WebApr 1, 2024 · It can be a regular button, or even a mini-map, if the main QGraphicsView acts as a large map. In general, what exactly is a similar widget is not important. The bottom line is that there is the main QWidget, inside which the rest of the QWidget objects are located, which have absolute positioning inside this widget. Web我有一个数据框，主要是零(稀疏数据框架?)类似于的东西name,factor_1,factor_2,factor_3ABC,1,0,0DEF,0,1,0GHI,0,0,1实际数据约为90,000行，具有10,000个功能.我可以将其转换为稀疏的矩阵吗?我希望通过利用稀疏矩阵而不是数据框来获得时间和空间效率.任何帮助将不
How can I draw inside existing QGraphicsVIew? - Stack Overflow
WebConstant Value Description; QGraphicsView::FullViewportUpdate: 0: When any visible part of the scene changes or is reexposed, QGraphicsView will update the entire viewport. This approach is fastest when QGraphicsView spends more time figuring out what to draw than it would spend drawing (e.g., when very many small items are repeatedly updated). This is … WebDec 27, 2024 · Even using the clear() method does not imply that the view is cleaned but you have to set the path in the item. Going to the problem, an equivalent method is to establish a new QPainterPath, in addition it is not necessary to call the update() method of the scene. The use of clear() or set an empty QPainterPath are equivalent from the … how do supersaturated solutions form
图形视图框架 事件处理（item） - 代码天地
WebMay 7, 2024 · Avoid call QGraphicsItem::update() very often, or it can be even slower than without caching. If you need to change something in your item, two options are: to draw it in a child, or use QGraphicsView::drawForeground(). Group Similar QPainter Drawing Operations. Prefer drawLines over calling drawLine multiple times; favor drawPoints over ... WebJul 20, 2012 · 6. I have a custom class derived from QGraphicsView that implements a slot call scrollHorizontal (int dx), inside the code is simply. void CustomView::scrollHorizontal (int dx) { scrollContentsBy (dx, 0); } My problem is, scrolling like this works but doesn't update the scene properly, instead any pixels found on the edge of the view are ... WebBy default, the view coordinate system matches the widget’s pixel coordinates and automatically updates when the view is resized. This can be overridden by setting autoPixelRange=False. The exact visible range can be set with setRange (). how much should an 8 month old eat