#pragma once

#include <QtWidgets/QWidget>
#include<QSlider>		//滑動(dòng)條頭文件
#include<QSpinBox>		//增減控件頭文件
#include<QBoxLayout>	//界面布局頭文件，包含了水平布局<QHBoxLayout>和垂直布局<QVBoxLayout>
#include<QSpacerItem>	//彈簧頭文件
#include<QPushButton>	//按鈕頭文件
#include<QDebug>		//qDebug輸出頭文件
#include "ui_Widget.h"	//ui界面

class Widget : public QWidget
{
	Q_OBJECT

public:
	Widget(QWidget *parent = Q_NULLPTR);
	QSlider *slider;		//定義一個(gè)滑動(dòng)條，在cpp文件的構(gòu)建函數(shù)中設(shè)置屬性，下列控件同
	QSpinBox *box;			//定義一個(gè)增減控件

	QSpacerItem *spacer;	//彈簧1
	QSpacerItem *spacer2;	//彈簧2

	QPushButton *btn_setMedi;		//設(shè)置中間值的按鈕
	QPushButton *btn_getValue;		//打印當(dāng)前值的按鈕

private:
	Ui::WidgetClass ui;
};

#include "Widget.h"

Widget::Widget(QWidget *parent)
	: QWidget(parent)
{
	ui.setupUi(this);

	QSpinBox *box = new QSpinBox(this);	
	QSlider *slider = new QSlider(Qt::Horizontal,this);	//Qt::Horizontal設(shè)置為水平的滑動(dòng)條
	
	QSpacerItem *spacer = new QSpacerItem(20, 20);  //彈簧的w和h為20，20
	QSpacerItem *spacer2 = new QSpacerItem(20, 20);
	QSpacerItem *spacer3 = new QSpacerItem(20, 20);
	QSpacerItem *spacer4 = new QSpacerItem(20, 20);
	
	QPushButton *btn_setMedi = new QPushButton("set median", this);	//按鈕文本為“set median”
	QPushButton *btn_getValue = new QPushButton("get value", this);

	QHBoxLayout *loyout = new QHBoxLayout;//相當(dāng)于this->setLayout(loyout);定義一個(gè)水平布局
	loyout->addItem(spacer);			//添加彈簧用addItem
	loyout->addWidget(box);				//添加控件和按鈕用addWidget
	loyout->addWidget(slider);
	loyout->addItem(spacer2);

	QHBoxLayout *btnLayout = new QHBoxLayout;
	btnLayout->addItem(spacer3);
	btnLayout->addWidget(btn_setMedi);
	btnLayout->addWidget(btn_getValue);
	btnLayout->addItem(spacer4);
	
	//垂直布局設(shè)置了this，讓布局依賴在widget上
	//前面的兩個(gè)水平布局不用設(shè)置，因?yàn)樗讲季忠蕾囋诹舜怪辈季稚希恍枳钔鈱釉O(shè)置依賴
	QVBoxLayout *vloyout = new QVBoxLayout(this);	//添加垂直布局，把前面的兩個(gè)水平布局放進(jìn)來
	vloyout->addLayout(loyout);
	vloyout->addLayout(btnLayout);
	
	this->setFixedSize(400, 300);	//把窗體大小固定

	//數(shù)值改變，滑動(dòng)條跟著改變
	//函數(shù)QSpinBox::valueChanged出現(xiàn)了函數(shù)重載（int或char），需要定義一個(gè)函數(shù)指針排除二義性
	void (QSpinBox:: *box_signal ) (int) = &QSpinBox::valueChanged;
	connect(box ,box_signal , slider, &QSlider::setValue);

	//滑動(dòng)條改變，數(shù)值跟著改變
	connect(slider, &QSlider::valueChanged, box, &QSpinBox::setValue);

	//設(shè)置中間值
	//使用了Lambda表達(dá)式[](){}
	connect(btn_setMedi, &QPushButton::clicked, [=]() {
		slider->setValue(50);
	});

	//打印當(dāng)前值
	connect(btn_getValue, &QPushButton::clicked, [=]() {
		qDebug() << box->value();
	});
}

#include "Widget.h"
#include <QtWidgets/QApplication>

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
	Widget w;
	w.show();
	return a.exec();
}

class MySliderUI : public QWidget
{
? ? Q_OBJECT
public:
? ? explicit MySliderUI(QWidget *parent = 0);
? ? ~MySliderUI();
protected:
? ? bool eventFilter(QObject *obj, QEvent *event);

private:
? ? Ui::EpsSliderUI *ui;
};

MySliderUI::MySliderUI(QWidget *parent) :
? ? QWidget(parent)
{
? ? ui->slider->installEventFilter(this);
}

bool MySliderUI::eventFilter(QObject *obj, QEvent *event)
{
? ? if( obj == ui->slider)
? ? {
? ? ? ? if (event->type() == QEvent::MouseButtonPress)
? ? ? ? {
? ? ? ? ? ? QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event);
? ? ? ? ? ? if (mouseEvent->button() == Qt::LeftButton)
? ? ? ? ? ? {
? ? ? ? ? ? ? ? ui->slider->event(event);
? ? ? ? ? ? ? ? double pos = mouseEvent->pos().y() / (double)ui->slider->height();
? ? ? ? ? ? ?? ?int value = ?pos * (ui->slider->maximum() - ui->slider->minimum())?
? ? ? ? ? ? ?? ??? ??? ??? ??? ? ?+ ui->slider->minimum()+0.5;
? ? ? ? ? ? ? ? ui->slider->setValue(value);
? ? ? ? ? ? ? ? return true;
? ? ? ? ? ? }
? ? ? ? }
? ? ? ? else if (event->type() == QEvent::MouseButtonDblClick)
? ? ? ? {
? ? ? ? ? ? return true;
? ? ? ? }
? ? ? ? else if (event->type() == QEvent::MouseMove)
? ? ? ? {
? ? ? ? ? ? QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event);
? ? ? ? ? ? ui->slider->event(event);
? ? ? ? ? ? double pos = mouseEvent->pos().y() / (double)ui->slider->height();
? ? ? ? ? ? int value = ?pos * (ui->slider->maximum() - ui->slider->minimum())?
? ? ? ? ? ? ?? ??? ??? ??? ??? ?+ ui->slider->minimum()+0.5;
? ? ? ? ? ? ui->slider->setValue(value);
? ? ? ? ? ? return true;
? ? ? ? }
? ? }
? ? return QObject::eventFilter(obj,event);
}

class MySlider : public QSlider
{
? ? Q_OBJECT
public:
? ? MySlider(QWidget *parent = nullptr);
? ? ~MySlider();

protected:
? ? void mousePressEvent(QMouseEvent *event); ?//單擊
? ? void mouseMoveEvent(QMouseEvent *event);
};

#include "myslider.h"
#include <QMouseEvent>

MySlider::MySlider(QWidget *parent)
? ? :QSlider (parent)
{
}

MySlider::~MySlider()
{
}

void MySlider::mousePressEvent(QMouseEvent *event)
{
? ? if (event->button() == Qt::LeftButton)?? ?//判斷左鍵
? ? {
? ? ? ? //注意應(yīng)先調(diào)用父類的鼠標(biāo)點(diǎn)擊處理事件，這樣可以不影響拖動(dòng)的情況
? ? ? ? QSlider::mousePressEvent(event);
? ? ? ? double pos = ((double)height() - event->pos().y()) / (double)height();
? ? ? ? int value = pos * (maximum() - minimum()) + minimum();
? ? ? ? setValue(value);
? ? }
}
void MySlider::mouseMoveEvent(QMouseEvent *event)
{
? ? //注意應(yīng)先調(diào)用父類的鼠標(biāo)點(diǎn)擊處理事件，這樣可以不影響拖動(dòng)的情況
? ? QSlider::mouseMoveEvent(event);
? ? double pos = ?((double)height() - event->pos().y()) / (double)height();
? ? int value = pos * (maximum() - minimum()) + minimum();
? ? setValue(value);
}