Image.h

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#ifndef Image_h
#define Image_h

#include "Color.h"
#include "Math.h"
#include <string>

struct Pixel {
    unsigned char r, g, b;
};

class Image {
 public:
    Image(const std::string& name);
    Image(int xres, int yres);
    ~Image();
    void set(int x, int y, const Color& c) {
        Pixel p;
        p.r = c.r() < 0.f? 0: c.r() >= 1.f? 255 : (int)(c.r() * 255.f);
        p.g = c.g() < 0.f? 0: c.g() >= 1.f? 255 : (int)(c.g() * 255.f);
        p.b = c.b() < 0.f? 0: c.b() >= 1.f? 255 : (int)(c.b() * 255.f);
        data[y][x] = p;
    }
    void write(const std::string& filename) const;
    double aspect_ratio() const {
        return double(xres)/double(yres);
    }
    int getXresolution() {
        return xres;
    }
    int getYresolution() {
        return yres;
    }
    Color interpolate(float x, float y) const {
        x *= xres; y *= yres;
        int ix = Floor(x)%xres;
        if(ix<0)
            ix += xres;
        int ix1 = (ix+1)%xres;
        int iy = Floor(y)%yres;
        if(iy<0)
            iy += yres;
        int iy1 = (iy+1)%yres;
        float fx = x-ix;
        float fy = y-iy;

        Color c00 = Color(data[iy][ix].r,   data[iy][ix].g,   data[iy][ix].b);
        Color c01 = Color(data[iy][ix1].r,  data[iy][ix1].g,  data[iy][ix1].b);
        Color c10 = Color(data[iy1][ix].r,  data[iy1][ix].g,  data[iy1][ix].b);
        Color c11 = Color(data[iy1][ix1].r, data[iy1][ix1].g, data[iy1][ix1].b);
        Color c = c00*(1-fx)*(1-fy) + c01*fx*(1-fy) + c10*(1-fx)*fy + c11*fx*fy;
        return c*(1./255);
    }
 protected:
    Pixel** data;  // row pointers
    int xres, yres;
    Image(const Image&);
    Image& operator=(const Image&);
 private:
    void read_png_file(const char* file_name, int &width, int &height);
    void write_png_file(const char* file_name, int width, int height) const;
};

#endif

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