编写一款2D CAD/CAM软件（十六）交互绘制图形

绘制步骤

以交互绘制圆形为例：

1. 点击鼠标左键，确定圆心位置；
2. 抬起鼠标，移动鼠标，半径随鼠标位置变化；
3. 点击左键确定半径，完成圆的绘制。

绘制结果

Code

/// j-operator-create-circle.h
 
#pragma once
 
#include "j-operator.h"
#include "j-geometry/j-geometry-circle.h"
 
namespace JNSOperator {
 
    enum class JCreateCircleStep {
        eCreateCircleStepInit = 0,
        eCreateCircleStepFirstDown,
        eCreateCircleStepFirstRelease,
        eCreateCircleStepSecondDown,
        eCreateCircleStepSecondRelease
    };
 
    class JOperatorCreateCircle : public JOperator {
    public:
        JOperatorCreateCircle(JOperatorManager *manager);
        virtual ~JOperatorCreateCircle();
 
        unsigned GetClassId() const override {
            return ID_OP_CREATE_CIRCLE;