ximaint.cpp

用Cximage 库显示各种格式图片小程序

// xImaInt.cpp : interpolation functions
/* 02/2004 - Branko Brevensek 
 * CxImage version 6.0.0 02/Feb/2008 - Davide Pizzolato - www.xdp.it
 */

#include "ximage.h"
#include "ximath.h"

#if CXIMAGE_SUPPORT_INTERPOLATION

////////////////////////////////////////////////////////////////////////////////
/**
 * Recalculates coordinates according to specified overflow method.
 * If pixel (x,y) lies within image, nothing changes.
 *
 *  \param x, y - coordinates of pixel
 *  \param ofMethod - overflow method
 * 
 *  \return x, y - new coordinates (pixel (x,y) now lies inside image)
 *
 *  \author ***bd*** 2.2004
 */
void CxImage::OverflowCoordinates(long &x, long &y, OverflowMethod const ofMethod)
{
  if (IsInside(x,y)) return;  //if pixel is within bounds, no change
  switch (ofMethod) {
    case OM_REPEAT:
      //clip coordinates
      x=max(x,0); x=min(x, head.biWidth-1);
      y=max(y,0); y=min(y, head.biHeight-1);
      break;
    case OM_WRAP:
      //wrap coordinates
      x = x % head.biWidth;
      y = y % head.biHeight;
      if (x<0) x = head.biWidth + x;
      if (y<0) y = head.biHeight + y;
      break;
    case OM_MIRROR:
      //mirror pixels near border
      if (x<0) x=((-x) % head.biWidth);
      else if (x>=head.biWidth) x=head.biWidth-(x % head.biWidth + 1);
      if (y<0) y=((-y) % head.biHeight);
      else if (y>=head.biHeight) y=head.biHeight-(y % head.biHeight + 1);
      break;
    default:
      return;
  }//switch
}

////////////////////////////////////////////////////////////////////////////////
/**
 * See OverflowCoordinates for integer version 
 * \author ***bd*** 2.2004
 */
void CxImage::OverflowCoordinates(float &x, float &y, OverflowMethod const ofMethod)
{
  if (x>=0 && x<head.biWidth && y>=0 && y<head.biHeight) return;  //if pixel is within bounds, no change
  switch (ofMethod) {
    case OM_REPEAT:
      //clip coordinates
      x=max(x,0); x=min(x, head.biWidth-1);
      y=max(y,0); y=min(y, head.biHeight-1);
      break;
    case OM_WRAP:
      //wrap coordinates
      x = (float)fmod(x, (float) head.biWidth);
      y = (float)fmod(y, (float) head.biHeight);
      if (x<0) x = head.biWidth + x;
      if (y<0) y = head.biHeight + y;
      break;
    case OM_MIRROR:
      //mirror pixels near border
      if (x<0) x=(float)fmod(-x, (float) head.biWidth);
      else if (x>=head.biWidth) x=head.biWidth-((float)fmod(x, (float) head.biWidth) + 1);
      if (y<0) y=(float)fmod(-y, (float) head.biHeight);
      else if (y>=head.biHeight) y=head.biHeight-((float)fmod(y, (float) head.biHeight) + 1);
      break;
    default:
      return;
  }//switch
}

////////////////////////////////////////////////////////////////////////////////
/**
 * Method return pixel color. Different methods are implemented for out of bounds pixels.
 * If an image has alpha channel, alpha value is returned in .RGBReserved.
 *
 *  \param x,y : pixel coordinates
 *  \param ofMethod : out-of-bounds method:
 *    - OF_WRAP - wrap over to pixels on other side of the image
 *    - OF_REPEAT - repeat last pixel on the edge
 *    - OF_COLOR - return input value of color
 *    - OF_BACKGROUND - return background color (if not set, return input color)
 *    - OF_TRANSPARENT - return transparent pixel
 *
 *  \param rplColor : input color (returned for out-of-bound coordinates in OF_COLOR mode and if other mode is not applicable)
 *
 * \return color : color of pixel
 * \author ***bd*** 2.2004
 */
RGBQUAD CxImage::GetPixelColorWithOverflow(long x, long y, OverflowMethod const ofMethod, RGBQUAD* const rplColor)
{
  RGBQUAD color;          //color to return
  if ((!IsInside(x,y)) || pDib==NULL) {     //is pixel within bouns?:
    //pixel is out of bounds or no DIB
    if (rplColor!=NULL)
      color=*rplColor;
    else {
      color.rgbRed=color.rgbGreen=color.rgbBlue=255; color.rgbReserved=0; //default replacement colour: white transparent
    }//if
    if (pDib==NULL) return color;
    //pixel is out of bounds:
    switch (ofMethod) {
      case OM_TRANSPARENT:
#if CXIMAGE_SUPPORT_ALPHA
        if (AlphaIsValid()) {
          //alpha transparency is supported and image has alpha layer
          color.rgbReserved=0;
        } else {
#endif //CXIMAGE_SUPPORT_ALPHA
          //no alpha transparency
          if (GetTransIndex()>=0) {
            color=GetTransColor();    //single color transparency enabled (return transparent color)
          }//if
#if CXIMAGE_SUPPORT_ALPHA
        }//if
#endif //CXIMAGE_SUPPORT_ALPHA
        return color;
      case OM_BACKGROUND:
		  //return background color (if it exists, otherwise input value)
		  if (info.nBkgndIndex >= 0) {
			  if (head.biBitCount<24) color = GetPaletteColor((BYTE)info.nBkgndIndex);
			  else color = info.nBkgndColor;
		  }//if
		  return color;
      case OM_REPEAT:
      case OM_WRAP:
      case OM_MIRROR:
        OverflowCoordinates(x,y,ofMethod);
        break;
      default:
        //simply return replacement color (OM_COLOR and others)
        return color;
    }//switch
  }//if
  //just return specified pixel (it's within bounds)
  return BlindGetPixelColor(x,y);
}

////////////////////////////////////////////////////////////////////////////////
/**
 * This method reconstructs image according to chosen interpolation method and then returns pixel (x,y).
 * (x,y) can lie between actual image pixels. If (x,y) lies outside of image, method returns value
 * according to overflow method.
 * This method is very useful for geometrical image transformations, where destination pixel
 * can often assume color value lying between source pixels.
 *
 *  \param (x,y) - coordinates of pixel to return
 *           GPCI method recreates "analogue" image back from digital data, so x and y
 *           are float values and color value of point (1.1,1) will generally not be same
 *           as (1,1). Center of first pixel is at (0,0) and center of pixel right to it is (1,0).
 *           (0.5,0) is half way between these two pixels.
 *  \param inMethod - interpolation (reconstruction) method (kernel) to use:
 *    - IM_NEAREST_NEIGHBOUR - returns colour of nearest lying pixel (causes stairy look of 
 *                            processed images)
 *    - IM_BILINEAR - interpolates colour from four neighbouring pixels (softens image a bit)
 *    - IM_BICUBIC - interpolates from 16 neighbouring pixels (can produce "halo" artifacts)
 *    - IM_BICUBIC2 - interpolates from 16 neighbouring pixels (perhaps a bit less halo artifacts 
                     than IM_BICUBIC)
 *    - IM_BSPLINE - interpolates from 16 neighbouring pixels (softens image, washes colours)
 *                  (As far as I know, image should be prefiltered for this method to give 
 *                   good results... some other time :) )
 *                  This method uses bicubic interpolation kernel from CXImage 5.99a and older
 *                  versions.
 *    - IM_LANCZOS - interpolates from 12*12 pixels (slow, ringing artifacts)
 *
 *  \param ofMethod - overflow method (see comments at GetPixelColorWithOverflow)
 *  \param rplColor - pointer to color used for out of borders pixels in OM_COLOR mode
 *              (and other modes if colour can't calculated in a specified way)
 *
 *  \return interpolated color value (including interpolated alpha value, if image has alpha layer)
 * 
 *  \author ***bd*** 2.2004
 */
RGBQUAD CxImage::GetPixelColorInterpolated(
  float x,float y, 
  InterpolationMethod const inMethod, 
  OverflowMethod const ofMethod, 
  RGBQUAD* const rplColor)
{
  //calculate nearest pixel
  int xi=(int)(x); if (x<0) xi--;   //these replace (incredibly slow) floor (Visual c++ 2003, AMD Athlon)
  int yi=(int)(y); if (y<0) yi--;
  RGBQUAD color;                    //calculated colour

  switch (inMethod) {
    case IM_NEAREST_NEIGHBOUR:
      return GetPixelColorWithOverflow((long)(x+0.5f), (long)(y+0.5f), ofMethod, rplColor);
    default: {
      //IM_BILINEAR: bilinear interpolation
      if (xi<-1 || xi>=head.biWidth || yi<-1 || yi>=head.biHeight) {  //all 4 points are outside bounds?:
        switch (ofMethod) {
          case OM_COLOR: case OM_TRANSPARENT: case OM_BACKGROUND:
            //we don't need to interpolate anything with all points outside in this case
            return GetPixelColorWithOverflow(-999, -999, ofMethod, rplColor);
          default:
            //recalculate coordinates and use faster method later on
            OverflowCoordinates(x,y,ofMethod);
            xi=(int)(x); if (x<0) xi--;   //x and/or y have changed ... recalculate xi and yi
            yi=(int)(y); if (y<0) yi--;
        }//switch
      }//if
      //get four neighbouring pixels
      if ((xi+1)<head.biWidth && xi>=0 && (yi+1)<head.biHeight && yi>=0 && head.biClrUsed==0) {
        //all pixels are inside RGB24 image... optimize reading (and use fixed point arithmetic)
        WORD wt1=(WORD)((x-xi)*256.0f), wt2=(WORD)((y-yi)*256.0f);
        WORD wd=wt1*wt2>>8;
        WORD wb=wt1-wd;
        WORD wc=wt2-wd;
        WORD wa=256-wt1-wc;
        WORD wrr,wgg,wbb;
        BYTE *pxptr=(BYTE*)info.pImage+yi*info.dwEffWidth+xi*3;
        wbb=wa*(*pxptr++); wgg=wa*(*pxptr++); wrr=wa*(*pxptr++);
        wbb+=wb*(*pxptr++); wgg+=wb*(*pxptr++); wrr+=wb*(*pxptr);
        pxptr+=(info.dwEffWidth-5); //move to next row
        wbb+=wc*(*pxptr++); wgg+=wc*(*pxptr++); wrr+=wc*(*pxptr++); 
        wbb+=wd*(*pxptr++); wgg+=wd*(*pxptr++); wrr+=wd*(*pxptr); 
        color.rgbRed=(BYTE) (wrr>>8); color.rgbGreen=(BYTE) (wgg>>8); color.rgbBlue=(BYTE) (wbb>>8);
#if CXIMAGE_SUPPORT_ALPHA
        if (pAlpha) {
          WORD waa;
          //image has alpha layer... we have to do the same for alpha data
          pxptr=AlphaGetPointer(xi,yi);                           //pointer to first byte
          waa=wa*(*pxptr++); waa+=wb*(*pxptr);   //first two pixels
          pxptr+=(head.biWidth-1);                                //move to next row
          waa+=wc*(*pxptr++); waa+=wd*(*pxptr);   //and second row pixels
          color.rgbReserved=(BYTE) (waa>>8);
        } else
#endif
		{ //Alpha not supported or no alpha at all
			color.rgbReserved = 0;
		}
        return color;
      } else {
        //default (slower) way to get pixels (not RGB24 or some pixels out of borders)
        float t1=x-xi, t2=y-yi;
        float d=t1*t2;
        float b=t1-d;
        float c=t2-d;
        float a=1-t1-c;
        RGBQUAD rgb11,rgb21,rgb12,rgb22;
        rgb11=GetPixelColorWithOverflow(xi, yi, ofMethod, rplColor);
        rgb21=GetPixelColorWithOverflow(xi+1, yi, ofMethod, rplColor);
        rgb12=GetPixelColorWithOverflow(xi, yi+1, ofMethod, rplColor);
        rgb22=GetPixelColorWithOverflow(xi+1, yi+1, ofMethod, rplColor);
        //calculate linear interpolation
        color.rgbRed=(BYTE) (a*rgb11.rgbRed+b*rgb21.rgbRed+c*rgb12.rgbRed+d*rgb22.rgbRed);
        color.rgbGreen=(BYTE) (a*rgb11.rgbGreen+b*rgb21.rgbGreen+c*rgb12.rgbGreen+d*rgb22.rgbGreen);
        color.rgbBlue=(BYTE) (a*rgb11.rgbBlue+b*rgb21.rgbBlue+c*rgb12.rgbBlue+d*rgb22.rgbBlue);
#if CXIMAGE_SUPPORT_ALPHA
        if (AlphaIsValid())
			color.rgbReserved=(BYTE) (a*rgb11.rgbReserved+b*rgb21.rgbReserved+c*rgb12.rgbReserved+d*rgb22.rgbReserved);
		else
#endif
		{ //Alpha not supported or no alpha at all
			color.rgbReserved = 0;
		}
        return color;
      }//if
    }//default
    case IM_BICUBIC: 
    case IM_BICUBIC2:
    case IM_BSPLINE:
	case IM_BOX:
	case IM_HERMITE:
	case IM_HAMMING:
	case IM_SINC:
	case IM_BLACKMAN:
	case IM_BESSEL:
	case IM_GAUSSIAN:
	case IM_QUADRATIC:
	case IM_MITCHELL:
	case IM_CATROM:
	case IM_HANNING:
	case IM_POWER:
      //bicubic interpolation(s)
      if (((xi+2)<0) || ((xi-1)>=head.biWidth) || ((yi+2)<0) || ((yi-1)>=head.biHeight)) { //all points are outside bounds?:
        switch (ofMethod) {
          case OM_COLOR: case OM_TRANSPARENT: case OM_BACKGROUND:
            //we don't need to interpolate anything with all points outside in this case
            return GetPixelColorWithOverflow(-999, -999, ofMethod, rplColor);
            break;
          default:
            //recalculate coordinates and use faster method later on
            OverflowCoordinates(x,y,ofMethod);
            xi=(int)(x); if (x<0) xi--;   //x and/or y have changed ... recalculate xi and yi
            yi=(int)(y); if (y<0) yi--;
        }//switch
      }//if

      //some variables needed from here on
      int xii,yii;                      //x any y integer indexes for loops
      float kernel, kernelyc;           //kernel cache
      float kernelx[12], kernely[4];    //precalculated kernel values
      float rr,gg,bb,aa;                //accumulated color values
      //calculate multiplication factors for all pixels
	  int i;
      switch (inMethod) {
        case IM_BICUBIC:
          for (i=0; i<4; i++) {
            kernelx[i]=KernelCubic((float)(xi+i-1-x));
            kernely[i]=KernelCubic((float)(yi+i-1-y));
          }//for i
          break;
        case IM_BICUBIC2:
          for (i=0; i<4; i++) {
            kernelx[i]=KernelGeneralizedCubic((float)(xi+i-1-x), -0.5);
            kernely[i]=KernelGeneralizedCubic((float)(yi+i-1-y), -0.5);
          }//for i
          break;
        case IM_BSPLINE:
          for (i=0; i<4; i++) {
            kernelx[i]=KernelBSpline((float)(xi+i-1-x));
            kernely[i]=KernelBSpline((float)(yi+i-1-y));
          }//for i
          break;
        case IM_BOX:
          for (i=0; i<4; i++) {
            kernelx[i]=KernelBox((float)(xi+i-1-x));
            kernely[i]=KernelBox((float)(yi+i-1-y));
          }//for i
          break;
        case IM_HERMITE:
          for (i=0; i<4; i++) {
            kernelx[i]=KernelHermite((float)(xi+i-1-x));
            kernely[i]=KernelHermite((float)(yi+i-1-y));
          }//for i
          break;
        case IM_HAMMING:
          for (i=0; i<4; i++) {
            kernelx[i]=KernelHamming((float)(xi+i-1-x));
            kernely[i]=KernelHamming((float)(yi+i-1-y));
          }//for i
          break;
        case IM_SINC:
          for (i=0; i<4; i++) {
            kernelx[i]=KernelSinc((float)(xi+i-1-x));
            kernely[i]=KernelSinc((float)(yi+i-1-y));
          }//for i
          break;
        case IM_BLACKMAN:
          for (i=0; i<4; i++) {