"
 COPYRIGHT (c) 1992 by Claus Gittinger
              All Rights Reserved

 This software is furnished under a license and may be used
 only in accordance with the terms of that license and with the
 inclusion of the above copyright notice.   This software may not
 be provided or otherwise made available to, or used by, any
 other person.  No title to or ownership of the software is
 hereby transferred.
"
"{ Package: 'stx:libview' }"

"{ NameSpace: Smalltalk }"

DisplayTransform variableFloatSubclass:#ScaleTransform
	instanceVariableNames:'scale'
	classVariableNames:''
	poolDictionaries:''
	category:'Graphics-Transformations'
!

!ScaleTransform class methodsFor:'documentation'!

copyright
"
 COPYRIGHT (c) 1992 by Claus Gittinger
              All Rights Reserved

 This software is furnished under a license and may be used
 only in accordance with the terms of that license and with the
 inclusion of the above copyright notice.   This software may not
 be provided or otherwise made available to, or used by, any
 other person.  No title to or ownership of the software is
 hereby transferred.
"
!

documentation
"
    instances of ScaleTransform can be used to scale other objects in 2D space.
    This one is used, if only a scale is applied, but no translation.
 
    All 2-D objects are supposed to be able to be transformed using instances of me.  
    Multiple instances of me can also be combined to form a single composite transformation.

    [Instance variables:]
        scale           <Number> or <Point> representing a linear scaling factor.
                        nil is interpreted as 1@1

    [author:]
        Claus Gittinger
"
!

examples
"
    example :
                                                                        [exBegin]
     |v|

     v := View new extent:200@200; openAndWait.
     v paint:Color green.
     v fillRectangle:(10@10 corner:40@40).
     v displayLineFrom:50@50 to:75@100. 

     v transformation:(ScaleTransform withScale:2).
     v paint:Color red.
     v fillRectangle:(10@10 corner:40@40).
     v displayLineFrom:50@50 to:75@100. 
                                                                        [exEnd]

"
! !

!ScaleTransform class methodsFor:'instance creation'!

scale:scaleFactor
    ^ self new scale:scaleFactor
!

withScale:scaleFactor
    ^ self new scale:scaleFactor
! !

!ScaleTransform methodsFor:'accessing'!

inverseTransformation
    "Return the inverse transformation of the receiver"

    ^ ScaleTransform withScale:(1 / scale)
!

scale
    "return a copy of the Point that represents the
     current scale of the receiver."

    scale isNil ifTrue:[^ Point x:1 y:1 ].
    ^ scale copy
!

scale:aScale
    "Set the receiver's scale to aScale, a Point or Number."

    aScale isNil ifTrue:[
        scale := aScale
    ] ifFalse:[
        aScale = 1 ifTrue:[
            scale := nil
        ] ifFalse:[
            scale := aScale asPoint.
            (scale x = 1 and:[scale y = 1]) ifTrue:[
                scale := nil
            ].
        ]
    ].

    "Modified: / 13.6.1998 / 14:04:51 / cg"
!

scaleOfOne
    "Set the scale of the receiver to the identity scale"

    scale := nil
!

scaleX
    "return the current x-scale of the receiver."

    scale isNil ifTrue:[^ 1].
    ^ scale x

    "Created: 21.5.1996 / 21:13:49 / cg"
!

scaleY
    "return the current x-scale of the receiver."

    scale isNil ifTrue:[^ 1].
    ^ scale y

    "Created: 21.5.1996 / 21:13:59 / cg"
!

translation
    "return a copy of the receiver's translation."

    ^ Point x:0 y:0
!

translationX
    "return the x part of the receiver's translation."

    ^ 0 
!

translationY
    "return the y part of the receiver's translation."

    ^ 0 
! !

!ScaleTransform methodsFor:'applying transform'!

applyInverseScaleX:aNumber
    "apply the scale only (if widths are to be transformed)"

    scale isNil ifTrue:[^ aNumber].
    ^ aNumber / scale x
!

applyInverseScaleY:aNumber
    "apply the scale only (if heights are to be transformed)"

    scale isNil ifTrue:[^ aNumber].
    ^ aNumber / scale y
!

applyInverseTo:anObject 
    "Apply the inverse of the receiver to anObject
     and return the result. This can be used to map back from logical
     to physical coordinates, for example."

    scale isNil ifTrue:[
        ^ anObject
    ].
    ^ anObject scaledBy:self inverseScale 
!

applyInverseToX:aNumber
    "Apply the receiver to a number representing an x-coordinate
     and return the result."

    |s|

    scale isNil ifTrue:[s := 1] ifFalse:[s := scale x].
    ^ aNumber / s
!

applyInverseToY:aNumber
    "Apply the receiver to a number representing an y-coordinate
     and return the result."

    |s|

    scale isNil ifTrue:[s := 1] ifFalse:[s := scale y].
    ^ aNumber / s
!

applyScaleX:aNumber
    "apply the scale only (if widths are to be transformed)"

    scale isNil ifTrue:[^ aNumber].
    ^ aNumber * scale x
!

applyScaleY:aNumber
    "apply the scale only (if heights are to be transformed)"

    scale isNil ifTrue:[^ aNumber].
    ^ aNumber * scale y
!

transformPoint:p 
    "Apply the receiver to a point, returning a new point."

    scale isNil ifTrue:[
        ^ p
    ].
    ^ p * scale
!

transformRectangle:aRectangle 
    "Apply the receiver to a rectangle, returning a new rectangle."

    scale isNil ifTrue:[
        ^ aRectangle.
    ].
    ^ aRectangle scaledBy:scale.
! !

!ScaleTransform methodsFor:'printing & storing'!

printOn:aStream
    "append a user printed representation of the receiver to aStream.
     The format is suitable for a human - not meant to be read back."

    aStream nextPutAll:self class name.
    aStream nextPutAll:' scale: '.
    scale printOn:aStream.
! !

!ScaleTransform methodsFor:'private'!

checkScale:aScale
    "Converts aScale to the internal format of a floating-point Point."

    |checkedScale|

    checkedScale := aScale asPoint.
    ^ (checkedScale x asFloat) @ (checkedScale y asFloat)

    "Modified: / 22-01-2015 / 14:21:11 / az"
!

inverseScale
    "return with a Point representing the inverse of my
     scale."

    |newScale|

    newScale := self checkScale:scale.
    ^ (1.0 / newScale x) @ (1.0 / newScale y)
! !

!ScaleTransform methodsFor:'testing'!

isIdentityTransformation
    "return true if this is an identity transformation;
     return false, otherwise."

    ^ scale isNil or:[scale x = 1 and:[scale y = 1]]
!

isNoScale
    "return true if the identity scale is in effect (i.e. saleFactor is 1);
     return false, otherwise."

    scale isNil ifTrue:[^ true].
    ^ scale x = 1 and:[scale y = 1]
! !

!ScaleTransform methodsFor:'transformations'!

scaleBy:aScale 
    "scale the receiver.
     This is a destructive operation, modifying the transformation
     represented by the receiver"

    |newScale|

    aScale isNil ifTrue:[^ self].

    scale isNil ifTrue:[
        newScale := aScale asPoint
    ] ifFalse:[
        newScale := scale * aScale
    ].
    self scale:newScale.
!

scaledBy:aScale 
    "return a new WindowingTransformation with the scale and translation of 
     the receiver both scaled by aScale."

    |checkedScale newScale|

    aScale isNil ifTrue:[
        newScale := scale.
    ] ifFalse:[
        checkedScale := self checkScale:aScale.
        scale isNil ifTrue:[
            newScale := checkedScale
        ] ifFalse:[
            newScale := scale * checkedScale
        ].
    ].
    ^ (self class) withScale:newScale
!

translateBy:aTranslation 
    "translate the receiver.
     This is a destructive operation, modifying the transformation
     represented by the receiver"

    self error:'not allowed'
!

translatedBy:aPoint 
    "return a new WindowingTransformation with the same scale and 
     rotations as the receiver and with a translation of the current 
     translation plus aPoint."

    ^ WindowingTransformation
          scale:scale
          translation:aPoint
! !

!ScaleTransform class methodsFor:'documentation'!

version
    ^ '$Header$'
!

version_CVS
    ^ '$Header$'
! !