DisplayTransform subclass:#CompositeTransform
	instanceVariableNames:'globalTransform localTransform'
	classVariableNames:''
	poolDictionaries:''
	category:'Graphics-Transformations'
!

CompositeTransform comment:'A composite transform provides the effect of several levels of coordinate transformations.'!


!CompositeTransform methodsFor:'accessing'!

inverseTransformation
	"Return the inverse transformation of the receiver"
	^self species new
		globalTransform: localTransform inverseTransformation
		localTransform: globalTransform inverseTransformation! !

!CompositeTransform methodsFor:'converting'!

asCompositeTransform
	^self!

asMatrixTransform2x3
	^globalTransform asMatrixTransform2x3
		composedWithLocal: localTransform asMatrixTransform2x3! !

!CompositeTransform methodsFor:'initialization'!

globalTransform: gt localTransform: lt
	globalTransform _ gt.
	localTransform _ lt! !

!CompositeTransform methodsFor:'testing'!

isCompositeTransform
	^true!

isIdentity
	^ globalTransform isIdentity and: [localTransform isIdentity]!

isPureTranslation
	^ globalTransform isPureTranslation and: [localTransform isPureTranslation]! !

!CompositeTransform methodsFor:'transformations'!

invert: aPoint
	^ globalTransform invert: (localTransform invert: aPoint)!

scale
	^ localTransform scale * globalTransform scale!

transform: aPoint
	^ localTransform transform: (globalTransform transform: aPoint)! !

!CompositeTransform methodsFor:'transforming points'!

globalPointToLocal: aPoint
	"Transform aPoint from global coordinates into local coordinates"
	^localTransform globalPointToLocal:
		(globalTransform globalPointToLocal: aPoint)!

localPointToGlobal: aPoint
	"Transform aPoint from global coordinates into local coordinates"
	^globalTransform localPointToGlobal:
		(localTransform localPointToGlobal: aPoint)! !

!CompositeTransform class methodsFor:'documentation'!

version
    ^ '$Header: /cvs/stx/stx/libview2/CompositeTransform.st,v 1.1 1999-10-06 22:23:08 cg Exp $'
! !