2: #include <petscdraw.h>     /*I "petscdraw.h"  I*/

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

  9:     Collective on PetscDraw

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

 16:   Level: advanced

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

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

 32:   PetscDrawIsNull(draw,&isnull);
 33:   if (isnull) return(0);

 35:   PetscDrawCheckResizedWindow(draw);
 36:   PetscDrawClear(draw);
 37:   PetscDrawCollectiveBegin(draw);
 38:   (*func)(draw,ctx);
 39:   PetscDrawCollectiveEnd(draw);
 40:   PetscDrawFlush(draw);

 42:   PetscDrawGetPause(draw,&dpause);
 43:   if (dpause >= 0) {
 44:     PetscSleep(dpause);
 45:     goto theend;
 46:   }
 47:   if (dpause != -1) goto theend;

 49:   PetscDrawGetMouseButton(draw,&button,&xc,&yc,NULL,NULL);
 50:   PetscDrawGetCoordinates(draw,&xl,&yl,&xr,&yr);
 51:   xmin = xl; xmax = xr; w = xr - xl;
 52:   ymin = yl; ymax = yr; h = yr - yl;

 54:   while (button != PETSC_BUTTON_NONE && button != PETSC_BUTTON_RIGHT) {
 55:     switch (button) {
 56:     case PETSC_BUTTON_LEFT:       scale = 0.5;   break;
 57:     case PETSC_BUTTON_CENTER:     scale = 2.0;   break;
 58:     case PETSC_BUTTON_WHEEL_UP:   scale = 8/10.; break;
 59:     case PETSC_BUTTON_WHEEL_DOWN: scale = 10/8.; break;
 60:     default:                      scale = 1.0;
 61:     }
 62:     xl = scale*(xl + w - xc) + xc - w*scale;
 63:     xr = scale*(xr - w - xc) + xc + w*scale;
 64:     yl = scale*(yl + h - yc) + yc - h*scale;
 65:     yr = scale*(yr - h - yc) + yc + h*scale;
 66:     w *= scale; h *= scale;
 67:     PetscDrawClear(draw);
 68:     PetscDrawSetCoordinates(draw,xl,yl,xr,yr);
 69:     PetscDrawCollectiveBegin(draw);
 70:     (*func)(draw,ctx);
 71:     PetscDrawCollectiveEnd(draw);
 72:     PetscDrawFlush(draw);
 73:     PetscDrawGetMouseButton(draw,&button,&xc,&yc,NULL,NULL);
 74:   }
 75:   PetscDrawSetCoordinates(draw,xmin,ymin,xmax,ymax);
 76: theend:
 77:   return(0);
 78: }