Class SnapToHelper

java.lang.Object
org.eclipse.gef.SnapToHelper
All Implemented Interfaces:
org.eclipse.draw2d.PositionConstants
Direct Known Subclasses:
CompoundSnapToHelper, SnapToGeometry, SnapToGrid, SnapToGuides

public abstract class SnapToHelper extends Object implements org.eclipse.draw2d.PositionConstants
A helper used temporarily by Tools for snapping certain mouse interactions. SnapToHelpers should not be reused by tools or by the editparts which provide them to the tools. For example, for a move operation, the life-cycle of a SnapToHelper begins when a drag is initiated, and ends when the drag is over. If another drag is initiated right after the first one is completed, new SnapToHelpers are employed. This means that helpers can assume that everything else is static, and there is no need to track changes outside of the helper.
Since:
3.0
  • Field Summary

    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

    Constructors
    Constructor
    Description
     
  • Method Summary

    Modifier and Type
    Method
    Description
    protected void
    makeAbsolute(org.eclipse.draw2d.IFigure figure, org.eclipse.draw2d.geometry.Translatable t)
    Translates from a given figure to absolute coordinates.
    protected void
    makeRelative(org.eclipse.draw2d.IFigure figure, org.eclipse.draw2d.geometry.Translatable t)
    Translates from absolute to coordinates relative to the given figure.
    int
    snapPoint(Request request, int snapDirections, org.eclipse.draw2d.geometry.PrecisionPoint where, org.eclipse.draw2d.geometry.PrecisionPoint result)
    Applies a snapping correction to the given result.
    int
    snapPoint(Request request, int snapLocations, org.eclipse.draw2d.geometry.PrecisionRectangle[] rects, org.eclipse.draw2d.geometry.PrecisionPoint result)
    A convenience method for snapping a Point based on an array of rectangles.
    int
    snapRectangle(Request request, int snapOrientation, org.eclipse.draw2d.geometry.PrecisionRectangle[] baseRects, org.eclipse.draw2d.geometry.PrecisionRectangle result)
    A convenience method for snapping a Rectangle based on one or more rectangles.
    abstract int
    snapRectangle(Request request, int snapOrientation, org.eclipse.draw2d.geometry.PrecisionRectangle baseRect, org.eclipse.draw2d.geometry.PrecisionRectangle result)
    Applies a snap correction to a Rectangle based on a given Rectangle.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • SnapToHelper

      public SnapToHelper()
  • Method Details

    • makeAbsolute

      protected void makeAbsolute(org.eclipse.draw2d.IFigure figure, org.eclipse.draw2d.geometry.Translatable t)
      Translates from a given figure to absolute coordinates.
      Parameters:
      figure - the reference figure
      t - the object to translate
    • makeRelative

      protected void makeRelative(org.eclipse.draw2d.IFigure figure, org.eclipse.draw2d.geometry.Translatable t)
      Translates from absolute to coordinates relative to the given figure.
      Parameters:
      figure - the reference figure
      t - the object to translate
    • snapPoint

      public int snapPoint(Request request, int snapDirections, org.eclipse.draw2d.geometry.PrecisionPoint where, org.eclipse.draw2d.geometry.PrecisionPoint result)
      Applies a snapping correction to the given result. Snapping can occur in the four primary directions: NORTH, SOUTH, EAST, WEST, as defined on PositionConstants. By default a Point is treated as an empty Rectangle. Only NORTH and WEST should be used in general. But SOUTH and EAST may also be used. Similarly, VERTICAL and HORIZONTAL may be used to allow a point to snap to the "center" or "middle" as defined by the concrete subclass.

      The returned value should be a subset of the given snapDirections based on what correction was applied to the result. e.g., if the x value was adjusted, the returned value should not contain WEST, EAST, or HORIZONTAL.

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

      Parameters:
      request - a request or null
      snapDirections - the directions in which snapping should occur.
      where - the rectangle used to determine snapping
      result - the result
      Returns:
      the remaining snap locations
    • snapPoint

      public int snapPoint(Request request, int snapLocations, org.eclipse.draw2d.geometry.PrecisionRectangle[] rects, org.eclipse.draw2d.geometry.PrecisionPoint result)
      A convenience method for snapping a Point based on an array of rectangles. By default, this method will construct an empty rectangle at the same locations as the provided point, and call snapRectangle(Request, int, PrecisionRectangle[], PrecisionRectangle) . The intended usage of this method is when dragging one or more parts in a diagram.

      The returned value should be a subset of the given snapDirections based on what correction was applied to the result. e.g., if the x value was adjusted, the returned value should not contain WEST, EAST, or HORIZONTAL.

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

      Parameters:
      request - the request or null
      snapLocations - the types of snapping to perform
      rects - an array of one or more rectangles used to perform the snapping
      result - the correction will be applied to this point
      Returns:
      the remaining snap locations
    • snapRectangle

      public int snapRectangle(Request request, int snapOrientation, org.eclipse.draw2d.geometry.PrecisionRectangle[] baseRects, org.eclipse.draw2d.geometry.PrecisionRectangle result)
      A convenience method for snapping a Rectangle based on one or more rectangles. This method will call snapRectangle(Request, int, PrecisionRectangle, PrecisionRectangle) for each rectangle in the array or until no more snap locations remain.

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

      Parameters:
      request - the request or null
      baseRects - the prioritized rectangles to snap to
      result - the output
      snapOrientation - the input snap locations
      Returns:
      the remaining snap locations
    • snapRectangle

      public abstract int snapRectangle(Request request, int snapOrientation, org.eclipse.draw2d.geometry.PrecisionRectangle baseRect, org.eclipse.draw2d.geometry.PrecisionRectangle result)
      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.

      Parameters:
      request - the request or null
      baseRect - the input rectangle
      result - the correction is applied to this rectangle
      snapOrientation - the input snap locations
      Returns:
      the remaining snap locations
      Since:
      3.0