QPainter is the class used to perform drawing operations. QPaintDevice represents a device that can be painted on using a QPainter. QPaintEngine provides the interface that the painter uses to draw onto different types of devices.

QPainter provides standard functions to draw points, lines, ellipses, arcs, Bézier curves, and other primitives. More complex painting operations include support for polygons and vector paths, allowing detailed drawings to be prepared in advance and drawn using a single function call.

These examples show the most common techniques that are used when painting with Qt, from basic concepts such as drawing simple primitives to the use of transformations. Demonstrates how affine transformations in QPainter work. The Basic Drawing example shows how to display basic graphics primitives in a variety of styles using the QPainter class.

QPainter类是Qt框架中用于在窗口或图像上进行绘制的核心类。它提供了丰富的绘图功能，包括绘制线条、形状、图像、文本以及复杂的图形路径等。QPainter可以与QWidget、QPixmap、QBitmap、QImage等绘制目标（也称为设备上下文或画布）结合使用，以在其上进行绘制操作。

QPainter performs low-level painting on widgets and other paint devices. The class can draw everything from simple lines to complex shapes like pies and chords. It can also draw aligned text and pixmaps.

2016年4月18日 · In the first example, you can think of QPainter::begin(this) being called in the constructor and QPainter::end() in the destructor. For the reason, I'm guessing: As QPaintDevices are usually double buffered in QT4, QPainter::end() might be where the image is transferred to the graphic memory.

2019年6月5日 · In this tutorial we'll take a look at QPainter — Qt's API for performing bitmap graphic operations and the basis for drawing your own widgets. We'll go through some basic drawing operations and finally put it all together to create our own little Paint app.

2024年4月7日 · QPainter 是Qt框架中的一个类，主要用于在各种设备上进行2D图形绘制，如窗口、位图、打印设备等。 它提供了一系列绘图函数，可以实现绘制点、线、曲线、形状、文本、图像以及复杂的绘画操作。 使用 QPainter 进行绘图的基本步骤如下： 创建一个 QPainter 对象。 将 QPainter 与要绘图的设备（如 QPixmap 、 QImage 或 QWidget）关联起来，通过调用 begin() …

The QPainter class does low-level painting e.g. on widgets. The painter provides highly optimized functions to do most of the drawing GUI programs require. QPainter can draw everything from simple lines to complex shapes like pies and chords. It can also draw aligned text and pixmaps.

QPainter provides highly optimized functions to do most of the drawing GUI programs require. It can draw everything from simple lines to complex shapes like pies and chords. It can also draw aligned text and pixmaps.