/src/freeimage-svn/FreeImage/trunk/Source/FreeImageToolkit/ClassicRotate.cpp

Source
// ==========================================================
// Bitmap rotation by means of 3 shears.
//
// Design and implementation by
// - Herv� Drolon (drolon@infonie.fr)
// - Thorsten Radde (support@IdealSoftware.com)
// - Mihail Naydenov (mnaydenov@users.sourceforge.net)
//
// This file is part of FreeImage 3
//
// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES
// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE
// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED
// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT
// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY
// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL
// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER
// THIS DISCLAIMER.
//
// Use at your own risk!
// ==========================================================

/* 
 ============================================================
 References : 
 [1] Paeth A., A Fast Algorithm for General Raster Rotation. 
 Graphics Gems, p. 179, Andrew Glassner editor, Academic Press, 1990. 
 [2] Yariv E., High quality image rotation (rotate by shear). 
 [Online] http://www.codeproject.com/bitmap/rotatebyshear.asp
 [3] Treskunov A., Fast and high quality true-color bitmap rotation function.
 [Online] http://anton.treskunov.net/Software/doc/fast_and_high_quality_true_color_bitmap_rotation_function.html
 ============================================================
*/

#include "FreeImage.h"
#include "Utilities.h"

#define RBLOCK    64  // image blocks of RBLOCK*RBLOCK pixels

// --------------------------------------------------------------------------

/**
Skews a row horizontally (with filtered weights). 
Limited to 45 degree skewing only. Filters two adjacent pixels.
Parameter T can be BYTE, WORD of float. 
@param src Pointer to source image to rotate
@param dst Pointer to destination image
@param row Row index
@param iOffset Skew offset
@param dWeight Relative weight of right pixel
@param bkcolor Background color
*/
template <class T> void 
HorizontalSkewT(FIBITMAP *src, FIBITMAP *dst, int row, int iOffset, double weight, const void *bkcolor = NULL) {
  int iXPos;

  const unsigned src_width  = FreeImage_GetWidth(src);
  const unsigned dst_width  = FreeImage_GetWidth(dst);

  T pxlSrc[4], pxlLeft[4], pxlOldLeft[4]; // 4 = 4*sizeof(T) max
  
  // background
  const T pxlBlack[4] = {0, 0, 0, 0 };
  const T *pxlBkg = static_cast<const T*>(bkcolor); // assume at least bytespp and 4*sizeof(T) max
  if(!pxlBkg) {
    // default background color is black
    pxlBkg = pxlBlack;
  }

  // calculate the number of bytes per pixel
  const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);
  // calculate the number of samples per pixel
  const unsigned samples = bytespp / sizeof(T);

  BYTE *src_bits = FreeImage_GetScanLine(src, row);
  BYTE *dst_bits = FreeImage_GetScanLine(dst, row);

  // fill gap left of skew with background
  if(bkcolor) {
    for(int k = 0; k < iOffset; k++) {
      memcpy(&dst_bits[k * bytespp], bkcolor, bytespp);
    }
    AssignPixel((BYTE*)&pxlOldLeft[0], (BYTE*)bkcolor, bytespp);
  } else {
    if(iOffset > 0) {
      memset(dst_bits, 0, iOffset * bytespp);
    }    
    memset(&pxlOldLeft[0], 0, bytespp);
  }

  for(unsigned i = 0; i < src_width; i++) {
    // loop through row pixels
    AssignPixel((BYTE*)&pxlSrc[0], (BYTE*)src_bits, bytespp);
    // calculate weights
    for(unsigned j = 0; j < samples; j++) {
      pxlLeft[j] = static_cast<T>(pxlBkg[j] + (pxlSrc[j] - pxlBkg[j]) * weight + 0.5);
    }
    // check boundaries 
    iXPos = i + iOffset;
    if((iXPos >= 0) && (iXPos < (int)dst_width)) {
      // update left over on source
      for(unsigned j = 0; j < samples; j++) {
        pxlSrc[j] = pxlSrc[j] - (pxlLeft[j] - pxlOldLeft[j]);
      }
      AssignPixel((BYTE*)&dst_bits[iXPos*bytespp], (BYTE*)&pxlSrc[0], bytespp);
    }
    // save leftover for next pixel in scan
    AssignPixel((BYTE*)&pxlOldLeft[0], (BYTE*)&pxlLeft[0], bytespp);

    // next pixel in scan
    src_bits += bytespp;
  }     

  // go to rightmost point of skew
  iXPos = src_width + iOffset; 

  if((iXPos >= 0) && (iXPos < (int)dst_width)) {
    dst_bits = FreeImage_GetScanLine(dst, row) + iXPos * bytespp;

    // If still in image bounds, put leftovers there
    AssignPixel((BYTE*)dst_bits, (BYTE*)&pxlOldLeft[0], bytespp);

    // clear to the right of the skewed line with background
    dst_bits += bytespp;
    if(bkcolor) {
      for(unsigned i = 0; i < dst_width - iXPos - 1; i++) {
        memcpy(&dst_bits[i * bytespp], bkcolor, bytespp);
      }
    } else {
      memset(dst_bits, 0, bytespp * (dst_width - iXPos - 1));
    }

  }
}

/**
Skews a row horizontally (with filtered weights). 
Limited to 45 degree skewing only. Filters two adjacent pixels.
@param src Pointer to source image to rotate
@param dst Pointer to destination image
@param row Row index
@param iOffset Skew offset
@param dWeight Relative weight of right pixel
@param bkcolor Background color
*/
static void 
HorizontalSkew(FIBITMAP *src, FIBITMAP *dst, int row, int iOffset, double dWeight, const void *bkcolor) {
  FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(src);

  switch(image_type) {
    case FIT_BITMAP:
      switch(FreeImage_GetBPP(src)) {
        case 8:
        case 24:
        case 32:
          HorizontalSkewT<BYTE>(src, dst, row, iOffset, dWeight, bkcolor);
        break;
      }
      break;
    case FIT_UINT16:
    case FIT_RGB16:
    case FIT_RGBA16:
      HorizontalSkewT<WORD>(src, dst, row, iOffset, dWeight, bkcolor);
      break;
    case FIT_FLOAT:
    case FIT_RGBF:
    case FIT_RGBAF:
      HorizontalSkewT<float>(src, dst, row, iOffset, dWeight, bkcolor);
      break;
  }
}

/**
Skews a column vertically (with filtered weights). 
Limited to 45 degree skewing only. Filters two adjacent pixels.
Parameter T can be BYTE, WORD of float. 
@param src Pointer to source image to rotate
@param dst Pointer to destination image
@param col Column index
@param iOffset Skew offset
@param dWeight Relative weight of upper pixel
@param bkcolor Background color
*/
template <class T> void 
VerticalSkewT(FIBITMAP *src, FIBITMAP *dst, int col, int iOffset, double weight, const void *bkcolor = NULL) {
  int iYPos;

  unsigned src_height = FreeImage_GetHeight(src);
  unsigned dst_height = FreeImage_GetHeight(dst);

  T pxlSrc[4], pxlLeft[4], pxlOldLeft[4]; // 4 = 4*sizeof(T) max

  // background
  const T pxlBlack[4] = {0, 0, 0, 0 };
  const T *pxlBkg = static_cast<const T*>(bkcolor); // assume at least bytespp and 4*sizeof(T) max
  if(!pxlBkg) {
    // default background color is black
    pxlBkg = pxlBlack;
  }

  // calculate the number of bytes per pixel
  const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);
  // calculate the number of samples per pixel
  const unsigned samples = bytespp / sizeof(T);

  const unsigned src_pitch = FreeImage_GetPitch(src);
  const unsigned dst_pitch = FreeImage_GetPitch(dst);
  const unsigned index = col * bytespp;

  BYTE *src_bits = FreeImage_GetBits(src) + index;
  BYTE *dst_bits = FreeImage_GetBits(dst) + index;

  // fill gap above skew with background
  if(bkcolor) {
    for(int k = 0; k < iOffset; k++) {
      memcpy(dst_bits, bkcolor, bytespp);
      dst_bits += dst_pitch;
    }
    memcpy(&pxlOldLeft[0], bkcolor, bytespp);
  } else {
    for(int k = 0; k < iOffset; k++) {
      memset(dst_bits, 0, bytespp);
      dst_bits += dst_pitch;
    }
    memset(&pxlOldLeft[0], 0, bytespp);
  }

  for(unsigned i = 0; i < src_height; i++) {
    // loop through column pixels
    AssignPixel((BYTE*)(&pxlSrc[0]), src_bits, bytespp);
    // calculate weights
    for(unsigned j = 0; j < samples; j++) {
      pxlLeft[j] = static_cast<T>(pxlBkg[j] + (pxlSrc[j] - pxlBkg[j]) * weight + 0.5);
    }
    // check boundaries
    iYPos = i + iOffset;
    if((iYPos >= 0) && (iYPos < (int)dst_height)) {
      // update left over on source
      for(unsigned j = 0; j < samples; j++) {
        pxlSrc[j] = pxlSrc[j] - (pxlLeft[j] - pxlOldLeft[j]);
      }
      dst_bits = FreeImage_GetScanLine(dst, iYPos) + index;
      AssignPixel(dst_bits, (BYTE*)(&pxlSrc[0]), bytespp);
    }
    // save leftover for next pixel in scan
    AssignPixel((BYTE*)(&pxlOldLeft[0]), (BYTE*)(&pxlLeft[0]), bytespp);

    // next pixel in scan
    src_bits += src_pitch;
  }
  // go to bottom point of skew
  iYPos = src_height + iOffset;

  if((iYPos >= 0) && (iYPos < (int)dst_height)) {
    dst_bits = FreeImage_GetScanLine(dst, iYPos) + index;

    // if still in image bounds, put leftovers there        
    AssignPixel((BYTE*)(dst_bits), (BYTE*)(&pxlOldLeft[0]), bytespp);

    // clear below skewed line with background
    if(bkcolor) {
      while(++iYPos < (int)dst_height) {         
        dst_bits += dst_pitch;
        AssignPixel((BYTE*)(dst_bits), (BYTE*)(bkcolor), bytespp);
      }
    } else {
      while(++iYPos < (int)dst_height) {         
        dst_bits += dst_pitch;
        memset(dst_bits, 0, bytespp);
      }
    }
  }
}

/**
Skews a column vertically (with filtered weights). 
Limited to 45 degree skewing only. Filters two adjacent pixels.
@param src Pointer to source image to rotate
@param dst Pointer to destination image
@param col Column index
@param iOffset Skew offset
@param dWeight Relative weight of upper pixel
@param bkcolor Background color
*/
static void 
VerticalSkew(FIBITMAP *src, FIBITMAP *dst, int col, int iOffset, double dWeight, const void *bkcolor) {
  FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(src);

  switch(image_type) {
    case FIT_BITMAP:
      switch(FreeImage_GetBPP(src)) {
        case 8:
        case 24:
        case 32:
          VerticalSkewT<BYTE>(src, dst, col, iOffset, dWeight, bkcolor);
          break;
      }
      break;
      case FIT_UINT16:
      case FIT_RGB16:
      case FIT_RGBA16:
        VerticalSkewT<WORD>(src, dst, col, iOffset, dWeight, bkcolor);
        break;
      case FIT_FLOAT:
      case FIT_RGBF:
      case FIT_RGBAF:
        VerticalSkewT<float>(src, dst, col, iOffset, dWeight, bkcolor);
        break;
  }
} 

/**
Rotates an image by 90 degrees (counter clockwise). 
Precise rotation, no filters required.<br>
Code adapted from CxImage (http://www.xdp.it/cximage.htm)
@param src Pointer to source image to rotate
@return Returns a pointer to a newly allocated rotated image if successful, returns NULL otherwise
*/
static FIBITMAP* 
Rotate90(FIBITMAP *src) {

  const unsigned bpp = FreeImage_GetBPP(src);

  const unsigned src_width  = FreeImage_GetWidth(src);
  const unsigned src_height = FreeImage_GetHeight(src); 
  const unsigned dst_width  = src_height;
  const unsigned dst_height = src_width;

  FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(src);

  // allocate and clear dst image
  FIBITMAP *dst = FreeImage_AllocateT(image_type, dst_width, dst_height, bpp);
  if(NULL == dst) return NULL;

  // get src and dst scan width
  const unsigned src_pitch  = FreeImage_GetPitch(src);
  const unsigned dst_pitch  = FreeImage_GetPitch(dst);

  switch(image_type) {
    case FIT_BITMAP:
      if(bpp == 1) {
        // speedy rotate for BW images

        BYTE *bsrc  = FreeImage_GetBits(src); 
        BYTE *bdest = FreeImage_GetBits(dst);

        BYTE *dbitsmax = bdest + dst_height * dst_pitch - 1;

        for(unsigned y = 0; y < src_height; y++) {
          // figure out the column we are going to be copying to
          const div_t div_r = div(y, 8);
          // set bit pos of src column byte
          const BYTE bitpos = (BYTE)(128 >> div_r.rem);
          BYTE *srcdisp = bsrc + y * src_pitch;
          for(unsigned x = 0; x < src_pitch; x++) {
            // get source bits
            BYTE *sbits = srcdisp + x;
            // get destination column
            BYTE *nrow = bdest + (dst_height - 1 - (x * 8)) * dst_pitch + div_r.quot;
            for (int z = 0; z < 8; z++) {
               // get destination byte
              BYTE *dbits = nrow - z * dst_pitch;
              if ((dbits < bdest) || (dbits > dbitsmax)) break;
              if (*sbits & (128 >> z)) *dbits |= bitpos;
            }
          }
        }
      }
      else if((bpp == 8) || (bpp == 24) || (bpp == 32)) {
        // anything other than BW :
        // This optimized version of rotation rotates image by smaller blocks. It is quite
        // a bit faster than obvious algorithm, because it produces much less CPU cache misses.
        // This optimization can be tuned by changing block size (RBLOCK). 96 is good value for current
        // CPUs (tested on Athlon XP and Celeron D). Larger value (if CPU has enough cache) will increase
        // speed somehow, but once you drop out of CPU's cache, things will slow down drastically.
        // For older CPUs with less cache, lower value would yield better results.

        BYTE *bsrc  = FreeImage_GetBits(src);  // source pixels
        BYTE *bdest = FreeImage_GetBits(dst);  // destination pixels

        // calculate the number of bytes per pixel (1 for 8-bit, 3 for 24-bit or 4 for 32-bit)
        const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);
        
        // for all image blocks of RBLOCK*RBLOCK pixels
        
        // x-segment
        for(unsigned xs = 0; xs < dst_width; xs += RBLOCK) {
          // y-segment
          for(unsigned ys = 0; ys < dst_height; ys += RBLOCK) {
            for(unsigned y = ys; y < MIN(dst_height, ys + RBLOCK); y++) {    // do rotation
              const unsigned y2 = dst_height - y - 1;
              // point to src pixel at (y2, xs)
              BYTE *src_bits = bsrc + (xs * src_pitch) + (y2 * bytespp);
              // point to dst pixel at (xs, y)
              BYTE *dst_bits = bdest + (y * dst_pitch) + (xs * bytespp);
              for(unsigned x = xs; x < MIN(dst_width, xs + RBLOCK); x++) {
                // dst.SetPixel(x, y, src.GetPixel(y2, x));
                AssignPixel(dst_bits, src_bits, bytespp);
                dst_bits += bytespp;
                src_bits += src_pitch;
              }
            }
          }
        }
      }
      break;
    case FIT_UINT16:
    case FIT_RGB16:
    case FIT_RGBA16:
    case FIT_FLOAT:
    case FIT_RGBF:
    case FIT_RGBAF:
    {
      BYTE *bsrc  = FreeImage_GetBits(src);  // source pixels
      BYTE *bdest = FreeImage_GetBits(dst);  // destination pixels

      // calculate the number of bytes per pixel
      const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);

      for(unsigned y = 0; y < dst_height; y++) {
        BYTE *src_bits = bsrc + (src_width - 1 - y) * bytespp;
        BYTE *dst_bits = bdest + (y * dst_pitch);
        for(unsigned x = 0; x < dst_width; x++) {
          AssignPixel(dst_bits, src_bits, bytespp);
          src_bits += src_pitch;
          dst_bits += bytespp;
        }
      }
    }
    break;
  }

  return dst;
}

/**
Rotates an image by 180 degrees (counter clockwise). 
Precise rotation, no filters required.
@param src Pointer to source image to rotate
@return Returns a pointer to a newly allocated rotated image if successful, returns NULL otherwise
*/
static FIBITMAP* 
Rotate180(FIBITMAP *src) {
  int x, y, k, pos;

  const int bpp = FreeImage_GetBPP(src);

  const int src_width  = FreeImage_GetWidth(src);
  const int src_height = FreeImage_GetHeight(src);
  const int dst_width  = src_width;
  const int dst_height = src_height;

  FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(src);

  FIBITMAP *dst = FreeImage_AllocateT(image_type, dst_width, dst_height, bpp);
  if(NULL == dst) return NULL;

  switch(image_type) {
    case FIT_BITMAP:
      if(bpp == 1) {
        for(int y = 0; y < src_height; y++) {
          BYTE *src_bits = FreeImage_GetScanLine(src, y);
          BYTE *dst_bits = FreeImage_GetScanLine(dst, dst_height - y - 1);
          for(int x = 0; x < src_width; x++) {
            // get bit at (x, y)
            k = (src_bits[x >> 3] & (0x80 >> (x & 0x07))) != 0;
            // set bit at (dst_width - x - 1, dst_height - y - 1)
            pos = dst_width - x - 1;
            k ? dst_bits[pos >> 3] |= (0x80 >> (pos & 0x7)) : dst_bits[pos >> 3] &= (0xFF7F >> (pos & 0x7));
          }     
        }
        break;
      }
      // else if((bpp == 8) || (bpp == 24) || (bpp == 32)) FALL TROUGH
    case FIT_UINT16:
    case FIT_RGB16:
    case FIT_RGBA16:
    case FIT_FLOAT:
    case FIT_RGBF:
    case FIT_RGBAF:
    {
       // Calculate the number of bytes per pixel
      const int bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);

      for(y = 0; y < src_height; y++) {
        BYTE *src_bits = FreeImage_GetScanLine(src, y);
        BYTE *dst_bits = FreeImage_GetScanLine(dst, dst_height - y - 1) + (dst_width - 1) * bytespp;
        for(x = 0; x < src_width; x++) {
          // get pixel at (x, y)
          // set pixel at (dst_width - x - 1, dst_height - y - 1)
          AssignPixel(dst_bits, src_bits, bytespp);
          src_bits += bytespp;
          dst_bits -= bytespp;          
        }       
      }
    }
    break;
  }

  return dst;
}

/**
Rotates an image by 270 degrees (counter clockwise). 
Precise rotation, no filters required.<br>
Code adapted from CxImage (http://www.xdp.it/cximage.htm)
@param src Pointer to source image to rotate
@return Returns a pointer to a newly allocated rotated image if successful, returns NULL otherwise
*/
static FIBITMAP* 
Rotate270(FIBITMAP *src) {
  int x2, dlineup;

  const unsigned bpp = FreeImage_GetBPP(src);

  const unsigned src_width  = FreeImage_GetWidth(src);
  const unsigned src_height = FreeImage_GetHeight(src); 
  const unsigned dst_width  = src_height;
  const unsigned dst_height = src_width;

  FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(src);

  // allocate and clear dst image
  FIBITMAP *dst = FreeImage_AllocateT(image_type, dst_width, dst_height, bpp);
  if(NULL == dst) return NULL;

  // get src and dst scan width
  const unsigned src_pitch  = FreeImage_GetPitch(src);
  const unsigned dst_pitch  = FreeImage_GetPitch(dst);
  
  switch(image_type) {
    case FIT_BITMAP:
      if(bpp == 1) {
        // speedy rotate for BW images
        
        BYTE *bsrc  = FreeImage_GetBits(src); 
        BYTE *bdest = FreeImage_GetBits(dst);
        BYTE *dbitsmax = bdest + dst_height * dst_pitch - 1;
        dlineup = 8 * dst_pitch - dst_width;

        for(unsigned y = 0; y < src_height; y++) {
          // figure out the column we are going to be copying to
          const div_t div_r = div(y + dlineup, 8);
          // set bit pos of src column byte
          const BYTE bitpos = (BYTE)(1 << div_r.rem);
          const BYTE *srcdisp = bsrc + y * src_pitch;
          for(unsigned x = 0; x < src_pitch; x++) {
            // get source bits
            const BYTE *sbits = srcdisp + x;
            // get destination column
            BYTE *nrow = bdest + (x * 8) * dst_pitch + dst_pitch - 1 - div_r.quot;
            for(unsigned z = 0; z < 8; z++) {
               // get destination byte
              BYTE *dbits = nrow + z * dst_pitch;
              if ((dbits < bdest) || (dbits > dbitsmax)) break;
              if (*sbits & (128 >> z)) *dbits |= bitpos;
            }
          }
        }
      } 
      else if((bpp == 8) || (bpp == 24) || (bpp == 32)) {
        // anything other than BW :
        // This optimized version of rotation rotates image by smaller blocks. It is quite
        // a bit faster than obvious algorithm, because it produces much less CPU cache misses.
        // This optimization can be tuned by changing block size (RBLOCK). 96 is good value for current
        // CPUs (tested on Athlon XP and Celeron D). Larger value (if CPU has enough cache) will increase
        // speed somehow, but once you drop out of CPU's cache, things will slow down drastically.
        // For older CPUs with less cache, lower value would yield better results.

        BYTE *bsrc  = FreeImage_GetBits(src);  // source pixels
        BYTE *bdest = FreeImage_GetBits(dst);  // destination pixels

        // Calculate the number of bytes per pixel (1 for 8-bit, 3 for 24-bit or 4 for 32-bit)
        const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);

        // for all image blocks of RBLOCK*RBLOCK pixels

        // x-segment
        for(unsigned xs = 0; xs < dst_width; xs += RBLOCK) {
          // y-segment
          for(unsigned ys = 0; ys < dst_height; ys += RBLOCK) {
            for(unsigned x = xs; x < MIN(dst_width, xs + RBLOCK); x++) {    // do rotation
              x2 = dst_width - x - 1;
              // point to src pixel at (ys, x2)
              BYTE *src_bits = bsrc + (x2 * src_pitch) + (ys * bytespp);
              // point to dst pixel at (x, ys)
              BYTE *dst_bits = bdest + (ys * dst_pitch) + (x * bytespp);
              for(unsigned y = ys; y < MIN(dst_height, ys + RBLOCK); y++) {
                // dst.SetPixel(x, y, src.GetPixel(y, x2));
                AssignPixel(dst_bits, src_bits, bytespp);
                src_bits += bytespp;
                dst_bits += dst_pitch;
              }
            }
          }
        }
      }
      break;
    case FIT_UINT16:
    case FIT_RGB16:
    case FIT_RGBA16:
    case FIT_FLOAT:
    case FIT_RGBF:
    case FIT_RGBAF:
    {
      BYTE *bsrc  = FreeImage_GetBits(src);  // source pixels
      BYTE *bdest = FreeImage_GetBits(dst);  // destination pixels

      // calculate the number of bytes per pixel
      const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);

      for(unsigned y = 0; y < dst_height; y++) {
        BYTE *src_bits = bsrc + (src_height - 1) * src_pitch + y * bytespp;
        BYTE *dst_bits = bdest + (y * dst_pitch);
        for(unsigned x = 0; x < dst_width; x++) {
          AssignPixel(dst_bits, src_bits, bytespp);
          src_bits -= src_pitch;
          dst_bits += bytespp;
        }
      }
    }
    break;
  }

  return dst;
}

/**
Rotates an image by a given degree in range [-45 .. +45] (counter clockwise) 
using the 3-shear technique.
@param src Pointer to source image to rotate
@param dAngle Rotation angle
@return Returns a pointer to a newly allocated rotated image if successful, returns NULL otherwise
*/
static FIBITMAP* 
Rotate45(FIBITMAP *src, double dAngle, const void *bkcolor) {
  const double ROTATE_PI = double(3.1415926535897932384626433832795);

  unsigned u;

  const unsigned bpp = FreeImage_GetBPP(src);

  const double dRadAngle = dAngle * ROTATE_PI / double(180); // Angle in radians
  const double dSinE = sin(dRadAngle);
  const double dTan = tan(dRadAngle / 2);

  const unsigned src_width  = FreeImage_GetWidth(src);
  const unsigned src_height = FreeImage_GetHeight(src);

  FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(src);

  // Calc first shear (horizontal) destination image dimensions 
  const unsigned width_1  = src_width + unsigned((double)src_height * fabs(dTan) + 0.5);
  const unsigned height_1 = src_height; 

  // Perform 1st shear (horizontal)
  // ----------------------------------------------------------------------

  // Allocate image for 1st shear
  FIBITMAP *dst1 = FreeImage_AllocateT(image_type, width_1, height_1, bpp);
  if(NULL == dst1) {
    return NULL;
  }
  
  for(u = 0; u < height_1; u++) {  
    double dShear;

    if(dTan >= 0) {
      // Positive angle
      dShear = (u + 0.5) * dTan;
    }
    else {
      // Negative angle
      dShear = (double(u) - height_1 + 0.5) * dTan;
    }
    int iShear = int(floor(dShear));
    HorizontalSkew(src, dst1, u, iShear, dShear - double(iShear), bkcolor);
  }

  // Perform 2nd shear  (vertical)
  // ----------------------------------------------------------------------

  // Calc 2nd shear (vertical) destination image dimensions
  const unsigned width_2  = width_1;
  unsigned height_2 = unsigned((double)src_width * fabs(dSinE) + (double)src_height * cos(dRadAngle) + 0.5) + 1;

  // Allocate image for 2nd shear
  FIBITMAP *dst2 = FreeImage_AllocateT(image_type, width_2, height_2, bpp);
  if(NULL == dst2) {
    FreeImage_Unload(dst1);
    return NULL;
  }

  double dOffset;     // Variable skew offset
  if(dSinE > 0) {   
    // Positive angle
    dOffset = (src_width - 1.0) * dSinE;
  }
  else {
    // Negative angle
    dOffset = -dSinE * (double(src_width) - width_2);
  }

  for(u = 0; u < width_2; u++, dOffset -= dSinE) {
    int iShear = int(floor(dOffset));
    VerticalSkew(dst1, dst2, u, iShear, dOffset - double(iShear), bkcolor);
  }

  // Perform 3rd shear (horizontal)
  // ----------------------------------------------------------------------

  // Free result of 1st shear
  FreeImage_Unload(dst1);

  // Calc 3rd shear (horizontal) destination image dimensions
  const unsigned width_3  = unsigned(double(src_height) * fabs(dSinE) + double(src_width) * cos(dRadAngle) + 0.5) + 1;
  const unsigned height_3 = height_2;

  // Allocate image for 3rd shear
  FIBITMAP *dst3 = FreeImage_AllocateT(image_type, width_3, height_3, bpp);
  if(NULL == dst3) {
    FreeImage_Unload(dst2);
    return NULL;
  }

  if(dSinE >= 0) {
    // Positive angle
    dOffset = (src_width - 1.0) * dSinE * -dTan;
  }
  else {
    // Negative angle
    dOffset = dTan * ( (src_width - 1.0) * -dSinE + (1.0 - height_3) );
  }
  for(u = 0; u < height_3; u++, dOffset += dTan) {
    int iShear = int(floor(dOffset));
    HorizontalSkew(dst2, dst3, u, iShear, dOffset - double(iShear), bkcolor);
  }
  // Free result of 2nd shear    
  FreeImage_Unload(dst2);

  // Return result of 3rd shear
  return dst3;      
}

/**
Rotates a 1-, 8-, 24- or 32-bit image by a given angle (given in degree). 
Angle is unlimited, except for 1-bit images (limited to integer multiples of 90 degree). 
3-shears technique is used.
@param src Pointer to source image to rotate
@param dAngle Rotation angle
@return Returns a pointer to a newly allocated rotated image if successful, returns NULL otherwise
*/
static FIBITMAP* 
RotateAny(FIBITMAP *src, double dAngle, const void *bkcolor) {
  if(NULL == src) {
    return NULL;
  }

  FIBITMAP *image = src;

  while(dAngle >= 360) {
    // Bring angle to range of (-INF .. 360)
    dAngle -= 360;
  }
  while(dAngle < 0) {
    // Bring angle to range of [0 .. 360) 
    dAngle += 360;
  }
  if((dAngle > 45) && (dAngle <= 135)) {
    // Angle in (45 .. 135] 
    // Rotate image by 90 degrees into temporary image,
    // so it requires only an extra rotation angle 
    // of -45 .. +45 to complete rotation.
    image = Rotate90(src);
    dAngle -= 90;
  }
  else if((dAngle > 135) && (dAngle <= 225)) { 
    // Angle in (135 .. 225] 
    // Rotate image by 180 degrees into temporary image,
    // so it requires only an extra rotation angle 
    // of -45 .. +45 to complete rotation.
    image = Rotate180(src);
    dAngle -= 180;
  }
  else if((dAngle > 225) && (dAngle <= 315)) { 
    // Angle in (225 .. 315] 
    // Rotate image by 270 degrees into temporary image,
    // so it requires only an extra rotation angle 
    // of -45 .. +45 to complete rotation.
    image = Rotate270(src);
    dAngle -= 270;
  }

  // If we got here, angle is in (-45 .. +45]

  if(NULL == image) {
    // Failed to allocate middle image
    return NULL;
  }

  if(0 == dAngle) {
    if(image == src) {
      // Nothing to do ...
      return FreeImage_Clone(src);
    } else {
      // No more rotation needed
      return image;
    }
  }
  else {
    // Perform last rotation
    FIBITMAP *dst = Rotate45(image, dAngle, bkcolor);

    if(src != image) {
      // Middle image was required, free it now.
      FreeImage_Unload(image);
    }

    return dst;
  }
}

// ==========================================================

FIBITMAP *DLL_CALLCONV 
FreeImage_Rotate(FIBITMAP *dib, double angle, const void *bkcolor) {
  if(!FreeImage_HasPixels(dib)) return NULL;

  if(0 == angle) {
    return FreeImage_Clone(dib);
  }
  // DIB are stored upside down ...
  angle *= -1;

  try {
    unsigned bpp = FreeImage_GetBPP(dib);
    FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(dib);
    
    switch(image_type) {
      case FIT_BITMAP:
        if(bpp == 1) {
          // only rotate for integer multiples of 90 degree
          if(fmod(angle, 90) != 0)
            return NULL;

          // perform the rotation
          FIBITMAP *dst = RotateAny(dib, angle, bkcolor);
          if(!dst) throw(1);

          // build a greyscale palette
          RGBQUAD *dst_pal = FreeImage_GetPalette(dst);
          if(FreeImage_GetColorType(dib) == FIC_MINISBLACK) {
            dst_pal[0].rgbRed = dst_pal[0].rgbGreen = dst_pal[0].rgbBlue = 0;
            dst_pal[1].rgbRed = dst_pal[1].rgbGreen = dst_pal[1].rgbBlue = 255;     
          } else {
            dst_pal[0].rgbRed = dst_pal[0].rgbGreen = dst_pal[0].rgbBlue = 255;
            dst_pal[1].rgbRed = dst_pal[1].rgbGreen = dst_pal[1].rgbBlue = 0;     
          }

          // copy metadata from src to dst
          FreeImage_CloneMetadata(dst, dib);

          return dst;
        }
        else if((bpp == 8) || (bpp == 24) || (bpp == 32)) {
          FIBITMAP *dst = RotateAny(dib, angle, bkcolor);
          if(!dst) throw(1);
          
          if(bpp == 8) {
            // copy original palette to rotated bitmap
            RGBQUAD *src_pal = FreeImage_GetPalette(dib);
            RGBQUAD *dst_pal = FreeImage_GetPalette(dst);
            memcpy(&dst_pal[0], &src_pal[0], 256 * sizeof(RGBQUAD));

            // copy transparency table 
            FreeImage_SetTransparencyTable(dst, FreeImage_GetTransparencyTable(dib), FreeImage_GetTransparencyCount(dib));

            // copy background color 
            RGBQUAD bkcolor; 
            if( FreeImage_GetBackgroundColor(dib, &bkcolor) ) {
              FreeImage_SetBackgroundColor(dst, &bkcolor); 
            }

          }

          // copy metadata from src to dst
          FreeImage_CloneMetadata(dst, dib);

          return dst;
        }
        break;
      case FIT_UINT16:
      case FIT_RGB16:
      case FIT_RGBA16:
      case FIT_FLOAT:
      case FIT_RGBF:
      case FIT_RGBAF:
      {
        FIBITMAP *dst = RotateAny(dib, angle, bkcolor);
        if(!dst) throw(1);

        // copy metadata from src to dst
        FreeImage_CloneMetadata(dst, dib);

        return dst;
      }
      break;
    }

  } catch(int) {
    return NULL;
  }

  return NULL;
}


Coverage Report

Created: 2025-10-28 06:24