The TGIS_Editor class was recently enhanced with advanced snapping features for vector editing. Snapping enables accurate placement of new (or edited) vertices to the exact locations of already existing geometry (vertices, line segments, polygon edges, intersections, etc.) that may exist in the layer being edited or in other layers. Snapping requires the user to select the snap-to layer(s), a snap-type mode, and a distance tolerance. Then position the mouse cursor (or finger on a tablet computer) within the distance tolerance relative to the snap-to feature, and click. Pursuant to the snap settings, eligible snap-to points relative to the cursor position are highlighted dynamically.
As with all TGIS_Editor class functionality, the advanced snapping features are available in the TatukGIS Developer Kernel and desktop GIS Editor products.
The most significant new snapping related features are:
- new snap-type modes and properties:
Snap-type modes and properties in drop down selection menu.
The first seven options visible in the above image (those located above the horizontal line) are snap-type modes. The two items below the horizontal line (e.g., Snap tracing and Snap to intersection) are additional snap-type properties (i.e., options) that can be used with a selected snap-type mode. The Snapping settings... option opens a menu for setting the distance tolerance and grid spacing.
- interactive tracing to vertices, line segment or polygon edge midpoints, shape intersections, etc.:
Eligible snap-to geometric features highlighted using red polygon or an x.
- support for using a single or concurrent snap-to layers:
Snap-to layer selection list.
- snap settings (distance tolerance and grid spacing):
More about TatukGIS editing functionality is found in the Vector Editing article in the Developer Kernel documentation wiki.