Qt's paint system enables painting on screen and print devices using the same API, and is primarily based on the QPainter, QPaintDevice, and QPaintEngine classes.. QPainter is used to perform drawing operations, QPaintDevice is an abstraction of a two-dimensional space that can be painted on using a QPainter, and QPaintEngine provides the interface that the painter uses to draw onto different ...

Settings. There are several settings that you can customize to make QPainter draw according to your preferences: font() is the font used for drawing text.If the painter isActive(), you can retrieve information about the currently set font, and its metrics, using the fontInfo() and fontMetrics() functions respectively.; brush() defines the color or pattern that is used for filling shapes.

Widget. The QWidget class is the base class of user interface elements in the Qt Widgets module. It receives mouse, keyboard and other events from the window system, and paints a representation of itself on the screen. Image. The QImage class provides a hardware-independent image representation which is designed and optimized for …

不同的QGrahpicsItem的子类对 paint()函数做了不同的实现，我们也可以按照自己的需要，实现自己的paint()函数（比如原来实现效率太低需要实现一个高效率的版本等等），比如我们可以考虑给paint函数里所在的类设置一个类成 员函数指针，在paint中调用这个成员函数 ...

QPainter can paint on QWidget only in paintEvent(QPaintEvent*). Sample code: void paintEvent (QPaintEvent *) {QPainter painter (this); QLineF line (10.0, 80.0, 90.0, 20.0); painter. drawLine (line);} This snippet will draw black line on the widget. Now we know how to create QPainter object and draw on widgets. But this isn't only supported ...

2018年12月29日 · 不同的QGrahpicsItem的子类对 paint()函数做了不同的实现，我们也可以按照自己的需要，实现自己的paint()函数（比如原来实现效率太低需要实现一个高效率的版本等等），比如我们可以考虑给paint函数里所在的类设置一个类成 员函数指针，在paint中调用这个成员函数 ...

2016年4月18日 · You need to initialize the painter with the widget you want to paint on. Usually this is done using the constructor which takes a QPaintDevice but you can also do it by calling begin(). Share. Improve this answer. Follow edited Apr 18, 2016 at 20:36. Angie Quijano. 4,473 3 …

2022年2月15日 · QPaintDevice类就是绘制的位置，是QPaintDevice类对象或派生类对象就是可以绘画的地方。当整个窗口或窗口的一部分需要重新绘制时，会调用绘制事件处理函数。QPainter类，就是Qt中进行绘图类。1.2.3 多次绘制，并且之前的绘画还在。在QPainter类中存在各种绘制功 …

2018年8月30日 · 文章浏览阅读1w次，点赞5次，收藏27次。官方解析重写于QAbstractItemDelegate::paint()。通过使用option与painter对指定的index位置的委托进行渲染。当描述各种item的时候使用view的QStyle。当从子类重新实现paint这个函数时候，要用initStyleOption()这个函数去重新设置option这个参数。

The primary paint engine provided is the raster paint engine, which contains a software rasterizer which supports the full feature set on all supported platforms. This is the default for painting on QWidget -based classes in e.g. on Windows, X11 and macOS, it is the backend for painting on QImage and it is used as a fallback for paint engines ...