Object subclass:#WindowingTransformation

	instanceVariableNames:'scale translation'

	classVariableNames:''

	poolDictionaries:''

	category:'Graphics-Support'

!

!WindowingTransformation class methodsFor:'instance creation'!

identity

    "returns a windowing transformation with no scaling (1@1) 

     and no translation (0@0)."

    ^ self basicNew scale:nil translation:nil 

!

scale:aScale translation:aTranslation 

    "returns a windowing transformation with a scale factor of  

     aScale and a translation offset of aTranslation."

    ^ self basicNew scale:aScale translation:aTranslation

    "

     |v|

     v := View new realize.

     (Delay forSeconds:3) wait.

     v transformation:(WindowingTransformation scale:2 translation:0).

     'now, everything is magnfied by 2'.

     v displayLineFrom:10@10 to:30@30 

    "

    "

     |v|

     v := View new realize.

     (Delay forSeconds:3) wait.

     v transformation:(WindowingTransformation scale:0.5 translation:0).

     'now, everything is shrunk by 2'.

     v displayLineFrom:10@10 to:30@30 

    "

!

unit:unitSymbol on:device 

    "returns a windowing transformation with scaling 

     for unitSymbol and no translation (0@0).

     With such a transformation, you can draw in your preferred 

     units.

     UnitSymbol may be #mm, #cm, #inch, #point, #twip or #pixel (default).

     Twip is 1/20th of a point, point is 1/72th of an inch

     (i.e. the print-unit which is also used for font sizes etc.) 

     - not to confuse with device pixels."

    |pixelPerUnitV pixelPerUnitH|

    unitSymbol == #mm ifTrue:[

	pixelPerUnitV := device verticalPixelPerMillimeter.

	pixelPerUnitH := device horizontalPixelPerMillimeter 

    ] ifFalse:[

	unitSymbol == #cm ifTrue:[

	    pixelPerUnitV := device verticalPixelPerMillimeter * 10.

	    pixelPerUnitH := device horizontalPixelPerMillimeter * 10 

	] ifFalse:[

	    unitSymbol == #twip ifTrue:[

		pixelPerUnitV := device verticalPixelPerInch / 1440.

		pixelPerUnitH := device horizontalPixelPerInch / 1440 

	    ] ifFalse:[

		unitSymbol == #point ifTrue:[

		    pixelPerUnitV := device verticalPixelPerInch / 72.

		    pixelPerUnitH := device horizontalPixelPerInch / 72 

		] ifFalse:[

		    unitSymbol == #inch ifTrue:[

			pixelPerUnitV := device verticalPixelPerInch.

			pixelPerUnitH := device horizontalPixelPerInch 

		    ] ifFalse:[

			"sorry: unknown unit is taken as pixel"

			^ self new scale:nil translation:nil

		    ]

		]

	    ]

	]

    ].

    ^ self basicNew scale:(pixelPerUnitH @ pixelPerUnitV) translation:nil

    "

     |v|

     v := View new realize.

     (Delay forSeconds:3) wait.

     v transformation:(WindowingTransformation unit:#inch on:Display).

     'now, we can think of drawing in inches ...'.

     v displayLineFrom:0.5@0.5 to:1@1 

    "

window:sourceRectangle viewport:destinationRectangle 

    "returns a windowing transformation with a scale and

     translation computed from sourceRectangle and destinationRectangle.

     The scale and transformation are computed such that sourceRectangle

     is transformed to destinationRectangle. Typically sourceRectangle

     represents the logical coordinateSpace while destinationRectangle 

     represents the device coordinateSpace."

    |sX sY tX tY newScale newTranslation|

    sX := destinationRectangle width / sourceRectangle width.

    sY := destinationRectangle height / sourceRectangle height.

    tX := destinationRectangle left - sourceRectangle left.

    tY := destinationRectangle top - sourceRectangle top.

    ((tX = 1.0) and:[tY = 1.0]) ifTrue:[

	newTranslation := nil

    ] ifFalse:[

	newTranslation := tX @ tY

    ].

    ((sX = 1.0) and:[sY = 1.0]) ifTrue:[

	newScale := nil

    ] ifFalse:[

	newScale := sX @ sY

    ].

    ^ self basicNew scale:newScale translation:newTranslation

    "

     |v|

     v := View new realize.

     (Delay forSeconds:3) wait.

     v transformation:(WindowingTransformation 

				window:(0@0 corner:1@1)

				viewport:(0@0 corner:100@100)).

     'now, we can think of drawing in 0..1/0..1 coordinates'.

     v displayLineFrom:0.1@0.1 to:0.9@0.9 

    "

! !

!

version

    ^ '$Header: /cvs/stx/stx/libview/WindowingTransformation.st,v 1.11 1996-04-23 20:10:42 cg Exp $'

!WindowingTransformation methodsFor:'accessing'!

scale

    "return a copy of the Point that represents the

     current scale of the receiver."

    scale isNil ifTrue:[^ (1@1) copy].

    ^ scale copy

!

scale:aScale

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

    aScale isNil ifTrue:[

	scale := aScale

	scale := aScale asPoint.

scale:aScale translation:aTranslation

    "sets the scale to aScale and the translation to aTranslation."

    aScale isNil ifTrue:[

	scale := aScale

    ] ifFalse:[

	scale := aScale asPoint.

    ].

    aTranslation isNil ifTrue:[

	translation := aTranslation

    ] ifFalse:[

	translation := aTranslation asPoint

    ]

scaleOfOne

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

    scale := nil

translation

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

    translation isNil ifTrue:[^ (0@0) copy].

    ^ translation copy

!

translation:aTranslation

    "Set the receiver's translation to aTranslation, a Point or Number."

    aTranslation isNil ifTrue:[

	translation := aTranslation

    ] ifFalse:[

	translation := aTranslation asPoint

    ]

applyInverseToX:aNumber

    "Apply the receiver to a number representing an x-coordinate

     and return the result."

    |t s|

    scale isNil ifTrue:[s := 1] ifFalse:[s := scale x].

    translation isNil ifTrue:[t := 0] ifFalse:[t := translation x].

    ^ (aNumber - t) / s

!

applyInverseToY:aNumber

    "Apply the receiver to a number representing an y-coordinate

     and return the result."

    |t s|

    scale isNil ifTrue:[s := 1] ifFalse:[s := scale y].

    translation isNil ifTrue:[t := 0] ifFalse:[t := translation y].

    ^ (aNumber - t) / 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

!

applyTo:anObject 

    "Apply the receiver to anObject and return the result."

    |transformedObject|

	    ^ anObject

	^ anObject translatedBy:translation 

    ].

    transformedObject := anObject scaledBy:scale.

    translation notNil ifTrue:[

	transformedObject translateBy:translation.

    ^ transformedObject

!

applyToX:aNumber

    "Apply the receiver to a number representing an x-coordinate

     and return the result."

    |t s|

    scale isNil ifTrue:[s := 1] ifFalse:[s := scale x].

    translation isNil ifTrue:[t := 0] ifFalse:[t := translation x].

    ^ aNumber * s + t

!

applyToY:aNumber

    "Apply the receiver to a number representing an y-coordinate

     and return the result."

    |t s|

    scale isNil ifTrue:[s := 1] ifFalse:[s := scale y].

    translation isNil ifTrue:[t := 0] ifFalse:[t := translation y].

    ^ aNumber * s + t

transformPoint:p 

    "Apply the receiver to a point.

     This is destructive in that the point is being modified,

     not a copy."

    scale isNil ifTrue:[

	translation isNil ifTrue:[

	    ^ p

	^ p + translation

    ].

    translation isNil ifTrue:[

	^ p * scale

    ^ (p * scale + translation)

! !

!WindowingTransformation methodsFor:'printing'!

printOn:aStream

    aStream nextPutAll:self class name.

    aStream nextPutAll:' scale: '.

    scale printOn:aStream.

    aStream nextPutAll:' translation: '.

    translation printOn:aStream