效果
学以致用,使用设计模式之建造者模式
绘制小猪。
代码
接口:申明绘制的步骤
PigBuilder.h
#ifndef PIGBUILDER_H
#define PIGBUILDER_H
#include <QObject>
#include <QPainter>
class PigBuilder : public QObject
{
Q_OBJECT
public:
explicit PigBuilder(QObject *parent = nullptr) : QObject(parent)
{
}
virtual ~PigBuilder()
{
}
// 绘制身体
virtual void drawBody(QPainter &painter) = 0;
// 绘制胳膊
virtual void drawEars(QPainter &painter) = 0;
// 绘制眼睛
virtual void drawEyes(QPainter &painter) = 0;
// 绘制鼻子
virtual void drawNose(QPainter &painter) = 0;
// 绘制腿
virtual void drawLegs(QPainter &painter) = 0;
// 绘制尾巴
virtual void drawTail(QPainter &painter) = 0;
};
#endif // PIGBUILDER_H
实例化:实例出具体绘制的小猪
SimplePig
#include "pigbuilder.h"
class SimplePig : public PigBuilder
{
Q_OBJECT
public:
explicit SimplePig(QObject *parent = nullptr) : PigBuilder(parent){
}
virtual ~SimplePig()
{
}
virtual void drawBody(QPainter &painter)
{
painter.setBrush(QBrush(QColor(247, 204, 148)));
painter.setPen(Qt::NoPen);
painter.drawEllipse(QPointF(250, 250), 100, 120);
}
virtual void drawEars(QPainter &painter)
{
painter.setBrush(QBrush(QColor(247, 204, 148)));
painter.setPen(Qt::NoPen);
painter.drawEllipse(QPointF(200, 180), 40, 50);
painter.drawEllipse(QPointF(300, 180), 40, 50);
}
virtual void drawEyes(QPainter &painter)
{
painter.setBrush(QBrush(QColor(255, 255, 255)));
painter.setPen(Qt::NoPen);
painter.drawEllipse(QPointF(225, 235), 15, 25);
painter.drawEllipse(QPointF(275, 235), 15, 25);
painter.setBrush(QBrush(QColor(0, 0, 0)));
painter.drawEllipse(QPointF(225, 235), 8, 15);
painter.drawEllipse(QPointF(275, 235), 8, 15);
}
virtual void drawNose(QPainter &painter)
{
painter.setBrush(QBrush(QColor(255, 185, 185)));
painter.setPen(Qt::NoPen);
painter.drawEllipse(QPointF(250, 270), 15, 20);
}
virtual void drawLegs(QPainter &painter)
{
painter.setBrush(QBrush(QColor(247, 204, 148)));
painter.setPen(Qt::NoPen);
painter.drawEllipse(QPointF(200, 320), 20, 40);
painter.drawEllipse(QPointF(300, 320), 20, 40);
}
virtual void drawTail(QPainter &painter)
{
painter.setBrush(QBrush(QColor(247, 204, 148)));
painter.setPen(Qt::NoPen);
painter.drawEllipse(QPointF(320, 250), 20, 40);
}
};
建造者:用于创建小猪
PigDirector
class PigDirector : public QObject
{
Q_OBJECT
public:
explicit PigDirector(QObject *parent = nullptr) : QObject(parent)
{
m_pigBuilder = nullptr;
}
virtual ~PigDirector()
{
}
void setBuilder(PigBuilder *pigBuilder)
{
m_pigBuilder = pigBuilder;
}
void draw(QPainter &painter){
if (m_pigBuilder != nullptr)
{
m_pigBuilder->drawBody(painter);
m_pigBuilder->drawEars(painter);
m_pigBuilder->drawEyes(painter);
m_pigBuilder->drawNose(painter);
m_pigBuilder->drawLegs(painter);
m_pigBuilder->drawTail(painter);
}
}
private:
PigBuilder *m_pigBuilder;
};
窗体:用于显示
MainWidget
class MainWidget : public QWidget
{
Q_OBJECT
public:
MainWidget(QWidget *parent = nullptr)
: QWidget(parent)
{
setFixedSize(500, 500);
// 创建简单的小猪
PigBuilder *pigBuilder = new SimplePig();
// 设置小猪的构建方式
m_pigDirector.setBuilder(pigBuilder);
}
~MainWidget()
{
}
protected:
void paintEvent(QPaintEvent *event) override
{
Q_UNUSED(event);
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing);
// 构建并绘制小猪
m_pigDirector.draw(painter);
}
private:
PigDirector m_pigDirector;
};
调用:
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWidget w;
w.show();
return a.exec();
}