case Conditional: myPolygon << QPointF(-100, 0) << QPointF(0, 100) << QPointF(100, 0) << QPointF(0, -100) << QPointF(-100, 0); break;用这种代码方式画个圆
时间: 2024-02-09 10:07:39 浏览: 29
这段代码是用于绘制一个菱形的多边形,如果要绘制一个圆形,可以使用Qt中的QPainter类的drawEllipse函数来实现。
示例代码:
```cpp
void MyWidget::paintEvent(QPaintEvent *)
{
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing, true); // 抗锯齿
QPen pen(Qt::black, 2); // 设置画笔颜色和线宽
painter.setPen(pen);
QBrush brush(Qt::red); // 设置画刷颜色
painter.setBrush(brush);
QRectF rect(50, 50, 200, 200); // 圆的外接矩形
painter.drawEllipse(rect); // 绘制圆形
}
```
上述代码中,我们在QWidget的paintEvent事件中绘制一个圆形,首先创建了一个QPainter对象,并设置了画笔和画刷的颜色,然后通过QPainter的drawEllipse函数绘制圆形。其中,drawEllipse函数的参数是圆形的外接矩形,这里我们使用QRectF类来创建圆的外接矩形。
相关问题
DiagramItem::DiagramItem(DiagramType diagramType, QMenu *contextMenu, QGraphicsItem *parent) : QGraphicsPolygonItem(parent), myDiagramType(diagramType) , myContextMenu(contextMenu) { QPainterPath path; switch (myDiagramType) { case StartEnd: path.moveTo(200, 50); path.arcTo(150, 0, 50, 50, 0, 90); path.arcTo(50, 0, 50, 50, 90, 90); path.arcTo(50, 50, 50, 50, 180, 90); path.arcTo(150, 50, 50, 50, 270, 90); path.lineTo(200, 25); myPolygon = path.toFillPolygon(); break; case Conditional: myPolygon << QPointF(-100, 0) << QPointF(0, 100) << QPointF(100, 0) << QPointF(0, -100) << QPointF(-100, 0); break; case Step: myPolygon << QPointF(-100, -100) << QPointF(100, -100) << QPointF(100, 100) << QPointF(-100, 100) << QPointF(-100, -100); break; default: myPolygon << QPointF(-120, -80) << QPointF(-70, 80) << QPointF(120, 80) << QPointF(70, -80) << QPointF(-120, -80); break; } setPolygon(myPolygon); setFlag(QGraphicsItem::ItemIsMovable, true); setFlag(QGraphicsItem::ItemIsSelectable, true); setFlag(QGraphicsItem::ItemSendsGeometryChanges, true); }
这段代码是关于一个名为“DiagramItem”的类的构造函数的实现。它继承自QGraphicsPolygonItem类,并接受三个参数:diagramType表示图表类型,contextMenu表示上下文菜单,parent表示该图形项的父项。在构造函数中,根据图表类型来绘制不同形状的多边形,这里包括四种类型:StartEnd、Conditional、Step和默认。最后,设置了一些标志来使图形项可移动、可选择,并可以发送其几何变化。
def f(x): if x < 0: return -x elif x >= 0 and x < 5: return x + 1 else: return 2*x - 5
This is a Python function that takes a numerical input x and returns a value based on the following conditions:
- If x is less than 0, return the absolute value of x (i.e. -x).
- If x is between 0 (inclusive) and 5 (exclusive), return x.
- If x is greater than or equal to 5, return 2x - 5.
The function is defined using the "def" keyword, followed by the name of the function (in this case, "f") and the input parameter (x). The function body consists of three conditional statements, each of which returns a different value depending on the value of x. The last line of the function, which reads "1", is likely a mistake and should be removed.
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