Snaptoline

Snaptoline is a feature found in certain computer-aided design (CAD) and graphics editing software that allows users to automatically align objects to a predefined line or guideline. The feature works by creating a hidden line, often called a snaptoline, that is invisible to the user but can be used as a reference point when moving or drawing new elements. When objects are moved close to the line, the program automatically snaps them to the exact position, thereby improving accuracy and reducing manual adjustment.

The concept of snaptoline was introduced by the developers of VectorStudio, a popular open‑source drafting tool, in 2018 with version 3.0. It was created to address a common need among designers who frequently required precise alignment to existing geometry or custom manual guidelines. Prior to its release, users had to rely on manual snapping or use separate guideline tools. Snaptoline integrated the guideline and snap functionality into one seamless process.

User interaction with snaptoline typically involves selecting a tool to create the line, then choosing the snapping mode—such as endpoint, midpoint, or center—before drawing or moving an object. Software developers can also programmatically reference snaptoline coordinates to automate layout tasks. An optional visibility toggle allows the creation of temporary or permanent snaptolines, giving flexibility to project workflows.

The feature has received positive feedback from small‑business designers and hobbyists who value speed and precision. Critics have noted that snaptoline may conflict with other snapping options when multiple guidelines are active, and that the user interface can be less intuitive for beginners. Despite these concerns, snaptoline remains a widely adopted tool in many CAD suites for its convenience in aligning objects with reference geometry.