I'm trying to develop a custom QProgressBar
that will look like the following image :
我正在尝试开发一个自定义的QProgressBar,它看起来像以下图片:
I created a class that extends QProgressBar and implemented the paintEvent() :
我创建了一个扩展QProgressBar的类并实现了paintEvent():
void CircularProgressBar::paintEvent(QPaintEvent*) {
int progress = this->value();
int progressInDegrees = (double)(progress*360)/100;
int barWidth = 20;
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing, true);
painter.setPen(QPen(Qt::black, barWidth, Qt::SolidLine,Qt::RoundCap));
painter.drawArc(barWidth/2, barWidth/2, this->width() - barWidth, this->height() - barWidth,
90*16, progressInDegrees*-16);}
This works great to draw the circular progress bar, but I'm having trouble with the linear gradient color of the bar. I tried creating a QPen
with a QLinearGradient
object and I tried setting the QPainter
brush to a QLinearGradient
object, but neither strategy worked. Is it possible to draw an arc with QPainter
that has a linear gradient color?
这很好地画出了循环进度条,但是我遇到了线性渐变颜色的问题。我尝试用一个q线性渐变对象创建一个QPen,我尝试将QPainter画笔设置为一个QLinearGradient对象,但这两个策略都不起作用。是否可以用一个有线性渐变颜色的QPainter绘制一个圆弧?
2 个解决方案
#1
6
I know this is an old question but I came across it some days ago and I think I have a solution. What you want is to create a conical gradient and clip the disk you want to use as circular loading bar. Here is an example:
我知道这是个老问题,但几天前我遇到了这个问题,我想我有一个解决办法。你想要的是创建一个圆锥渐变,并剪辑你想要用作圆形加载吧的磁盘。这是一个例子:
widget.h:
widget.h:
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
class QPaintEvent;
class Widget : public QWidget
{
Q_OBJECT
public:
explicit Widget(QWidget *parent = 0);
~Widget();
void setLoadingAngle(int loadingAngle);
int loadingAngle() const;
void setDiscWidth(int width);
int discWidth() const;
protected:
void paintEvent(QPaintEvent *);
private:
int m_loadingAngle;
int m_width;
};
#endif // WIDGET_H
widget.cpp:
widget.cpp:
#include "widget.h"
#include <QPaintEvent>
#include <QPainter>
#include <QConicalGradient>
#include <QPen>
Widget::Widget(QWidget *parent) :
QWidget(parent),
m_loadingAngle(0),
m_width(0)
{
}
Widget::~Widget()
{
}
void Widget::setLoadingAngle(int loadingAngle)
{
m_loadingAngle = loadingAngle;
}
int Widget::loadingAngle() const
{
return m_loadingAngle;
}
void Widget::setDiscWidth(int width)
{
m_width = width;
}
int Widget::discWidth() const
{
return m_width;
}
void Widget::paintEvent(QPaintEvent *)
{
QRect drawingRect;
drawingRect.setX(rect().x() + m_width);
drawingRect.setY(rect().y() + m_width);
drawingRect.setWidth(rect().width() - m_width * 2);
drawingRect.setHeight(rect().height() - m_width * 2);
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing);
QConicalGradient gradient;
gradient.setCenter(drawingRect.center());
gradient.setAngle(90);
gradient.setColorAt(0, QColor(178, 255, 246));
gradient.setColorAt(1, QColor(5, 44, 50));
int arcLengthApproximation = m_width + m_width / 3;
QPen pen(QBrush(gradient), m_width);
pen.setCapStyle(Qt::RoundCap);
painter.setPen(pen);
painter.drawArc(drawingRect, 90 * 16 - arcLengthApproximation, -m_loadingAngle * 16);
}
main.cpp:
main.cpp:
#include "widget.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Widget w;
w.setDiscWidth(20);
w.setLoadingAngle(270);
w.show();
return a.exec();
}
And the result is:
结果是:
Of course, it is not the complete and exact solution but I think it is everything you need to know in order to achieve what you want. The rest are details not hard to implement.
当然,这并不是一个完整准确的解决方案,但我认为,为了实现你想要的,你需要知道的一切。其余的细节并不难实现。
#2
2
This solution is not exactly what you're after; the gradient goes from top to bottom, rather than around the circle:
这个解决方案不是你想要的;梯度从上到下,而不是围绕着圆:
#include <QtWidgets>
class Widget : public QWidget
{
public:
Widget() {
resize(200, 200);
}
void paintEvent(QPaintEvent *) {
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing);
const QRectF bounds(0, 0, width(), height());
painter.fillRect(bounds, "#1c1c1c");
QPen pen;
pen.setCapStyle(Qt::RoundCap);
pen.setWidth(20);
QLinearGradient gradient;
gradient.setStart(bounds.width() / 2, 0);
gradient.setFinalStop(bounds.width() / 2, bounds.height());
gradient.setColorAt(0, "#1c1c1c");
gradient.setColorAt(1, "#28ecd6");
QBrush brush(gradient);
pen.setBrush(brush);
painter.setPen(pen);
QRectF rect = QRectF(pen.widthF() / 2.0, pen.widthF() / 2.0, width() - pen.widthF(), height() - pen.widthF());
painter.drawArc(rect, 90 * 16, 0.65 * -360 * 16);
}
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Widget w;
w.show();
return app.exec();
}
However, it is an arc with a linear gradient! :p
然而,它是一个线性渐变的弧线!:p
#1
6
I know this is an old question but I came across it some days ago and I think I have a solution. What you want is to create a conical gradient and clip the disk you want to use as circular loading bar. Here is an example:
我知道这是个老问题,但几天前我遇到了这个问题,我想我有一个解决办法。你想要的是创建一个圆锥渐变,并剪辑你想要用作圆形加载吧的磁盘。这是一个例子:
widget.h:
widget.h:
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
class QPaintEvent;
class Widget : public QWidget
{
Q_OBJECT
public:
explicit Widget(QWidget *parent = 0);
~Widget();
void setLoadingAngle(int loadingAngle);
int loadingAngle() const;
void setDiscWidth(int width);
int discWidth() const;
protected:
void paintEvent(QPaintEvent *);
private:
int m_loadingAngle;
int m_width;
};
#endif // WIDGET_H
widget.cpp:
widget.cpp:
#include "widget.h"
#include <QPaintEvent>
#include <QPainter>
#include <QConicalGradient>
#include <QPen>
Widget::Widget(QWidget *parent) :
QWidget(parent),
m_loadingAngle(0),
m_width(0)
{
}
Widget::~Widget()
{
}
void Widget::setLoadingAngle(int loadingAngle)
{
m_loadingAngle = loadingAngle;
}
int Widget::loadingAngle() const
{
return m_loadingAngle;
}
void Widget::setDiscWidth(int width)
{
m_width = width;
}
int Widget::discWidth() const
{
return m_width;
}
void Widget::paintEvent(QPaintEvent *)
{
QRect drawingRect;
drawingRect.setX(rect().x() + m_width);
drawingRect.setY(rect().y() + m_width);
drawingRect.setWidth(rect().width() - m_width * 2);
drawingRect.setHeight(rect().height() - m_width * 2);
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing);
QConicalGradient gradient;
gradient.setCenter(drawingRect.center());
gradient.setAngle(90);
gradient.setColorAt(0, QColor(178, 255, 246));
gradient.setColorAt(1, QColor(5, 44, 50));
int arcLengthApproximation = m_width + m_width / 3;
QPen pen(QBrush(gradient), m_width);
pen.setCapStyle(Qt::RoundCap);
painter.setPen(pen);
painter.drawArc(drawingRect, 90 * 16 - arcLengthApproximation, -m_loadingAngle * 16);
}
main.cpp:
main.cpp:
#include "widget.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Widget w;
w.setDiscWidth(20);
w.setLoadingAngle(270);
w.show();
return a.exec();
}
And the result is:
结果是:
Of course, it is not the complete and exact solution but I think it is everything you need to know in order to achieve what you want. The rest are details not hard to implement.
当然,这并不是一个完整准确的解决方案,但我认为,为了实现你想要的,你需要知道的一切。其余的细节并不难实现。
#2
2
This solution is not exactly what you're after; the gradient goes from top to bottom, rather than around the circle:
这个解决方案不是你想要的;梯度从上到下,而不是围绕着圆:
#include <QtWidgets>
class Widget : public QWidget
{
public:
Widget() {
resize(200, 200);
}
void paintEvent(QPaintEvent *) {
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing);
const QRectF bounds(0, 0, width(), height());
painter.fillRect(bounds, "#1c1c1c");
QPen pen;
pen.setCapStyle(Qt::RoundCap);
pen.setWidth(20);
QLinearGradient gradient;
gradient.setStart(bounds.width() / 2, 0);
gradient.setFinalStop(bounds.width() / 2, bounds.height());
gradient.setColorAt(0, "#1c1c1c");
gradient.setColorAt(1, "#28ecd6");
QBrush brush(gradient);
pen.setBrush(brush);
painter.setPen(pen);
QRectF rect = QRectF(pen.widthF() / 2.0, pen.widthF() / 2.0, width() - pen.widthF(), height() - pen.widthF());
painter.drawArc(rect, 90 * 16, 0.65 * -360 * 16);
}
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Widget w;
w.show();
return app.exec();
}
However, it is an arc with a linear gradient! :p
然而,它是一个线性渐变的弧线!:p