QT5笔记：36. QGraphicsView 综合示例（完结撒花！）

合集 - Qt入门(36)

1.QT5笔记：1.UI文件设计与运行机制2022-05-02 2.QT5笔记：2.可视化UI设计2022-05-02 3.QT5笔记：6. QT 与 C++2023-03-15 4.QT5笔记：5. QtCreator 的快捷键2023-03-15 5.QT5笔记：4. 设置应用图标2022-05-02 6.QT5笔记：3.手动撸界面和可视化托界面混合2022-05-02 7.QT5笔记： 14. SpinBox的常用功能2023-03-15 8.QT5笔记：13. QString 的常用功能2023-03-15 9.QT5笔记：12. 字符串和数值之间的转换2023-03-15 10.QT5笔记：11. Qt类库的模块2023-03-15 11.QT5笔记：10. 容器类的迭代2023-03-15 12.QT5笔记：9. QT的容器类2023-03-15 13.QT5笔记： 8. QT的全局变量（基本数据类型、函数、宏）2023-03-15 14.QT5笔记：7. 自定义类、自定义信号及类的元对象信息2023-03-15 15.QT5笔记： 30. 二进制文件读写2023-03-16 16.QT5笔记： 29. 文本文件读写2023-03-16 17.QT5笔记： 28. SplashWindow 没听懂，无内容2023-03-16 18.QT5笔记：27. MDI应用程序设计2023-03-16 19.QT5笔记： 26. 多窗体应用程序设计2023-03-16 20.QT5笔记： 25. 非模态的自定义对话框2023-03-16 21.QT5笔记：24. 自定义对话框以及模态调用2023-03-16 22.QT5笔记： 23. 标准对话框2023-03-16 23.QT5笔记： 22. 自定义代理2023-03-16 24.QT5笔记： 21. QStandardItemModel2023-03-16 25.QT5笔记： 20. QStringListModel的使用2023-03-16 26.QT5笔记： 19. QFileSystemModel 联动 QListView QTableView QTreeView2023-03-16 27.QT5笔记：18 QPainter基本绘图2023-03-15 28.QT5笔记：17. QComboBox和QPlainTextEdit2023-03-15 29.QT5笔记： 16. 时间和定时器的常用功能2023-03-15 30.QT5笔记： 15. 其他显示组件的常用功能2023-03-15

31.QT5笔记：36. QGraphicsView 综合示例（完结撒花！）2023-03-16

32.QT5笔记： 35. QGraphicsView 视图2023-03-16 33.QT5笔记：34. 视口和窗口2023-03-16 34.QT5笔记：33. 坐标系统和坐标变换2023-03-16 35.QT5笔记： 32. QPainter 基本绘制2023-03-16 36.QT5笔记： 31. 文件目录操作2023-03-16

通过此示例可以比较熟悉QGraphincsView的流程以及操作
坐标关系以及获取：

View坐标：左上角为原点，通过鼠标移动事件获取

Scene坐标：中心为原点，横竖为X,Y轴。通过View.mapToScene(View坐标)获取

Item坐标：Item中心为原点，由于可旋转，X,Y轴方向不定。通过item.mapFromScene(Scene坐标，View.Transform)获取
View缩放：X、Y可以不同比例

ui->graphicsView->scale(1.1, 1.1);//放大
ui->graphicsView->scale(0.9, 0.9);//缩小
ui->graphicsView->resetTransform();//恢复比例
设置item可以拖动、选中、获取焦点

item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
可以框选多个

ui->graphicsView->setDragMode(QGraphicsView::RubberBandDrag);//鼠标框选
item缩放

item->setScale(item->scale() - 0.1);//缩小
item->setScale(item->scale() + 0.1);//放大
item->setScale(1);//恢复比例
item旋转

item->setRotation(item->rotation() - 3);//逆时针转3度
item->setRotation(item->rotation() + 3);//顺时针转3度
item前置&后置

item->setZValue(item->zValue() + 1);//前置
item->setZValue(item->zValue() - 1);//后置
item组合&打散

//组合
QGraphicsItemGroup *group = new QGraphicsItemGroup();
group->addToGroup(item);
group->setFlags(QGraphicsItemGroup::ItemIsFocusable | QGraphicsItemGroup::ItemIsSelectable | QGraphicsItemGroup::ItemIsMovable);
scene->addItem(group);

//打散
QGraphicsItem *item = scene->selectedItems().at(i);
if (item->type() == QGraphicsItemGroup::Type) {
QGraphicsItemGroup *group = qgraphicsitem_cast<QGraphicsItemGroup *>(item);
scene->destroyItemGroup(group);
}
item删除

scene->removeItem(item);//删除

例子：

GraphicsView.h重写的 QGraphicsView，重写鼠标、键盘事件

 #ifndef GRAPHICSVIEW_H
#define GRAPHICSVIEW_H
 
#include <QGraphicsView>
 
class GraphicsView : public QGraphicsView
{
    Q_OBJECT
public:
    explicit GraphicsView(QWidget *parent = nullptr);
 
signals:
    void keyPress(QKeyEvent *event);
    void mouseDoubleClick(QPoint point);
    void mousePress(QPoint point);
    void mouseMove(QPoint point);
 
    // QWidget interface
protected:
    void mouseDoubleClickEvent(QMouseEvent *event) override;
    void mousePressEvent(QMouseEvent *event) override;
    void mouseMoveEvent(QMouseEvent *event) override;
    void keyPressEvent(QKeyEvent *event) override;
 
};
 
#endif // GRAPHICSVIEW_H

GraphicsView.cpp

 #include "GraphicsView.h"
 
#include <QMouseEvent>
 
GraphicsView::GraphicsView(QWidget *parent) : QGraphicsView(parent)
{
 
}
 
 
void GraphicsView::mouseDoubleClickEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        emit(mouseDoubleClick(event->pos()));
    }
    QGraphicsView::mouseDoubleClickEvent(event);//交还事件给父类处理
}
 
void GraphicsView::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        emit(mousePress(event->pos()));
    }
    QGraphicsView::mousePressEvent(event);
}
 
void GraphicsView::mouseMoveEvent(QMouseEvent *event)
{
    emit(mouseMove(event->pos()));
    QGraphicsView::mouseMoveEvent(event);
}
 
void GraphicsView::keyPressEvent(QKeyEvent *event)
{
    emit(keyPress(event));
    QGraphicsView::keyPressEvent(event);
}

MainWindow.h

 #ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QGraphicsScene>
#include <QLabel>
#include <QMainWindow>
#include <QMouseEvent>
 
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
 
private:
    Ui::MainWindow *ui;
 
    QGraphicsScene *scene;
    static const int itemID = 1;
    static const int description = 2;
    int seqNum = 0;//item的ID序列
 
    QLabel   *labView = new QLabel("View坐标：", this);
    QLabel  *labViewCoord = new QLabel("(000 , 000)\t", this);
    QLabel  *labScene = new QLabel("Scene坐标：", this);
    QLabel  *labSceneCoord = new QLabel("(000 , 000)\t", this);
    QLabel  *labItem = new QLabel("Item坐标：", this);
    QLabel  *labItemCoord = new QLabel("(000 , 000)\t", this);
    QLabel  *labItemID = new QLabel("ItemID：", this);
    QLabel  *labItemInfo = new QLabel("", this);
 
private slots:
    void onKeyPress(QKeyEvent *event);
    void onMouseDoubleClick(QPoint point);
    void onMousePress(QPoint point);
    void onMouseMove(QPoint point);
    void on_actItem_Rect_triggered();
    void on_actItem_Polygon_triggered();
    void on_actItem_Triangle_triggered();
    void on_actItem_Circle_triggered();
    void on_actItem_Ellipse_triggered();
    void on_actItem_Line_triggered();
    void on_actItem_Text_triggered();
    void on_actZoomIn_triggered();
    void on_actZoomOut_triggered();
    void on_actRestore_triggered();
    void on_actRotateLeft_triggered();
    void on_actRotateRight_triggered();
    void on_actEdit_Front_triggered();
    void on_actEdit_Back_triggered();
    void on_actGroup_triggered();
    void on_actGroupBreak_triggered();
    void on_actEdit_Delete_triggered();
};
#endif // MAINWINDOW_H

MainWindow.cpp

 #include "mainwindow.h"
#include "ui_mainwindow.h"
 
#include <QColorDialog>
#include <QFontDialog>
#include <QGraphicsRectItem>
#include <QInputDialog>
 
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
 
    scene = new QGraphicsScene(-300, -100, 600, 200);
    ui->graphicsView->setScene(scene);
    ui->graphicsView->setCursor(Qt::CrossCursor);
    ui->graphicsView->setMouseTracking(true);
    ui->graphicsView->setDragMode(QGraphicsView::RubberBandDrag);//鼠标框选
 
    ui->statusbar->addWidget(this->labView);
    ui->statusbar->addWidget(this->labViewCoord);
    ui->statusbar->addWidget(this->labScene);
    ui->statusbar->addWidget(this->labSceneCoord);
    ui->statusbar->addWidget(this->labItem);
    ui->statusbar->addWidget(this->labItemCoord);
    ui->statusbar->addWidget(this->labItemID);
    ui->statusbar->addWidget(this->labItemInfo);
 
    connect(ui->graphicsView, SIGNAL(keyPress(QKeyEvent *)), this, SLOT(onKeyPress(QKeyEvent *)));
    connect(ui->graphicsView, SIGNAL(mouseDoubleClick(QPoint)), this, SLOT(onMouseDoubleClick(QPoint)));
    connect(ui->graphicsView, SIGNAL(mousePress(QPoint)), this, SLOT(onMousePress(QPoint)));
    connect(ui->graphicsView, SIGNAL(mouseMove(QPoint)), this, SLOT(onMouseMove(QPoint)));
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::on_actItem_Rect_triggered()//矩形
{
    QBrush brush;
    brush.setColor(QColor(169, 134, 49, 200));
    brush.setStyle(Qt::SolidPattern);
 
    QGraphicsRectItem *item = new QGraphicsRectItem(-50, -30, 100, 60);
    item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
    item->setBrush(brush);
    item->setData(itemID, seqNum++);
    item->setData(description, "矩形");
    scene->addItem(item);
    scene->clearSelection();
    item->setSelected(true);
}
 
void MainWindow::on_actItem_Polygon_triggered()//梯形/多边形
{
    QBrush brush;
    brush.setColor(QColor(255, 78, 55));
    brush.setStyle(Qt::Dense4Pattern);
 
    QVector<QPointF> points;
    points << QPointF(-50, -70) << QPointF(50, -70) << QPointF(70, -30) << QPointF(-70, -30);
    QPolygonF polygon = QPolygonF(points);
    QGraphicsPolygonItem *item = new QGraphicsPolygonItem(points);
    item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
    item->setBrush(brush);
    item->setData(itemID, seqNum++);
    item->setData(description, "梯形");
    scene->addItem(item);
    scene->clearSelection();
    item->setSelected(true);
}
 
void MainWindow::on_actItem_Triangle_triggered()//三角形
{
    QBrush brush;
    brush.setColor(QColor(81, 181, 110));
    brush.setStyle(Qt::Dense4Pattern);
 
    QVector<QPointF> points;
    points << QPointF(0, -30) << QPointF(-30, 0) << QPointF(30, 0);
    QPolygonF polygon = QPolygonF(points);
    QGraphicsPolygonItem *item = new QGraphicsPolygonItem(points);
    item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
    item->setBrush(brush);
    item->setData(itemID, seqNum++);
    item->setData(description, "三角形");
    scene->addItem(item);
    scene->clearSelection();
    item->setSelected(true);
}
 
void MainWindow::on_actItem_Circle_triggered()
{
    QBrush brush;
    brush.setColor(QColor(151, 151, 151));
    brush.setStyle(Qt::SolidPattern);
 
    QGraphicsEllipseItem *item = new QGraphicsEllipseItem(0, 0, 10, 10);
    item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
    item->setBrush(brush);
    item->setData(itemID, seqNum++);
    item->setData(description, "圆形");
    scene->addItem(item);
    scene->clearSelection();
    item->setSelected(true);
}
 
void MainWindow::on_actItem_Ellipse_triggered()
{
    QBrush brush;
    brush.setColor(QColor(195, 195, 195));
    brush.setStyle(Qt::Dense4Pattern);
 
    QGraphicsEllipseItem *item = new QGraphicsEllipseItem(0, 0, 15, 10);
    item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
    item->setBrush(brush);
    item->setData(itemID, seqNum++);
    item->setData(description, "椭圆形");
    scene->addItem(item);
    scene->clearSelection();
    item->setSelected(true);
}
 
void MainWindow::on_actItem_Line_triggered()
{
    QPen pen;
    pen.setWidth(2);
 
    QGraphicsLineItem *item = new QGraphicsLineItem(-100, 0, 100, 0);
    item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
    item->setPen(pen);
    item->setData(itemID, seqNum++);
    item->setData(description, "直线");
    scene->addItem(item);
    scene->clearSelection();
    item->setSelected(true);
}
 
void MainWindow::on_actItem_Text_triggered()
{
    QFont font;
    font.setPointSize(12);
    font.setFamily("MiSans");
 
    QString text = QInputDialog::getText(this, "", "文本内容");
    QGraphicsTextItem *item = new QGraphicsTextItem(text);
    item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
    item->setFont(font);
    item->setData(itemID, seqNum++);
    item->setData(description, "文本");
    scene->addItem(item);
    scene->clearSelection();
    item->setSelected(true);
}
 
void MainWindow::on_actZoomIn_triggered()//放大
{
    int count = scene->selectedItems().count();
    if (count != 0) {
        for (int i = 0; i < count; i++) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            item->setScale(item->scale() + 0.1);
        }
    } else {
        ui->graphicsView->scale(1.1, 1.1);
    }
}
 
void MainWindow::on_actZoomOut_triggered()//缩小
{
    int count = scene->selectedItems().count();
    if (count != 0) {
        for (int i = 0; i < count; i++) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            item->setScale(item->scale() - 0.1);
        }
    } else {
        ui->graphicsView->scale(0.9, 0.9);
    }
}
 
void MainWindow::on_actRestore_triggered()//恢复比例
{
    int count = scene->selectedItems().count();
    if (count != 0) {
        for (int i = 0; i < count; i++) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            item->setScale(1);
        }
    } else {
        ui->graphicsView->resetTransform();//恢复比例
    }
}
 
void MainWindow::on_actRotateLeft_triggered()//左旋转
{
    int count = scene->selectedItems().count();
    if (count != 0) {
        for (int i = 0; i < count; i++) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            item->setRotation(item->rotation() - 3);
        }
    }
}
 
void MainWindow::on_actRotateRight_triggered()//右旋转
{
    int count = scene->selectedItems().count();
    if (count != 0) {
        for (int i = 0; i < count; i++) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            item->setRotation(item->rotation() + 3);
        }
    }
}
 
void MainWindow::on_actEdit_Front_triggered()//前置
{
    int count = scene->selectedItems().count();
    if (count != 0) {
        for (int i = 0; i < count; i++) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            item->setZValue(item->zValue() + 1);
        }
    }
}
 
void MainWindow::on_actEdit_Back_triggered()//后置
{
    int count = scene->selectedItems().count();
    if (count != 0) {
        for (int i = 0; i < count; i++) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            item->setZValue(item->zValue() - 1);
        }
    }
}
 
void MainWindow::on_actGroup_triggered()//组合
{
    int count = scene->selectedItems().count();
    if (count > 0) {
        QGraphicsItemGroup *group = new QGraphicsItemGroup();
        for (int i = count - 1; i >= 0; i--) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            item->setSelected(false);
            group->addToGroup(item);
        }
        group->setFlags(QGraphicsItemGroup::ItemIsFocusable | QGraphicsItemGroup::ItemIsSelectable | QGraphicsItemGroup::ItemIsMovable);
        scene->addItem(group);
        group->setSelected(true);
    }
}
 
void MainWindow::on_actGroupBreak_triggered()//打散
{
    int count = scene->selectedItems().count();
    if (count > 0) {
        for (int i = count - 1; i >= 0; i--) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            if (item->type() == QGraphicsItemGroup::Type) {
                QGraphicsItemGroup *group = qgraphicsitem_cast<QGraphicsItemGroup *>(item);
                scene->destroyItemGroup(group);
            }
        }
    }
}
 
void MainWindow::on_actEdit_Delete_triggered()//删除
{
    int count = scene->selectedItems().count();
    if (count != 0) {
        for (int i = count - 1; i >= 0; i--) {
            QGraphicsItem *item = scene->selectedItems().at(i);
            scene->removeItem(item);
        }
    }
}
 
void MainWindow::onMouseDoubleClick(QPoint point)//双击修改颜色或字体
{
    QPointF pointScene = ui->graphicsView->mapToScene(point);
    QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
    if (item != nullptr) {
        switch (item->type()) {
            case QGraphicsRectItem::Type: {//矩形
                    QGraphicsRectItem *itemRect = qgraphicsitem_cast<QGraphicsRectItem *>(item);
                    QBrush brush = itemRect->brush();
                    QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
                    if (color.isValid()) {
                        brush.setColor(color);
                        itemRect->setBrush(brush);
                    }
                    break;
                }
            case QGraphicsPolygonItem::Type: {//多边形：梯形、三角形
                    QGraphicsPolygonItem *itemPolygon = qgraphicsitem_cast<QGraphicsPolygonItem *>(item);
                    QBrush brush = itemPolygon->brush();
                    QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
                    if (color.isValid()) {
                        brush.setColor(color);
                        itemPolygon->setBrush(brush);
                    }
                    break;
                }
            case QGraphicsEllipseItem::Type: {//椭圆 & 圆
                    QGraphicsEllipseItem *itemEllipse = qgraphicsitem_cast<QGraphicsEllipseItem *>(item);
                    QBrush brush = itemEllipse->brush();
                    QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
                    if (color.isValid()) {
                        brush.setColor(color);
                        itemEllipse->setBrush(brush);
                    }
                    break;
                }
            case QGraphicsTextItem::Type: {//文本
                    QGraphicsTextItem *itemText = qgraphicsitem_cast<QGraphicsTextItem *>(item);
                    bool ok = false;
                    QFont font = QFontDialog::getFont(&ok, itemText->font(), this, "选择字体", QFontDialog::DontUseNativeDialog);
                    if (ok) {
                        itemText->setFont(font);
                    }
 
                    QColor color = QColorDialog::getColor(itemText->defaultTextColor(), this, "选择一个颜色", QColorDialog::DontUseNativeDialog);//使用Qt的标准颜色对话框而不是操作系统的本机颜色对话框。
                    if (color.isValid()) {
                        itemText->setDefaultTextColor(color);
                    }
                    break;
                }
            case QGraphicsLineItem::Type: {//直线
                    QGraphicsLineItem *itemLine = qgraphicsitem_cast<QGraphicsLineItem *>(item);
                    QPen pen = itemLine->pen();
                    QColor color = QColorDialog::getColor(pen.color(), this, "选择一个颜色");
                    if (color.isValid()) {
                        pen.setColor(color);
                        itemLine->setPen(pen);
                    }
                    break;
                }
            default: break;
        }
    }
}
 
void MainWindow::onKeyPress(QKeyEvent *event)
{
    QList<QGraphicsItem *> items = scene->selectedItems();
    int count = items.count();
    if (count > 0) {
        switch (event->key()) {
            case Qt::Key_Delete://刪除
            case Qt::Key_Backspace://退格键
                on_actEdit_Delete_triggered();
                break;
            case Qt::Key_Left://左
                for (int i = 0; i < count; i++) {
                    QGraphicsItem *item = items.at(i);
                    item->setX(item->x() - 1);
                }
                break;
            case Qt::Key_Right://右
                for (int i = 0; i < count; i++) {
                    QGraphicsItem *item = items.at(i);
                    item->setX(item->x() + 1);
                }
                break;
            case Qt::Key_Up://上
                for (int i = 0; i < count; i++) {
                    QGraphicsItem *item = items.at(i);
                    item->setY(item->y() - 1);
                }
                break;
            case Qt::Key_Down://下
                for (int i = 0; i < count; i++) {
                    QGraphicsItem *item = items.at(i);
                    item->setY(item->y() + 1);
                }
                break;
            case Qt::Key_Space: on_actRotateRight_triggered(); break;//往右转
            case Qt::Key_PageUp: on_actZoomIn_triggered(); break;//放大
            case Qt::Key_PageDown: on_actZoomOut_triggered(); break;//缩小
        }
    }
}
 
void MainWindow::onMousePress(QPoint point)//将鼠标点击的itemID显示在状态栏
{
    QPointF pointScene = ui->graphicsView->mapToScene(point);
    QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
    if (item != nullptr) {
        labItemInfo->setText(item->data(itemID).toString());
    }
}
 
void MainWindow::onMouseMove(QPoint point)//鼠标移动事件
{
    this->labViewCoord->setText(QString::asprintf("(%4d , %4d)\t", point.x(), point.y()));//View 坐標
 
    QPointF pointScene  = ui->graphicsView->mapToScene(point);
    this->labSceneCoord->setText(QString::asprintf("(%4.0f , %4.0f)\t", pointScene.x(), pointScene.y()));//Scene 坐標
 
    QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
    if (item != nullptr) {
        QPointF itemPoint = item->mapFromScene(pointScene);//item坐标
        this->labItemCoord->setText(QString::asprintf("(%4.0f , %4.0f)\t", itemPoint.x(), itemPoint.x()));
        this->labItemInfo->setText(item->data(itemID).toString());
    } else {
        this->labItemCoord->setText("(0000 , 0000)");
        this->labItemInfo->setText("");
    }
}

界面

Qt5 完结撒花，感谢陪伴！！！

reference:

参考视频：https://www.bilibili.com/video/BV1AX4y1w7Nt

NOTICE

参考视频到此还没有结束，但是我忘记写笔记了，emmmm，大家想看的，可以去B站看

__EOF__

本文作者：echo_lovely
本文链接：https://www.cnblogs.com/echo-lovely/p/17222278.html
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QT5笔记：36. QGraphicsView 综合示例（完结撒花！）

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	ui->graphicsView->scale(1.1, 1.1);//放大
	ui->graphicsView->scale(0.9, 0.9);//缩小
	ui->graphicsView->resetTransform();//恢复比例

	item->setScale(item->scale() - 0.1);//缩小
	item->setScale(item->scale() + 0.1);//放大
	item->setScale(1);//恢复比例

	item->setRotation(item->rotation() - 3);//逆时针转3度
	item->setRotation(item->rotation() + 3);//顺时针转3度

	item->setZValue(item->zValue() + 1);//前置
	item->setZValue(item->zValue() - 1);//后置

	//组合
	QGraphicsItemGroup *group = new QGraphicsItemGroup();
	group->addToGroup(item);
	group->setFlags(QGraphicsItemGroup::ItemIsFocusable \| QGraphicsItemGroup::ItemIsSelectable \| QGraphicsItemGroup::ItemIsMovable);
	scene->addItem(group);

	//打散
	QGraphicsItem *item = scene->selectedItems().at(i);
	if (item->type() == QGraphicsItemGroup::Type) {
	QGraphicsItemGroup group = qgraphicsitem_cast<QGraphicsItemGroup >(item);
	scene->destroyItemGroup(group);
	}

	#ifndef GRAPHICSVIEW_H
	#define GRAPHICSVIEW_H

	#include <QGraphicsView>

	class GraphicsView : public QGraphicsView
	{
	Q_OBJECT
	public:
	explicit GraphicsView(QWidget *parent = nullptr);

	signals:
	void keyPress(QKeyEvent *event);
	void mouseDoubleClick(QPoint point);
	void mousePress(QPoint point);
	void mouseMove(QPoint point);

	// QWidget interface
	protected:
	void mouseDoubleClickEvent(QMouseEvent *event) override;
	void mousePressEvent(QMouseEvent *event) override;
	void mouseMoveEvent(QMouseEvent *event) override;
	void keyPressEvent(QKeyEvent *event) override;

	};

	#endif // GRAPHICSVIEW_H

	#include "GraphicsView.h"

	#include <QMouseEvent>

	GraphicsView::GraphicsView(QWidget *parent) : QGraphicsView(parent)
	{

	}


	void GraphicsView::mouseDoubleClickEvent(QMouseEvent *event)
	{
	if (event->button() == Qt::LeftButton) {
	emit(mouseDoubleClick(event->pos()));
	}
	QGraphicsView::mouseDoubleClickEvent(event);//交还事件给父类处理
	}

	void GraphicsView::mousePressEvent(QMouseEvent *event)
	{
	if (event->button() == Qt::LeftButton) {
	emit(mousePress(event->pos()));
	}
	QGraphicsView::mousePressEvent(event);
	}

	void GraphicsView::mouseMoveEvent(QMouseEvent *event)
	{
	emit(mouseMove(event->pos()));
	QGraphicsView::mouseMoveEvent(event);
	}

	void GraphicsView::keyPressEvent(QKeyEvent *event)
	{
	emit(keyPress(event));
	QGraphicsView::keyPressEvent(event);
	}

	#ifndef MAINWINDOW_H
	#define MAINWINDOW_H

	#include <QGraphicsScene>
	#include <QLabel>
	#include <QMainWindow>
	#include <QMouseEvent>

	QT_BEGIN_NAMESPACE
	namespace Ui { class MainWindow; }
	QT_END_NAMESPACE

	class MainWindow : public QMainWindow
	{
	Q_OBJECT

	public:
	MainWindow(QWidget *parent = nullptr);
	~MainWindow();

	private:
	Ui::MainWindow *ui;

	QGraphicsScene *scene;
	static const int itemID = 1;
	static const int description = 2;
	int seqNum = 0;//item的ID序列

	QLabel *labView = new QLabel("View坐标：", this);
	QLabel *labViewCoord = new QLabel("(000 , 000)\t", this);
	QLabel *labScene = new QLabel("Scene坐标：", this);
	QLabel *labSceneCoord = new QLabel("(000 , 000)\t", this);
	QLabel *labItem = new QLabel("Item坐标：", this);
	QLabel *labItemCoord = new QLabel("(000 , 000)\t", this);
	QLabel *labItemID = new QLabel("ItemID：", this);
	QLabel *labItemInfo = new QLabel("", this);

	private slots:
	void onKeyPress(QKeyEvent *event);
	void onMouseDoubleClick(QPoint point);
	void onMousePress(QPoint point);
	void onMouseMove(QPoint point);
	void on_actItem_Rect_triggered();
	void on_actItem_Polygon_triggered();
	void on_actItem_Triangle_triggered();
	void on_actItem_Circle_triggered();
	void on_actItem_Ellipse_triggered();
	void on_actItem_Line_triggered();
	void on_actItem_Text_triggered();
	void on_actZoomIn_triggered();
	void on_actZoomOut_triggered();
	void on_actRestore_triggered();
	void on_actRotateLeft_triggered();
	void on_actRotateRight_triggered();
	void on_actEdit_Front_triggered();
	void on_actEdit_Back_triggered();
	void on_actGroup_triggered();
	void on_actGroupBreak_triggered();
	void on_actEdit_Delete_triggered();
	};
	#endif // MAINWINDOW_H

	#include "mainwindow.h"
	#include "ui_mainwindow.h"

	#include <QColorDialog>
	#include <QFontDialog>
	#include <QGraphicsRectItem>
	#include <QInputDialog>

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

	scene = new QGraphicsScene(-300, -100, 600, 200);
	ui->graphicsView->setScene(scene);
	ui->graphicsView->setCursor(Qt::CrossCursor);
	ui->graphicsView->setMouseTracking(true);
	ui->graphicsView->setDragMode(QGraphicsView::RubberBandDrag);//鼠标框选

	ui->statusbar->addWidget(this->labView);
	ui->statusbar->addWidget(this->labViewCoord);
	ui->statusbar->addWidget(this->labScene);
	ui->statusbar->addWidget(this->labSceneCoord);
	ui->statusbar->addWidget(this->labItem);
	ui->statusbar->addWidget(this->labItemCoord);
	ui->statusbar->addWidget(this->labItemID);
	ui->statusbar->addWidget(this->labItemInfo);

	connect(ui->graphicsView, SIGNAL(keyPress(QKeyEvent )), this, SLOT(onKeyPress(QKeyEvent )));
	connect(ui->graphicsView, SIGNAL(mouseDoubleClick(QPoint)), this, SLOT(onMouseDoubleClick(QPoint)));
	connect(ui->graphicsView, SIGNAL(mousePress(QPoint)), this, SLOT(onMousePress(QPoint)));
	connect(ui->graphicsView, SIGNAL(mouseMove(QPoint)), this, SLOT(onMouseMove(QPoint)));
	}

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

	void MainWindow::on_actItem_Rect_triggered()//矩形
	{
	QBrush brush;
	brush.setColor(QColor(169, 134, 49, 200));
	brush.setStyle(Qt::SolidPattern);

	QGraphicsRectItem *item = new QGraphicsRectItem(-50, -30, 100, 60);
	item->setFlags(QGraphicsItem::ItemIsSelectable \| QGraphicsItem::ItemIsFocusable \| QGraphicsItem::ItemIsMovable);
	item->setBrush(brush);
	item->setData(itemID, seqNum++);
	item->setData(description, "矩形");
	scene->addItem(item);
	scene->clearSelection();
	item->setSelected(true);
	}

	void MainWindow::on_actItem_Polygon_triggered()//梯形/多边形
	{
	QBrush brush;
	brush.setColor(QColor(255, 78, 55));
	brush.setStyle(Qt::Dense4Pattern);

	QVector<QPointF> points;
	points << QPointF(-50, -70) << QPointF(50, -70) << QPointF(70, -30) << QPointF(-70, -30);
	QPolygonF polygon = QPolygonF(points);
	QGraphicsPolygonItem *item = new QGraphicsPolygonItem(points);
	item->setFlags(QGraphicsItem::ItemIsSelectable \| QGraphicsItem::ItemIsFocusable \| QGraphicsItem::ItemIsMovable);
	item->setBrush(brush);
	item->setData(itemID, seqNum++);
	item->setData(description, "梯形");
	scene->addItem(item);
	scene->clearSelection();
	item->setSelected(true);
	}

	void MainWindow::on_actItem_Triangle_triggered()//三角形
	{
	QBrush brush;
	brush.setColor(QColor(81, 181, 110));
	brush.setStyle(Qt::Dense4Pattern);

	QVector<QPointF> points;
	points << QPointF(0, -30) << QPointF(-30, 0) << QPointF(30, 0);
	QPolygonF polygon = QPolygonF(points);
	QGraphicsPolygonItem *item = new QGraphicsPolygonItem(points);
	item->setFlags(QGraphicsItem::ItemIsSelectable \| QGraphicsItem::ItemIsFocusable \| QGraphicsItem::ItemIsMovable);
	item->setBrush(brush);
	item->setData(itemID, seqNum++);
	item->setData(description, "三角形");
	scene->addItem(item);
	scene->clearSelection();
	item->setSelected(true);
	}

	void MainWindow::on_actItem_Circle_triggered()
	{
	QBrush brush;
	brush.setColor(QColor(151, 151, 151));
	brush.setStyle(Qt::SolidPattern);

	QGraphicsEllipseItem *item = new QGraphicsEllipseItem(0, 0, 10, 10);
	item->setFlags(QGraphicsItem::ItemIsSelectable \| QGraphicsItem::ItemIsFocusable \| QGraphicsItem::ItemIsMovable);
	item->setBrush(brush);
	item->setData(itemID, seqNum++);
	item->setData(description, "圆形");
	scene->addItem(item);
	scene->clearSelection();
	item->setSelected(true);
	}

	void MainWindow::on_actItem_Ellipse_triggered()
	{
	QBrush brush;
	brush.setColor(QColor(195, 195, 195));
	brush.setStyle(Qt::Dense4Pattern);

	QGraphicsEllipseItem *item = new QGraphicsEllipseItem(0, 0, 15, 10);
	item->setFlags(QGraphicsItem::ItemIsSelectable \| QGraphicsItem::ItemIsFocusable \| QGraphicsItem::ItemIsMovable);
	item->setBrush(brush);
	item->setData(itemID, seqNum++);
	item->setData(description, "椭圆形");
	scene->addItem(item);
	scene->clearSelection();
	item->setSelected(true);
	}

	void MainWindow::on_actItem_Line_triggered()
	{
	QPen pen;
	pen.setWidth(2);

	QGraphicsLineItem *item = new QGraphicsLineItem(-100, 0, 100, 0);
	item->setFlags(QGraphicsItem::ItemIsSelectable \| QGraphicsItem::ItemIsFocusable \| QGraphicsItem::ItemIsMovable);
	item->setPen(pen);
	item->setData(itemID, seqNum++);
	item->setData(description, "直线");
	scene->addItem(item);
	scene->clearSelection();
	item->setSelected(true);
	}

	void MainWindow::on_actItem_Text_triggered()
	{
	QFont font;
	font.setPointSize(12);
	font.setFamily("MiSans");

	QString text = QInputDialog::getText(this, "", "文本内容");
	QGraphicsTextItem *item = new QGraphicsTextItem(text);
	item->setFlags(QGraphicsItem::ItemIsSelectable \| QGraphicsItem::ItemIsFocusable \| QGraphicsItem::ItemIsMovable);
	item->setFont(font);
	item->setData(itemID, seqNum++);
	item->setData(description, "文本");
	scene->addItem(item);
	scene->clearSelection();
	item->setSelected(true);
	}

	void MainWindow::on_actZoomIn_triggered()//放大
	{
	int count = scene->selectedItems().count();
	if (count != 0) {
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	item->setScale(item->scale() + 0.1);
	}
	} else {
	ui->graphicsView->scale(1.1, 1.1);
	}
	}

	void MainWindow::on_actZoomOut_triggered()//缩小
	{
	int count = scene->selectedItems().count();
	if (count != 0) {
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	item->setScale(item->scale() - 0.1);
	}
	} else {
	ui->graphicsView->scale(0.9, 0.9);
	}
	}

	void MainWindow::on_actRestore_triggered()//恢复比例
	{
	int count = scene->selectedItems().count();
	if (count != 0) {
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	item->setScale(1);
	}
	} else {
	ui->graphicsView->resetTransform();//恢复比例
	}
	}

	void MainWindow::on_actRotateLeft_triggered()//左旋转
	{
	int count = scene->selectedItems().count();
	if (count != 0) {
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	item->setRotation(item->rotation() - 3);
	}
	}
	}

	void MainWindow::on_actRotateRight_triggered()//右旋转
	{
	int count = scene->selectedItems().count();
	if (count != 0) {
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	item->setRotation(item->rotation() + 3);
	}
	}
	}

	void MainWindow::on_actEdit_Front_triggered()//前置
	{
	int count = scene->selectedItems().count();
	if (count != 0) {
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	item->setZValue(item->zValue() + 1);
	}
	}
	}

	void MainWindow::on_actEdit_Back_triggered()//后置
	{
	int count = scene->selectedItems().count();
	if (count != 0) {
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	item->setZValue(item->zValue() - 1);
	}
	}
	}

	void MainWindow::on_actGroup_triggered()//组合
	{
	int count = scene->selectedItems().count();
	if (count > 0) {
	QGraphicsItemGroup *group = new QGraphicsItemGroup();
	for (int i = count - 1; i >= 0; i--) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	item->setSelected(false);
	group->addToGroup(item);
	}
	group->setFlags(QGraphicsItemGroup::ItemIsFocusable \| QGraphicsItemGroup::ItemIsSelectable \| QGraphicsItemGroup::ItemIsMovable);
	scene->addItem(group);
	group->setSelected(true);
	}
	}

	void MainWindow::on_actGroupBreak_triggered()//打散
	{
	int count = scene->selectedItems().count();
	if (count > 0) {
	for (int i = count - 1; i >= 0; i--) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	if (item->type() == QGraphicsItemGroup::Type) {
	QGraphicsItemGroup group = qgraphicsitem_cast<QGraphicsItemGroup >(item);
	scene->destroyItemGroup(group);
	}
	}
	}
	}

	void MainWindow::on_actEdit_Delete_triggered()//删除
	{
	int count = scene->selectedItems().count();
	if (count != 0) {
	for (int i = count - 1; i >= 0; i--) {
	QGraphicsItem *item = scene->selectedItems().at(i);
	scene->removeItem(item);
	}
	}
	}

	void MainWindow::onMouseDoubleClick(QPoint point)//双击修改颜色或字体
	{
	QPointF pointScene = ui->graphicsView->mapToScene(point);
	QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
	if (item != nullptr) {
	switch (item->type()) {
	case QGraphicsRectItem::Type: {//矩形
	QGraphicsRectItem itemRect = qgraphicsitem_cast<QGraphicsRectItem >(item);
	QBrush brush = itemRect->brush();
	QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
	if (color.isValid()) {
	brush.setColor(color);
	itemRect->setBrush(brush);
	}
	break;
	}
	case QGraphicsPolygonItem::Type: {//多边形：梯形、三角形
	QGraphicsPolygonItem itemPolygon = qgraphicsitem_cast<QGraphicsPolygonItem >(item);
	QBrush brush = itemPolygon->brush();
	QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
	if (color.isValid()) {
	brush.setColor(color);
	itemPolygon->setBrush(brush);
	}
	break;
	}
	case QGraphicsEllipseItem::Type: {//椭圆 & 圆
	QGraphicsEllipseItem itemEllipse = qgraphicsitem_cast<QGraphicsEllipseItem >(item);
	QBrush brush = itemEllipse->brush();
	QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
	if (color.isValid()) {
	brush.setColor(color);
	itemEllipse->setBrush(brush);
	}
	break;
	}
	case QGraphicsTextItem::Type: {//文本
	QGraphicsTextItem itemText = qgraphicsitem_cast<QGraphicsTextItem >(item);
	bool ok = false;
	QFont font = QFontDialog::getFont(&ok, itemText->font(), this, "选择字体", QFontDialog::DontUseNativeDialog);
	if (ok) {
	itemText->setFont(font);
	}

	QColor color = QColorDialog::getColor(itemText->defaultTextColor(), this, "选择一个颜色", QColorDialog::DontUseNativeDialog);//使用Qt的标准颜色对话框而不是操作系统的本机颜色对话框。
	if (color.isValid()) {
	itemText->setDefaultTextColor(color);
	}
	break;
	}
	case QGraphicsLineItem::Type: {//直线
	QGraphicsLineItem itemLine = qgraphicsitem_cast<QGraphicsLineItem >(item);
	QPen pen = itemLine->pen();
	QColor color = QColorDialog::getColor(pen.color(), this, "选择一个颜色");
	if (color.isValid()) {
	pen.setColor(color);
	itemLine->setPen(pen);
	}
	break;
	}
	default: break;
	}
	}
	}

	void MainWindow::onKeyPress(QKeyEvent *event)
	{
	QList<QGraphicsItem *> items = scene->selectedItems();
	int count = items.count();
	if (count > 0) {
	switch (event->key()) {
	case Qt::Key_Delete://刪除
	case Qt::Key_Backspace://退格键
	on_actEdit_Delete_triggered();
	break;
	case Qt::Key_Left://左
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = items.at(i);
	item->setX(item->x() - 1);
	}
	break;
	case Qt::Key_Right://右
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = items.at(i);
	item->setX(item->x() + 1);
	}
	break;
	case Qt::Key_Up://上
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = items.at(i);
	item->setY(item->y() - 1);
	}
	break;
	case Qt::Key_Down://下
	for (int i = 0; i < count; i++) {
	QGraphicsItem *item = items.at(i);
	item->setY(item->y() + 1);
	}
	break;
	case Qt::Key_Space: on_actRotateRight_triggered(); break;//往右转
	case Qt::Key_PageUp: on_actZoomIn_triggered(); break;//放大
	case Qt::Key_PageDown: on_actZoomOut_triggered(); break;//缩小
	}
	}
	}

	void MainWindow::onMousePress(QPoint point)//将鼠标点击的itemID显示在状态栏
	{
	QPointF pointScene = ui->graphicsView->mapToScene(point);
	QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
	if (item != nullptr) {
	labItemInfo->setText(item->data(itemID).toString());
	}
	}

	void MainWindow::onMouseMove(QPoint point)//鼠标移动事件
	{
	this->labViewCoord->setText(QString::asprintf("(%4d , %4d)\t", point.x(), point.y()));//View 坐標

	QPointF pointScene = ui->graphicsView->mapToScene(point);
	this->labSceneCoord->setText(QString::asprintf("(%4.0f , %4.0f)\t", pointScene.x(), pointScene.y()));//Scene 坐標

	QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
	if (item != nullptr) {
	QPointF itemPoint = item->mapFromScene(pointScene);//item坐标
	this->labItemCoord->setText(QString::asprintf("(%4.0f , %4.0f)\t", itemPoint.x(), itemPoint.x()));
	this->labItemInfo->setText(item->data(itemID).toString());
	} else {
	this->labItemCoord->setText("(0000 , 0000)");
	this->labItemInfo->setText("");
	}
	}

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QT5笔记：36. QGraphicsView 综合示例（完结撒花！）