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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

  

• 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

 1 #ifndef PATCHWINDOW\_H
 2 #define PATCHWINDOW\_H
 3 
 4 #include 
 5 #include 
 6 #include 
 7 #include 
 8 #include 
 9 #include 
10 
11 enum CursorRegion{
12  NONE,
13  TOPLEFT,
14  TOPRIGHT,
15  BOTTOMRIGHT,
16  BOTTOMLEFT
17 };
18 
19 namespace Ui {
20 class Patchwindow;
21 }
22 
23 class Patchwindow : public QWidget
24 {
25  Q\_OBJECT
26 
27 public:
28 explicit Patchwindow(QWidget *parent = 0);
29 ~Patchwindow();
30  CursorRegion getCursorRegion(QPoint);
31 
32 public:
33 int borderWidth;
34 int handleSize;
35 
36 bool mousePressed;
37  QPoint previousPos;
38 
39 private:
40 Ui::Patchwindow *ui;
41 
42 protected:
43 void mousePressEvent(QMouseEvent*);
44 void mouseReleaseEvent(QMouseEvent*);
45 void mouseMoveEvent(QMouseEvent*);
46 
47 signals:
48 void send\_widget\_rx\_ry(int rx,int ry);
49 };
50 
51 #endif // PATCHWINDOW\_H

View Code

 patchwindow.cpp

 1 #include "patchwindow.h"
 2 #include "ui\_patchwindow.h"
 3 
 4 Patchwindow::Patchwindow(QWidget *parent) :
 5  QWidget(parent),
 6     ui(new Ui::Patchwindow)
 7 {
 8     ui->setupUi(this);
 9 
10     this->setMouseTracking(true);
11 
12  setFocusPolicy(Qt::StrongFocus);
13 
14     mousePressed = false;
15     borderWidth = 1;
16     handleSize = 8;
17 
18 }
19 
20 Patchwindow::~Patchwindow()
21 {
22     delete ui;
23 }
24 
25 
26 //设置鼠标形状
27 CursorRegion Patchwindow::getCursorRegion(QPoint pos)
28 {
29     if (pos.x() > 0 && pos.x() < (handleSize + borderWidth) &&
30         pos.y() > 0 && pos.y() < (handleSize + borderWidth) ){
31         if (this->hasFocus())
32             this->setCursor(QCursor(Qt::SizeFDiagCursor));
33         return CursorRegion::TOPLEFT;
34  }
35 
36     if (pos.x() > (this->width() - handleSize - borderWidth) && pos.x() < this->width() &&
37         pos.y() > 0 && pos.y() < (handleSize + borderWidth) ){
38         if (this->hasFocus())
39             this->setCursor(QCursor(Qt::SizeBDiagCursor));
40         return CursorRegion::TOPRIGHT;
41  }
42 
43     if (pos.x() > (this->width() - handleSize - borderWidth) && pos.x() < this->width() &&
44         pos.y() > (this->height() - handleSize - borderWidth) && pos.y() < this->height() ){
45         if (this->hasFocus())
46             this->setCursor(QCursor(Qt::SizeFDiagCursor));
47         return CursorRegion::BOTTOMRIGHT;
48  }
49 
50 
51     if (pos.x() > 0 && pos.x() < (handleSize + borderWidth) &&
52         pos.y() > (this->height() - handleSize - borderWidth) && pos.y() < this->height() ){
53         if (this->hasFocus())
54             this->setCursor(QCursor(Qt::SizeBDiagCursor));
55         return CursorRegion::BOTTOMLEFT;
56  }
57 
58     this->setCursor(Qt::ArrowCursor);
59     return CursorRegion::NONE;
60 }
61 
62 void Patchwindow::mousePressEvent(QMouseEvent *event)
63 {
64     mousePressed = true;
65     previousPos = this->mapToParent(event->pos());
66     //qDebug()<<"previousPos = "<
67 }
68 
69 void Patchwindow::mouseReleaseEvent(QMouseEvent*)
70 {
71 mousePressed = false;
72 }
73 
74 void Patchwindow::mouseMoveEvent(QMouseEvent *event)
75 {
76 if (mousePressed){
77 QPoint \_curPos = this->mapToParent(event->pos());
78 QPoint \_offPos = \_curPos - previousPos;
79 previousPos = \_curPos;
80 //qDebug()<<"\_offPos = "<<\_offPos;
81 //qDebug()<<"\_curPos = "<<\_curPos;
82  emit send\_widget\_rx\_ry(\_offPos.rx(),\_offPos.ry());
83  }
84 }

View Code

 mainwindow.h

 1 #ifndef MAINWINDOW\_H
 2 #define MAINWINDOW\_H
 3 
 4 #include 
 5 #include 
 6 #include 
 7 #include 
 8 
 9 
10 namespace Ui {
11 class MainWindow;
12 }
13 
14 class MainWindow : public QMainWindow
15 {
16  Q\_OBJECT
17 
18 public:
19 explicit MainWindow(QWidget *parent = 0);
20 ~MainWindow();
21 
22 QScrollArea *m\_pScroll;
23 
24 
25 private:
26 Ui::MainWindow *ui;
27 
28 private slots:
29 void remove\_widget(int r\_x,int r\_y);
30 
31 
32 };
33 
34 #endif // MAINWINDOW\_H

View Code

 mainwindow.cpp

 1 #include "mainwindow.h"
 2 #include "ui\_mainwindow.h"
 3 #include 
 4 
 5 #include 
 6 
 7 MainWindow::MainWindow(QWidget *parent) :
 8  QMainWindow(parent),
 9 ui(new Ui::MainWindow)
10 {
11 ui->setupUi(this);
12 //this->resize(600,600);
13 
14 //给父窗体填充颜色
15 QPalette palette = ui->widget\_2->palette();
16 palette.setBrush(QPalette::Window,QBrush(QColor(61,61,61)));
17 ui->widget\_2->setAutoFillBackground(true);
18 ui->widget\_2->setPalette(palette);
19 
20 ui->widget\_2->setAttribute(Qt::WA\_StyledBackground);
21 ui->widget\_2->setStyleSheet("QWidget{background: black}");
22 
23 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
24 
25 m\_pScroll = new QScrollArea(ui->widget);
26 m\_pScroll->setWidget(ui->widget\_2);//给widget\_2设置滚动条
27 //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
28 
29 QHBoxLayout *pLayout = new QHBoxLayout;
30 pLayout->addWidget(m\_pScroll);
31 pLayout->setMargin(0);
32 pLayout->setSpacing(0);
33 ui->widget->setLayout(pLayout);
34 
35 connect(ui->widget\_2,&Patchwindow::send\_widget\_rx\_ry,this,&MainWindow::remove\_widget);
36 
37 }
38 
39 MainWindow::~MainWindow()
40 {
41 delete ui;
42 }
43 
44 void MainWindow::remove\_widget(int r\_x,int r\_y)
45 {
46 r\_y = m\_pScroll->verticalScrollBar()->value()-r\_y;
47 r\_x = m\_pScroll->horizontalScrollBar()->value()-r\_x;
48 
49 if((0 < r\_y) | (r\_y == 0))
50  {
51 if(r\_y > m\_pScroll->verticalScrollBar()->maximum())
52  {
53 r\_y = m\_pScroll->verticalScrollBar()->maximum();
54  }
55  }
56 else
57  {
58 r\_y = 0;
59  }
60 
61 if((0 < r\_x) | (r\_x == 0))
62  {
63 if(r\_x > m\_pScroll->horizontalScrollBar()->maximum())
64  {
65 r\_x = m\_pScroll->horizontalScrollBar()->maximum();
66  }
67  }
68 else
69  {
70 r\_x = 0;
71  }
72 
73 m\_pScroll->verticalScrollBar()->setValue(r\_y);
74 m\_pScroll->horizontalScrollBar()->setValue(r\_x);
75 
76 }

View Code

• 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：

  

  工程源码下载路径：

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