網(wǎng)上有很多關(guān)于pos機(jī)刷卡怎么撤回,Qt QUndoStack的知識(shí)，也有很多人為大家解答關(guān)于pos機(jī)刷卡怎么撤回的問題，今天pos機(jī)之家(www.rcqwhg.com)為大家整理了關(guān)于這方面的知識(shí)，讓我們一起來看下吧!
本文目錄一覽：
pos機(jī)刷卡怎么撤回
用到的類:1 QUndoStack： 一個(gè)存放 QUndoCommand 命令的棧.2 QUndoCommand：The QUndoCommand class is the base class of all commands stored on a QUndoStack.3 QUndoView：The QUndoView class displays the contents of a QUndoStack.（顯示QUndoStack的內(nèi)容）
下面的例子是根據(jù) Qt 自帶的例子(undoframework)寫的:
重寫 QgraphicsPolygonItem (方塊)【領(lǐng)QT開發(fā)教程學(xué)習(xí)資料，點(diǎn)擊下方鏈接免費(fèi)領(lǐng)取↓↓，先碼住不迷路~】
點(diǎn)擊→領(lǐng)取「鏈接」
myitem.h
#ifndef MYITEM_H#define MYITEM_H#include <QGraphicsItem>class myItem :public QGraphicsPolygonItem{public: enum {Type = UserType +1}; explicit myItem(QGraphicsItem *parent = 0); int type() const override{return Type;}private: QPolygonF m_boxItem;};#endif // MYITEM_H
myitem.cpp
#include "myitem.h"#include <QBrush>myItem::myItem(QGraphicsItem *parent){ m_boxItem << QPointF(0,0) << QPointF(30,0) << QPointF(30,30) << QPointF(0,30) << QPointF(0,0); setPolygon(m_boxItem); //顏色隨機(jī) QColor color( (qrand() % 256),(qrand() % 256),(qrand() % 256) ); QBrush brush(color); setBrush(brush); //可移動(dòng) setFlag(QGraphicsItem::ItemIsMovable); //可選中 setFlag(QGraphicsItem::ItemIsSelectable);}重寫 QGraphicsScene(場景)
myscene.h
#ifndef MYSCENE_H#define MYSCENE_H#include <QGraphicsScene>#include <QObject>#include "myitem.h"class myScene : public QGraphicsScene{ Q_OBJECTpublic: myScene(QObject *parent = 0);signals: void itemMoveSignal(myItem* item,const QPointF position);protected: void mousePressEvent(QGraphicsSceneMouseEvent *event); void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);private: QGraphicsItem * m_Item; QPointF m_oldPos;};#endif // MYSCENE_H
myscene.cpp
#include "myscene.h"#include <QGraphicsSceneMouseEvent>#include <QDebug>myScene::myScene(QObject *parent){ m_Item = 0;}void myScene::mousePressEvent(QGraphicsSceneMouseEvent *event){ QPointF mousePos (event->buttonDownScenePos(Qt::LeftButton).x(), event->buttonDownScenePos(Qt::LeftButton).y()); const QList<QGraphicsItem* >itemList = items(mousePos); m_Item = itemList.isEmpty() ? 0 :itemList.first(); if(m_Item != 0 && event->button() == Qt::LeftButton) m_oldPos = m_Item->pos(); QGraphicsScene::mousePressEvent(event);}void myScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *event){ if(m_Item != 0 && event->button() == Qt::LeftButton) { if(m_oldPos != m_Item->pos()) //發(fā)送位置移動(dòng)的信號(hào) emit itemMoveSignal(qgraphicsitem_cast<myItem*>(m_Item),m_oldPos); m_Item = 0; } QGraphicsScene::mouseReleaseEvent(event);}下面重寫的 QUndoCommand 才是實(shí)現(xiàn)撤回和回撤的模塊
重寫 QUndoCommand 就是重寫父類的 undo() 和 redo() 方法
mycommand.h
1 #ifndef MYCOMMAND_H 2 #define MYCOMMAND_H 3 4 #include <QUndoCommand> 5 #include "myitem.h" 6 #include "myscene.h" 7 //添加item 8 class addCommand :public QUndoCommand 9 {10 public :11 addCommand(QGraphicsScene* graphicsScene,QUndoCommand* parent = 0);12 13 void redo() override;//重寫這兩個(gè)函數(shù)14 void undo() override;15 private:16 17 myItem* m_item;18 19 QGraphicsScene* m_scene;20 21 QPointF m_initPos;22 };23 //移動(dòng)item24 class moveCommand:public QUndoCommand25 {26 public:27 moveCommand(myItem* item,const QPointF oldPos,QUndoCommand* parent = 0);28 29 void redo() override;//重寫這兩個(gè)函數(shù)30 void undo() override;31 private:32 myItem* m_item;33 QPointF m_oldPos;34 QPointF m_newPos;35 36 };37 38 #endif // MYCOMMAND_H
mycommand.cpp
【領(lǐng)QT開發(fā)教程學(xué)習(xí)資料，點(diǎn)擊下方鏈接免費(fèi)領(lǐng)取↓↓，先碼住不迷路~】
點(diǎn)擊→領(lǐng)取「鏈接」
1 #include "mycommand.h" 2 3 4 addCommand::addCommand(QGraphicsScene *graphicsScene, QUndoCommand *parent) 5 { 6 m_scene = graphicsScene; 7 8 m_item = new myItem(); 9 10 m_initPos = QPointF(10,10); //初始化item 生成的位置11 12 setText("add item");//undoView 中就會(huì)顯示（父類的方法）13 }14 15 void addCommand::redo()//stack push 時(shí) 會(huì)自動(dòng)調(diào)用16 {17 m_scene->addItem(m_item);18 m_item->setPos(m_initPos);19 m_scene->clearSelection();20 m_scene->update();21 }22 23 void addCommand::undo()24 {25 m_scene->removeItem(m_item);26 m_scene->update();27 }28 29 moveCommand::moveCommand(myItem *item, const QPointF oldPos, QUndoCommand *parent)30 {31 m_item = item;32 33 m_newPos = m_item->pos();34 35 m_oldPos = oldPos;36 }37 38 void moveCommand::redo()39 {40 m_item->setPos(m_newPos);41 setText(QString("Move Item:(%1,%2)").arg(m_item->pos().rx()).arg(m_item->pos().ry()));42 }43 44 void moveCommand::undo()45 {46 m_item->setPos(m_oldPos);47 m_item->scene()->update();48 setText(QString("Move Item:(%1,%2)").arg(m_item->pos().rx()).arg(m_item->pos().ry()));49 }主界面
widget.h
1 #ifndef WIDGET_H 2 #define WIDGET_H 3 4 #include <QWidget> 5 #include <QPushButton> 6 #include <QGraphicsView> 7 #include <QUndoStack> 8 #include <QUndoView> 9 10 #include "myscene.h"11 #include "myitem.h"12 #include "mycommand.h"13 namespace Ui {14 class Widget;15 }16 17 class Widget : public QWidget18 {19 Q_OBJECT20 21 public:22 explicit Widget(QWidget *parent = 0);23 ~Widget();24 25 void initUi();26 27 void initAction();28 29 void addItem();30 31 void itemMoved(myItem* item,QPointF pos);32 33 private:34 Ui::Widget *ui;35 QPushButton* m_addItemBtn;36 QAction* m_undoAction;37 QAction* m_redoAction;38 myScene *m_scene;39 40 QUndoStack* m_undoStack;41 QUndoView* m_undoView;42 };43 44 #endif // WIDGET_H
widget.cpp
1 #include "widget.h" 2 #include "ui_widget.h" 3 #include <QLayout> 4 5 Widget::Widget(QWidget *parent) : 6 QWidget(parent), 7 ui(new Ui::Widget) 8 { 9 ui->setupUi(this);10 11 12 initAction();13 14 initUi();15 }16 17 Widget::~Widget()18 {19 delete ui;20 }21 22 void Widget::initUi()23 {24 this->setWindowTitle("碼農(nóng)小明--撤銷回撤");25 26 m_addItemBtn = new QPushButton();27 m_addItemBtn->setText("add Item");28 29 connect(m_addItemBtn,&QPushButton::clicked,this,&Widget::addItem);30 31 m_scene = new myScene();32 QBrush brush(Qt::gray);33 m_scene->setSceneRect(QRect(0,0,200,300));34 m_scene->setBackgroundBrush(brush);35 36 connect(m_scene,&myScene::itemMoveSignal,this,&Widget::itemMoved);37 38 39 QGraphicsView *view = new QGraphicsView(m_scene);40 41 QVBoxLayout *pLayout = new QVBoxLayout();42 pLayout->addWidget(m_addItemBtn);43 pLayout->addWidget(view);44 45 46 m_undoView = new QUndoView(m_undoStack);//右面顯示棧內(nèi)容的view(不setText就是空的)47 QHBoxLayout *pHLayout = new QHBoxLayout();48 pHLayout->addLayout(pLayout);49 pHLayout->addWidget(m_undoView);50 51 52 this->setLayout(pHLayout);53 54 this->resize(500,400);55 56 }57 58 void Widget::initAction()59 {60 m_undoStack = new QUndoStack(this);//存放操作的棧61 62 m_undoAction = m_undoStack->createUndoAction(this,"Undo");63 m_undoAction->setShortcut(QKeySequence::Undo);64 65 m_redoAction = m_undoStack->createRedoAction(this,"Redo");66 m_redoAction->setShortcut(QKeySequence::Redo);67 68 this->addAction(m_undoAction);69 this->addAction(m_redoAction);70 }71 72 void Widget::addItem()73 {74 QUndoCommand* add = new addCommand(m_scene);75 m_undoStack->push(add);//入棧操作 會(huì)自動(dòng)調(diào)用 addCommand 的 redo76 77 }78 79 void Widget::itemMoved(myItem *item, QPointF pos)80 {81 m_undoStack->push(new moveCommand(item,pos));//入棧操作
以上就是關(guān)于pos機(jī)刷卡怎么撤回,Qt QUndoStack的知識(shí)，后面我們會(huì)繼續(xù)為大家整理關(guān)于pos機(jī)刷卡怎么撤回的知識(shí)，希望能夠幫助到大家！
