c++cairo实现实现L文法系统

1.turtle.h

#ifndef _TURTLE_H_
#define _TURTLE_H_

#include <vector>

class CairoInner;

class Turtle {
public:
    Turtle();
    ~Turtle();

    void start(const std::vector<float> &A);
    void restore(std::vector<float> &A);
    void get_point(std::vector<float> &A);

    void forward(int L);
    void go(int L);
    void left(float angle);
    void right(float angle);

    void drawend();

    void resize(int with, int height);

    void setColor(int r, int g, int b, int a);
    void setPenWidth(int w);

    void save(const char *path);

private:
    CairoInner *inner;
    float P[3];
    int wt;
    int ht;
};

#endif

2.turtle.cpp

#include <stdio.h>
#include <math.h>
#include <cairo.h>
#include "turtle.h"

class CairoInner {
public:
    CairoInner();
    ~CairoInner();

    cairo_surface_t *surface;
        cairo_t *cr;
};

Turtle::Turtle()
{
    inner = new CairoInner();

    if(inner != NULL)
    {
        
    }
}

Turtle::~Turtle()
{
    if(inner != NULL)
    {
        if(inner->cr != NULL)
        {
            cairo_destroy(inner->cr);

            inner->cr = NULL;
        }

        delete inner;

        inner = NULL;
    }
}

void Turtle::start(const std::vector<float> &A)
{
    P[0] = A[0];
    P[1] = A[1];
    P[2] = A[2];

    cairo_move_to(inner->cr, P[0], ht-P[1]);
}

void Turtle::restore(std::vector<float> &A)
{
    P[0] = A[0];
    P[1] = A[1];
    P[2] = A[2];
}

void Turtle::get_point(std::vector<float> &A)
{
    A[0] = P[0];
    A[1] = P[1];
    A[2] = P[2];
}


void Turtle::setColor(int r, int g, int b, int a)
{
    double r2 = (double)r / 255;
    double g2 = (double)g / 255;
    double b2 = (double)b / 255;
    double a2 = (double)a / 255;

    if(r2 > 1.0)
    {
        r2 = 1.0;
    }

    if(g2 > 1.0)
    {
        g2 = 1.0;
    }

    if(b2 > 1.0)
    {
        b2 = 1.0;
    }

    if(a2 > 1.0)
    {
        a2 = 1.0;
    }

    cairo_set_source_rgba(inner->cr,r2,g2,b2,a2);
}

void Turtle::setPenWidth(int w)
{
    cairo_set_line_width(inner->cr, w);
}

void Turtle::save(const char *path)
{
    cairo_surface_write_to_png(inner->surface, path);
}

void Turtle::resize(int width, int height)
{
    inner->surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
    inner->cr = cairo_create(inner->surface);

    wt = width;
    ht = height;
}

void Turtle::forward(int L)
{
    float x1 = P[0] + L * cos(P[2]*M_PI/180);
    float y1 = P[1] + L * sin(P[2]*M_PI/180);

    cairo_line_to(inner->cr, x1, ht-y1);

    P[0] = x1;
    P[1] = y1;
}

void Turtle::go(int L)
{
    float x1 = P[0] + L * cos(P[2]*M_PI/180);
    float y1 = P[1] + L * sin(P[2]*M_PI/180);

    P[0] = x1;
    P[1] = y1;
}

void Turtle::left(float angle)
{
    P[2] += angle;
}

void Turtle::right(float angle)
{
    P[2] -= angle;
}

void Turtle::drawend()
{
    cairo_stroke(inner->cr);
}

CairoInner::CairoInner()
{
    surface = NULL;
    cr = NULL;
}

CairoInner::~CairoInner()
{
    surface = NULL;
    cr = NULL;
}

3.lsystem.h

#ifndef _L_SYSTEM_H_
#define _L_SYSTEM_H_

#include <string>
#include <map>

class Turtle;

struct LSRule {
    float angle;
    std::string axiom;
    std::vector<std::string> P;
};

class LSystem {
public:
    LSystem(Turtle *turtle);
    ~LSystem();

    void run(const LSRule &LS, const std::vector<float> &A, int L, int n);

private:
    std::map<char, std::string> plot_v;
    Turtle *m_turtle;
};

#endif

4.lsystem.cpp

#include <iostream>
#include <stack>
#include "turtle.h"
#include "lsystem.h"

using namespace std;

LSystem::LSystem(Turtle *turtle)
{
    m_turtle = turtle;

    plot_v = {
        std::pair<char, std::string>('F', "Move forward by line length drawing a line"),
        std::pair<char, std::string>('f', "Move forward by line length without drawing a line"),
        std::pair<char, std::string>('+', "Turn left by turning angle"),
        std::pair<char, std::string>('-', "Turn right by turning angle"),
        std::pair<char, std::string>('[', "push"),
        std::pair<char, std::string>(']', "pop")
    };
}

LSystem::~LSystem()
{
    m_turtle = NULL;
}

void LSystem::run(const LSRule &LS, const std::vector<float> &A, int L, int n)
{
    float angle = LS.angle;
    std::string axiom = LS.axiom;
    std::vector<std::string> P = LS.P;
    int i = 0;
    std::string new_str = axiom;

    while(i < n)
    {
        std::string s;

        for(char alpha : new_str)
        {
            int k = 0;

            for(std::string rule : P)
            {
                int pos = rule.find("->");

                if(pos != std::string::npos)
                {
                    std::string origin = rule.substr(0, pos);
                    std::string desti = rule.substr(pos+2, rule.length()-pos-2);

                    if(alpha == origin[0])
                    {
                        if(desti != "")
                        {
                            s.append(desti);
                        }

                        k = 1;
                    }
                }
            }

            if(k == 0)
            {
                s.push_back(alpha);
            }
        }

        new_str = s;

        std::cout << new_str << std::endl;

        i++;
    }

    m_turtle->start(A);

    std::stack<std::vector<float>> s;
    std::vector<float> c;

    c.resize(3);

    for(char alpha : new_str)
    {
        if(plot_v.find(alpha) == plot_v.end())
        {
            continue;
        }

        if(alpha == 'F')
        {
            m_turtle->forward(L);
        }
        else if(alpha == 'f')
        {
            m_turtle->go(L);
        }
        else if(alpha == '+')
        {
            m_turtle->left(angle);
        }
        else if(alpha == '-')
        {
            m_turtle->right(angle);
        }
        else if(alpha == '[')
        {
            m_turtle->get_point(c);
            s.push(c);
        }
        else if(alpha == ']')
        {
            c = s.top();
            s.pop();
            m_turtle->restore(c);
        }
    }

    m_turtle->drawend();
}

int main()
{
    LSRule LS = {45, "FX", {"F->", "Y->+FX--FY+", "X->-FX++FY-"}};
    Turtle turtle;
    LSystem lsys(&turtle);
    std::vector<float> A = {300, 450, 0};

    turtle.resize(800, 800);

    turtle.setColor(0, 255, 255, 255);
    turtle.setPenWidth(1);

    lsys.run(LS, A, 10, 10);

    turtle.save("2.png");

    return 0;
}

5.编译源码

$ g++ -o example turtle.cpp lsystem.cpp -std=c++11 -I/opt/apps/cairo/include -I/opt/apps/cairo/include/cairo -L/opt/apps/cairo/lib -lcairo -Wl,-rpath=/opt/apps/cairo/lib

6.运行结果