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org.eclipse.gef
Class SnapToHelper
java.lang.Object
org.eclipse.gef.SnapToHelper
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All Implemented Interfaces:
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PositionConstants
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Direct Known Subclasses:
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CompoundSnapToHelper,
SnapToGeometry,
SnapToGrid,
SnapToGuides
- public abstract class SnapToHelper
- extends java.lang.Object
- implements
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.
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Since:
- 3.0
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Fields inherited from interface org.eclipse.draw2d.
PositionConstants
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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
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Method Summary
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protected void
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makeAbsolute
(
IFigure figure,
Translatable t)
Translates from a given figure to absolute coordinates. |
protected void
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makeRelative
(
IFigure figure,
Translatable t)
Translates from absolute to coordinates relative to the given figure. |
int
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snapPoint
(
Request request,
int snapDirections,
PrecisionPoint where,
PrecisionPoint result)
Applies a snapping correction to the given result. |
int
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snapPoint
(
Request request,
int snapLocations,
PrecisionRectangle[] rects,
PrecisionPoint result)
A convenience method for snapping a Point based on an array of rectangles. |
int
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snapRectangle
(
Request request,
int snapOrientation,
PrecisionRectangle[] baseRects,
PrecisionRectangle result)
A convenience method for snapping a Rectangle based on one or more rectangles. |
abstract int
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snapRectangle
(
Request request,
int snapOrientation,
PrecisionRectangle baseRect,
PrecisionRectangle result)
Applies a snap correction to a Rectangle based on a given Rectangle. |
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Methods inherited from class java.lang.Object
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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SnapToHelper
public SnapToHelper()
makeAbsolute
protected void makeAbsolute(
IFigure figure,
Translatable t)
- Translates from a given figure to absolute coordinates.
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Parameters:
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figure - the reference figure -
t - the object to translate
makeRelative
protected void makeRelative(
IFigure figure,
Translatable t)
- Translates from absolute to coordinates relative to the given figure.
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Parameters:
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figure - the reference figure -
t - the object to translate
snapPoint
public int snapPoint(
Request request,
int snapDirections,
PrecisionPoint where,
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.
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Parameters:
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request - a request or null
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snapDirections - the directions in which snapping should occur. -
where - the rectangle used to determine snapping -
result - the result
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Returns:
- the remaining snap locations
snapPoint
public int snapPoint(
Request request,
int snapLocations,
PrecisionRectangle[] rects,
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.
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Parameters:
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request - the request or null
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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
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Returns:
- the remaining snap locations
snapRectangle
public int snapRectangle(
Request request,
int snapOrientation,
PrecisionRectangle[] baseRects,
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.
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Parameters:
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request - the request or null
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baseRects - the prioritized rectangles to snap to -
result - the output -
snapOrientation - the input snap locations
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Returns:
- the remaining snap locations
snapRectangle
public abstract int snapRectangle(
Request request,
int snapOrientation,
PrecisionRectangle baseRect,
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.
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Parameters:
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request - the request or null
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baseRect - the input rectangle -
result - the correction is applied to this rectangle -
snapOrientation - the input snap locations
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Returns:
- the remaining snap locations
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Since:
- 3.0
Copyright (c) IBM Corp. and others 2000, 2007. All Rights Reserved.
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