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QT创建一个qWidget界面
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
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
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_OBJECTpublic: 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_Hpatchwindow.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_OBJECTpublic: 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_Hmainwindow.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：
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