Class SnapToGuides

java.lang.Object
org.eclipse.gef.SnapToHelper
org.eclipse.gef.SnapToGuides
All Implemented Interfaces:
org.eclipse.draw2d.PositionConstants

public class SnapToGuides extends SnapToHelper
A helper used to perform snapping to guides. The guides are obtained from the viewer's horizontal and vertical RulerProviders. If snapping is performed, the request's extended data will contain keyed values indicating which guides were snapped to, and which side of the part should be attached. Generally snapping to a guide should attach the part to that guide, but application behavior may differ.

Snapping (and attaching) to a guide is only possible if a single part is being dragged. The current implementation will not snap if a request contains multiple parts. This may be relaxed in the future to allow snapping, but without setting the attachment extended data.

This helper does not keep up with changes in guides. Clients should instantiate a new helper each time one is requested and not hold on to instances of the helper.

Since:
3.0
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    The graphical editpart to which guides are relative.
    protected int[]
    The locations of the horizontal guides in the container's coordinates.
    static final String
    The key used to identify the horizontal anchor point.
    static final String
    The key used to identify the Horizontal Guide.
    static final String
    The key used to identify the vertical anchor point.
    static final String
    The key used to identify the Vertical Guide.
    protected static final double
    The threshold for snapping to guides.
    protected int[]
    The locations of the vertical guides in the container's coordinates.

    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
    Constructs a new snap-to-guides helper using the given container as the basis.
  • Method Summary

    Modifier and Type
    Method
    Description
    protected double
    getCorrectionFor(int[] guides, double near, double far, Map extendedData, boolean isVertical)
    Returns the correction for the given near and far sides of a rectangle or getThreshold() if no correction was found.
    protected double
    getCorrectionFor(int[] guides, double value, Map extendedData, boolean vert, int side)
    Returns the correction for the given location or getThreshold() if no correction was found.
    protected int[]
    Returns the horizontal guides in the coordinates of the container's contents pane.
    protected double
    Get the sensitivity of the snapping.
    protected int[]
    Returns the vertical guides in the coordinates of the container's contents pane.
    protected void
    setThreshold(double newThreshold)
    Set the sensitivity of the snapping.
    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 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 Details

    • KEY_VERTICAL_GUIDE

      public static final String KEY_VERTICAL_GUIDE
      The key used to identify the Vertical Guide. This key is used with the request's extended data map to store an Integer. The integer value is the location of the guide that is being snapped to.
      See Also:
    • KEY_HORIZONTAL_GUIDE

      public static final String KEY_HORIZONTAL_GUIDE
      The key used to identify the Horizontal Guide. This key is used with the request's extended data map to store an Integer. The integer value is the location of the guide that is being snapped to.
      See Also:
    • KEY_VERTICAL_ANCHOR

      public static final String KEY_VERTICAL_ANCHOR
      The key used to identify the vertical anchor point. This key is used with the request's extended data map to store an Integer. If the VERTICAL_GUIDE has been set, then this integer is a number identifying which side of the dragged object is being snapped to that guide.
      • -1 indicates the left side should be attached.
      • 0 indicates the center should be attached.
      • 1 indicates the right side should be attached.
      See Also:
    • KEY_HORIZONTAL_ANCHOR

      public static final String KEY_HORIZONTAL_ANCHOR
      The key used to identify the horizontal anchor point. This key is used with the request's extended data map to store an Integer. If the HORIZONTAL_GUIDE has been set, then this integer is a number identifying which side of the dragged object is being snapped to that guide.
      • -1 indicates the top side should be attached.
      • 0 indicates the middle should be attached.
      • 1 indicates the bottom side should be attached.
      See Also:
    • THRESHOLD

      protected static final double THRESHOLD
      The threshold for snapping to guides. The rectangle being snapped must be within +/- the THRESHOLD. The default value is 5.001;
      See Also:
    • container

      protected GraphicalEditPart container
      The graphical editpart to which guides are relative. This should also the parent of the parts being snapped to guides.
    • verticalGuides

      protected int[] verticalGuides
      The locations of the vertical guides in the container's coordinates. Use getVerticalGuides().
    • horizontalGuides

      protected int[] horizontalGuides
      The locations of the horizontal guides in the container's coordinates. Use getHorizontalGuides().
  • Constructor Details

    • SnapToGuides

      public SnapToGuides(GraphicalEditPart container)
      Constructs a new snap-to-guides helper using the given container as the basis.
      Parameters:
      container - the container editpart
  • Method Details

    • getThreshold

      protected double getThreshold()
      Get the sensitivity of the snapping. Corrections greater than this value will not occur.
      Returns:
      the snapping threshold
      Since:
      3.4
    • setThreshold

      protected void setThreshold(double newThreshold)
      Set the sensitivity of the snapping.
      Parameters:
      newThreshold - the new snapping threshold
      Since:
      3.4
      See Also:
    • getCorrectionFor

      protected double getCorrectionFor(int[] guides, double near, double far, Map extendedData, boolean isVertical)
      Returns the correction for the given near and far sides of a rectangle or getThreshold() if no correction was found. The near side represents the top or left side of a rectangle being snapped. Similar for far. If snapping occurs, the extendedData will have the guide and attachment point set.
      Parameters:
      guides - the location of the guides
      near - the top or left location
      far - the bottom or right location
      extendedData - the map for storing snap details
      isVertical - true if for vertical guides, false for horizontal.
      Returns:
      the correction amount or getThreshold() if no correction was made
    • getCorrectionFor

      protected double getCorrectionFor(int[] guides, double value, Map extendedData, boolean vert, int side)
      Returns the correction for the given location or getThreshold() if no correction was found. If correction occurs, the extendedData will have the guide and attachment point set. The attachment point is identified by the side parameter.

      The correction's magnitude will be less than getThreshold().

      Parameters:
      guides - the location of the guides
      value - the location being tested
      extendedData - the map for storing snap details
      vert - true if for vertical guides, false
      side - the integer indicating which side is being snapped
      Returns:
      a correction amount or getThreshold() if no correction was made
    • getHorizontalGuides

      protected int[] getHorizontalGuides()
      Returns the horizontal guides in the coordinates of the container's contents pane.
      Returns:
      the horizontal guides
    • getVerticalGuides

      protected int[] getVerticalGuides()
      Returns the vertical guides in the coordinates of the container's contents pane.
      Returns:
      the vertical guides
    • snapRectangle

      public int snapRectangle(Request request, int snapOrientation, org.eclipse.draw2d.geometry.PrecisionRectangle baseRect, org.eclipse.draw2d.geometry.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
      snapOrientation - the input snap locations
      baseRect - the input rectangle
      result - the correction is applied to this rectangle
      Returns:
      the remaining snap locations
      See Also: