Chapter 1 paintEvent绘制事件

void FuelRemaining::paintEvent(QPaintEvent *)
{
	QPainter painter(this);
	painter.setRenderHint(QPainter::Antialiasing); // 设置渲染提示为抗锯齿
	painter.save();


	// 绘制中心的实心圆
	painter.setBrush(Qt::cyan);
	painter.drawEllipse(width() / 2 - 50, height() / 2 - 50, 100, 100);

	// 绘制外围的空心圆
	painter.setBrush(Qt::NoBrush);
	painter.setPen(QPen(Qt::cyan, 10));
	painter.drawEllipse(width() / 2 - 70, height() / 2 - 70, 140, 140);

	// 绘制上下左右的线段
	painter.setPen(QPen(Qt::cyan, 10));
	painter.drawLine(width() / 2, height() / 2 - 70, width() / 2, height() / 2 - 80); // 上
	painter.drawLine(width() / 2, height() / 2 + 70, width() / 2, height() / 2 + 80); // 下
	painter.drawLine(width() / 2 - 70, height() / 2, width() / 2 - 80, height() / 2); // 左
	painter.drawLine(width() / 2 + 70, height() / 2, width() / 2 + 80, height() / 2); // 右

	painter.restore();
	// 将坐标原点移动到窗口中心
	int centerX = width() / 2;
	int centerY = height() / 2;
	painter.translate(centerX, centerY);
	//倾斜坐标
	painter.rotate(30);
	QPixmap pic(R"(E:\ProjectEnvironment\data\System\Images\tools\navigator_earth\compass.png)");
	pic.scaled(60, 60);
	painter.drawPixmap(-pic.width() / 2, -pic.height() / 2, pic);

}