Actual source code: ximage.c
petsc-3.7.1 2016-05-15
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      1: /*
      2:     Code for getting raster images out of a X image or pixmap
      3: */

      5: #include <../src/sys/classes/draw/impls/x/ximpl.h>

      7: PETSC_INTERN PetscErrorCode PetscDrawGetImage_X(PetscDraw,unsigned char[][3],unsigned int*,unsigned int*,unsigned char*[]);

     12: PETSC_STATIC_INLINE PetscErrorCode PetscArgSortPixVal(const PetscDrawXiPixVal v[256],int idx[],int right)
     13: {
     14:   PetscDrawXiPixVal vl;
     15:   int               i,last,tmp;
     16:   PetscErrorCode    ierr;
     17: # define            SWAP(a,b) {tmp=a;a=b;b=tmp;}
     19:   if (right <= 1) {
     20:     if (right == 1) {
     21:       if (v[idx[0]] > v[idx[1]]) SWAP(idx[0],idx[1]);
     22:     }
     23:     return(0);
     24:   }
     25:   SWAP(idx[0],idx[right/2]);
     26:   vl = v[idx[0]]; last = 0;
     27:   for (i=1; i<=right; i++)
     28:     if (v[idx[i]] < vl) {last++; SWAP(idx[last],idx[i]);}
     29:   SWAP(idx[0],idx[last]);
     30:   PetscArgSortPixVal(v,idx,last-1);
     31:   PetscArgSortPixVal(v,idx+last+1,right-(last+1));
     32: # undef SWAP
     33:   return(0);
     34: }

     36: /*
     37:    Map a pixel value to PETSc color value (index in the colormap)
     38: */
     41: PETSC_STATIC_INLINE int PetscDrawXiPixelToColor(PetscDraw_X *Xwin,const int arg[256],PetscDrawXiPixVal pix)
     42: {
     43:   const PetscDrawXiPixVal *cmap = Xwin->cmapping;
     44:   int                     lo, mid, hi = 256;
     45:   /* linear search the first few entries */
     46:   for (lo=0; lo<8; lo++)
     47:     if (pix == cmap[lo])
     48:       return lo;
     49:   /* binary search the remaining entries */
     50:   while (hi - lo > 1) {
     51:     mid = lo + (hi - lo)/2;
     52:     if (pix < cmap[arg[mid]]) hi = mid;
     53:     else                      lo = mid;
     54:   }
     55:   return arg[lo];
     56: }

     60: PetscErrorCode PetscDrawGetImage_X(PetscDraw draw,unsigned char palette[256][3],unsigned int *out_w,unsigned int *out_h,unsigned char *out_pixels[])
     61: {
     62:   PetscDraw_X      *Xwin = (PetscDraw_X*)draw->data;
     63:   PetscMPIInt      rank;
     64:   PetscErrorCode   ierr;

     67:   if (out_w)      *out_w      = 0;
     68:   if (out_h)      *out_h      = 0;
     69:   if (out_pixels) *out_pixels = NULL;
     70:   MPI_Comm_rank(PetscObjectComm((PetscObject)draw),&rank);

     72:   /* make sure the X server processed requests from all processes */
     73:   PetscDrawCollectiveBegin(draw);
     74:   XSync(Xwin->disp,True);
     75:   PetscDrawCollectiveEnd(draw);
     76:   MPI_Barrier(PetscObjectComm((PetscObject)draw));

     78:   /* only the first process return image data */
     79:   PetscDrawCollectiveBegin(draw);
     80:   if (!rank) {
     81:     Window        root;
     82:     XImage        *ximage;
     83:     int           pmap[256];
     84:     unsigned char *pixels = NULL;
     85:     unsigned int  w,h,dummy;
     86:     int           x,y,p;
     87:     /* copy colormap palette to the caller */
     88:     PetscMemcpy(palette,Xwin->cpalette,sizeof(Xwin->cpalette));
     89:     /* get image out of the drawable */
     90:     XGetGeometry(Xwin->disp,PetscDrawXiDrawable(Xwin),&root,&x,&y,&w,&h,&dummy,&dummy);
     91:     ximage = XGetImage(Xwin->disp,PetscDrawXiDrawable(Xwin),0,0,w,h,AllPlanes,ZPixmap);
     92:     if (!ximage) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Cannot XGetImage()");
     93:     /* build indirect sort permutation (a.k.a argsort) of the color -> pixel mapping */
     94:     for (p=0; p<256; p++) pmap[p] = p; /* identity permutation */
     95:     PetscArgSortPixVal(Xwin->cmapping,pmap,255);
     96:     /* extract pixel values out of the image and map them to color indices */
     97:     PetscMalloc1(w*h,&pixels);
     98:     for (p=0,y=0; y<(int)h; y++)
     99:       for (x=0; x<(int)w; x++) {
    100:         PetscDrawXiPixVal pix = XGetPixel(ximage,x,y);
    101:         pixels[p++] = (unsigned char)PetscDrawXiPixelToColor(Xwin,pmap,pix);
    102:       }
    103:     XDestroyImage(ximage);
    104:     *out_w      = w;
    105:     *out_h      = h;
    106:     *out_pixels = pixels;
    107:   }
    108:   PetscDrawCollectiveEnd(draw);
    109:   return(0);
    110: }