---
name: "Grid"
section: "3"
platform: "linux"
package: "ivtools-dev"
version: "1.1.3-4"
release: "Debian 3.1 (Sarge)"
platforms: ["linux"]
url: "https://new.carta.tech/Grid"
---

# Grid(3)

displays a grid in a viewer and constrains points to lie on it

## NAME

Grid - displays a grid in a viewer and constrains points to lie on it

## SYNOPSIS

**#include \<Unidraw/grid.h\>**

## DESCRIPTION

The Grid object performs two functions: it displays a grid in a viewer, and it can constrain points to lie on the grid.  The base class draws the grid as a simple array of dots; subclasses can draw arbitrarily complex grids.

## PUBLIC OPERATIONS

- **Grid(float w, float h, float xincr, float yincr)**

  The constructor parameters correspond to a width, a height, and independent units of graduation for the horizontal and vertical axes, all in pixels.  The Grid base class employs a special-purpose graphic to render itself, one that draws an array of dots based on the information supplied in this constructor.

- **virtual Graphic\* GetGraphic()**

  Return the graphic used to render the grid.

- **virtual void Constrain(Coord&, Coord&)**

  Constrain the given coordinate pair to fall on the grid.  The pair is changed to fall on the nearest grid point by default.

- **virtual void Visiblity(boolean)**

  Make the grid visible (specify *true*) or invisible (specify *false*).

- **virtual boolean IsVisible()**

  Return whether the grid is visible or not.

- **virtual void SetSpacing(float xincr, float yincr)**

  Reset the grid's units of graduation.

## PROTECTED OPERATIONS

- **Grid(Graphic\*)**

  The protected constructor allows subclasses to specify an arbitrary graphic for rendering the grid.  Subclasses that use this constructor *must* also redefine the Constrain operation.

## SEE ALSO

Graphic(3U), Viewer(3U)