Package org.eclipse.swt.graphics

Class Transform

java.lang.Object
org.eclipse.swt.graphics.Resource
org.eclipse.swt.graphics.Transform
public class Transform extends Resource
Instances of this class represent transformation matrices for points expressed as (x, y) pairs of floating point numbers.

Application code must explicitly invoke the Transform.dispose() method to release the operating system resources managed by each instance when those instances are no longer required.

This class requires the operating system's advanced graphics subsystem which may not be available on some platforms.

Since:
3.1
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    long
    handle
    the OS resource for the Transform (Warning: This field is platform dependent)

  • Constructor Summary

    Constructors
    Constructor
    Description
    Transform(Device device)
    Constructs a new identity Transform.
    Transform(Device device, float[] elements)
    Constructs a new Transform given an array of elements that represent the matrix that describes the transformation.
    Transform(Device device, float m11, float m12, float m21, float m22, float dx, float dy)
    Constructs a new Transform given all of the elements that represent the matrix that describes the transformation.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    getElements(float[] elements)
    Fills the parameter with the values of the transformation matrix that the receiver represents, in the order {m11, m12, m21, m22, dx, dy}.
    void
    identity()
    Modifies the receiver such that the matrix it represents becomes the identity matrix.
    void
    invert()
    Modifies the receiver such that the matrix it represents becomes the mathematical inverse of the matrix it previously represented.
    boolean
    isDisposed()
    Returns true if the Transform has been disposed, and false otherwise.
    boolean
    isIdentity()
    Returns true if the Transform represents the identity matrix and false otherwise.
    void
    multiply(Transform matrix)
    Modifies the receiver such that the matrix it represents becomes the the result of multiplying the matrix it previously represented by the argument.
    void
    rotate(float angle)
    Modifies the receiver so that it represents a transformation that is equivalent to its previous transformation rotated by the specified angle.
    void
    scale(float scaleX, float scaleY)
    Modifies the receiver so that it represents a transformation that is equivalent to its previous transformation scaled by (scaleX, scaleY).
    void
    setElements(float m11, float m12, float m21, float m22, float dx, float dy)
    Modifies the receiver to represent a new transformation given all of the elements that represent the matrix that describes that transformation.
    void
    shear(float shearX, float shearY)
    Modifies the receiver so that it represents a transformation that is equivalent to its previous transformation sheared by (shearX, shearY).
    String
    toString()
    Returns a string containing a concise, human-readable description of the receiver.
    void
    transform(float[] pointArray)
    Given an array containing points described by alternating x and y values, modify that array such that each point has been replaced with the result of applying the transformation represented by the receiver to that point.
    void
    translate(float offsetX, float offsetY)
    Modifies the receiver so that it represents a transformation that is equivalent to its previous transformation translated by (offsetX, offsetY).

    Methods inherited from class org.eclipse.swt.graphics.Resource

    dispose, getDevice, setNonDisposeHandler

    Methods inherited from class java.lang.Object

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

  • Field Details

    • handle

      public long handle
      the OS resource for the Transform (Warning: This field is platform dependent)

      IMPORTANT: This field is not part of the SWT public API. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms and should never be accessed from application code.

      Restriction:
      This field is not intended to be referenced by clients.

  • Constructor Details

    • Transform

      public Transform(Device device)
      Constructs a new identity Transform.

      This operation requires the operating system's advanced graphics subsystem which may not be available on some platforms.

      You must dispose the transform when it is no longer required.

      Parameters:
      device - the device on which to allocate the Transform
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if device is null and there is no current device
      SWTException -
      • ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available
      SWTError -
      • ERROR_NO_HANDLES if a handle for the Transform could not be obtained
      See Also:

    • Transform

      public Transform(Device device, float[] elements)
      Constructs a new Transform given an array of elements that represent the matrix that describes the transformation.

      This operation requires the operating system's advanced graphics subsystem which may not be available on some platforms.

      You must dispose the transform when it is no longer required.

      Parameters:
      device - the device on which to allocate the Transform
      elements - an array of floats that describe the transformation matrix
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if device is null and there is no current device, or the elements array is null
      • ERROR_INVALID_ARGUMENT - if the elements array is too small to hold the matrix values
      SWTException -
      • ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available
      SWTError -
      • ERROR_NO_HANDLES if a handle for the Transform could not be obtained
      See Also:

    • Transform

      public Transform(Device device, float m11, float m12, float m21, float m22, float dx, float dy)
      Constructs a new Transform given all of the elements that represent the matrix that describes the transformation.

      This operation requires the operating system's advanced graphics subsystem which may not be available on some platforms.

      You must dispose the transform when it is no longer required.

      Parameters:
      device - the device on which to allocate the Transform
      m11 - the first element of the first row of the matrix
      m12 - the second element of the first row of the matrix
      m21 - the first element of the second row of the matrix
      m22 - the second element of the second row of the matrix
      dx - the third element of the first row of the matrix
      dy - the third element of the second row of the matrix
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if device is null and there is no current device
      SWTException -
      • ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available
      SWTError -
      • ERROR_NO_HANDLES if a handle for the Transform could not be obtained
      See Also:

  • Method Details

    • getElements

      public void getElements(float[] elements)
      Fills the parameter with the values of the transformation matrix that the receiver represents, in the order {m11, m12, m21, m22, dx, dy}.
      Parameters:
      elements - array to hold the matrix values
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the parameter is null
      • ERROR_INVALID_ARGUMENT - if the parameter is too small to hold the matrix values

    • identity

      public void identity()
      Modifies the receiver such that the matrix it represents becomes the identity matrix.
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed
      Since:
      3.4

    • invert

      public void invert()
      Modifies the receiver such that the matrix it represents becomes the mathematical inverse of the matrix it previously represented.
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed
      • ERROR_CANNOT_INVERT_MATRIX - if the matrix is not invertible

    • isDisposed

      public boolean isDisposed()
      Returns true if the Transform has been disposed, and false otherwise.

      This method gets the dispose state for the Transform. When a Transform has been disposed, it is an error to invoke any other method (except Resource.dispose()) using the Transform.

      Specified by:
      isDisposed in class Resource
      Returns:
      true when the Transform is disposed, and false otherwise

    • isIdentity

      public boolean isIdentity()
      Returns true if the Transform represents the identity matrix and false otherwise.
      Returns:
      true if the receiver is an identity Transform, and false otherwise

    • multiply

      public void multiply(Transform matrix)
      Modifies the receiver such that the matrix it represents becomes the the result of multiplying the matrix it previously represented by the argument.
      Parameters:
      matrix - the matrix to multiply the receiver by
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the parameter is null
      • ERROR_INVALID_ARGUMENT - if the parameter has been disposed

    • rotate

      public void rotate(float angle)
      Modifies the receiver so that it represents a transformation that is equivalent to its previous transformation rotated by the specified angle. The angle is specified in degrees and for the identity transform 0 degrees is at the 3 o'clock position. A positive value indicates a clockwise rotation while a negative value indicates a counter-clockwise rotation.
      Parameters:
      angle - the angle to rotate the transformation by
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

    • scale

      public void scale(float scaleX, float scaleY)
      Modifies the receiver so that it represents a transformation that is equivalent to its previous transformation scaled by (scaleX, scaleY).
      Parameters:
      scaleX - the amount to scale in the X direction
      scaleY - the amount to scale in the Y direction
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

    • setElements

      public void setElements(float m11, float m12, float m21, float m22, float dx, float dy)
      Modifies the receiver to represent a new transformation given all of the elements that represent the matrix that describes that transformation.
      Parameters:
      m11 - the first element of the first row of the matrix
      m12 - the second element of the first row of the matrix
      m21 - the first element of the second row of the matrix
      m22 - the second element of the second row of the matrix
      dx - the third element of the first row of the matrix
      dy - the third element of the second row of the matrix
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

    • shear

      public void shear(float shearX, float shearY)
      Modifies the receiver so that it represents a transformation that is equivalent to its previous transformation sheared by (shearX, shearY).
      Parameters:
      shearX - the shear factor in the X direction
      shearY - the shear factor in the Y direction
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed
      Since:
      3.4

    • transform

      public void transform(float[] pointArray)
      Given an array containing points described by alternating x and y values, modify that array such that each point has been replaced with the result of applying the transformation represented by the receiver to that point.
      Parameters:
      pointArray - an array of alternating x and y values to be transformed
      Throws:
      IllegalArgumentException -
      • ERROR_NULL_ARGUMENT - if the point array is null
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

    • translate

      public void translate(float offsetX, float offsetY)
      Modifies the receiver so that it represents a transformation that is equivalent to its previous transformation translated by (offsetX, offsetY).
      Parameters:
      offsetX - the distance to translate in the X direction
      offsetY - the distance to translate in the Y direction
      Throws:
      SWTException -
      • ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

    • toString

      public String toString()
      Returns a string containing a concise, human-readable description of the receiver.
      Overrides:
      toString in class Object
      Returns:
      a string representation of the receiver