Transform.h

// Copyright @ MyScript. All rights reserved.
 
#pragma once
 
#include <iink/Engine.h>
#include <iink/graphics/Point.h>
#include <iink/graphics/Rectangle.h>
 
#include <cmath>
#include <stdexcept>
#include <iostream>
 
namespace myscript {
namespace iink {
namespace graphics {
 
struct Transform
{
  double xx = 1.;
 
  double yx = 0.;
 
  double tx = 0.;
 
  double xy = 0.;
 
  double yy = 1.;
 
  double ty = 0.;
 
  Transform() =default;
 
  Transform(const Transform& other) =default;
 
  Transform(double xx, double yx, double tx, double xy, double yy, double ty) noexcept
    : xx(xx)
    , yx(yx)
    , tx(tx)
    , xy(xy)
    , yy(yy)
    , ty(ty)
  {
  }
 
  IINK_API bool isNear(const Transform& other) const noexcept;
 
  IINK_API bool isIdentity() const noexcept;
 
  IINK_API void invert();
 
  IINK_API void multiply(const Transform& other) noexcept;
 
  IINK_API void translate(double tx, double ty) noexcept;
 
  IINK_API void scale(double s) noexcept;
 
  IINK_API void scale(double sx, double sy) noexcept;
 
  IINK_API void rotate(double a);
 
  IINK_API void rotate(double a, double x0, double y0);
 
  IINK_API void rotate(double cosA, double sinA);
 
  IINK_API void rotate(double cosA, double sinA, double x0, double y0);
 
  Point apply(float x, float y) const noexcept
  {
    return Point((float)(x * xx + y * yx + tx), (float)(x * xy + y * yy + ty));
  }
 
  void apply(Point& p) const noexcept
  {
    float x = (float)(p.x * xx + p.y * yx + tx);
    float y = (float)(p.x * xy + p.y * yy + ty);
    p.x = x;
    p.y = y;
  }
 
  void apply(Point* points, int count) const noexcept
  {
    apply(points, 0, count);
  }
 
  void apply(Point* points, int offset, int count) const noexcept
  {
    for (int i = 0; i < count; ++i)
      apply(points[offset + i]);
  }
 
  void apply(Rectangle& rect) const
  {
    if (yx != 0 || xy != 0 || xx <= 0 || yy <= 0)
    {
      throw std::runtime_error("only positive scales and translations are allowed on rectangles");
    }
    graphics::Point bottomRight(rect.x + rect.width, rect.y + rect.height);
    apply(bottomRight);
    graphics::Point topLeft = apply(rect.x, rect.y);
    rect.x = topLeft.x;
    rect.y = topLeft.y;
    rect.width = bottomRight.x - topLeft.x;
    rect.height = bottomRight.y - topLeft.y;
  }
 
  IINK_API static Transform getTransform(const Rectangle& fromRect, const Rectangle& toRect);
 
  friend std::ostream& operator<<(std::ostream& os, const Transform& tr);
 
  bool operator==(const Transform& other) const noexcept
  {
    return xx == other.xx && yx == other.yx && tx == other.tx && xy == other.xy && yy == other.yy && ty == other.ty;
  }
 
  bool operator!=(const Transform& other) const noexcept
  {
    return !this->operator==(other);
  }
};
 
inline
std::ostream& operator<<(std::ostream& os, const Transform& tr)
{
  os << "Transform([" << tr.xx << ", " << tr.yx << ", " << tr.tx << "], [" << tr.xy << ", " << tr.yy << ", " << tr.ty << "])";
  return os;
}
 
}
}
}