QT QPainter draws basic graphics

Enterprise 2023-05-05 07:50:21 views: null

QT QPainter draws basic graphics

Introduction to QPainter

Combined with examples to introduce how to QPainterdraw various graphics, you can draw different shapes , use different brush colors , brush line widths , brush styles , select different brush connection points , and set different filling modes , spreading effects , gradient effects and brush colors , brush styles etc.

Realization of the drawing display area

Here you need the following variables to save basic information

    enum Shape{
    
    
        Line, // 直线  drawLine()
        Rect, // 长方形  drawRect()
        RoundedRect, // 圆角长方形 drawRoundedRect()
        Ellipse, // 椭圆形 drawEllipse()
        Polygon, // 多边形 drawPolygon()
        Polyline, // 多边线 drawPolyline()
        Points, // 点 drawPoints()
        Arc, // 弧 drawArc()
        Path, // 路径 drawPath(const QPainterPath &path)
        Text, // 文字 drawText
        PixMap, // 图片 drawPixmap
    };
private:
    Shape shape; // shape类型
    QPen pen; // 画笔
    QBrush brush; // 画刷
    Qt::FillRule fillRule; // 路径和多边形 填充方法

Refer to the Qt help manual, the following figure QPainterprovides functions for drawing most graphics: drawPoint()、drawPoints()、drawLine()、drawRect()、drawRoundedRect()、drawEllipse()、drawArc()、drawPie()、drawChord()、drawPolyline()、drawPolygon()、drawConvexPolygon() 和 drawCubicBezier().

Using QPainterPaththe class , use the function drawPathto draw the outline with the current pen, fill with the current brush, and draw the given graphic path. Text can be drawn through functions drawText. Images can be drawn through functions drawPixmap.

displayarea.h

class DisplayArea : public QWidget
{
    
    
    Q_OBJECT
public:
    enum Shape{
    
    
        Line, // 直线  drawLine()
        Rect, // 长方形  drawRect()
        RoundedRect, // 圆角方形 drawRoundRect()
        Ellipse, // 椭圆形 drawEllipse()
        Polygon, // 多边形 drawPolygon()
        Polyline, // 多边线 drawPolyline()
        Points, // 点 drawPoints()
        Arc, // 弧 drawArc()
        Path, // 路径 drawPath(const QPainterPath &path)
        Text, // 文字 drawText
        PixMap, // 图片 drawPixmap
    };

public:
    explicit DisplayArea(QWidget *parent = nullptr);
    void setShape(Shape shape);
    void setPen(QPen pen);
    void setBrush(QBrush brush);
    void setFillRule(Qt::FillRule fillRule);
    void paintEvent(QPaintEvent *event) override; // 重绘事件
signals:
private:
    Shape shape; // shape类型
    QPen pen; // 画笔
    QBrush brush; // 画刷
    Qt::FillRule fillRule; // 路径和多边形 填充方法
};

Set the form background color

DisplayArea::DisplayArea(QWidget *parent) : QWidget(parent)
{
    
    
    // 设置背景
    QPalette p = palette();
    p.setColor(QPalette::Window, Qt::white);
    setPalette(p);
}

Parameter setting function implementation

setShape、setPen、setBrush、setFillRulefunction implementation

void DisplayArea::setShape(DisplayArea::Shape shape)
{
    
    
    this->shape = shape;
    update(); // 触发重绘
}

void DisplayArea::setPen(QPen pen)
{
    
    
    this->pen = pen;
    update();
}

void DisplayArea::setBrush(QBrush brush)
{
    
    
    this->brush = brush;
    update();
}

void DisplayArea::setFillRule(Qt::FillRule fillRule)
{
    
    
    this->fillRule = fillRule;
    update();
}

Redraw function paintEvent implementation

Draw graphics in the drawing display area according QPainterto different settings.

When drawing here, use the default value set in advance to draw. Pay attention to the use of QPainterPath, see the Qt manual.

void DisplayArea::paintEvent(QPaintEvent *event)
{
    
    
    QPainter p(this); // 新建一个QPainter对象 注意指定parent
    p.setPen(pen); // 设置画笔
    p.setBrush(brush); // 设置画刷

    // 默认值
    static const QPoint point1(50,50);
    static const QPoint point2(400,400); // 这里固定了位置，根据实际需要可以通过设置修改

    static const QRect rect(50,50,400,400);
    static const QPoint points4[4] = {
    
    
        QPoint(50, 50),
        QPoint(400, 100),
        QPoint(450, 350),
        QPoint(100, 300)
    };

    static const QPoint points5[5] = {
    
    
        QPoint(50, 50),
        QPoint(400, 100),
        QPoint(450, 350),
        QPoint(100, 300),
        QPoint(200, 250)
    };
    int startAngle =  30*16; // 弧形 起始角 QPainter 中画弧形使用的角度值以 1/16度 为单位， 30*16 为 30度
    int spanAngle = 120*16; // 弧形 跨度角

    QPainterPath path;
    //addRect  将给定的矩形作为闭合的子路径添加到此路径。将该矩形作为一组顺时针的线添加。
    // 添加矩形后，绘制路径的当前位置在矩形的左上角。
    path.addRect(100, 100, 100, 100);
    // 将当前点移动到给定点，隐式开始一个新的子路径并关闭前一个
    path.moveTo(0, 0);
    // 使用 c1 和 c2 指定的控制点在当前位置和给定端点之间添加三次贝塞尔曲线。
    // 添加曲线后，当前位置更新为曲线的终点。
    // void QPainterPath::cubicTo(const QPointF &c1, const QPointF &c2, const QPointF &endPoint)
    path.cubicTo(300, 0,  200, 200,  300, 300);
    path.cubicTo(0, 300,  200, 200,  0, 0);
    path.setFillRule(fillRule);

    switch(shape){
    
     // 根据不同的图形选择进行绘制
    case Line:{
    
     // 直线 drawLine()
        p.drawLine(point1,point2); // 有不同的实现
        break;
    }
    case Rect:{
    
     // 长方形 drawRect()
        p.drawRect(rect);
        break;
    }
    case RoundedRect:{
    
     // 圆角方形 drawRoundRect()
        p.drawRoundRect(rect);
        break;
    }
    case Ellipse:{
    
     // 椭圆形 drawEllipse()
        p.drawEllipse(rect);
        break;
    }
    case Polygon:{
    
     // 多边形 drawPolygon()
        p.drawPolygon(points4,4,fillRule);
        break;
    }
    case Polyline:{
    
     // 多边线 drawPolyline()
        p.drawPolyline(points5,5);
        break;
    }
    case Points:{
    
     // 点 drawPoints()
        p.drawPoints(points5,5);
        break;
    }
    case Arc:{
    
     // 弧 drawArc()
        p.drawArc(rect,startAngle,spanAngle);
        break;
    }
    case Path:{
    
     // 路径 drawPath(const QPainterPath &path)
        p.drawPath(path);
        break;
    }
    case Text:{
    
     // 文字 drawText
        p.drawText(rect,Qt::AlignCenter,tr("Hello World!"));
        break;
    }
    case PixMap: {
    
     // 图片 drawPixmap
        p.drawPixmap(50,50,QPixmap(":/shape.png"));
        break;
    }
    default:
        break;
    }
}

Main option area implementation

** qpaintersimpleexample.h**Header file

class QPainterSimpleExample : public QWidget
{
    
    
    Q_OBJECT

public:
    QPainterSimpleExample(QWidget *parent = nullptr);
    ~QPainterSimpleExample();
protected slots:
    void DisplayShape(int value); // 形状
    void DisplayPenColor(); // 画笔颜色
    void DisplayPenLineWidth(int value); // 画笔线宽
    void DisplayPenStyle(int value); // 画笔风格
    void DisplayPenCap(int value); // 画笔笔帽
    void DisplayPenJoin(int value); // 画笔连接点
    void DisplayFillStyle(int value); // 填充样式
    void DisplaySpreadStyle(int value); // 平铺效果
    void DisplayBrushColor(); // 画刷颜色
    void DisplayBrushStyle(int value); // 画刷风格
private:
    // 绘制显示区
    DisplayArea *displayArea;
    // 布局
    QGridLayout *optiAreaLayout; // 右侧选项区布局
    QHBoxLayout *mainLayout; // 主窗口顶层布局
    // 形状
    QLabel *shapeLabel;
    QComboBox *shapeComboBox;
    // 画笔颜色
    QLabel *penColorLabel;
    QFrame *penColorFrame;
    QPushButton *penColorBtn;
    // 画笔线宽
    QLabel *penLineWidthLabel;
    QSpinBox *penLineWidthSpinBox;
    // 画笔风格
    QLabel *penStyleLabel;
    QComboBox *penStyleComboBox;
    // 画笔笔帽
    QLabel *penCapLabel;
    QComboBox *penCapComboBox;
    // 画笔连接点
    QLabel *penJoinLabel;
    QComboBox *penJoinComboBox;
    // 填充样式
    QLabel *fillStyleLabel;
    QComboBox *fillStyleComboBox;
    // 平铺效果
    QLabel *spreadStyleLabel;
    QComboBox *spreadStyleComboBox;
    // 画刷颜色
    QLabel *brushColorLabel;
    QFrame *brushColorFrame;
    QPushButton *brushColorBtn;
    // 画刷风格
    QLabel *brushStyleLabel;
    QComboBox *brushStyleComboBox;
};

Constructor

Create option controls, set layouts, and connectfunctions

QPainterSimpleExample::QPainterSimpleExample(QWidget *parent)
    : QWidget(parent)
{
    
    
    // 绘制显示区
    displayArea = new DisplayArea;
    // 形状
    shapeLabel = new QLabel(tr("形状:"));
    shapeComboBox = new QComboBox;
    shapeComboBox->addItem(tr("Line 直线"), DisplayArea::Line);
    shapeComboBox->addItem(tr("Rect 长方形"), DisplayArea::Rect);
    shapeComboBox->addItem(tr("RoundedRect 圆角方形"), DisplayArea::RoundedRect);
    shapeComboBox->addItem(tr("Ellipse 椭圆形"), DisplayArea::Ellipse);
    shapeComboBox->addItem(tr("Polygon 多边形"), DisplayArea::Polygon);
    shapeComboBox->addItem(tr("Polyline 多边线"), DisplayArea::Polyline);
    shapeComboBox->addItem(tr("Points 点"), DisplayArea::Points);
    shapeComboBox->addItem(tr("Arc 弧"), DisplayArea::Arc);
    shapeComboBox->addItem(tr("Path 路径"), DisplayArea::Path);
    shapeComboBox->addItem(tr("Text 文字"), DisplayArea::Text);
    shapeComboBox->addItem(tr("PixMap 图片"), DisplayArea::PixMap);
    connect(shapeComboBox,SIGNAL(activated(int)),this,SLOT(DisplayShape(int)));
    // 画笔颜色
    penColorLabel = new QLabel(tr("画笔颜色:"));
    penColorFrame = new QFrame;
    penColorFrame->setFrameStyle(QFrame::Panel|QFrame::Sunken);
    penColorFrame->setAutoFillBackground(true);//可以改变背景色
    penColorFrame->setPalette(QPalette(Qt::blue));
    penColorBtn = new QPushButton(tr("修改"));
    connect(penColorBtn,SIGNAL(clicked()),this,SLOT(DisplayPenColor()));
    // 画笔线宽
    penLineWidthLabel = new QLabel(tr("画笔线宽:"));
    penLineWidthSpinBox = new QSpinBox;
    penLineWidthSpinBox->setRange(0,20);
    connect(penLineWidthSpinBox,SIGNAL(valueChanged(int)),this,SLOT(DisplayPenLineWidth(int)));
    // 画笔风格
    penStyleLabel = new QLabel(tr("画笔风格:"));
    penStyleComboBox = new QComboBox;
    penStyleComboBox->addItem(tr("SolidLine"),static_cast<int>(Qt::SolidLine));
    penStyleComboBox->addItem(tr("DashLine"),static_cast<int>(Qt::DashLine));
    penStyleComboBox->addItem(tr("DotLine"),static_cast<int>(Qt::DotLine));
    penStyleComboBox->addItem(tr("DashDotLine"),static_cast<int>(Qt::DashDotLine));
    penStyleComboBox->addItem(tr("DashDotDotLine"),static_cast<int>(Qt::DashDotDotLine));
    penStyleComboBox->addItem(tr("CustomDashLine"),static_cast<int>(Qt::CustomDashLine));
    connect(penStyleComboBox,SIGNAL(activated(int)),this,SLOT(DisplayPenStyle(int)));
    // 画笔笔帽
    penCapLabel = new QLabel(tr("画笔笔帽:"));
    penCapComboBox = new QComboBox;
    penCapComboBox->addItem(tr("FlatCap"),static_cast<int>(Qt::FlatCap));
    penCapComboBox->addItem(tr("SquareCap"),static_cast<int>(Qt::SquareCap));
    penCapComboBox->addItem(tr("RoundCap"),static_cast<int>(Qt::RoundCap));
    connect(penCapComboBox,SIGNAL(activated(int)),this,SLOT(DisplayPenCap(int)));
    // 画笔连接点
    penJoinLabel = new QLabel(tr("画笔连接点:"));
    penJoinComboBox = new QComboBox;
    penJoinComboBox->addItem(tr("MiterJoin"),static_cast<int>(Qt::MiterJoin));
    penJoinComboBox->addItem(tr("BevelJoin"),static_cast<int>(Qt::BevelJoin));
    penJoinComboBox->addItem(tr("RoundJoin"),static_cast<int>(Qt::RoundJoin));
    connect(penJoinComboBox,SIGNAL(activated(int)),this,SLOT(DisplayPenJoin(int)));
    // 填充样式
    fillStyleLabel = new QLabel(tr("填充样式:"));
    fillStyleComboBox = new QComboBox;
    fillStyleComboBox->addItem(tr("OddEvenMode"),static_cast<int>(QPaintEngine::OddEvenMode));
    fillStyleComboBox->addItem(tr("WindingMode"),static_cast<int>(QPaintEngine::WindingMode));
    connect(fillStyleComboBox,SIGNAL(activated(int)),this,SLOT(DisplayFillStyle(int)));
    // 铺展效果
    spreadStyleLabel = new QLabel(tr("铺展效果:"));
    spreadStyleComboBox = new QComboBox;
    spreadStyleComboBox->addItem(tr("PadSpread"),static_cast<int>(QGradient::PadSpread));
    spreadStyleComboBox->addItem(tr("RepeatSpread"),static_cast<int>(QGradient::RepeatSpread));
    spreadStyleComboBox->addItem(tr("ReflectSpread"),static_cast<int>(QGradient::ReflectSpread));
    connect(spreadStyleComboBox,SIGNAL(activated(int)),this,SLOT(DisplaySpreadStyle(int)));
    // 画刷颜色
    brushColorLabel = new QLabel(tr("画刷颜色:"));
    brushColorFrame = new QFrame;
    brushColorFrame->setFrameStyle(QFrame::Panel|QFrame::Sunken);
    brushColorFrame->setAutoFillBackground(true);//可以改变背景色
    brushColorFrame->setPalette(QPalette(Qt::yellow));
    brushColorBtn = new QPushButton(tr("修改"));
    connect(brushColorBtn,SIGNAL(clicked()),this,SLOT(DisplayBrushColor()));
    // 画刷风格
    brushStyleLabel = new QLabel(tr("画刷风格:"));
    brushStyleComboBox = new QComboBox;
    brushStyleComboBox->addItem(tr("SolidPattern"),static_cast<int>(Qt::SolidPattern));
    brushStyleComboBox->addItem(tr("Dense1Pattern"),static_cast<int>(Qt::Dense1Pattern));
    brushStyleComboBox->addItem(tr("Dense2Pattern"),static_cast<int>(Qt::Dense2Pattern));
    brushStyleComboBox->addItem(tr("Dense3Pattern"),static_cast<int>(Qt::Dense3Pattern));
    brushStyleComboBox->addItem(tr("Dense4Pattern"),static_cast<int>(Qt::Dense4Pattern));
    brushStyleComboBox->addItem(tr("Dense5Pattern"),static_cast<int>(Qt::Dense5Pattern));
    brushStyleComboBox->addItem(tr("Dense6Pattern"),static_cast<int>(Qt::Dense6Pattern));
    brushStyleComboBox->addItem(tr("Dense7Pattern"),static_cast<int>(Qt::Dense7Pattern));
    brushStyleComboBox->addItem(tr("HorPattern"),static_cast<int>(Qt::HorPattern));
    brushStyleComboBox->addItem(tr("VerPattern"),static_cast<int>(Qt::VerPattern));
    brushStyleComboBox->addItem(tr("CrossPattern"),static_cast<int>(Qt::CrossPattern));
    brushStyleComboBox->addItem(tr("BDiagPattern"),static_cast<int>(Qt::BDiagPattern));
    brushStyleComboBox->addItem(tr("FDiagPattern"),static_cast<int>(Qt::FDiagPattern));
    brushStyleComboBox->addItem(tr("DiagCrossPattern"),static_cast<int>(Qt::DiagCrossPattern));
    brushStyleComboBox->addItem(tr("LinearGradientPattern"),static_cast<int>(Qt::LinearGradientPattern));
    brushStyleComboBox->addItem(tr("ConicalGradientPattern"),static_cast<int>(Qt::ConicalGradientPattern));
    brushStyleComboBox->addItem(tr("RadialGradientPattern"),static_cast<int>(Qt::RadialGradientPattern));
    brushStyleComboBox->addItem(tr("TexturePattern"),static_cast<int>(Qt::TexturePattern));
    connect(brushStyleComboBox,SIGNAL(activated(int)),this,SLOT(DisplayBrushStyle(int)));

    // 布局
    optiAreaLayout = new QGridLayout;
    mainLayout = new QHBoxLayout(this); // 注意指定parent
    // 形状
    optiAreaLayout->addWidget(shapeLabel,0,0);
    optiAreaLayout->addWidget(shapeComboBox,0,1);
    // 画笔颜色
    optiAreaLayout->addWidget(penColorLabel,1,0);
    optiAreaLayout->addWidget(penColorFrame,1,1);
    optiAreaLayout->addWidget(penColorBtn,1,2);
    // 画笔线宽
    optiAreaLayout->addWidget(penLineWidthLabel,2,0);
    optiAreaLayout->addWidget(penLineWidthSpinBox,2,1);
    // 画笔风格
    optiAreaLayout->addWidget(penStyleLabel,3,0);
    optiAreaLayout->addWidget(penStyleComboBox,3,1);
    // 画笔笔帽
    optiAreaLayout->addWidget(penCapLabel,4,0);
    optiAreaLayout->addWidget(penCapComboBox,4,1);
    // 画笔连接点
    optiAreaLayout->addWidget(penJoinLabel,5,0);
    optiAreaLayout->addWidget(penJoinComboBox,5,1);
    // 填充样式
    optiAreaLayout->addWidget(fillStyleLabel,6,0);
    optiAreaLayout->addWidget(fillStyleComboBox,6,1);
    // 铺展效果
    optiAreaLayout->addWidget(spreadStyleLabel,7,0);
    optiAreaLayout->addWidget(spreadStyleComboBox,7,1);
    // 画刷颜色
    optiAreaLayout->addWidget(brushColorLabel,8,0);
    optiAreaLayout->addWidget(brushColorFrame,8,1);
    optiAreaLayout->addWidget(brushColorBtn,8,2);
    // 画刷风格
    optiAreaLayout->addWidget(brushStyleLabel,9,0);
    optiAreaLayout->addWidget(brushStyleComboBox,9,1);

    mainLayout->addWidget(displayArea);
    mainLayout->addLayout(optiAreaLayout);
    mainLayout->setStretchFactor(displayArea,1);
    mainLayout->setStretchFactor(optiAreaLayout,1);
}

DisplayShapefunction to set and display the graph

void QPainterSimpleExample::DisplayShape(int value)
{
    
    
    DisplayArea::Shape shape = DisplayArea::Shape(shapeComboBox->
                              itemData(value,Qt::UserRole).toInt());
    displayArea->setShape(shape);
}

QComboBoxThe itemDatamethod returns the data of the currently displayed drop-down list box, which is an QVariantobject, which is related to the type inserted when the control is initialized

DisplayPenColorThe function sets and displays the brush color

Passed QFramebackground color to display the selected color

void QPainterSimpleExample::DisplayPenColor()
{
    
    
    // 画笔颜色
    QColor color = QColorDialog::getColor(Qt::blue);
    penColorFrame->setPalette(QPalette(color));
    // 画笔线宽
    int value = penLineWidthSpinBox->value();
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}

DisplayPenLineWidthThe function sets and displays the brush line width

void QPainterSimpleExample::DisplayPenLineWidth(int value)
{
    
    
    // 画笔颜色
    QColor color = penColorFrame->palette().color(QPalette::Window); // 获取penColorFrame 背景色
    // 画笔线宽 就是 value
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}

DisplayPenStyleThe function sets and displays the brush style

void QPainterSimpleExample::DisplayPenStyle(int penStyleValue)
{
    
    
    // 画笔颜色
    QColor color = penColorFrame->palette().color(QPalette::Window); // 获取penColorFrame 背景色
    // 画笔线宽
    int value = penLineWidthSpinBox->value();
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}

Introduction to Brush Styles

DisplayPenCapThe function sets and displays the brush cap

// 画笔笔帽
void QPainterSimpleExample::DisplayPenCap(int penCapValue)
{
    
    
    // 画笔颜色
    QColor color = penColorFrame->palette().color(QPalette::Window); // 获取penColorFrame 背景色
    // 画笔线宽
    int value = penLineWidthSpinBox->value();
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}

Brief introduction of brush cap

DisplayPenJoinThe function sets and displays the brush connection point

void QPainterSimpleExample::DisplayPenJoin(int penJoinValue)
{
    
    
    // 画笔颜色
    QColor color = penColorFrame->palette().color(QPalette::Window); // 获取penColorFrame 背景色
    // 画笔线宽
    int value = penLineWidthSpinBox->value();
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}

Introduction to Brush Connection Points

DisplayFillStyleFunction to set and display fill style

void QPainterSimpleExample::DisplayFillStyle(int value)
{
    
    
    Qt::FillRule fillRule = Qt::FillRule(fillStyleComboBox->itemData(fillStyleComboBox->currentIndex(),
                                                                    Qt::UserRole).toInt());
    // 设置填充样式
    displayArea->setFillRule(fillRule);
}

Introduction to fill styles

DisplaySpreadStyleThe function sets and displays the spread style

void QPainterSimpleExample::DisplaySpreadStyle(int value)
{
    
    
    QGradient::Spread spread = QGradient::Spread(spreadStyleComboBox->itemData(spreadStyleComboBox->currentIndex(),
                                                                             Qt::UserRole).toInt());
    this->spread = spread;
}

Introduction to Spread Styles

DisplayBrushColorThe function sets and displays the brush color

void QPainterSimpleExample::DisplayBrushColor()
{
    
    
    // 画刷颜色
    QColor color = QColorDialog::getColor(Qt::yellow);
    brushColorFrame->setPalette(QPalette(color));
    DisplayBrushStyle(brushStyleComboBox->currentIndex());
}

DisplayBrushStyleFunctions to set and display brush style, gradient and spread effects

// 画刷风格
void QPainterSimpleExample::DisplayBrushStyle(int value)
{
    
    
    //获得画刷的颜色
    QColor color = brushColorFrame->palette().color(QPalette:: Window);
    Qt::BrushStyle style = Qt::BrushStyle(brushStyleComboBox-> itemData(value,Qt::UserRole).toInt());
    if(style == Qt::LinearGradientPattern) {
    
     // 线性渐变
        QLinearGradient linearGradient(0,0,500,500);
        linearGradient.setColorAt(0.0,Qt::white);
        linearGradient.setColorAt(0.2,color);
        linearGradient.setColorAt(1.0,Qt::black);
        linearGradient.setSpread(spread);
        displayArea->setBrush(linearGradient);
    } else if(style == Qt::RadialGradientPattern) {
    
     // 圆形渐变
        QRadialGradient radialGradient(250,250,200,0,500);// 圆心 半径 焦点值
        radialGradient.setColorAt(0.0,Qt::white);
        radialGradient.setColorAt(0.2,color);
        radialGradient.setColorAt(1.0,Qt::black);
        radialGradient.setSpread(spread);
        displayArea->setBrush(radialGradient);
    } else if(style == Qt::ConicalGradientPattern) {
    
     // 锥形渐变
        QConicalGradient conicalGradient(200,200,30); // 顶点 夹角
        conicalGradient.setColorAt(0.0,Qt::white);
        conicalGradient.setColorAt(0.2,color);
        conicalGradient.setColorAt(1.0,Qt::black);
        displayArea->setBrush(conicalGradient);
    } else if(style == Qt::TexturePattern) {
    
     // 图片
        displayArea->setBrush(QBrush(QPixmap(":/texture.png")));
    } else {
    
    
        displayArea->setBrush(QBrush(color,style));
    }
}

Introduction to Brush Styles

qpaintersimpleexample.cppdocument

Main option area implementation code summary

QPainterSimpleExample::QPainterSimpleExample(QWidget *parent)
    : QWidget(parent)
{
    
    
    // 绘制显示区
    displayArea = new DisplayArea;
    // 形状
    shapeLabel = new QLabel(tr("形状:"));
    shapeComboBox = new QComboBox;
    shapeComboBox->addItem(tr("Line 直线"), DisplayArea::Line);
    shapeComboBox->addItem(tr("Rect 长方形"), DisplayArea::Rect);
    shapeComboBox->addItem(tr("RoundedRect 圆角方形"), DisplayArea::RoundedRect);
    shapeComboBox->addItem(tr("Ellipse 椭圆形"), DisplayArea::Ellipse);
    shapeComboBox->addItem(tr("Polygon 多边形"), DisplayArea::Polygon);
    shapeComboBox->addItem(tr("Polyline 多边线"), DisplayArea::Polyline);
    shapeComboBox->addItem(tr("Points 点"), DisplayArea::Points);
    shapeComboBox->addItem(tr("Arc 弧"), DisplayArea::Arc);
    shapeComboBox->addItem(tr("Path 路径"), DisplayArea::Path);
    shapeComboBox->addItem(tr("Text 文字"), DisplayArea::Text);
    shapeComboBox->addItem(tr("PixMap 图片"), DisplayArea::PixMap);
    connect(shapeComboBox,SIGNAL(activated(int)),this,SLOT(DisplayShape(int)));
    // 画笔颜色
    penColorLabel = new QLabel(tr("画笔颜色:"));
    penColorFrame = new QFrame;
    penColorFrame->setFrameStyle(QFrame::Panel|QFrame::Sunken);
    penColorFrame->setAutoFillBackground(true);//可以改变背景色
    penColorFrame->setPalette(QPalette(Qt::blue));
    penColorBtn = new QPushButton(tr("修改"));
    connect(penColorBtn,SIGNAL(clicked()),this,SLOT(DisplayPenColor()));
    // 画笔线宽
    penLineWidthLabel = new QLabel(tr("画笔线宽:"));
    penLineWidthSpinBox = new QSpinBox;
    penLineWidthSpinBox->setRange(0,20);
    connect(penLineWidthSpinBox,SIGNAL(valueChanged(int)),this,SLOT(DisplayPenLineWidth(int)));
    // 画笔风格
    penStyleLabel = new QLabel(tr("画笔风格:"));
    penStyleComboBox = new QComboBox;
    penStyleComboBox->addItem(tr("SolidLine"),static_cast<int>(Qt::SolidLine));
    penStyleComboBox->addItem(tr("DashLine"),static_cast<int>(Qt::DashLine));
    penStyleComboBox->addItem(tr("DotLine"),static_cast<int>(Qt::DotLine));
    penStyleComboBox->addItem(tr("DashDotLine"),static_cast<int>(Qt::DashDotLine));
    penStyleComboBox->addItem(tr("DashDotDotLine"),static_cast<int>(Qt::DashDotDotLine));
    penStyleComboBox->addItem(tr("CustomDashLine"),static_cast<int>(Qt::CustomDashLine));
    connect(penStyleComboBox,SIGNAL(activated(int)),this,SLOT(DisplayPenStyle(int)));
    // 画笔笔帽
    penCapLabel = new QLabel(tr("画笔笔帽:"));
    penCapComboBox = new QComboBox;
    penCapComboBox->addItem(tr("FlatCap"),static_cast<int>(Qt::FlatCap));
    penCapComboBox->addItem(tr("SquareCap"),static_cast<int>(Qt::SquareCap));
    penCapComboBox->addItem(tr("RoundCap"),static_cast<int>(Qt::RoundCap));
    connect(penCapComboBox,SIGNAL(activated(int)),this,SLOT(DisplayPenCap(int)));
    // 画笔连接点
    penJoinLabel = new QLabel(tr("画笔连接点:"));
    penJoinComboBox = new QComboBox;
    penJoinComboBox->addItem(tr("MiterJoin"),static_cast<int>(Qt::MiterJoin));
    penJoinComboBox->addItem(tr("BevelJoin"),static_cast<int>(Qt::BevelJoin));
    penJoinComboBox->addItem(tr("RoundJoin"),static_cast<int>(Qt::RoundJoin));
    connect(penJoinComboBox,SIGNAL(activated(int)),this,SLOT(DisplayPenJoin(int)));
    // 填充样式
    fillStyleLabel = new QLabel(tr("填充样式:"));
    fillStyleComboBox = new QComboBox;
    fillStyleComboBox->addItem(tr("OddEvenMode"),static_cast<int>(QPaintEngine::OddEvenMode));
    fillStyleComboBox->addItem(tr("WindingMode"),static_cast<int>(QPaintEngine::WindingMode));
    connect(fillStyleComboBox,SIGNAL(activated(int)),this,SLOT(DisplayFillStyle(int)));
    // 铺展效果
    spreadStyleLabel = new QLabel(tr("铺展效果:"));
    spreadStyleComboBox = new QComboBox;
    spreadStyleComboBox->addItem(tr("PadSpread"),static_cast<int>(QGradient::PadSpread));
    spreadStyleComboBox->addItem(tr("RepeatSpread"),static_cast<int>(QGradient::RepeatSpread));
    spreadStyleComboBox->addItem(tr("ReflectSpread"),static_cast<int>(QGradient::ReflectSpread));
    connect(spreadStyleComboBox,SIGNAL(activated(int)),this,SLOT(DisplaySpreadStyle(int)));
    // 画刷颜色
    brushColorLabel = new QLabel(tr("画刷颜色:"));
    brushColorFrame = new QFrame;
    brushColorFrame->setFrameStyle(QFrame::Panel|QFrame::Sunken);
    brushColorFrame->setAutoFillBackground(true);//可以改变背景色
    brushColorFrame->setPalette(QPalette(Qt::yellow));
    brushColorBtn = new QPushButton(tr("修改"));
    connect(brushColorBtn,SIGNAL(clicked()),this,SLOT(DisplayBrushColor()));
    // 画刷风格
    brushStyleLabel = new QLabel(tr("画刷风格:"));
    brushStyleComboBox = new QComboBox;
    brushStyleComboBox->addItem(tr("SolidPattern"),static_cast<int>(Qt::SolidPattern));
    brushStyleComboBox->addItem(tr("Dense1Pattern"),static_cast<int>(Qt::Dense1Pattern));
    brushStyleComboBox->addItem(tr("Dense2Pattern"),static_cast<int>(Qt::Dense2Pattern));
    brushStyleComboBox->addItem(tr("Dense3Pattern"),static_cast<int>(Qt::Dense3Pattern));
    brushStyleComboBox->addItem(tr("Dense4Pattern"),static_cast<int>(Qt::Dense4Pattern));
    brushStyleComboBox->addItem(tr("Dense5Pattern"),static_cast<int>(Qt::Dense5Pattern));
    brushStyleComboBox->addItem(tr("Dense6Pattern"),static_cast<int>(Qt::Dense6Pattern));
    brushStyleComboBox->addItem(tr("Dense7Pattern"),static_cast<int>(Qt::Dense7Pattern));
    brushStyleComboBox->addItem(tr("HorPattern"),static_cast<int>(Qt::HorPattern));
    brushStyleComboBox->addItem(tr("VerPattern"),static_cast<int>(Qt::VerPattern));
    brushStyleComboBox->addItem(tr("CrossPattern"),static_cast<int>(Qt::CrossPattern));
    brushStyleComboBox->addItem(tr("BDiagPattern"),static_cast<int>(Qt::BDiagPattern));
    brushStyleComboBox->addItem(tr("FDiagPattern"),static_cast<int>(Qt::FDiagPattern));
    brushStyleComboBox->addItem(tr("DiagCrossPattern"),static_cast<int>(Qt::DiagCrossPattern));
    brushStyleComboBox->addItem(tr("LinearGradientPattern"),static_cast<int>(Qt::LinearGradientPattern));
    brushStyleComboBox->addItem(tr("ConicalGradientPattern"),static_cast<int>(Qt::ConicalGradientPattern));
    brushStyleComboBox->addItem(tr("RadialGradientPattern"),static_cast<int>(Qt::RadialGradientPattern));
    brushStyleComboBox->addItem(tr("TexturePattern"),static_cast<int>(Qt::TexturePattern));
    connect(brushStyleComboBox,SIGNAL(activated(int)),this,SLOT(DisplayBrushStyle(int)));

    // 布局
    optiAreaLayout = new QGridLayout;
    mainLayout = new QHBoxLayout(this); // 注意指定parent
    // 形状
    optiAreaLayout->addWidget(shapeLabel,0,0);
    optiAreaLayout->addWidget(shapeComboBox,0,1);
    // 画笔颜色
    optiAreaLayout->addWidget(penColorLabel,1,0);
    optiAreaLayout->addWidget(penColorFrame,1,1);
    optiAreaLayout->addWidget(penColorBtn,1,2);
    // 画笔线宽
    optiAreaLayout->addWidget(penLineWidthLabel,2,0);
    optiAreaLayout->addWidget(penLineWidthSpinBox,2,1);
    // 画笔风格
    optiAreaLayout->addWidget(penStyleLabel,3,0);
    optiAreaLayout->addWidget(penStyleComboBox,3,1);
    // 画笔笔帽
    optiAreaLayout->addWidget(penCapLabel,4,0);
    optiAreaLayout->addWidget(penCapComboBox,4,1);
    // 画笔连接点
    optiAreaLayout->addWidget(penJoinLabel,5,0);
    optiAreaLayout->addWidget(penJoinComboBox,5,1);
    // 填充样式
    optiAreaLayout->addWidget(fillStyleLabel,6,0);
    optiAreaLayout->addWidget(fillStyleComboBox,6,1);
    // 铺展效果
    optiAreaLayout->addWidget(spreadStyleLabel,7,0);
    optiAreaLayout->addWidget(spreadStyleComboBox,7,1);
    // 画刷颜色
    optiAreaLayout->addWidget(brushColorLabel,8,0);
    optiAreaLayout->addWidget(brushColorFrame,8,1);
    optiAreaLayout->addWidget(brushColorBtn,8,2);
    // 画刷风格
    optiAreaLayout->addWidget(brushStyleLabel,9,0);
    optiAreaLayout->addWidget(brushStyleComboBox,9,1);

    mainLayout->addWidget(displayArea);
    mainLayout->addLayout(optiAreaLayout);
    mainLayout->setStretchFactor(displayArea,1);
    mainLayout->setStretchFactor(optiAreaLayout,1);
}

QPainterSimpleExample::~QPainterSimpleExample()
{
    
    
}
// 形状
void QPainterSimpleExample::DisplayShape(int value)
{
    
    
    DisplayArea::Shape shape = DisplayArea::Shape(shapeComboBox->
                              itemData(value,Qt::UserRole).toInt());
    displayArea->setShape(shape);
}
// 画笔颜色
void QPainterSimpleExample::DisplayPenColor()
{
    
    
    // 画笔颜色
    QColor color = QColorDialog::getColor(Qt::blue);
    penColorFrame->setPalette(QPalette(color));
    // 画笔线宽
    int value = penLineWidthSpinBox->value();
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}
// 画笔线宽
void QPainterSimpleExample::DisplayPenLineWidth(int value)
{
    
    
    // 画笔颜色
    QColor color = penColorFrame->palette().color(QPalette::Window); // 获取penColorFrame 背景色
    // 画笔线宽 就是 value
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}
// 画笔风格
void QPainterSimpleExample::DisplayPenStyle(int penStyleValue)
{
    
    
    // 画笔颜色
    QColor color = penColorFrame->palette().color(QPalette::Window); // 获取penColorFrame 背景色
    // 画笔线宽
    int value = penLineWidthSpinBox->value();
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}

// 画笔笔帽
void QPainterSimpleExample::DisplayPenCap(int penCapValue)
{
    
    
    // 画笔颜色
    QColor color = penColorFrame->palette().color(QPalette::Window); // 获取penColorFrame 背景色
    // 画笔线宽
    int value = penLineWidthSpinBox->value();
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}
// 画笔连接点
void QPainterSimpleExample::DisplayPenJoin(int penJoinValue)
{
    
    
    // 画笔颜色
    QColor color = penColorFrame->palette().color(QPalette::Window); // 获取penColorFrame 背景色
    // 画笔线宽
    int value = penLineWidthSpinBox->value();
    // 画笔风格
    Qt::PenStyle style = Qt::PenStyle(penStyleComboBox->itemData(penStyleComboBox->currentIndex(),
                                                    Qt::UserRole).toInt());
    // 画笔笔帽
    Qt::PenCapStyle cap = Qt::PenCapStyle(penCapComboBox->itemData(penCapComboBox->currentIndex(),
                                                                   Qt::UserRole).toInt());
    // 画笔连接点
    Qt::PenJoinStyle join = Qt::PenJoinStyle(penJoinComboBox->itemData(penJoinComboBox->currentIndex(),
                                                                     Qt::UserRole).toInt());
    // 设置画笔
    displayArea->setPen(QPen(color,value,style,cap,join));
}
// 填充样式
void QPainterSimpleExample::DisplayFillStyle(int value)
{
    
    
    Qt::FillRule fillRule = Qt::FillRule(fillStyleComboBox->itemData(fillStyleComboBox->currentIndex(),
                                                                    Qt::UserRole).toInt());
    // 设置填充样式
    displayArea->setFillRule(fillRule);
}
// 铺展效果
void QPainterSimpleExample::DisplaySpreadStyle(int value)
{
    
    
    QGradient::Spread spread = QGradient::Spread(spreadStyleComboBox->itemData(spreadStyleComboBox->currentIndex(),
                                                                             Qt::UserRole).toInt());
    this->spread = spread;
}
// 画刷颜色
void QPainterSimpleExample::DisplayBrushColor()
{
    
    
    // 画刷颜色
    QColor color = QColorDialog::getColor(Qt::yellow);
    brushColorFrame->setPalette(QPalette(color));
    DisplayBrushStyle(brushStyleComboBox->currentIndex());
}
// 画刷风格
void QPainterSimpleExample::DisplayBrushStyle(int value)
{
    
    
    //获得画刷的颜色
    QColor color = brushColorFrame->palette().color(QPalette:: Window);
    Qt::BrushStyle style = Qt::BrushStyle(brushStyleComboBox-> itemData(value,Qt::UserRole).toInt());
    if(style == Qt::LinearGradientPattern) {
    
     // 线性渐变
        QLinearGradient linearGradient(0,0,500,500);
        linearGradient.setColorAt(0.0,Qt::white);
        linearGradient.setColorAt(0.2,color);
        linearGradient.setColorAt(1.0,Qt::black);
        linearGradient.setSpread(spread);
        displayArea->setBrush(linearGradient);
    } else if(style == Qt::RadialGradientPattern) {
    
     // 圆形渐变
        QRadialGradient radialGradient(250,250,200,0,500);// 圆心 半径 焦点值
        radialGradient.setColorAt(0.0,Qt::white);
        radialGradient.setColorAt(0.2,color);
        radialGradient.setColorAt(1.0,Qt::black);
        radialGradient.setSpread(spread);
        displayArea->setBrush(radialGradient);
    } else if(style == Qt::ConicalGradientPattern) {
    
     // 锥形渐变
        QConicalGradient conicalGradient(200,200,30); // 顶点 夹角
        conicalGradient.setColorAt(0.0,Qt::white);
        conicalGradient.setColorAt(0.2,color);
        conicalGradient.setColorAt(1.0,Qt::black);
        displayArea->setBrush(conicalGradient);
    } else if(style == Qt::TexturePattern) {
    
     // 图片
        displayArea->setBrush(QBrush(QPixmap(":/texture.png")));
    } else {
    
    
        displayArea->setBrush(QBrush(color,style));
    }
}

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