1: #define PETSC_DLL

 3:  #include petscdraw.h

  7: /*@C
  8:     PetscDrawZoom - Allows one to create a graphic that users may zoom into.

 10:     Collective on PetscDraw

 12:     Input Parameters:
 13: +   draw - the window where the graph will be made.
 14: .   func - users function that draws the graphic
 15: -   ctx - pointer to any user required data

 17:   Level: advanced

 19:   Concepts: graphics^zooming
 20:   Concepts: drawing^zooming
 21:   Concepts: zooming^in graphics

 23: .seealso:  
 24: @*/
 25: PetscErrorCode  PetscDrawZoom(PetscDraw draw,PetscErrorCode (*func)(PetscDraw,void *),void *ctx)
 26: {
 27:   PetscErrorCode  ierr;
 28:   int             dpause;
 29:   PetscDrawButton button;
 30:   PetscReal       xc,yc,scale = 1.0,w,h,xr,xl,yr,yl,xmin,xmax,ymin,ymax;
 31:   PetscTruth      isnull;

 34:   PetscDrawIsNull(draw,&isnull);
 35:   if (isnull) return(0);

 37:   PetscDrawSynchronizedClear(draw);
 38:   (*func)(draw,ctx);
 39:   PetscDrawSynchronizedFlush(draw);

 41:   PetscDrawGetPause(draw,&dpause);
 42:   if (dpause >= 0) {
 43:     PetscSleep(dpause);
 44:     return(0);
 45:   }

 47:   PetscDrawCheckResizedWindow(draw);
 48:   PetscDrawSynchronizedGetMouseButton(draw,&button,&xc,&yc,0,0);
 49:   PetscDrawGetCoordinates(draw,&xl,&yl,&xr,&yr);
 50:   w    = xr - xl; xmin = xl; ymin = yl; xmax = xr; ymax = yr;
 51:   h    = yr - yl;

 53:   if (button != BUTTON_NONE) {
 54:     while (button != BUTTON_RIGHT) {

 56:       PetscDrawSynchronizedClear(draw);
 57:       if (button == BUTTON_LEFT)        scale = .5;
 58:       else if (button == BUTTON_CENTER) scale = 2.;
 59:       xl = scale*(xl + w - xc) + xc - w*scale;
 60:       xr = scale*(xr - w - xc) + xc + w*scale;
 61:       yl = scale*(yl + h - yc) + yc - h*scale;
 62:       yr = scale*(yr - h - yc) + yc + h*scale;
 63:       w *= scale; h *= scale;
 64:       PetscDrawSetCoordinates(draw,xl,yl,xr,yr);

 66:       (*func)(draw,ctx);
 67:       PetscDrawCheckResizedWindow(draw);
 68:       PetscDrawSynchronizedGetMouseButton(draw,&button,&xc,&yc,0,0);
 69:     }
 70:   }
 71:   PetscDrawSetCoordinates(draw,xmin,ymin,xmax,ymax);
 72:   return(0);
 73: }