"{ Encoding: utf8 }"
"{ Package: 'stx:libview' }"
"{ NameSpace: Smalltalk }"
DisplayTransform variableFloatSubclass:#ScaleTransform
instanceVariableNames:'scale'
classVariableNames:''
poolDictionaries:''
category:'Graphics-Transformations'
!
!ScaleTransform class methodsFor:'documentation'!
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'!
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
^ '$Header$'
! !