Qt实现手动切换多种布局

引言

之前写了一个手动切换多个布局的程序，下面来记录一下。
程序运行效果如下：
在这里插入图片描述

示例

需求

通过点击程序界面上不同的布局按钮，使主工作区呈现出不同的页面布局，多个布局之间可以通过点击不同布局按钮切换。支持的最多的窗口为9个。不同布局下窗口数随之变化。

开发环境

使用的QtCreator12.0.2,基于Qt5.15.2库开发。

代码实现

创建基于QApplication的应用程序。
下面是实现代码：
main.cpp

#include "manullayoutdialog.h"#include <QApplication>int main(int argc, char *argv[])
{QApplication a(argc, argv);ManulLayoutDialog w;w.show();ObjectPooling*m_pool = ObjectPooling::getInstance(9);return a.exec();
}

ObjectPooling.h

#ifndef OBJECTPOOLING_H
#define OBJECTPOOLING_H#include <QObject>
#include <QWidget>
#include <QVector>class ObjectPooling:public QObject
{Q_OBJECT
private:ObjectPooling(qint32 num);ObjectPooling(const ObjectPooling &) = delete;ObjectPooling& operator=(const ObjectPooling&)=delete;
public:static ObjectPooling *getInstance(qint32 num);~ObjectPooling();QWidget* takeOut();void putIn(QWidget *pWidget);int getSize()const;
private:QVector<QWidget*> m_vecWidget;
};#endif // OBJECTPOOLING_H

ObjectPooling.cpp

#include "objectpooling.h"
#include <qDebug>ObjectPooling::ObjectPooling(qint32 num):QObject() {for(int i = 0; i < num;++i){QWidget *pWidget = new QWidget;if(pWidget){pWidget->setStyleSheet("background-color:back;");m_vecWidget.push_back(pWidget);}}
}ObjectPooling *ObjectPooling::getInstance(qint32 num)
{static ObjectPooling instance(num);return &instance;
}ObjectPooling::~ObjectPooling()
{if(m_vecWidget.size()<1)return;for(auto it = m_vecWidget.begin();it != m_vecWidget.end();++it){if(*it){delete *it;(*it) = nullptr;}}m_vecWidget.clear();
}QWidget *ObjectPooling::takeOut()
{if(m_vecWidget.size()){QWidget*pWidget = m_vecWidget.back();
//        qDebug()<<"takeOut-befor : "<<m_vecWidget.size();m_vecWidget.pop_back();
//       qDebug()<<"takeOut-back : "<<m_vecWidget.size();return pWidget;}qDebug()<<"对象池没有对象了！！";return nullptr;
}void ObjectPooling::putIn(QWidget *pWidget)
{m_vecWidget.push_back(pWidget);
}int ObjectPooling::getSize() const
{return m_vecWidget.size();
}

ManulLayoutDialog.h

#ifndef MANULLAYOUTDIALOG_H
#define MANULLAYOUTDIALOG_H#include <QDialog>
#include "objectpooling.h"QT_BEGIN_NAMESPACE
namespace Ui {
class ManulLayoutDialog;
}
QT_END_NAMESPACEclass ManulLayoutDialog : public QDialog
{Q_OBJECTpublic:ManulLayoutDialog(QWidget *parent = nullptr);~ManulLayoutDialog();
private:void initLayout();void clearLastLayout(int n);//n——新的布局中窗口的总数void threeColumnLayout(int r,int c);//r——行数，c——列数
private slots:void on_pushButton_clicked();void on_pushButton_2_clicked();void on_pushButton_3_clicked();void on_pushButton_4_clicked();void on_pushButton_5_clicked();private:Ui::ManulLayoutDialog *ui;qint32 m_n;//布局中窗口的总个数QVector<QWidget*> m_vecWidget;//保存布局中的窗口ObjectPooling* m_pool;
};
#endif // MANULLAYOUTDIALOG_H

ManulLayoutDialog.cpp

#include "manullayoutdialog.h"
#include "ui_manullayoutdialog.h"
#include <QDebug>ManulLayoutDialog::ManulLayoutDialog(QWidget *parent): QDialog(parent), ui(new Ui::ManulLayoutDialog)
{ui->setupUi(this);initLayout();
}ManulLayoutDialog::~ManulLayoutDialog()
{for(QWidget *pWidget:m_vecWidget){pWidget->setParent(nullptr);//不设置被回收的窗口父对象为空，会被再次释放ObjectPooling::getInstance(9)->putIn(pWidget);}m_vecWidget.clear();delete ui;//若被回收的窗口没有设置父对象为空，这里会析构该窗口，回收到对象池后会再次析构
}void ManulLayoutDialog::initLayout()
{QHBoxLayout *pHLayout = new QHBoxLayout(ui->widget);pHLayout->setContentsMargins(0,0,0,0);QWidget *pWidget = ObjectPooling::getInstance(9)->takeOut();pHLayout->addWidget(pWidget);m_n = 1;m_vecWidget.push_back(pWidget);m_pool = ObjectPooling::getInstance(9);
}void ManulLayoutDialog::clearLastLayout(int n)
{QLayout *pLayout = ui->widget->layout();
//    qDebug()<<"移除前的窗口数m_vecWidget: "<<m_vecWidget.size();if(m_n>n){for(int i =0; i <m_n -n;++i){//趟数//移除窗口中的控件，回收到对象池QWidget *pWidget = m_vecWidget.back();if(pLayout && pWidget){qDebug()<<"准备移除窗口===";pLayout->removeWidget(pWidget);pWidget->setParent(nullptr);m_vecWidget.pop_back();}// if(pLayout){qDebug()<<"布局不为空 ";}// if(pWidget){qDebug()<<"窗口不为空 ";}// QWidget *fWidget = pWidget->parentWidget();ObjectPooling::getInstance(9)->putIn(pWidget);// qDebug()<<"对象池窗口数m_vecWidget： "<<ObjectPooling::getInstance(9)->getSize();// qDebug()<<"移除后的窗口数m_vecWidget： "<<m_vecWidget.size();}}else if(m_n <n){//为了防止二次重设父对象，先将上一次的父对象清空for(auto it = m_vecWidget.begin();it != m_vecWidget.end();++it){if(*it){(*it)->setParent(nullptr);}}for(int i = 0; i < n-m_n;++i){m_vecWidget.push_back(ObjectPooling::getInstance(9)->takeOut());}}//删除窗口原本的布局delete pLayout;//    ui->widget->setLayout(nullptr);
}void ManulLayoutDialog::threeColumnLayout(int r, int c)
{int total = r*c;if(m_n == total){return ;}clearLastLayout(total);QGridLayout *pGridLayout = new QGridLayout(ui->widget);pGridLayout->setContentsMargins(0,0,0,0);for(int i = 0; i < r;++i){for(int j = 0; j < c; ++j){pGridLayout->addWidget(m_vecWidget[i+j+2*i],i,j);//找下标对应的位置与元素之间的关系}}m_n = total;
}void ManulLayoutDialog::on_pushButton_clicked()
{if(m_n == 1){return ;}else{clearLastLayout(1);}QHBoxLayout *pHLayout = new QHBoxLayout(ui->widget);pHLayout->setContentsMargins(0,0,0,0);// qDebug()<<"布局1中的窗口数m_vecWidget： "<<m_vecWidget.size();pHLayout->addWidget(m_vecWidget.back());m_n = 1;
}void ManulLayoutDialog::on_pushButton_2_clicked()
{if(m_n == 2){return ;}else if(m_n > 2){clearLastLayout(2);QHBoxLayout *pLayout = new QHBoxLayout(ui->widget);pLayout->setContentsMargins(0,0,0,0);for(auto it = m_vecWidget.begin();it != m_vecWidget.end();++it){pLayout->addWidget(*it);}}else{QLayout *pLayout = ui->widget->layout();QWidget *pWidget = ObjectPooling::getInstance(9)->takeOut();pLayout->addWidget(pWidget);m_vecWidget.push_back(pWidget);}m_n = 2;// qDebug()<<"布局2中的窗口数m_vecWidget: "<<m_vecWidget.size();
}void ManulLayoutDialog::on_pushButton_3_clicked()
{if(m_n == 4){return ;}clearLastLayout(4);//只能先清理之前的布局，不能与下面的新布局互换位置QGridLayout *pGridLayout = new QGridLayout(ui->widget);pGridLayout->setContentsMargins(0,0,0,0);for(int i = 0; i < 2;++i){for(int j = 0; j < 2; ++j){pGridLayout->addWidget(m_vecWidget[i+j+i],i,j);//找下标对应的位置与元素之间的关系}}m_n = 4;
}void ManulLayoutDialog::on_pushButton_4_clicked()
{threeColumnLayout(2,3);
}void ManulLayoutDialog::on_pushButton_5_clicked()
{threeColumnLayout(3,3);
}

运行结果

选一种的2行6列布局下的效果的截图。具体的运行效果和文章开始的效果一样。
在这里插入图片描述

程序分析

项目中先创建了一个单例模式下的对象池，负责布局中总窗口的创建、回收，取出、以及存入。同时创建了一个手动布局类ManulLayoutDialog，在该类中实现了在界面上点击不同布局按钮的响应，ObjectPooling类作为手动布局类ManulLayoutDialog的成员函数，两个类之间是一种关联的关系。采用队列存放布局中的窗口，当要切换的布局中的窗口数大于当前的窗口布局中的窗口数，则先清除之前的窗口布局，将布局中的窗口回收到窗口数组中，同时向对象池中取出相差数量的窗口，放入窗口数组，创建新的布局，将窗口数组中的窗口加入新布局；当要切换的布局中的窗口数小于当前的窗口布局中的窗口数，则先从布局中移除相差数量的窗口，将移除的窗口从窗口数组中去除，删除窗口原来的布局，同时将移除的窗口存入对象池中，创建新的布局，将窗口数组中的窗口加入到新的布局。