layout with QLayout::addWidget I see it.. but is not what I want..
Some ideas?
Without being assigned to a layout the widget doesn't know, where it should draw, if you don't tell it explicitly. You must call QWidget::setGeometry explicitly to position it.
However placing regular Qt widgets on top of a QGLWidget has some merits. The QGLWidget actually creates a subwindow parented by the top level window. Regular widgets however don't have their own, deidicated subwindows, which means, that from the point of view of the graphics system they're on the same Z stacking level than the top level window itself. And the QGLWidget's actual subwindow has a higher Z stacking level. Parenting a QLabel to the QGLWidget should place it at the right Z stacking level. But then OpenGL drawing operations are different than Qt drawing operations, so your drawing on the QGLWidget may mess up the QLabel.
Simply spoken, there's a reason why QGLWidget has a function "drawText".
Does anyone know how to draw a header (and other simple elements), just like in, for example, QTreeWidget, in my own widget?
I would like to use style and call something like:
drawElement(CE_Header, rect, painter);
to draw standard header in specified rect.
QStyle::drawControl can't do it, because it draws control over whole widget.
Qt documentation doesn't say much about it.
Subclass QHeaderView and reimplement the paint method, inside there you can use the QStyleOption data. Then use QTreeWidget::setHeader(QHeaderView* header) to set your header in the widget.
The Scenario is I am getting Rects of Images over the socket and I need to draw it in a Scrollable Canvas. at the moment I am using a QGraphicsScene and drawing using QGraphicsPixmapItem but after few times when one pixmap overlaps another there is no need to keep the bottom one. and I dont know any simple way to find out the overlapped item and delete it. so its supposed to take huge memory if overlapping goes on like this.
there exists another way out. Make a QWidget and put it in a QScrollArea now draw the QWidget using a QPainter (outside paintEvent ?). If I draw it outside paintEvent I need to inherit the QWidget and make a custom one. pass it a Pixmap and let it draw in its own paintEvent by calling update()
Any critiques ? any other Straight forward solutions there ?