Snapping

Snapping is a method to restrict the mouse coordinate to certain locations. This makes it possible to place objects and points, or to create objects on numerically exact positions. smile2 offers different snapping methods described in the following:

Snap to grid

The action Snap to grid could be switched on/off in the document settings or with the help of the Snap to grid button snap_to_grid located in the Main Toolbar.

If the action Snap to grid snap_to_grid is on, points of the creating objects would be placed only at the vertices of the lattice with the chosen parameter of the cell, given in a black box on the right of the action button snapping_grid. In Fig.1 the snap to grid with 5mkm lattice size is shown. The point stays in one of the lattice vertex till the pointer goes outside of the point quadrant with the size equal to the half lattice size. Note that the lattice vertices always proportional to the lattice size with no offset (the point (0,0) is by default belongs to the lattice).

_images/snap_to_point_4nearest_points.png

Snapping to the grid, 5 µm lattice size: the orange point stays at the same spot as long as the distance between the point and the pointer less than 2.5 µm (half lattice size, area shown with an orange box), for higher values (the pointer is outside of the first orange box in (a)) the orange point jumps to the next nearest spot on the chosen lattice/grid with its own half lattice size area. Positions of four nearest points are shown in (a-d).

Snap to guide lines

One of the most often used helping tool is the Guide lines. As there is a possibility to snap the pointer to the guide lines in the document, one can create complicated objects in one single step. How to work with the guide lines can be found elsewhere.

If the function “Snap to guide lines” is on, the guide lines once made act as ‘magnets’ for many tools.

_images/guide_line_regular_polygon_creation.png

Using snapping property of guide lines for e.g. the regular polygon creation (no other snapping mechanism is on): (a) prepared guide lines grid, (b) the first point snapped to the point (-90, 50), (c) the size of the regular polygon is controlled by the second point, which could be snapped to the guide line.

More information on guide lines could be found in Guide Lines.

Grid snapping is always enabled, if the Show guide lines attribute is on. It can be toggled in the document tool-bar with the showguides action.

Snap to control points

If enabled, object points (like the corners of a polygon), object centers and the edges of bounding boxes act as ‘magnets’ for the mouse.

Point snapping can be eanbled with the snap-to-points action in the main tool-bar.

_images/snapping_to_point.png

Snapping to the control points, snap to grid is off: (a-b) the pointer is far from the object control points,(c) the point snaps to the object control point in the object center,(d) the point snaps to the object control point on the object contour.

Note

Point snapping can be temporary enabled (or disabled, if already on) by pressing and holding the P` key. This is handy, if the point snapping is just required for a short time (eg. placing one point)

Interactive polar snapping

Unlike the other snapping methods, polar snapping can be enabled only for a short time, by pressing and holding the Sift key or the Sift``+``Ctrl key:

  • Pressing and holding the Sift key enables snapping with the Default snapping angle (default: 10°).
  • Pressing and holding the Sift and the``Ctrl`` key, at the same time, enables snapping with the Fine snapping angle (default: 1°).

Both values are adjustable in the Document settings sheet in the Attribute Editor.

Note

If Grid snapping is enabled, polar snapping uses the Grid snapping distance for the length.