折线图：

#ifndef LINE_CHART_H
#define LINE_CHART_H#include <QWidget>
#include <QPainter>
#include "circle.h"
class line_chart : public QWidget
{Q_OBJECT
public:explicit line_chart(QWidget *parent = nullptr);
protected:void paintEvent(QPaintEvent *event) override;
private:QVector<int> h;int max,min,sum;
signals:};#endif // LINE_CHART_H

#include "line_chart.h"
#include <QDebug>
line_chart::line_chart(QWidget *parent) : QWidget(parent)
{sum=0;for(int i=0;i<30;i++){if(i%5==0)h<<i;else{h<<0;}}//最大值，最小值for(int i=0;i<30;++i){if(i==0){max=h.at(i);min=h.at(i);}else{if(max<h.at(i))max=h.at(i);if(min>h.at(i))min=h.at(i);}sum+=h.at(i);}
}void line_chart::paintEvent(QPaintEvent *event)
{QPainter painter(this);painter.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform | QPainter::TextAntialiasing, true);//画背景painter.save();painter.setPen(Qt::NoPen);painter.setBrush(QBrush(QColor(255,255,255)));painter.drawRect(rect());painter.restore();//画横线painter.save();//确定条数//4,0:3//5,0:4int count=max-min-1;int x1,x2,y;x1=5;x2=width()-5;y=height()-10;int w=(height()-20)/count;QPen pen;pen.setColor(QColor(214, 223, 255));pen.setWidth(1);pen.setStyle(Qt::SolidLine);painter.setPen(pen);for(int i=0;i<count;++i){painter.drawLine(x1,y,x2,y);y=y-w;}painter.restore();//画蓝色折线painter.save();double w1=width()-20;x1=10;double space=w1/(h.count()-1);QVector<QLine> lines;QPen pen1;pen1.setColor(QColor(133, 159, 255));pen1.setWidth(2);pen1.setStyle(Qt::SolidLine);painter.setPen(pen1);painter.setBrush(QBrush(QColor(243, 246, 255)));double h1=(height()-20)/(max-min);//每一小块的长度painter.translate(0,height()-10-10);for(int i=0;i<h.count()-1;++i){double y1,y2;y1=(h.at(i)-min)*h1;//高度y2=(h.at(i+1)-min)*h1;//高度lines.append(QLine(x1,-y1,x1+space,-y2));x1+=space;}painter.drawLines(lines);painter.restore();}

窗体控件透明度

QT 窗体控件的透明度设置（三种方法）_qt paint setbrush 透明_chenyazhou88的博客-CSDN博客

    opacityEffect=new QGraphicsOpacityEffect(this);this->setGraphicsEffect(opacityEffect);opacityEffect->setOpacity(0.2);

自定义按钮

#ifndef BTN5_H
#define BTN5_H#include <QPushButton>
#include "btn1.h"
class btn5 : public btn1
{Q_OBJECT
public:btn5(QWidget * parent = nullptr);void set_normal_icon(QString icon);void init(QSize size,QSize hover_size);
protected:void paintEvent(QPaintEvent *) override;void enterEvent(QEvent *event) override;void leaveEvent(QEvent *event) override;
private:QString normal_icon;QSize icon_size,size,hover_size;bool hover;
signals:void mouse_enter();void mouse_leave();
};#endif // BTN5_H

#include "btn5.h"
#include <QDebug>
#include <QPainter>
#pragma execution_character_set("utf-8")
#pragma execution_character_set("utf-8")
btn5::btn5(QWidget * parent ): btn1(parent)
{init(QSize(50,50),QSize(150,50));icon_size=QSize(25,25);
}void btn5::set_normal_icon(QString icon)
{normal_icon=icon;
}void btn5::init(QSize s,QSize hover_s)
{size=s;hover_size=hover_s;QSizePolicy sizePolicy1(QSizePolicy::Fixed, QSizePolicy::Fixed);sizePolicy1.setHorizontalStretch(0);sizePolicy1.setVerticalStretch(0);sizePolicy1.setHeightForWidth(this->sizePolicy().hasHeightForWidth());this->setSizePolicy(sizePolicy1);//宽高this->setMinimumSize(size);this->setMaximumSize(size);hover=false;
}void btn5::enterEvent(QEvent *event)
{Q_UNUSED(event);qDebug()<<"进入事件发生";hover=true;//显示
}void btn5::leaveEvent(QEvent *event)
{Q_UNUSED(event);qDebug()<<"离开事件发生";hover=false;//隐藏
}void btn5::paintEvent(QPaintEvent *)
{QPainter painter(this);painter.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform | QPainter::TextAntialiasing, true);QPen pen;pen.setColor(QColor(230,230,230));pen.setStyle(Qt::SolidLine);pen.setWidth(1);//透明背景painter.save();painter.setPen(Qt::NoPen);painter.setBrush(QBrush(QColor(255,255,255,0)));painter.drawRect(rect());painter.restore();if(!hover){this->setMinimumSize(size);this->setMaximumSize(size);painter.save();//画圆角矩形painter.setPen(pen);painter.setBrush(QBrush(QColor(255,255,255)));double side=qMin(width(),height());painter.drawRoundedRect(rect(),side/2,side/2,Qt::AbsoluteSize);painter.restore();painter.save();//画图标QPixmap pix(normal_icon);pix=pix.scaled(icon_size,Qt::IgnoreAspectRatio);painter.translate(width()/2,height()/2);QRectF target(-icon_size.width()/2,-icon_size.height()/2,icon_size.width(),icon_size.height());QRectF source(0,0,icon_size.width(),icon_size.height());painter.drawPixmap(target,pix,source);painter.restore();}else{this->setMinimumSize(hover_size);this->setMaximumSize(hover_size);painter.save();//画圆角矩形painter.setPen(pen);painter.setBrush(QBrush(QColor(255,255,255)));double side=qMin(width(),height());painter.drawRoundedRect(rect(),side/2,side/2,Qt::AbsoluteSize);painter.restore();painter.save();//画图标QPixmap pix(normal_icon);pix=pix.scaled(icon_size,Qt::IgnoreAspectRatio);//图标所占宽度：与之前一样painter.translate(size.width()/2,height()/2);QRectF target(-icon_size.width()/2,-icon_size.height()/2,icon_size.width(),icon_size.height());QRectF source(0,0,icon_size.width(),icon_size.height());painter.drawPixmap(target,pix,source);painter.restore();//画文字painter.save();painter.translate(size.width(),height()/2);QFont font;font.setPointSize(10);painter.setFont(font);QPen pen;pen.setColor(QColor(50,50,50));painter.setPen(pen);painter.drawText(0,-height()/2,hover_size.width()-size.width(),height(),Qt::AlignLeft | Qt::AlignVCenter,text());painter.restore();}
}