C++ Qt 学习（八）：Qt 绘图技术与图形视图

1. 常见 18 种 Qt 绘图技术

在这里插入图片描述

1.1 widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <memory>
#include <QTreeView>
#include "CPaintWidget.h"

using namespace std;

class Widget : public QWidget {
    Q_OBJECT

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

private:
    void treeView();

private slots:
    void treeViewExpand(const QModelIndex &index);

private:
    QTreeView* m_pLeftTree = nullptr;
    CPaintWidget* m_pPaintWidget = nullptr;
};

#endif // WIDGET_H

1.2 widget.cpp

#pragma execution_character_set("utf-8")

#include "widget.h"
#include <QStandardItemModel>
#include <QHBoxLayout>
#include "drawtype.h"

Widget::Widget(QWidget* parent) : QWidget(parent) {
    setWindowTitle(u8"draw all");

    QHBoxLayout* pHLay = new QHBoxLayout(this);
    // 创建左边树形视图
    m_pLeftTree = new QTreeView(this);
    m_pLeftTree->setEditTriggers(QAbstractItemView::NoEditTriggers);  //设置不可编辑
    m_pLeftTree->setFixedWidth(300);
    // 创建右边绘图窗口
    m_pPaintWidget = new CPaintWidget(this);
    // 添加进水平布局
    pHLay->addWidget(m_pLeftTree);
    pHLay->addWidget(m_pPaintWidget);

    treeView();
}

Widget::~Widget() {}

void Widget::treeView() {
    m_pLeftTree->setFrameShape(QFrame::NoFrame);

    QStandardItemModel* model = new QStandardItemModel(m_pLeftTree);
    model->setHorizontalHeaderLabels(QStringList() << "draw all");

    QStandardItem* pParentItem = NULL;
    QStandardItem* pChildItem = NULL;

    // 点
    pParentItem = new QStandardItem(QIcon(":/resources/point.png"), "draw ponit");
    model->appendRow(pParentItem);

    pChildItem = new QStandardItem(QIcon(":/resources/point.png"), "point");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/multipoints.png"), "multipoints");
    pParentItem->appendRow(pChildItem);

    // 线
    pParentItem = new QStandardItem(QIcon(":/resources/line.png"), "draw line");
    model->appendRow(pParentItem);

    pChildItem = new QStandardItem(QIcon(":/resources/line.png"), "line");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/arc.png"), "arc");
    pParentItem->appendRow(pChildItem);

    // 封闭的图形
    pParentItem = new QStandardItem(QIcon(":/resources/rect.png"), "draw rect");
    model->appendRow(pParentItem);

    pChildItem = new QStandardItem(QIcon(":/resources/rect.png"), "rect");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/roundrect.png"), "roundrect");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/chord.png"), "chord");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/ellipse.png"), "ellipse");
    pParentItem->appendRow(pChildItem);

    // 任意路径绘制
    pParentItem = new QStandardItem(QIcon(":/resources/polygon.png"), "draw polygon");
    model->appendRow(pParentItem);

    pChildItem = new QStandardItem(QIcon(":/resources/polygon.png"), "polygon");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/polyline.png"), "polyline");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/ConvexPloygon.png"), "ConvexPloygon");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/lines.png"), "lines");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/path.png"), "path");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/pie.png"), "pie");
    pParentItem->appendRow(pChildItem);

    // 图片绘制
    pParentItem = new QStandardItem(QIcon(":/resources/image.png"), "draw image");
    model->appendRow(pParentItem);

    pChildItem = new QStandardItem(QIcon(":/resources/image.png"), "image");
    pParentItem->appendRow(pChildItem);

    pChildItem = new QStandardItem(QIcon(":/resources/pixmap.png"), "pixmap");
    pParentItem->appendRow(pChildItem);

    // 文本绘制
    pParentItem = new QStandardItem(QIcon(":/resources/text.png"), "draw text");
    model->appendRow(pParentItem);

    // 擦除
    pParentItem = new QStandardItem(QIcon(":/resources/erase.png"), "draw erase");
    model->appendRow(pParentItem);

    // 路径填充
    pParentItem = new QStandardItem(QIcon(":/resources/fillpath.png"), "draw fillpath");
    model->appendRow(pParentItem);

    // 矩形填充
    pParentItem = new QStandardItem(QIcon(":/resources/fillrect.png"), "draw fillrect");
    model->appendRow(pParentItem);

    m_pLeftTree->setModel(model);  // 模型视图

    connect(m_pLeftTree, &QAbstractItemView::clicked, this, &Widget::treeViewExpand);
}

void Widget::treeViewExpand(const QModelIndex& index) {
    QString text = index.data().toString();

    if (text.compare("point") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::point);
        // 不更新就不会立即显示
        m_pPaintWidget->update();  
    } else if (text.compare("multipoints") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::multipoints);
        m_pPaintWidget->update();  
    } else if (text.compare("line") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::line);
        m_pPaintWidget->update();
    } else if (text.compare("arc") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::arc);
        m_pPaintWidget->update();
    } else if (text.compare("rect") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::rect);
        m_pPaintWidget->update();
    } else if (text.compare("roundrect") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::roundrect);
        m_pPaintWidget->update();
    } else if (text.compare("chord") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::chord);
        m_pPaintWidget->update();
    } else if (text.compare("ellipse") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::ellipse);
        m_pPaintWidget->update();
    } else if (text.compare("polygon") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::polygon);
        m_pPaintWidget->update();
    } else if (text.compare("polyline") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::polyline);
        m_pPaintWidget->update();
    } else if (text.compare("ConvexPloygon") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::ConvexPloygon);
        m_pPaintWidget->update();
    } else if (text.compare("lines") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::lines);
        m_pPaintWidget->update();  
    } else if (text.compare("path") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::path);
        m_pPaintWidget->update();
    } else if (text.compare("pie") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::pie);
        m_pPaintWidget->update();
    } else if (text.compare("image") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::image);
        m_pPaintWidget->update();
    } else if (text.compare("pixmap") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::pixmap);
        m_pPaintWidget->update();
    } else if (text.compare("draw text") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::draw_text);
        m_pPaintWidget->update();
    } else if (text.compare("draw erase") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::draw_erase);
        m_pPaintWidget->update();
    } else if (text.compare("draw fillpath") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::draw_fillpath);
        m_pPaintWidget->update();
    } else if (text.compare("draw fillrect") == 0) {
        m_pPaintWidget->setDrawType(DRAW_TYPE::draw_fillrect);
        m_pPaintWidget->update();
    }
}

1.3 CPaintWidget.h

#pragma once
#include <QWidget>
#include "drawtype.h"

class CPaintWidget : public QWidget {
	Q_OBJECT

public:
	CPaintWidget(QWidget* p = nullptr);
	~CPaintWidget() {}

	void setDrawType(DRAW_TYPE type);

private:
	void paintEvent(QPaintEvent* event) override;

private:
    void draw_point();
    void draw_multipoints();
    void draw_line();
    void draw_arc();
    void draw_rect();
    void draw_roundrect();
    void draw_chord();
    void draw_ellipse();
    void draw_polygon();
    void draw_polyline();
    void draw_ConvexPloygon();
    void draw_lines();
    void draw_path();
    void draw_pie();
    void draw_image();
    void draw_pixmap();
    void draw_text();
    void draw_erase();
    void draw_fillpath();
    void draw_fillrect();
    
private:
	DRAW_TYPE m_drawType;

	int W = 0;
	int H = 0;
};

1.4 CPaintWidget.cpp

#include "CPaintWidget.h"
#include <QPainter>
#include <QPainterPath>

CPaintWidget::CPaintWidget(QWidget* p) :QWidget(p) {
	this->setMinimumSize(800, 600);

	m_drawType = DRAW_TYPE::polygon;
}

void CPaintWidget::paintEvent(QPaintEvent* event) {
	W = this->width();
	H = this->height();

	switch (m_drawType) {
	case DRAW_TYPE::point:
		draw_point();
		break;

	case DRAW_TYPE::multipoints:
		draw_multipoints();
		break;

	case DRAW_TYPE::line:
		draw_line();
		break;

	case DRAW_TYPE::arc:
		draw_arc();
		break;

	case DRAW_TYPE::rect:
		draw_rect();
		break;

	case DRAW_TYPE::roundrect:
		draw_roundrect();
		break;

	case DRAW_TYPE::chord:
		draw_chord();
		break;

	case DRAW_TYPE::ellipse:
		draw_ellipse();
		break;

	case DRAW_TYPE::polygon:
		draw_polygon();
		break;

	case DRAW_TYPE::polyline:
		draw_polyline();
		break;

	case DRAW_TYPE::ConvexPloygon:
		draw_ConvexPloygon();
		break;

	case DRAW_TYPE::lines:
		draw_lines();
		break;

	case DRAW_TYPE::path:
		draw_path();
		break;

	case DRAW_TYPE::pie:
		draw_pie();
		break;

	case DRAW_TYPE::image:
		draw_image();
		break;

	case DRAW_TYPE::pixmap:
		draw_pixmap();
		break;

	case DRAW_TYPE::draw_text:
		draw_text();
		break;

	case DRAW_TYPE::draw_erase:
		draw_erase();
		break;

	case DRAW_TYPE::draw_fillpath:
		draw_fillpath();
		break;

	case DRAW_TYPE::draw_fillrect:
		draw_fillrect();
		break;

	default:
		break;
	}
}

void CPaintWidget::draw_point() {
	QPainter painter(this);
	QPen pen;
	pen.setWidth(10);
	pen.setColor(Qt::red);
	pen.setStyle(Qt::SolidLine);
	painter.setPen(pen);
	painter.drawPoint(QPoint(W / 2, H / 2));
}

void CPaintWidget::draw_multipoints() {
	QPainter painter(this);
	QPen pen;
	pen.setWidth(10);
	pen.setColor(Qt::blue);
	pen.setStyle(Qt::SolidLine);
	painter.setPen(pen);

	// 画很多点
	QPoint points[] = {
		QPoint(5 * W / 12,H / 4),
		QPoint(3 * W / 4, 5 * H / 12),
		QPoint(2 * W / 4, 5 * H / 12)};
	painter.drawPoints(points, 3);
}

void CPaintWidget::draw_line() {
	QPainter painter(this);

	//QLine Line(W / 4, H / 4, W / 2, H / 2);
	QLine Line(W / 4, H / 4, W / 2, H / 4);
	painter.drawLine(Line);
}

void CPaintWidget::draw_arc() {
	QPainter painter(this);
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	int startAngle = 90 * 16;
	int spanAngle = 90 * 16;       //旋转 90°
	painter.drawArc(rect, startAngle, spanAngle);
}

void CPaintWidget::draw_rect() {
	QPainter painter(this);

	// 画矩形
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	painter.drawRect(rect);
}

void CPaintWidget::draw_roundrect() {
	QPainter painter(this);

	// 画圆角矩形
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	painter.drawRoundedRect(rect, 20, 20);
}

void CPaintWidget::draw_chord() {
	QPainter painter(this);
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	int startAngle = 90 * 16;
	int spanAngle = 90 * 16;
	painter.drawChord(rect, startAngle, spanAngle);
}

void CPaintWidget::draw_ellipse() {
	QPainter painter(this);

	QRect rect(W / 4, H / 4, W / 2, H / 2);
	painter.drawEllipse(rect);
}

void CPaintWidget::draw_polygon() {
	QPainter painter(this);
	painter.setRenderHint(QPainter::Antialiasing);

	QPen pen;  // 画笔描边
	pen.setWidth(10);
	pen.setColor(Qt::red);
	pen.setStyle(Qt::SolidLine);
	pen.setCapStyle(Qt::SquareCap);
	pen.setJoinStyle(Qt::MiterJoin);  // 画笔断点的样式
	painter.setPen(pen);

	QBrush brush;  // 画刷填充
	brush.setColor(Qt::yellow);
	brush.setStyle(Qt::SolidPattern);
	painter.setBrush(brush);

	// 画多边形，最后一个点会和第一个点闭合
	QPoint points[] = {
		QPoint(5 * W / 12,H / 4),
		QPoint(3 * W / 4,5 * H / 12),
		QPoint(5 * W / 12,3 * H / 4),
		QPoint(2 * W / 4,5 * H / 12)};
	painter.drawPolygon(points, 4);
}

void CPaintWidget::draw_polyline() {
	QPainter painter(this);

	// 画多点连接的线，最后一个点不会和第一个点连接
	QPoint points[] = {
		QPoint(5 * W / 12, H / 4),
		QPoint(3 * W / 4, 5 * H / 12),
		QPoint(5 * W / 12, 3 * H / 4),
		QPoint(2 * W / 4, 5 * H / 12)};
	painter.drawPolyline(points, 4);
}

void CPaintWidget::draw_ConvexPloygon() {
	QPainter painter(this);

	QPoint points[4] = {
		QPoint(5 * W / 12, H / 4),
		QPoint(3 * W / 4, 5 * H / 12),
		QPoint(5 * W / 12, 3 * H / 4),
		QPoint(W / 4, 5 * H / 12)};
	painter.drawConvexPolygon(points, 4);
}

void CPaintWidget::draw_lines() {
	QPainter painter(this);

	// 画一批直线
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	QVector<QLine> Lines;
	Lines.append(QLine(rect.topLeft(), rect.bottomRight()));
	Lines.append(QLine(rect.topRight(), rect.bottomLeft()));
	Lines.append(QLine(rect.topLeft(), rect.bottomLeft()));
	Lines.append(QLine(rect.topRight(), rect.bottomRight()));
	painter.drawLines(Lines);
}

void CPaintWidget::draw_path() {
	QPainter painter(this);
	// 绘制由 QPainterPath 对象定义的路线
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	QPainterPath path;
	path.addEllipse(rect);
	path.addRect(rect);
	painter.drawPath(path);
}

void CPaintWidget::draw_pie() {
	QPainter painter(this);
	// 绘制扇形
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	int startAngle = 40 * 16;  // 起始 40
	int spanAngle = 120 * 16;  // 旋转 120
	painter.drawPie(rect, startAngle, spanAngle);
}

void CPaintWidget::draw_image() {
	QPainter painter(this);

	// 在指定的矩形区域内绘制图片
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	QImage image(":/resources/tupian.png");
	painter.drawImage(rect, image);
}

void CPaintWidget::draw_pixmap() {
	QPainter painter(this);
	// 绘制 Pixmap 图片
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	QPixmap pixmap(":/resources/tupix.png");
	painter.drawPixmap(rect, pixmap);
}

void CPaintWidget::draw_text() {
	QPainter painter(this);

	// 绘制文本，只能绘制单行文字，字体的大小等属性由 QPainter::font() 决定
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	QFont font;
	font.setPointSize(30);
	font.setBold(true);
	painter.setFont(font);
	painter.drawText(rect, "Hello,Qt");
}

void CPaintWidget::draw_erase() {
	QPainter painter(this);

	// 擦除某个矩形区域，等效于用背景色填充该区域
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	painter.eraseRect(rect);
}

void CPaintWidget::draw_fillpath() {
	QPainter painter(this);

	// 填充某个 QPainterPath 定义的绘图路径，但是轮廓线不显示
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	QPainterPath path;
	path.addEllipse(rect);
	path.addRect(rect);
	painter.fillPath(path, Qt::red);
}

void CPaintWidget::draw_fillrect() {
	QPainter painter(this);
	// 填充一个矩形，无边框线
	QRect rect(W / 4, H / 4, W / 2, H / 2);
	painter.fillRect(rect, Qt::green);
}

void CPaintWidget::setDrawType(DRAW_TYPE type) {
	m_drawType = type;
}

1.5 drawtype.h

#pragma once

enum class DRAW_TYPE {
    point,
    multipoints,
    line,
    arc,
    rect,
    roundrect,
    chord,
    ellipse,
    polygon,
    polyline,
    ConvexPloygon,
    lines,
    path,
    pie,
    image,
    pixmap,
    draw_text,
    draw_erase,
    draw_fillpath,
    draw_fillrect
};

2. Qt 鼠标手动绘图技术

2.1 mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QMenu>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow {
    Q_OBJECT

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

protected:
    // 右键菜单需要重写的类
    void contextMenuEvent(QContextMenuEvent* event) override;

private:
    Ui::MainWindow *ui;

    QMenu* m_pMenu;
};
#endif // MAINWINDOW_H

2.2 mainwindow.cpp

/*
使用方式：左键点击，移动鼠标开始绘制，双击左键结束绘制，或者右键点击结束绘制
*/
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMenu>
#include <QAction>

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

	m_pMenu = new QMenu(this);

	QAction* pAc1 = new QAction(QString::fromLocal8Bit("结束绘制"), this);
	pAc1->setShortcut(QKeySequence("Ctrl+E"));
	QAction* pAc2 = new QAction(QString::fromLocal8Bit("清除"), this);
	pAc2->setShortcut(QKeySequence("Ctrl+D"));

	// 这是个假动作，为了让菜单消失，且不影响绘制路径
	QAction* pAc3 = new QAction(QString::fromLocal8Bit("退出菜单"), this);

	m_pMenu->addAction(pAc1);
	m_pMenu->addAction(pAc2);
	m_pMenu->addAction(pAc3);

	m_pMenu->setStyleSheet("QMenu{font:18px;}");

	connect(pAc1, &QAction::triggered, [=] {
		ui->graphicsPainter->endDraw();
	});

	connect(pAc2, &QAction::triggered, [=] {
		ui->graphicsPainter->clearPath();
	});
}

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

// 右键菜单
void MainWindow::contextMenuEvent(QContextMenuEvent* event) {
	m_pMenu->move(cursor().pos());  // 移动右键菜单到鼠标当前位置
	m_pMenu->show();
}

2.3 MyPainterWidget.h

#ifndef GRAPHICSPAINTER_H
#define GRAPHICSPAINTER_H

#include <QWidget>

class MyPainterWidget : public QWidget {
    Q_OBJECT

public:
    explicit MyPainterWidget(QWidget *parent = nullptr);

    void endDraw();
    void clearPath();

protected:
    void paintEvent(QPaintEvent *) override;
    void mousePressEvent(QMouseEvent *e) override;            // 按下
    void mouseMoveEvent(QMouseEvent *e) override;             // 移动
    void mouseReleaseEvent(QMouseEvent *e) override;          // 松开
    void mouseDoubleClickEvent(QMouseEvent *event) override;  // 双击

    bool m_bStartDraw = false;  // 是否已经开始左键点击，同时标识是否开始进行绘制
    bool bMove = false;         // 是否处于绘制时的鼠标移动状态
    
    QVector<QPointF> pointList;
    QPointF movePoint;
};

#endif // GRAPHICSPAINTER_H

2.4 MyPainterWidget.cpp

#include "MyPainterWidget.h"
#include <QPainter>
#include <QMouseEvent>

MyPainterWidget::MyPainterWidget(QWidget *parent) : QWidget(parent) {
    setMouseTracking(true);

    pointList.clear();
}

void MyPainterWidget::paintEvent(QPaintEvent *) {
    QPainter painter(this);
    painter.setPen(QColor(255,0,0));

    QVector<QLineF> lines;

    for(int i = 0; i < pointList.size()-1; i++) {
        QLineF line(QPointF(pointList[i].x(), pointList[i].y()), 
            QPointF(pointList[i+1].x(), pointList[i+1].y()));

        lines.push_back(line);
    }

    if (m_bStartDraw) {
        int size = pointList.size();

        if (bMove && size > 0) {
            QLineF line(QPointF(pointList[pointList.size() - 1].x(), pointList[pointList.size() - 1].y()),
                movePoint);

            lines.push_back(line);
        }
    }

    painter.drawLines(lines);
}

// 按下
void MyPainterWidget::mousePressEvent(QMouseEvent *e) {
    if (e->button() == Qt::LeftButton) {
        if(!m_bStartDraw) {
            pointList.clear();
            m_bStartDraw = true;
        }
    }   
}

// 移动
void MyPainterWidget::mouseMoveEvent(QMouseEvent *e) {
    if(m_bStartDraw) {
        movePoint = e->pos();
        
        this->update();

        // 先刷新再设为true, 防止第一点和（0,0）连在一块
        bMove = true;
    }
}

// 松开
void MyPainterWidget::mouseReleaseEvent(QMouseEvent *e) {
    if (e->button() == Qt::LeftButton) {
        if (m_bStartDraw) {
            // 鼠标松开后的点需要添加到路径中
            pointList.push_back(QPointF(e->x(), e->y()));
            bMove = false;
            this->update();
        }
    }
}

// 双击结束绘制
void MyPainterWidget::mouseDoubleClickEvent(QMouseEvent *event) {
    endDraw();
}

void MyPainterWidget::endDraw() {
    m_bStartDraw = false;

    // 需要把第一个点连起来
    pointList.push_back(pointList[0]);
    this->update();
}

void MyPainterWidget::clearPath() {
    pointList.clear();
    this->update();
}

3. Qt 绘制带三角形箭头的窗口

在这里插入图片描述

3.1 widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget {
    Q_OBJECT

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

public slots:
    void on_pushButton_clicked();

private:
    Ui::Widget *ui;
};
#endif // WIDGET_H

3.2 widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include "triangledialog.h"
#include <QLabel>
#include "userinfowidget.h"
#include <QPropertyAnimation>

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

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

void Widget::on_pushButton_clicked() {
    int triangle_start_x = 60;

    TriangleDialog *pDialog = new TriangleDialog(343, 320, this);
    pDialog->setTriangleInfo(triangle_start_x, 20, 12);

    // 设置三角窗口的弹出位置， 有Qt::Popup属性
    QPoint p1 = ui->pushButton->mapToGlobal(QPoint(0, 0));  //按钮左上角相对于桌面的绝对位置
    QRect rect1 = ui->pushButton->rect();

    int x = p1.x() + rect1.width() / 2 - triangle_start_x - 20 / 2;
    int y = p1.y() + rect1.height() + 1 - 15;
    pDialog->move(x, y);

    pDialog->show();
}

3.3 userinfowidget.h

#ifndef USERINFOWIDGET_H
#define USERINFOWIDGET_H

#include <QWidget>

namespace Ui {
    class UserInfoWidget;
}

class UserInfoWidget : public QWidget {
    Q_OBJECT

public:
    explicit UserInfoWidget(QWidget *parent = nullptr);
    ~UserInfoWidget();

private:
    Ui::UserInfoWidget *ui;
};

#endif // USERINFOWIDGET_H

3.4 userinfowidget.cpp

#include "userinfowidget.h"
#include "ui_userinfowidget.h"

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

    setFixedSize(this->width(), this->height());

    setAttribute(Qt::WA_StyledBackground);
    QString qss = "QLabel{font-family:Microsoft YaHei; font-size:18px; color:#ffffff; background-color:#363636;}";

    ui->label_UserImage->setText("");
    QPixmap pmp1(":/resources/user_image.png");
    pmp1.scaled(ui->label_UserImage->size(), Qt::KeepAspectRatio);
    ui->label_UserImage->setScaledContents(true);
    ui->label_UserImage->setPixmap(pmp1);

    ui->label_UserName->setText(u8"没有做完的梦最痛");
    ui->label_UserName->setStyleSheet(qss);

    ui->label_VipInfo->setText("");
    QPixmap pmp2(":/resources/vipinfo.png");
    pmp2.scaled(ui->label_VipInfo->size(), Qt::KeepAspectRatio);
    ui->label_VipInfo->setScaledContents(true);
    ui->label_VipInfo->setPixmap(pmp2);
}

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

3.5 triangledialog.h

/*
    带三角形箭头的对话框
*/
#ifndef TRIANGLEDIALOG_H
#define TRIANGLEDIALOG_H

#include <QDialog>

class TriangleDialog : public QDialog {
    Q_OBJECT
public:
    explicit TriangleDialog(int fixedW, int fixedH, QWidget *parent = nullptr);

    // 设置小三角行的起始位置、宽、高
    void setTriangleInfo(int startX, int width, int height);

protected:
    void paintEvent(QPaintEvent *e);

private:
    // 小三角形的起始位置
    int m_startX;

    // 小三角形的宽度
    int m_triangleWidth;

    // 小三角形的高度
    int m_triangleHeight;
};

#endif // TRIANGLEDIALOG_H

3.6 triangledialog.cpp

#include "triangledialog.h"
#include <QVBoxLayout>
#include <QPainter>
#include <QGraphicsDropShadowEffect>
#include <QPainterPath>
#include "userinfowidget.h"

#define SHADOW_WIDTH    15                 // 窗口阴影宽度
#define TRIANGLE_WIDTH  15                 // 小三角行的宽度
#define TRIANGLE_HEIGHT 10                 // 小三角行的高度
#define BORDER_RADIUS   5                  // 窗口圆角

TriangleDialog::TriangleDialog(int fixedW, int fixedH, QWidget *parent) : QDialog(parent)
    ,m_startX(50)
    ,m_triangleWidth(TRIANGLE_WIDTH)
    ,m_triangleHeight(TRIANGLE_HEIGHT) {
    setWindowFlags(Qt::FramelessWindowHint | Qt::Popup | Qt::NoDropShadowWindowHint);
    setAttribute(Qt::WA_TranslucentBackground);  // 设置透明窗口, 为窗口阴影和圆角做准备

    UserInfoWidget* pUserinfoWidget = new UserInfoWidget(this);

    QVBoxLayout* pVlay = new QVBoxLayout(this);
    pVlay->addWidget(pUserinfoWidget);

    // 设置布局的四周边距
    pVlay->setContentsMargins(SHADOW_WIDTH, SHADOW_WIDTH + TRIANGLE_HEIGHT, SHADOW_WIDTH, SHADOW_WIDTH);

    // 设置阴影边框
    auto shadowEffect = new QGraphicsDropShadowEffect(this);
    shadowEffect->setOffset(0, 0);
    shadowEffect->setColor(Qt::red);
    shadowEffect->setBlurRadius(SHADOW_WIDTH);
    this->setGraphicsEffect(shadowEffect);

    // 设置窗口固定大小
    setFixedSize(fixedW, fixedH);
}

void TriangleDialog::setTriangleInfo(int startX, int width, int height) {
    m_startX = startX;
    m_triangleWidth = width;
    m_triangleHeight = height;
}

void TriangleDialog::paintEvent(QPaintEvent *e) {
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing, true);
    painter.setPen(Qt::NoPen);
    painter.setBrush(QColor(55, 55, 55));

    // 小三角区域，这里是等腰三角形
    QPolygon trianglePolygon;
    trianglePolygon << QPoint(m_startX, m_triangleHeight + SHADOW_WIDTH);
    trianglePolygon << QPoint(m_startX + m_triangleWidth / 2, SHADOW_WIDTH);
    trianglePolygon << QPoint(m_startX + m_triangleWidth, m_triangleHeight + SHADOW_WIDTH);

    QPainterPath drawPath;
    drawPath.addRoundedRect(QRect(SHADOW_WIDTH, SHADOW_WIDTH + m_triangleHeight,
                            this->width() - SHADOW_WIDTH * 2, this->height() - SHADOW_WIDTH * 2 - m_triangleHeight),
                            BORDER_RADIUS, BORDER_RADIUS);
    // 矩形路径加上三角形
    drawPath.addPolygon(trianglePolygon);

    // 绘制路径
    painter.drawPath(drawPath);
}

4. Qt 场景视图技术

4.1 简介

使用 QPainter 可以绘制一些常用的图形，如果需要对绘制的图形进行编辑，例如拉伸，拖拽，组合等，会比较复杂，用代码是可以实现的，但是会比较复杂，例如处理鼠标的形状，判定拉伸拖拽的点，然后重绘等等，如果拉伸的时候和其它图形有冲突，还需要做判定处理
- 使用 QPainter 的绘制技术不太适合对图形进行选择、编辑、拖放、修改等功能
Qt 提供了 Graphics View 图形架构，是一种基于图形项的模型/视图模式，使用 Graphics View 架构可以绘制复杂的有几万个基本图形元件的图形，并且每个图形元件是可选择、可拖放和修改的，类似于矢量绘图软件的绘图功能

4.2 Graphics View 基本组成

Graphics View 架构主要由 3 部分组成，即视图、场景和图形项，其构成的绘图系统结构如下图所示
- 视图 QGraphicsScene：提供绘图的视图组件，用于显示场景中的内容
  - 视图比场景大时，显示场景的全部内容（默认在中间部分显示）
  - 视图比场景小时，只能显示场景的部分内容，但是会自动提供卷滚条在整个场景内移动
- 场景 QGraphics View：提供绘图场景
  - 场景是不可见的，是管理图形项的容器，可以向场景添加图形项，获取场景中的某个图形项等
- 图形项 QGraphicsItem：一些基本的图形元件
  - 支持鼠标事件响应、键盘输入与按键事件
  - 支持拖放、组合操作

在这里插入图片描述

4.3 Graphics View 坐标系统

4.3.1 视图坐标

视图坐标与设备坐标相同，是物理坐标，缺省以左上角为原点 (0, 0)
- 所有的鼠标事件、拖放事件的坐标首先是由视图坐标定义的
- 用户需要将视图坐标映射为场景坐标，以便和图形项交互

4.3.2 场景坐标

场景的坐标一般以场景的中心为原点
场景是所有图形项的基础坐标，场景坐标描述了每个顶层图形项的位置，创建场景时可定义场景坐标范围
- scene 是左上角坐标为 (-400,-300)，宽度为 800，高度为 600 的矩形区域，单位是像素
```
scene = new QGraphicsScene(-400, -300, 800, 600);
```

4.3.3 图形项坐标

图形项使用自己的局部坐标，通常以其中心为原点 (0, 0)，也是各种坐标变换的中心
- 图形项的鼠标事件的坐标是用局部坐标表示的，创建自定义图形项，绘制图形项时只需考虑其局部坐标
一个图形项的位置是其中心点在父坐标系统中的坐标
- 对于没有父图形项的图形项，其父对象就是场景，图形项的位置就是在场景中的坐标
如果一个图形项还是其他图形项的父项，父项进行坐标变换时，子项也做同样的坐标变换

4.3.4 坐标映射

在场景中操作图形项时，进行场景到图形项、图形项到图形项，或视图到场景之间的坐标变换是比较有用的
- 例如在 QGraphicsView 的视口上单击鼠标时，通过函数 QGraphicsView::mapToScene() 可以将视图坐标映射为场景坐标，然后用 QGraphicsScene::itemAt() 函数可以获取场景中鼠标光标处的图形项

4.4 基本图元绘制

在这里插入图片描述

4.4.1 主界面

widget.h

#pragma once

#include <QWidget>
#include "ui_widget.h"
#include <QGraphicsScene>

class Widget : public QWidget {
    Q_OBJECT

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

private:
    void initGraphicsView();

private slots:
    void on_mouseMovePoint(QPoint point);
    void on_mouseClicked(QPoint point);

private:
    Ui::Widget *ui;

    QGraphicsScene *scene;
};

widget.cpp

#include "widget.h"
#include <QGraphicsRectItem>

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

    connect(ui->graphicView, &MyGraphicsView::mouseMovePoint, this, &Widget::on_mouseMovePoint);
    connect(ui->graphicView, &MyGraphicsView::mouseClicked, this, &Widget::on_mouseClicked);

    initGraphicsView();
}

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

// 视图初始化
void Widget::initGraphicsView() {
    QRectF rect(-200, -100, 400, 200);
    scene = new QGraphicsScene(rect); 

    // 给视图设置场景
    ui->graphicView->setScene(scene);

    // 画一个矩形框，大小等于 scene
    QGraphicsRectItem *item = new QGraphicsRectItem(rect); 
    // 可选，可以有焦点，但是不能移动
    item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable);
    QPen pen;
    pen.setWidth(20);
    item->setPen(pen);
    scene->addItem(item);

    // 一个位于 scene 中心的椭圆
    QGraphicsEllipseItem *item2 = new QGraphicsEllipseItem(-100, -50, 200, 100);
    item2->setPos(-200, 0);
    item2->setBrush(QBrush(Qt::blue));
    item2->setFlags(QGraphicsItem::ItemIsMovable
                   | QGraphicsItem::ItemIsSelectable
                   | QGraphicsItem::ItemIsFocusable);
    scene->addItem(item2);

    // 一个圆，中心位于 scene 的边缘
    QGraphicsEllipseItem *item3 = new QGraphicsEllipseItem(-50, -50, 100, 100);
    item3->setPos(rect.right(), rect.bottom());
    item3->setBrush(QBrush(Qt::red));
    item3->setFlags(QGraphicsItem::ItemIsMovable
                   | QGraphicsItem::ItemIsSelectable
                   | QGraphicsItem::ItemIsFocusable);
    scene->addItem(item3);

    scene->clearSelection();
}

// 鼠标移动事件，point是 GraphicsView 的坐标，物理坐标
void Widget::on_mouseMovePoint(QPoint point) {
    ui->label_viewpos->setText(QString::asprintf("%d, %d", point.x(), point.y()));
    QPointF pointScene = ui->graphicView->mapToScene(point);        // 视图转换到场景坐标
    ui->label_scenepos->setText(QString::asprintf("%.0f,%.0f", pointScene.x(), pointScene.y()));
}

// 鼠标单击事件
void Widget::on_mouseClicked(QPoint point) {
    QPointF pointScene = ui->graphicView->mapToScene(point);        // 视图转换到场景坐标
    QGraphicsItem *item = NULL;
    item = scene->itemAt(pointScene,ui->graphicView->transform());  // 获取光标下的绘图项
    if (item != NULL) {  // 有图形项
        QPointF pointItem = item->mapFromScene(pointScene);         // 场景坐标转换为图形项的局部坐标
        ui->label_itempos->setText(QString::asprintf("%.0f, %.0f", pointItem.x(), pointItem.y()));
    }
}

4.4.2 场景视图界面

MyGraphicsView.h

#pragma once

#include <QObject>
#include <QGraphicsView>

class MyGraphicsView : public QGraphicsView {
    Q_OBJECT

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

public:
    MyGraphicsView(QWidget *parent = 0);

signals:
    void mouseMovePoint(QPoint point);
    void mouseClicked(QPoint point);
};

MyGraphicsView.cpp

#include "MyGraphicsView.h"
#include <QMouseEvent>
#include <QPoint>

MyGraphicsView::MyGraphicsView(QWidget* parent) :QGraphicsView(parent) {
    // 设置视图的鼠标指针形状为十字光标
    this->setCursor(Qt::CrossCursor);
    // 启用鼠标追踪功能，即使没有按下鼠标按钮，也可以接收到鼠标移动事件
    this->setMouseTracking(true);
    // 设置视图的拖动模式为拉框拖动模式
    // 通过点击并按住鼠标左键来创建一个矩形框选择多个图形项
    this->setDragMode(QGraphicsView::RubberBandDrag);
}

// 鼠标移动事件
void MyGraphicsView::mouseMoveEvent(QMouseEvent *event) {
    QPoint point = event->pos();   // QGraphicsView 视图坐标
    emit mouseMovePoint(point);    // 释放信号
    QGraphicsView::mouseMoveEvent(event);
}

// 鼠标左键按下事件
void MyGraphicsView::mousePressEvent(QMouseEvent *event) {
    if (event->button() == Qt::LeftButton) {
        QPoint point = event->pos();  // 返回当前鼠标光标的位置（视图坐标系下）
        emit mouseClicked(point);     // 发射鼠标点击信号
    }

    QGraphicsView::mousePressEvent(event);  // 响应自身的鼠标移动事件
}

4.5 自定义图元实现拖拽、拉伸、旋转

在这里插入图片描述

4.5.1 主界面

ch88_CustomRectItem.h

#pragma once

#include <QtWidgets/QWidget>
#include "ui_ch88_CustomRectItem.h"

class ch88_CustomRectItem : public QWidget {
    Q_OBJECT

public:
    ch88_CustomRectItem(QWidget *parent = nullptr);
    ~ch88_CustomRectItem();

private:
    Ui::ch88_CustomRectItemClass ui;
};

ch88_CustomRectItem.cpp

#include "ch88_CustomRectItem.h"
#include "MyRectItem.h"

ch88_CustomRectItem::ch88_CustomRectItem(QWidget *parent) : QWidget(parent) {
    ui.setupUi(this);

    QRect rect = ui.graphicsView->rect();

    // 创建场景
    QGraphicsScene* pScene = new QGraphicsScene(rect);

    // 视图里设置场景
    ui.graphicsView->setScene(pScene);

    // 创建自定义图元
    MyRectItem* pRectItem = new MyRectItem();

    // 场景添加图元
    pScene->addItem(pRectItem);
}

ch88_CustomRectItem::~ch88_CustomRectItem() {}

4.5.2 自定义矩形图元

MyRectItem.h

/*
    自定义矩形图元
*/

#pragma once
#include <QGraphicsItem>

enum STATE_FLAG {
    DEFAULT_FLAG = 0,
    MOV_LEFT_LINE,         // 矩形的左边界区域
    MOV_TOP_LINE,          // 矩形的上边界区域
    MOV_RIGHT_LINE,        // 矩形的右边界区域
    MOV_BOTTOM_LINE,       // 矩形的下边界区域
    MOV_RIGHTBOTTOM_RECT,  // 矩形的右下角
    MOV_RECT,              // 移动状态
    ROTATE                 // 旋转状态
};

class MyRectItem : public QObject, public QGraphicsItem {
    Q_OBJECT

public:
    MyRectItem(QGraphicsItem* parent = nullptr);
    ~MyRectItem();

    // boundingRect() 是纯虚函数，必须由派生类重新实现
    QRectF boundingRect() const override;
    
    void setRectSize(QRectF mrect, bool bResetRotateCenter = true);

    void paint(QPainter* painter,
        const QStyleOptionGraphicsItem* option,
        QWidget* widget) override;

    void mousePressEvent(QGraphicsSceneMouseEvent* event) override;
    void mouseMoveEvent(QGraphicsSceneMouseEvent* event) override;
    void mouseReleaseEvent(QGraphicsSceneMouseEvent* event) override;

    void SetRotate(qreal RotateAngle, QPointF ptCenter = QPointF(-999, -999));
    // 获取旋转后的点
    QPointF getRotatePoint(QPointF ptCenter, QPointF ptIn, qreal angle);
    // 获取多个旋转后的点
    QList<QPointF> getRotatePoints(QPointF ptCenter, QList<QPointF> ptIns, qreal angle);
    // 将矩形旋转之后返回多边形
    QPolygonF getRotatePolygonFromRect(QPointF ptCenter, QRectF rectIn, qreal angle);
    QRectF getCrtPosRectToSceen();

    // 获取旋转时候矩形正上方的旋转标记矩形
    QPointF getSmallRotateRectCenter(QPointF ptA, QPointF ptB);
    QRectF  getSmallRotateRect(QPointF ptA, QPointF ptB);

private:
    QRectF  m_oldRect;
    QPolygonF m_oldRectPolygon;
    QRectF  m_RotateAreaRect;
    bool    m_bResize;
    QPolygonF m_insicedPolygon;
    QRectF  m_insicedRectf;
    QPolygonF m_leftPolygon;
    QRectF  m_leftRectf;
    QPolygonF m_topPolygon;
    QRectF  m_topRectf;
    QPolygonF m_rightPolygon;
    QRectF  m_rightRectf;
    QPolygonF m_bottomPolygon;
    QRectF  m_bottomRectf;
    QPointF m_startPos;
    STATE_FLAG m_StateFlag;
    QPointF* m_pPointFofSmallRotateRect;
    QRectF m_SmallRotateRect;        // 矩形顶部用来表示旋转的标记的矩形
    QPolygonF m_SmallRotatePolygon;  // 矩形顶部用来表示旋转的标记的矩形旋转后形成的多边形
    bool    m_bRotate;
    qreal   m_RotateAngle;
    QPointF m_RotateCenter;
};

MyRectItem.cpp

#include "MyRectItem.h"
#include <QtMath>
#include <QPainter>
#include <QStyleOptionGraphicsItem>
#include <QGraphicsSceneMouseEvent>
#include <QGraphicsScene>

MyRectItem::MyRectItem(QGraphicsItem* parent) :
    m_bResize(false),
    m_oldRect(0, 0, 200, 200),
    m_bRotate(false),
    m_RotateAngle(0),
    m_StateFlag(DEFAULT_FLAG) {

    setRectSize(m_oldRect);
    
    // 设置光标形状，手的形状
    setCursor(Qt::ArrowCursor);

    // 设置图元是可移动的
    setFlags(QGraphicsItem::ItemIsMovable
        | QGraphicsItem::ItemIsSelectable
        | QGraphicsItem::ItemIsFocusable);

    m_pPointFofSmallRotateRect = new QPointF[4];
    SetRotate(0);
}

MyRectItem::~MyRectItem() {
    delete[] m_pPointFofSmallRotateRect;
    m_pPointFofSmallRotateRect = nullptr;
}

QRectF MyRectItem::boundingRect() const {
    QRectF boundingRectF = m_oldRectPolygon.boundingRect();
    return QRectF(boundingRectF.x() - 40, boundingRectF.y() - 40, 
        boundingRectF.width() + 80, boundingRectF.height() + 80);
}

void MyRectItem::setRectSize(QRectF mrect, bool bResetRotateCenter) {
    m_oldRect = mrect;

    if (bResetRotateCenter) {
        m_RotateCenter.setX(m_oldRect.x() + m_oldRect.width() / 2);
        m_RotateCenter.setY(m_oldRect.y() + m_oldRect.height() / 2);
    }

    m_oldRectPolygon = getRotatePolygonFromRect(m_RotateCenter, m_oldRect, m_RotateAngle);

    m_insicedRectf = QRectF(m_oldRect.x() + 8, m_oldRect.y() + 8, m_oldRect.width() - 16, m_oldRect.height() - 16);
    m_insicedPolygon = getRotatePolygonFromRect(m_RotateCenter, m_insicedRectf, m_RotateAngle);

    m_leftRectf = QRectF(m_oldRect.x(), m_oldRect.y(), 8, m_oldRect.height() - 8);
    m_leftPolygon = getRotatePolygonFromRect(m_RotateCenter, m_leftRectf, m_RotateAngle);

    m_topRectf = QRectF(m_oldRect.x() + 8, m_oldRect.y(), m_oldRect.width() - 8, 8);
    m_topPolygon = getRotatePolygonFromRect(m_RotateCenter, m_topRectf, m_RotateAngle);

    m_rightRectf = QRectF(m_oldRect.right() - 8, m_oldRect.y() + 8, 8, m_oldRect.height() - 16);
    m_rightPolygon = getRotatePolygonFromRect(m_RotateCenter, m_rightRectf, m_RotateAngle);

    m_bottomRectf = QRectF(m_oldRect.x(), m_oldRect.bottom() - 8, m_oldRect.width() - 8, 8);
    m_bottomPolygon = getRotatePolygonFromRect(m_RotateCenter, m_bottomRectf, m_RotateAngle);

    m_SmallRotateRect = getSmallRotateRect(mrect.topLeft(), mrect.topRight());//矩形正上方的旋转标记矩形
    m_SmallRotatePolygon = getRotatePolygonFromRect(m_RotateCenter, m_SmallRotateRect, m_RotateAngle);
}

void MyRectItem::paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget) {
    // 反锯齿
    painter->setRenderHint(QPainter::Antialiasing, true);

    QPen mPen = QPen(Qt::black);
    mPen.setWidth(5);
    painter->setPen(mPen);

    // 绘制旋转后的矩形
    painter->drawPolygon(m_oldRectPolygon);

    // 绘制旋转圆形
    mPen.setWidth(2);
    mPen.setColor(Qt::green);
    painter->setPen(mPen);
    QPointF pf = getSmallRotateRectCenter(m_oldRectPolygon[0], m_oldRectPolygon[1]);
    QRectF rect = QRectF(pf.x() - 10, pf.y() - 10, 20, 20);

    // 绘制圆形
    painter->drawEllipse(rect);

    // 绘制点
    painter->drawPoint(pf);

    if (option->state & QStyle::State_Selected) {
        // 绘制选择后的虚线框
        const qreal penWidth = 1;

        // 边框区域颜色
        QColor color = QColor(Qt::white);

        painter->setPen(QPen(color, penWidth, Qt::DashLine));
        painter->setBrush(Qt::NoBrush);
        painter->drawPolygon(m_oldRectPolygon);
    }
}

void MyRectItem::mousePressEvent(QGraphicsSceneMouseEvent* event) {
    if (event->button() == Qt::LeftButton) {
        m_startPos = event->pos();
        if (m_SmallRotatePolygon.containsPoint(m_startPos, Qt::WindingFill)) {
            // 鼠标在旋转圆形内内
            setCursor(Qt::PointingHandCursor);
            m_StateFlag = ROTATE;
        } else if (m_insicedPolygon.containsPoint(m_startPos, Qt::WindingFill)) {
            // 在矩形内框区域时
            setCursor(Qt::ClosedHandCursor);  // 改变光标形状，手的形状
            m_StateFlag = MOV_RECT;
        } else if (m_leftPolygon.containsPoint(m_startPos, Qt::WindingFill)) {
            // 矩形的左边界区域
            setCursor(Qt::SizeHorCursor);
            m_StateFlag = MOV_LEFT_LINE;
        } else if (m_rightPolygon.containsPoint(m_startPos, Qt::WindingFill)) {
            // 矩形的右边界区域
            setCursor(Qt::SizeHorCursor);
            m_StateFlag = MOV_RIGHT_LINE;
        } else if (m_topPolygon.containsPoint(m_startPos, Qt::WindingFill)) {
            // 矩形的上边界区域
            setCursor(Qt::SizeVerCursor);
            m_StateFlag = MOV_TOP_LINE;
        } else if (m_bottomPolygon.containsPoint(m_startPos, Qt::WindingFill)) {
            // 矩形的下边界区域
            setCursor(Qt::SizeVerCursor);
            m_StateFlag = MOV_BOTTOM_LINE;
        } else {
            m_StateFlag = DEFAULT_FLAG;
        }
    } else {
        QGraphicsItem::mousePressEvent(event);
    }
}

void MyRectItem::mouseMoveEvent(QGraphicsSceneMouseEvent* event) {
    if (m_StateFlag == ROTATE) {
        // atan2 计算出来的是弧度值，需要转化为角度值
        int nRotateAngle = atan2((event->pos().x() - m_RotateCenter.x()), 
            (event->pos().y() - m_RotateCenter.y())) * 180 / M_PI;

        SetRotate(180 - nRotateAngle);
        setRectSize(m_oldRect);
    } else if (m_StateFlag == MOV_RECT) {
        QPointF point = (event->pos() - m_startPos);
        moveBy(point.x(), point.y());
        setRectSize(m_oldRect);
        scene()->update();
    } else if (m_StateFlag == MOV_LEFT_LINE) {
        QPointF pf = QPointF((m_oldRectPolygon.at(1).x() + m_oldRectPolygon.at(2).x()) / 2, ((m_oldRectPolygon.at(1).y() + m_oldRectPolygon.at(2).y()) / 2));

        // 计算到右侧边中点的距离
        qreal dis = sqrt((event->pos().x() - pf.x()) * (event->pos().x() - pf.x()) + (event->pos().y() - pf.y()) * (event->pos().y() - pf.y()));
        qreal dis2LT = sqrt((event->pos().x() - m_oldRectPolygon.at(0).x()) * (event->pos().x() - m_oldRectPolygon.at(0).x()) + (event->pos().y() - m_oldRectPolygon.at(0).y()) * (event->pos().y() - m_oldRectPolygon.at(0).y()));
        qreal dis2RT = sqrt((event->pos().x() - m_oldRectPolygon.at(1).x()) * (event->pos().x() - m_oldRectPolygon.at(1).x()) + (event->pos().y() - m_oldRectPolygon.at(1).y()) * (event->pos().y() - m_oldRectPolygon.at(1).y()));
        if (dis < 16 || dis2LT > dis2RT) {
            return;
        } else {
            QRectF newRect(m_oldRect);
            newRect.setLeft(m_oldRect.right() - dis);
            newRect.setRight(m_oldRect.right());
            setRectSize(newRect, false);
            m_RotateCenter = QPointF((m_oldRectPolygon.at(0).x() + m_oldRectPolygon.at(2).x()) / 2, (m_oldRectPolygon.at(0).y() + m_oldRectPolygon.at(2).y()) / 2);
            m_oldRect.moveCenter(m_RotateCenter);
            setRectSize(m_oldRect);

            // 必须要用scene()->update()，不能用update();否则会出现重影
            scene()->update();
        }
    } else if (m_StateFlag == MOV_TOP_LINE) {
        // 底边中点
        QPointF pf = QPointF((m_oldRectPolygon.at(2).x() + m_oldRectPolygon.at(3).x()) / 2, ((m_oldRectPolygon.at(2).y() + m_oldRectPolygon.at(3).y()) / 2));

        //计算到底边中点的距离
        qreal dis = sqrt((event->pos().x() - pf.x()) * (event->pos().x() - pf.x()) + (event->pos().y() - pf.y()) * (event->pos().y() - pf.y()));
        qreal dis2LT = sqrt((event->pos().x() - m_oldRectPolygon.at(0).x()) * (event->pos().x() - m_oldRectPolygon.at(0).x()) + (event->pos().y() - m_oldRectPolygon.at(0).y()) * (event->pos().y() - m_oldRectPolygon.at(0).y()));
        qreal dis2LB = sqrt((event->pos().x() - m_oldRectPolygon.at(3).x()) * (event->pos().x() - m_oldRectPolygon.at(3).x()) + (event->pos().y() - m_oldRectPolygon.at(3).y()) * (event->pos().y() - m_oldRectPolygon.at(3).y()));

        if (dis < 16 || dis2LT > dis2LB) {
            return;
        } else {
            QRectF newRect(m_oldRect);
            newRect.setTop(m_oldRect.bottom() - dis);
            newRect.setBottom(m_oldRect.bottom());
            setRectSize(newRect, false);
            m_RotateCenter = QPointF((m_oldRectPolygon.at(0).x() + m_oldRectPolygon.at(2).x()) / 2, (m_oldRectPolygon.at(0).y() + m_oldRectPolygon.at(2).y()) / 2);
            m_oldRect.moveCenter(m_RotateCenter);
            setRectSize(m_oldRect);
            scene()->update();  // 必须要用scene()->update()，不能用 update()，否则会出现重影
        }
    } else if (m_StateFlag == MOV_RIGHT_LINE) {
        QPointF pf = QPointF((m_oldRectPolygon.at(0).x() + m_oldRectPolygon.at(3).x()) / 2, ((m_oldRectPolygon.at(0).y() + m_oldRectPolygon.at(3).y()) / 2));

        // 计算到左侧边中点的距离
        qreal dis = sqrt((event->pos().x() - pf.x()) * (event->pos().x() - pf.x()) + (event->pos().y() - pf.y()) * (event->pos().y() - pf.y()));
        qreal dis2LT = sqrt((event->pos().x() - m_oldRectPolygon.at(0).x()) * (event->pos().x() - m_oldRectPolygon.at(0).x()) + (event->pos().y() - m_oldRectPolygon.at(0).y()) * (event->pos().y() - m_oldRectPolygon.at(0).y()));
        qreal dis2RT = sqrt((event->pos().x() - m_oldRectPolygon.at(1).x()) * (event->pos().x() - m_oldRectPolygon.at(1).x()) + (event->pos().y() - m_oldRectPolygon.at(1).y()) * (event->pos().y() - m_oldRectPolygon.at(1).y()));
        if (dis < 16 || dis2LT < dis2RT) {
            return;
        } else {
            QRectF newRect(m_oldRect);
            newRect.setLeft(m_oldRect.left());
            newRect.setRight(m_oldRect.left() + dis);
            setRectSize(newRect, false);
            m_RotateCenter = QPointF((m_oldRectPolygon.at(0).x() + m_oldRectPolygon.at(2).x()) / 2, (m_oldRectPolygon.at(0).y() + m_oldRectPolygon.at(2).y()) / 2);
            m_oldRect.moveCenter(m_RotateCenter);
            setRectSize(m_oldRect);

            // 必须要用 scene()->update()，不能用 update()，否则会出现重影
            scene()->update(); 
        }
    } else if (m_StateFlag == MOV_BOTTOM_LINE) {
        // 顶边中点
        QPointF pf = QPointF((m_oldRectPolygon.at(0).x() + m_oldRectPolygon.at(1).x()) / 2, ((m_oldRectPolygon.at(0).y() + m_oldRectPolygon.at(1).y()) / 2));

        // 计算到底边中点的距离
        qreal dis = sqrt((event->pos().x() - pf.x()) * (event->pos().x() - pf.x()) + (event->pos().y() - pf.y()) * (event->pos().y() - pf.y()));
        qreal dis2LT = sqrt((event->pos().x() - m_oldRectPolygon.at(0).x()) * (event->pos().x() - m_oldRectPolygon.at(0).x()) + (event->pos().y() - m_oldRectPolygon.at(0).y()) * (event->pos().y() - m_oldRectPolygon.at(0).y()));
        qreal dis2LB = sqrt((event->pos().x() - m_oldRectPolygon.at(3).x()) * (event->pos().x() - m_oldRectPolygon.at(3).x()) + (event->pos().y() - m_oldRectPolygon.at(3).y()) * (event->pos().y() - m_oldRectPolygon.at(3).y()));
        if (dis < 16 || dis2LT < dis2LB) {
            return;
        } else {
            QRectF newRect(m_oldRect);
            newRect.setTop(m_oldRect.top());
            newRect.setBottom(m_oldRect.top() + dis);
            setRectSize(newRect, false);
            m_RotateCenter = QPointF((m_oldRectPolygon.at(0).x() + m_oldRectPolygon.at(2).x()) / 2, (m_oldRectPolygon.at(0).y() + m_oldRectPolygon.at(2).y()) / 2);
            m_oldRect.moveCenter(m_RotateCenter);
            setRectSize(m_oldRect);

            // 必须要用 scene()->update()，不能用 update()，否则会出现重影
            scene()->update();
        }
    }
}

void MyRectItem::mouseReleaseEvent(QGraphicsSceneMouseEvent* event) {
    setCursor(Qt::ArrowCursor);
    if (m_StateFlag == MOV_RECT) {
        m_StateFlag = DEFAULT_FLAG;
    } else {
        QGraphicsItem::mouseReleaseEvent(event);
    }
}

void MyRectItem::SetRotate(qreal RotateAngle, QPointF ptCenter) {
    m_bRotate = true;
    if (ptCenter.x() == -999 && ptCenter.y() == -999) {
        m_RotateCenter = QPointF(m_oldRect.x() + m_oldRect.width() / 2, m_oldRect.y() + m_oldRect.height() / 2);
    } else {
        m_RotateCenter = ptCenter;
    }

    m_RotateAngle = RotateAngle;
    this->update();
}

QPointF MyRectItem::getRotatePoint(QPointF ptCenter, QPointF ptIn, qreal angle) {
    double dx = ptCenter.x();
    double dy = ptCenter.y();
    double x = ptIn.x();
    double y = ptIn.y();
    double xx, yy;
    xx = (x - dx) * cos(angle * M_PI / 180) - (y - dy) * sin(angle * M_PI / 180) + dx;
    yy = (x - dx) * sin(angle * M_PI / 180) + (y - dy) * cos(angle * M_PI / 180) + dy;

    return QPointF(xx, yy);
}

QList<QPointF> MyRectItem::getRotatePoints(QPointF ptCenter, QList<QPointF> ptIns, qreal angle) {
    QList<QPointF> lstPt;
    for (int i = 0; i < ptIns.count(); i++) {
        lstPt.append(getRotatePoint(ptCenter, ptIns.at(i), angle));
    }
    return lstPt;
}

QPolygonF MyRectItem::getRotatePolygonFromRect(QPointF ptCenter, QRectF rectIn, qreal angle) {
    QVector<QPointF> vpt;
    QPointF pf = getRotatePoint(ptCenter, rectIn.topLeft(), angle);
    vpt.append(pf);
    pf = getRotatePoint(ptCenter, rectIn.topRight(), angle);
    vpt.append(pf);
    pf = getRotatePoint(ptCenter, rectIn.bottomRight(), angle);
    vpt.append(pf);
    pf = getRotatePoint(ptCenter, rectIn.bottomLeft(), angle);
    vpt.append(pf);
    pf = getRotatePoint(ptCenter, rectIn.topLeft(), angle);
    vpt.append(pf);
    return QPolygonF(vpt);
}

QRectF MyRectItem::getCrtPosRectToSceen() {
    QRectF retRect = QRectF(m_oldRect.x() + pos().x(), m_oldRect.y() + pos().y(), m_oldRect.width(), m_oldRect.height());
    return retRect;
}

QRectF MyRectItem::getSmallRotateRect(QPointF ptA, QPointF ptB) {
    QPointF pt = getSmallRotateRectCenter(ptA, ptB);
    return QRectF(pt.x() - 10, pt.y() - 10, 20, 20);
}

QPointF MyRectItem::getSmallRotateRectCenter(QPointF ptA, QPointF ptB) {
    // A,B 点的中点 C
    QPointF ptCenter = QPointF((ptA.x() + ptB.x()) / 2, (ptA.y() + ptB.y()) / 2);

    // 中垂线方程式为 y=x*k + b
    qreal x, y;//旋转图标矩形的中心
    if (abs(ptB.y() - ptA.y()) < 0.1) {
        if (ptA.x() < ptB.x()) {  // 矩形左上角在上方
        
            x = ptCenter.x();
            y = ptCenter.y() - 20;
        } else {
            // 矩形左上角在下方
            x = ptCenter.x();
            y = ptCenter.y() + 20;
        }
    } else if (ptB.y() > ptA.y()) {  // 顺时针旋转 0-180
        qreal k = (ptA.x() - ptB.x()) / (ptB.y() - ptA.y());  // 中垂线斜率
        qreal b = (ptA.y() + ptB.y()) / 2 - k * (ptA.x() + ptB.x()) / 2;
        // 求 AB 线中垂线上离 AB 中点 20 个像素的点 C 的坐标
        x = 20 * cos(atan(k)) + ptCenter.x();
        y = k * x + b;
    } else if (ptB.y() < ptA.y()) {  // 顺时针旋转 180-360
        qreal k = (ptA.x() - ptB.x()) / (ptB.y() - ptA.y());  // 中垂线斜率
        qreal b = (ptA.y() + ptB.y()) / 2 - k * (ptA.x() + ptB.x()) / 2;

        // 求 AB 线中垂线上离 AB 中点 20 个像素的点 C 的坐标
        x = -20 * cos(atan(k)) + ptCenter.x();
        y = k * x + b;
    }

    return QPointF(x, y);
}