image_drawing.h

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// Copyright (c) 2009 libmv authors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
 
// Generic Image Processing Algorithm (GIPA)
// Use an ImageModel class that must implement the following :
//
// ::Contains(int y, int x) <= Tell if a point is inside or not the image
// ::operator(int y,int x)  <= Modification accessor over the pixel (y,x)
// ::Width()
// ::Height()
 
#ifndef LIBMV_IMAGE_IMAGE_DRAWING_H
#define LIBMV_IMAGE_IMAGE_DRAWING_H
 
namespace libmv {

template <class Image, class Color>
inline void safePutPixel(int yc, int xc, const Color& col, Image* pim) {
  if (!pim) {
    return;
  }
  if (pim->Contains(yc, xc)) {
    (*pim)(yc, xc) = col;
  }
}

template <class Image, class Color>
inline void safePutPixel(int yc, int xc, const Color* col, Image* pim) {
  if (!pim) {
    return;
  }
  if (pim->Contains(yc, xc)) {
    for (int i = 0; i < pim->Depth(); ++i) {
      (*pim)(yc, xc, i) = *(col + i);
    }
  }
}
 
// Bresenham approach to draw ellipse.
// http://raphaello.univ-fcomte.fr/ig/algorithme/ExemplesGLUt/BresenhamEllipse.htm
// Add the rotation of the ellipse.
// As the algo. use symmetry we must use 4 rotations.
template <class Image, class Color>
void DrawEllipse(int xc,
                 int yc,
                 int radiusA,
                 int radiusB,
                 const Color& col,
                 Image* pim,
                 double angle = 0.0) {
  int a = radiusA;
  int b = radiusB;
 
  // Counter Clockwise rotation matrix.
  double matXY[4] = {cos(angle), sin(angle), -sin(angle), cos(angle)};
  int x, y;
  double d1, d2;
  x = 0;
  y = b;
  d1 = b * b - a * a * b + a * a / 4;
 
  float rotX = (matXY[0] * x + matXY[1] * y);
  float rotY = (matXY[2] * x + matXY[3] * y);
  safePutPixel(yc + rotY, xc + rotX, col, pim);
  rotX = (matXY[0] * x - matXY[1] * y);
  rotY = (matXY[2] * x - matXY[3] * y);
  safePutPixel(yc + rotY, xc + rotX, col, pim);
  rotX = (-matXY[0] * x - matXY[1] * y);
  rotY = (-matXY[2] * x - matXY[3] * y);
  safePutPixel(yc + rotY, xc + rotX, col, pim);
  rotX = (-matXY[0] * x + matXY[1] * y);
  rotY = (-matXY[2] * x + matXY[3] * y);
  safePutPixel(yc + rotY, xc + rotX, col, pim);
 
  while (a * a * (y - .5) > b * b * (x + 1)) {
    if (d1 < 0) {
      d1 += b * b * (2 * x + 3);
      ++x;
    } else {
      d1 += b * b * (2 * x + 3) + a * a * (-2 * y + 2);
      ++x;
      --y;
    }
    rotX = (matXY[0] * x + matXY[1] * y);
    rotY = (matXY[2] * x + matXY[3] * y);
    safePutPixel(yc + rotY, xc + rotX, col, pim);
    rotX = (matXY[0] * x - matXY[1] * y);
    rotY = (matXY[2] * x - matXY[3] * y);
    safePutPixel(yc + rotY, xc + rotX, col, pim);
    rotX = (-matXY[0] * x - matXY[1] * y);
    rotY = (-matXY[2] * x - matXY[3] * y);
    safePutPixel(yc + rotY, xc + rotX, col, pim);
    rotX = (-matXY[0] * x + matXY[1] * y);
    rotY = (-matXY[2] * x + matXY[3] * y);
    safePutPixel(yc + rotY, xc + rotX, col, pim);
  }
  d2 = b * b * (x + .5) * (x + .5) + a * a * (y - 1) * (y - 1) - a * a * b * b;
  while (y > 0) {
    if (d2 < 0) {
      d2 += b * b * (2 * x + 2) + a * a * (-2 * y + 3);
      --y;
      ++x;
    } else {
      d2 += a * a * (-2 * y + 3);
      --y;
    }
    rotX = (matXY[0] * x + matXY[1] * y);
    rotY = (matXY[2] * x + matXY[3] * y);
    safePutPixel(yc + rotY, xc + rotX, col, pim);
    rotX = (matXY[0] * x - matXY[1] * y);
    rotY = (matXY[2] * x - matXY[3] * y);
    safePutPixel(yc + rotY, xc + rotX, col, pim);
    rotX = (-matXY[0] * x - matXY[1] * y);
    rotY = (-matXY[2] * x - matXY[3] * y);
    safePutPixel(yc + rotY, xc + rotX, col, pim);
    rotX = (-matXY[0] * x + matXY[1] * y);
    rotY = (-matXY[2] * x + matXY[3] * y);
    safePutPixel(yc + rotY, xc + rotX, col, pim);
  }
}
 
// Bresenham approach do not allow to draw concentric circle without holes.
// So it's better the use the Andres method.
// http://fr.wikipedia.org/wiki/Algorithme_de_tracé_de_cercle_d'Andres.
template <class Image, class Color>
void DrawCircle(int x, int y, int radius, const Color& col, Image* pim) {
  Image& im = *pim;
  if (im.Contains(y + radius, x + radius) ||
      im.Contains(y + radius, x - radius) ||
      im.Contains(y - radius, x + radius) ||
      im.Contains(y - radius, x - radius)) {
    int x1 = 0;
    int y1 = radius;
    int d = radius - 1;
    while (y1 >= x1) {
      // Draw the point for each octant.
      safePutPixel(y1 + y, x1 + x, col, pim);
      safePutPixel(x1 + y, y1 + x, col, pim);
      safePutPixel(y1 + y, -x1 + x, col, pim);
      safePutPixel(x1 + y, -y1 + x, col, pim);
      safePutPixel(-y1 + y, x1 + x, col, pim);
      safePutPixel(-x1 + y, y1 + x, col, pim);
      safePutPixel(-y1 + y, -x1 + x, col, pim);
      safePutPixel(-x1 + y, -y1 + x, col, pim);
      if (d >= 2 * x1) {
        d = d - 2 * x1 - 1;
        x1 += 1;
      } else {
        if (d <= 2 * (radius - y1)) {
          d = d + 2 * y1 - 1;
          y1 -= 1;
        } else {
          d = d + 2 * (y1 - x1 - 1);
          y1 -= 1;
          x1 += 1;
        }
      }
    }
  }
}
 
// Bresenham algorithm
template <class Image, class Color>
void DrawLine(int xa, int ya, int xb, int yb, const Color& col, Image* pim) {
  Image& im = *pim;
 
  // If one point is outside the image
  // Replace the outside point by the intersection of the line and
  // the limit (either x=width or y=height).
  if (!im.Contains(ya, xa) || !im.Contains(yb, xb)) {
    int width = pim->Width();
    int height = pim->Height();
    const bool xdir = xa < xb, ydir = ya < yb;
    float nx0 = xa, nx1 = xb, ny0 = ya, ny1 = yb, &xleft = xdir ? nx0 : nx1,
          &yleft = xdir ? ny0 : ny1, &xright = xdir ? nx1 : nx0,
          &yright = xdir ? ny1 : ny0, &xup = ydir ? nx0 : nx1,
          &yup = ydir ? ny0 : ny1, &xdown = ydir ? nx1 : nx0,
          &ydown = ydir ? ny1 : ny0;
 
    if (xright < 0 || xleft >= width) {
      return;
    }
    if (xleft < 0) {
      yleft -= xleft * (yright - yleft) / (xright - xleft);
      xleft = 0;
    }
    if (xright >= width) {
      yright -= (xright - width) * (yright - yleft) / (xright - xleft);
      xright = width - 1;
    }
    if (ydown < 0 || yup >= height) {
      return;
    }
    if (yup < 0) {
      xup -= yup * (xdown - xup) / (ydown - yup);
      yup = 0;
    }
    if (ydown >= height) {
      xdown -= (ydown - height) * (xdown - xup) / (ydown - yup);
      ydown = height - 1;
    }
 
    xa = (int)xleft;
    xb = (int)xright;
    ya = (int)yleft;
    yb = (int)yright;
  }
 
  int xbas, xhaut, ybas, yhaut;
  // Check the condition ybas < yhaut.
  if (ya <= yb) {
    xbas = xa;
    ybas = ya;
    xhaut = xb;
    yhaut = yb;
  } else {
    xbas = xb;
    ybas = yb;
    xhaut = xa;
    yhaut = ya;
  }
  // Initialize slope.
  int x, y, dx, dy, incrmX, incrmY, dp, N, S;
  dx = xhaut - xbas;
  dy = yhaut - ybas;
  if (dx > 0) {  // If xhaut > xbas we will increment X.
    incrmX = 1;
  } else {
    incrmX = -1;  // else we will decrement X.
    dx *= -1;
  }
  if (dy > 0) {  // Positive slope will increment X.
    incrmY = 1;
  } else {  // Negative slope.
    incrmY = -1;
  }
  if (dx >= dy) {
    dp = 2 * dy - dx;
    S = 2 * dy;
    N = 2 * (dy - dx);
    y = ybas;
    x = xbas;
    while (x != xhaut) {
      safePutPixel(y, x, col, pim);
      x += incrmX;
      if (dp <= 0) {  // Go in direction of the South Pixel.
        dp += S;
      } else {  // Go to the North.
        dp += N;
        y += incrmY;
      }
    }
  } else {
    dp = 2 * dx - dy;
    S = 2 * dx;
    N = 2 * (dx - dy);
    x = xbas;
    y = ybas;
    while (y < yhaut) {
      safePutPixel(y, x, col, pim);
      y += incrmY;
      if (dp <= 0) {  // Go in direction of the South Pixel.
        dp += S;
      } else {  // Go to the North.
        dp += N;
        x += incrmX;
      }
    }
  }
  safePutPixel(y, x, col, pim);
}
 
}  // namespace libmv
 
#endif  // LIBMV_IMAGE_IMAGE_DRAWING_H