Eclipse GEF and Draw2d Plug-in Developer Guide (Galileo) - SnapToGrid (Eclipse GEF API Specification)

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3.3

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org.eclipse.gef
Class SnapToGrid

java.lang.Object
  

org.eclipse.gef.SnapToHelper
      
org.eclipse.gef.SnapToGrid

All Implemented Interfaces:: PositionConstants

public class SnapToGrid
extends SnapToHelper

A helper used to perform snapping to a grid, which is specified on the graphical viewer via the various properties defined in this class. This helper can be used in conjunction with the DragEditPartsTracker when dragging editparts within a graphical viewer. When snapping a rectangle, the edges of the rectangle will snap along gridlines.

This helper does not keep up with changes made to the graphical viewer's properties. Clients should instantiate a new helper each time one is requested and not hold on to instances of the helper, if the grid properties specified on the viewer are subject to change.

Since:: 3.0
See Also:: GridLayer

Field Summary

protected GraphicalEditPart container
          The graphical part whose content's figure defines the grid.

static int DEFAULT_GAP
          Deprecated. use DEFAULT_GRID_SIZE

static int DEFAULT_GRID_SIZE
          The default grid size if the viewer does not specify a size.

protected int gridX
          The horizontal interval for the grid

protected int gridY
          The vertical interval for the grid

protected Point origin
          The origin of the grid.

static java.lang.String PROPERTY_GRID_ENABLED
          A viewer property indicating whether the snap function is enabled.

static java.lang.String PROPERTY_GRID_ORIGIN
          A viewer property indicating the grid's origin.

static java.lang.String PROPERTY_GRID_SPACING
          A viewer property indicating the grid spacing.

static java.lang.String PROPERTY_GRID_VISIBLE
          A viewer property indicating whether the grid should be displayed.

Fields inherited from interface org.eclipse.draw2d. PositionConstants

ALWAYS_LEFT, ALWAYS_RIGHT, BOTTOM, CENTER, EAST, EAST_WEST, HORIZONTAL, LEFT, LEFT_CENTER_RIGHT, MIDDLE, NONE, NORTH, NORTH_EAST, NORTH_SOUTH, NORTH_WEST, NSEW, RIGHT, SOUTH, SOUTH_EAST, SOUTH_WEST, TOP, TOP_MIDDLE_BOTTOM, VERTICAL, WEST

Constructor Summary

SnapToGrid ( GraphicalEditPart container)
          Constructs a gridded snap helper on the given editpart.

Method Summary

int snapRectangle ( Request request, int snapLocations, PrecisionRectangle rect, PrecisionRectangle result)
          Applies a snap correction to a Rectangle based on a given Rectangle.

Methods inherited from class org.eclipse.gef. SnapToHelper

makeAbsolute, makeRelative, snapPoint, snapPoint, snapRectangle

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

PROPERTY_GRID_ENABLED

public static final java.lang.String PROPERTY_GRID_ENABLED

A viewer property indicating whether the snap function is enabled. The value must be a Boolean.

See Also:: Constant Field Values

PROPERTY_GRID_VISIBLE

public static final java.lang.String PROPERTY_GRID_VISIBLE

A viewer property indicating whether the grid should be displayed. The value must be a Boolean.

See Also:: Constant Field Values

PROPERTY_GRID_SPACING

public static final java.lang.String PROPERTY_GRID_SPACING

A viewer property indicating the grid spacing. The value must be a Dimension.

See Also:: Constant Field Values

PROPERTY_GRID_ORIGIN

public static final java.lang.String PROPERTY_GRID_ORIGIN

A viewer property indicating the grid's origin. The value must be a Point.

See Also:: Constant Field Values

DEFAULT_GRID_SIZE

public static final int DEFAULT_GRID_SIZE

The default grid size if the viewer does not specify a size.

See Also:: PROPERTY_GRID_SPACING, Constant Field Values

DEFAULT_GAP

public static final int DEFAULT_GAP

Deprecated. use DEFAULT_GRID_SIZE

See Also:: Constant Field Values

container

protected 
GraphicalEditPart container

The graphical part whose content's figure defines the grid.

gridX

protected int gridX

The horizontal interval for the grid

gridY

protected int gridY

The vertical interval for the grid

origin

protected 
Point origin

The origin of the grid.

Constructor Detail

SnapToGrid

public SnapToGrid(
GraphicalEditPart container)

Constructs a gridded snap helper on the given editpart. The editpart should be the graphical editpart whose contentspane figure is used as the reference for the grid.
Parameters:: container - the editpart which the grid is on

Method Detail

snapRectangle

public int snapRectangle(
Request request,
                         int snapLocations,
                         
PrecisionRectangle rect,
                         
PrecisionRectangle result)

Description copied from class: SnapToHelper

Applies a snap correction to a Rectangle based on a given Rectangle. The provided baseRect will be used as a reference for snapping. The types of snapping to be performed are indicated by the snapOrientation parameter. The correction is applied to the result field.

The baseRect is not modified. The correction is applied to the result. The request's extended data may contain additional information about the snapping which was performed.

All coordinate information received and returned by this method should be in absolute coordinates.

Specified by:: snapRectangle in class SnapToHelper

Parameters:: request - the request or null; rect - the input rectangle; result - the correction is applied to this rectangle; snapLocations - the input snap locations
Returns:: the remaining snap locations
See Also:: SnapToHelper.snapRectangle(Request, int, PrecisionRectangle, PrecisionRectangle)