Actual source code: zoom.c
petsc-3.10.5 2019-03-28
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      2:  #include <petscdraw.h>

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

      7:     Collective on PetscDraw

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

     14:   Level: advanced

     16:   Concepts: graphics^zooming
     17:   Concepts: drawing^zooming
     18:   Concepts: zooming^in graphics

     20: .seealso:
     21: @*/
     22: PetscErrorCode  PetscDrawZoom(PetscDraw draw,PetscErrorCode (*func)(PetscDraw,void*),void *ctx)
     23: {
     24:   PetscErrorCode  ierr;
     25:   PetscDrawButton button;
     26:   PetscReal       dpause,xc,yc,scale = 1.0,w,h,xr,xl,yr,yl,xmin,xmax,ymin,ymax;
     27:   PetscBool       isnull;

     30:   PetscDrawIsNull(draw,&isnull);
     31:   if (isnull) return(0);

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

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

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

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