1: #include <petscdraw.h>

  3: /*@C
  4:   PetscDrawZoom - Allows one to provide a function that gets called for zooming in on a drawing using the mouse buttons

  6:   Collective draw

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

 13:   Calling sequence of func:
 14: + draw - the `PetscDraw` object to zoom on
 15: - ctx  - the context for the zooming operation

 17:   Level: advanced

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

 27:   PetscFunctionBegin;
 28:   PetscCall(PetscDrawIsNull(draw, &isnull));
 29:   if (isnull) PetscFunctionReturn(PETSC_SUCCESS);

 31:   PetscCall(PetscDrawCheckResizedWindow(draw));
 32:   PetscCall(PetscDrawClear(draw));
 33:   PetscDrawCollectiveBegin(draw);
 34:   PetscCall((*func)(draw, ctx));
 35:   PetscDrawCollectiveEnd(draw);
 36:   PetscCall(PetscDrawFlush(draw));

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

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

 54:   while (button != PETSC_BUTTON_NONE && button != PETSC_BUTTON_RIGHT) {
 55:     switch (button) {
 56:     case PETSC_BUTTON_LEFT:
 57:       scale = 0.5;
 58:       break;
 59:     case PETSC_BUTTON_CENTER:
 60:       scale = 2.0;
 61:       break;
 62:     case PETSC_BUTTON_WHEEL_UP:
 63:       scale = 8 / 10.;
 64:       break;
 65:     case PETSC_BUTTON_WHEEL_DOWN:
 66:       scale = 10 / 8.;
 67:       break;
 68:     default:
 69:       scale = 1.0;
 70:     }
 71:     xl = scale * (xl + w - xc) + xc - w * scale;
 72:     xr = scale * (xr - w - xc) + xc + w * scale;
 73:     yl = scale * (yl + h - yc) + yc - h * scale;
 74:     yr = scale * (yr - h - yc) + yc + h * scale;
 75:     w *= scale;
 76:     h *= scale;
 77:     PetscCall(PetscDrawClear(draw));
 78:     PetscCall(PetscDrawSetCoordinates(draw, xl, yl, xr, yr));
 79:     PetscDrawCollectiveBegin(draw);
 80:     PetscCall((*func)(draw, ctx));
 81:     PetscDrawCollectiveEnd(draw);
 82:     PetscCall(PetscDrawFlush(draw));
 83:     PetscCall(PetscDrawGetMouseButton(draw, &button, &xc, &yc, NULL, NULL));
 84:   }
 85:   PetscCall(PetscDrawSetCoordinates(draw, xmin, ymin, xmax, ymax));
 86: theend:
 87:   PetscFunctionReturn(PETSC_SUCCESS);
 88: }