This class represents a transformation for points, that is a combination of scale, offset, and rotation. It is implemented as a 2x3 matrix containing the transformation from the local coordinate system in the global coordinate system. Thus, transforming points from local to global coordinates is fast and cheap whereas transformations from global to local coordinate systems are relatively expensive.

Implementation Note: It is assumed that the transformation deals with Integer points. All transformations will return Integer coordinates (even though float points may be passed in here).

	comparing
	= hash

	composing
	composedWithLocal: composedWithLocal:into:

	converting
	asMatrixTransform2x3

	element access
	a11 a11: a12 a12: a13 a13: a21 a21: a22 a22: a23 a23:

	encoding
	encodeForRemoteCanvas

	initialize
	setIdentiy

	objects from disk
	writeOn:

	printing
	encodePostscriptOn: printOn:

	private
	setAngle: setOffset: setScale:

	testing
	isIdentity isMatrixTransform2x3 isPureTranslation

	transforming points
	globalPointToLocal: invertPoint: localPointToGlobal: transformDirection: transformPoint:

	transforming rects
	globalBounds:toLocal: globalBoundsToLocal: localBounds:toGlobal: localBoundsToGlobal:

	accessing	top
	at: Primitive. Assumes receiver is indexable. Answer the value of an indexable element in the receiver. Fail if the argument index is not an Integer or is out of bounds. Essential. See Object documentation whatIsAPrimitive.
	at:put: Primitive. Assumes receiver is indexable. Store the argument value in the indexable element of the receiver indicated by index. Fail if the index is not an Integer or is out of bounds. Or fail if the value is not of the right type for this kind of collection. Answer the value that was stored. Essential. See Object documentation whatIsAPrimitive.
	inverseTransformation Return the inverse transformation of the receiver. The inverse transformation is computed by first calculating the inverse offset and then computing transformations for the two identity vectors (1@0) and (0@1)
	offset
	offset:

	comparing	top
	= Answer whether the receiver and the argument represent the same object. If = is redefined in any subclass, consider also redefining the message hash.
	hash Answer a SmallInteger whose value is related to the receiver's identity. May be overridden, and should be overridden in any classes that define =

	composing	top
	composedWithLocal: Return the composition of the receiver and the local transformation passed in
	composedWithLocal:into: Return the composition of the receiver and the local transformation passed in. Store the composed matrix into result.

	converting	top
	asMatrixTransform2x3 Represent the receiver as a 2x3 matrix transformation

	element access	top
	a11
	a11:
	a12
	a12:
	a13
	a13:
	a21
	a21:
	a22
	a22:
	a23
	a23:

	encoding	top
	encodeForRemoteCanvas encode this transform into a string for use by a RemoteCanvas

	initialize	top
	setIdentiy Initialize the receiver to the identity transformation (e.g., not affecting points)

	objects from disk	top
	writeOn:

	printing	top
	encodePostscriptOn:
	printOn: Append to the argument, aStream, a sequence of characters that identifies the receiver.

	private	top
	setAngle: Set the raw rotation angle in the receiver
	setOffset: Set the raw offset in the receiver
	setScale: Set the raw scale in the receiver

	testing	top
	isIdentity Return true if the receiver is the identity transform; that is, if applying to a point returns the point itself.
	isMatrixTransform2x3 Return true if the receiver is 2x3 matrix transformation
	isPureTranslation Return true if the receiver specifies no rotation or scaling.

	transforming points	top
	globalPointToLocal: Transform aPoint from global coordinates into local coordinates
	invertPoint: Transform aPoint from global coordinates into local coordinates
	localPointToGlobal: Transform aPoint from local coordinates into global coordinates
	transformDirection: Transform aPoint from local coordinates into global coordinates
	transformPoint: Transform aPoint from local coordinates into global coordinates

	transforming rects	top
	globalBounds:toLocal: Transform aRectangle from global coordinates into local coordinates
	globalBoundsToLocal: Transform aRectangle from global coordinates into local coordinates
	localBounds:toGlobal: Transform aRectangle from local coordinates into global coordinates
	localBoundsToGlobal: Transform aRectangle from local coordinates into global coordinates

	instance creation	top
	fromRemoteCanvasEncoding: DisplayTransform fromRemoteCanvasEncoding: 'Matrix,1065353216,0,1137541120,0,1065353216,1131610112,'
	identity
	new Answer a new instance of the receiver (which is a class) with no indexable variables. Fail if the class is indexable.
	newFromStream: Only meant for my subclasses that are raw bits and word-like. For quick unpack form the disk.
	transformFromLocal:toGlobal:
	withAngle:
	withOffset:
	withRotation:
	withScale: