Qt动态进度条根据输入值改变

首先看下效果图:

核心部分代码如下:
psshowslider.h
class psshowslider : public QFrame
{
Q_OBJECT

public:
explicit psshowslider(QWidget parent = 0);
~psshowslider();
//设置最大值
void setMaxValue(double maxvalue);
//得到最大值
double getMaxValue();

//设置最小值
void setMinValue(double minvalue);
//得到最小值
double getMinValue();

//设置值
void setValue(double value);
//取得值
double getValue();

protected:
void paintEvent(QPaintEvent );

private:
Ui::psshowslider *ui;
//滑动条最大值
double maxvalue;
//滑动条最小值
double minvalue;
//设置显示的值
double value;

};

?
psshowslider.cpp里面主要是paintEvent()函数的重写.
void psshowslider::paintEvent(QPaintEvent ) {
QPainter painter(this);
//移动坐标系
painter.translate(20, height() / 2);
QPen pen(Qt::white, 3, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin);
painter.setPen(pen);
painter.drawLine(0, 40, 0, -40);

//画上边直线
painter.drawLine(0, -30, 320, -30);
//画下边直线
painter.drawLine(0, 30, 320, 30);
//画上下直线刻度以及文字
int num = 1;
int x, y;
QPen pen2(Qt::white, 2, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin);
QPoint point;
painter.setPen(pen2);
for (; num < 21; num++) {
x = 15 num;
if (num % 2 == 0) {
y = -20;
point.setX(x - 8);
point.setY(y + 10);
painter.drawText(point, QString::number(50 num));
} else {
y = -25;
}
painter.drawLine(x, -30, x, y);
}

//设置线性渐变
QLinearGradient linearGradient = QLinearGradient(0, 0, 300, 0);
linearGradient.setColorAt(0.0, Qt::cyan);
linearGradient.setColorAt(0.6, Qt::yellow);
linearGradient.setColorAt(1, Qt::red);
//设置画刷
QBrush qsh(linearGradient);
painter.setBrush(qsh);

painter.setPen(Qt::cyan);
//画矩形
painter.drawRect(0, -5, this->getValue() / this->getMaxValue() 300, 34);

}

每次当类属性value改变之后,只需要调用类的update()方法或者repaint()方法即可.