QT之“飛鏢盤”自定義控件

前言

現在發一個我之前看過有人寫了一個抽獎轉盤，所以閒來無事寫了一個飛鏢盤控件，在我看來它其它沒有什麼實用價值，純屬寫來玩玩而已。

控件預覽

實現

1. 畫背景

void QDartboard::drawBkg(QPainter *painter,)
{
	int radius = 95;
    painter->save();
    painter->setBrush(bkgColor);
    painter->drawEllipse(-radius, -radius, radius << 1, radius << 1);
    painter->restore();
}

2. 畫扇形

void QDartboard::drawFans(QPainter *painter)
{
    float rad = 0;
    float panAngle = 360 / fanNum;
    int radius = 80;

    for(int i = 1; i <= fanNum; i++)
    {
        if(i % 2 == 0)
        {
            gradientArc(painter, radius, rad + panAngle * i, panAngle, qRgb(200, 0, 0));
            gradientArc(painter, radius - ringSize, rad + panAngle * i,  panAngle, qRgb(0, 200, 0));
            gradientArc(painter, radius - 30, rad + panAngle * i,  panAngle, qRgb(200, 0, 0));
            gradientArc(painter, radius - 30 - ringSize, rad + panAngle * i,  panAngle, qRgb(0, 200, 0));
        }
        else
        {
            gradientArc(painter, radius, rad + panAngle * i,  panAngle, qRgb(0, 200, 0));
            gradientArc(painter, radius - ringSize, rad + panAngle * i,  panAngle, qRgb(200, 0, 0));
            gradientArc(painter, radius - 30, rad + panAngle * i,  panAngle, qRgb(0, 200, 0));
            gradientArc(painter, radius - 30 - ringSize, rad + panAngle * i,  panAngle, qRgb(200, 0, 0));
        }
    }

    gradientArc(painter, radius - 70, 0,  360, qRgb(0, 200, 0));
    gradientArc(painter, radius - 75, 0,  360, qRgb(200, 0, 0));
}

void QDartboard::gradientArc(QPainter *painter, int radius, int startAngle, int angleLength, QRgb color)
{
    painter->save();
    // 漸變色
    //QRadialGradient gradient(0, 0, radius);
    //gradient.setColorAt(0, Qt::white);
    //gradient.setColorAt(1.0, color);
    //painter->setBrush(QColor(color));
    //painter->setPen(color);

    // << 1（左移1位）相當於radius*2 即：150*2=300
    //QRectF(-150, -150, 300, 300)
    QRectF rect(-radius, -radius, radius << 1, radius << 1);
    QPainterPath path;
    path.arcTo(rect, startAngle, angleLength);

    painter->setPen(Qt::NoPen);
    painter->drawPath(path);
    painter->fillPath(path, QBrush(QColor(color)));
    painter->restore();
}

3. 畫刻度值

void QDartboard::drawScaleNum(QPainter *painter)
{
    int radius = 85;
    painter->save();
    painter->setPen(Qt::white);
    QFont font("Arial", 6, QFont::Bold, false);
    //設置字體的類型，大小，加粗，斜體
    painter->setFont(font);

    painter->rotate(90 + ((360 / fanNum) / 2));
    for (int i = 1; i <= fanNum; i++)
    {
        QString strValue = QString("%1").arg(i);
        double textWidth = fontMetrics().width(strValue);
        //double textHeight = fontMetrics().height();
        painter->rotate(-360 / fanNum);
        painter->drawText(0 - textWidth / 2, -radius, strValue);
    }

    painter->restore();
}