Qt基于QScrollArea实现界面嵌套移动_C/C++

在实际的应用场景中，经常会出现软件界面战场图大于实际窗体大小，利用QScrollArea可以为widget窗体添加滚动条，可以实现小窗体利用滚动条显示大界面需求。实现如下：

QT创建一个qWidget界面

Qt基于QScrollArea实现界面嵌套移动

在ui界面中利用QT自带的widget控件布局一个如下图所示的层叠关系，widget_2界面大小需大于widget大小

Qt基于QScrollArea实现界面嵌套移动

界面布局好后，将widget_2提升为类，提升之前需为工程新添加一个设计界面类，添加完之后，将widget_2提升为类类名和前面新添加的设计界面类名一致

Qt基于QScrollArea实现界面嵌套移动

源码实现如下

patchwindow.h

#ifndef PATCHWINDOW_H
#define PATCHWINDOW_H

#include <QDebug>
#include <QPainter>
#include <QWidget>
#include <QMouseEvent>
#include <QStyleOption>
#include <QPaintEvent>

enum CursorRegion{
  NONE,
  TOPLEFT,
  TOPRIGHT,
  BOTTOMRIGHT,
  BOTTOMLEFT
};

namespace Ui {
class Patchwindow;
}

class Patchwindow : public QWidget
{
  Q_OBJECT

public:
  explicit Patchwindow(QWidget *parent = 0);
  ~Patchwindow();
  CursorRegion getCursorRegion(QPoint);

public:
  int borderWidth;
  int handleSize;

  bool mousePressed;
  QPoint previousPos;

private:
  Ui::Patchwindow *ui;

protected:
  void mousePressEvent(QMouseEvent*);
  void mouseReleaseEvent(QMouseEvent*);
  void mouseMoveEvent(QMouseEvent*);

signals:
  void send_widget_rx_ry(int rx,int ry);
};

#endif // PATCHWINDOW_H

patchwindow.cpp

#include "patchwindow.h"
#include "ui_patchwindow.h"

Patchwindow::Patchwindow(QWidget *parent) :
  QWidget(parent),
  ui(new Ui::Patchwindow)
{
  ui->setupUi(this);

  this->setMouseTracking(true);

  setFocusPolicy(Qt::StrongFocus);

  mousePressed = false;
  borderWidth = 1;
  handleSize = 8;

}

Patchwindow::~Patchwindow()
{
  delete ui;
}


//设置鼠标形状
CursorRegion Patchwindow::getCursorRegion(QPoint pos)
{
  if (pos.x() > 0 && pos.x() < (handleSize + borderWidth) &&
      pos.y() > 0 && pos.y() < (handleSize + borderWidth)  ){
      if (this->hasFocus())
          this->setCursor(QCursor(Qt::SizeFDiagCursor));
      return CursorRegion::TOPLEFT;
  }

  if (pos.x() > (this->width() - handleSize - borderWidth) && pos.x() < this->width() &&
      pos.y() > 0 && pos.y() < (handleSize + borderWidth)  ){
      if (this->hasFocus())
          this->setCursor(QCursor(Qt::SizeBDiagCursor));
      return CursorRegion::TOPRIGHT;
  }

  if (pos.x() > (this->width() - handleSize - borderWidth) && pos.x() < this->width() &&
      pos.y() > (this->height() - handleSize - borderWidth) && pos.y() < this->height()  ){
      if (this->hasFocus())
          this->setCursor(QCursor(Qt::SizeFDiagCursor));
      return CursorRegion::BOTTOMRIGHT;
  }


  if (pos.x() > 0 && pos.x() < (handleSize + borderWidth) &&
      pos.y() > (this->height() - handleSize - borderWidth) && pos.y() < this->height()  ){
      if (this->hasFocus())
          this->setCursor(QCursor(Qt::SizeBDiagCursor));
      return CursorRegion::BOTTOMLEFT;
  }

  this->setCursor(Qt::ArrowCursor);
  return CursorRegion::NONE;
}

void Patchwindow::mousePressEvent(QMouseEvent *event)
{
  mousePressed = true;
  previousPos = this->mapToParent(event->pos());
  //qDebug()<<"previousPos = "<<previousPos;
}

void Patchwindow::mouseReleaseEvent(QMouseEvent*)
{
  mousePressed = false;
}

void Patchwindow::mouseMoveEvent(QMouseEvent *event)
{
  if (mousePressed){
      QPoint _curPos = this->mapToParent(event->pos());
      QPoint _offPos = _curPos - previousPos;
      previousPos = _curPos;
      //qDebug()<<"_offPos = "<<_offPos;
      //qDebug()<<"_curPos = "<<_curPos;
      emit send_widget_rx_ry(_offPos.rx(),_offPos.ry());
  }
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QHBoxLayout>
#include <QDebug>
#include <QScrollArea>


namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
  Q_OBJECT

public:
  explicit MainWindow(QWidget *parent = 0);
  ~MainWindow();

  QScrollArea *m_pScroll;


private:
  Ui::MainWindow *ui;

private slots:
  void remove_widget(int r_x,int r_y);


};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QPalette>

#include <QScrollBar>

MainWindow::MainWindow(QWidget *parent) :
  QMainWindow(parent),
  ui(new Ui::MainWindow)
{
  ui->setupUi(this);
  //this->resize(600,600);

  //给父窗体填充颜色
  QPalette palette = ui->widget_2->palette();
  palette.setBrush(QPalette::Window,QBrush(QColor(61,61,61)));
  ui->widget_2->setAutoFillBackground(true);
  ui->widget_2->setPalette(palette);

  ui->widget_2->setAttribute(Qt::WA_StyledBackground);
  ui->widget_2->setStyleSheet("QWidget{background: black}");

  ui->widget_3->setAttribute(Qt::WA_TransparentForMouseEvents, true);//设置该层鼠标事件透明，可以设置为显示层

  m_pScroll = new QScrollArea(ui->widget);
  m_pScroll->setWidget(ui->widget_2);//给widget_2设置滚动条
  //ui->widget_2->setMinimumSize(1500,1000);//这里注意，要比主窗体的尺寸要大，不然太小的话会留下一片空白

  QHBoxLayout *pLayout = new QHBoxLayout;
  pLayout->addWidget(m_pScroll);
  pLayout->setMargin(0);
  pLayout->setSpacing(0);
  ui->widget->setLayout(pLayout);

  connect(ui->widget_2,&Patchwindow::send_widget_rx_ry,this,&MainWindow::remove_widget);

}

MainWindow::~MainWindow()
{
  delete ui;
}

void MainWindow::remove_widget(int r_x,int r_y)
{
  r_y = m_pScroll->verticalScrollBar()->value()-r_y;
  r_x = m_pScroll->horizontalScrollBar()->value()-r_x;

  if((0 < r_y) | (r_y == 0))
  {
      if(r_y > m_pScroll->verticalScrollBar()->maximum())
      {
          r_y = m_pScroll->verticalScrollBar()->maximum();
      }
  }
  else
  {
      r_y = 0;
  }

  if((0 < r_x) | (r_x == 0))
  {
      if(r_x > m_pScroll->horizontalScrollBar()->maximum())
      {
          r_x = m_pScroll->horizontalScrollBar()->maximum();
      }
  }
  else
  {
      r_x = 0;
  }

  m_pScroll->verticalScrollBar()->setValue(r_y);
  m_pScroll->horizontalScrollBar()->setValue(r_x);

}

最终实现效果如下，可以通过滚轮滚动界面，也可以通过鼠标拖拽来实现界面拖拽效果：

Qt基于QScrollArea实现界面嵌套移动