My instances are used to transform objects from a source coordinate system to a destination coordinate system. Each instance contains a scale and a translation which can be applied to objects that respond to scaleBy: and translateBy:. It can be created with a default identity scale and translation, or with a specified scale and translation, or with a scale and translation computed from a window (a Rectangle in the source coordinate system) and a viewport (a Rectangle in the destination coordinate system). In applying a WindowingTransformation to an object, the object is first scaled (around the origin of the source coordinate system) and then translated. WindowingTransformations can be composed to form a single compound transformation.

	printing
	printOn:

	private
	checkScale: setScale:translation:

	scrolling
	scrollBy:

	transforming
	align:with: noScale scale scaleBy: translateBy: translation

	applying transform	top
	applyInverseTo: Apply the inverse of the receiver to anObject and answer the result. Used to map some object in destination coordinates to one in source coordinates.
	applyTo: Apply the receiver to anObject and answer the result. Used to map some object in source coordinates to one in destination coordinates.
	compose: Answer a WindowingTransformation that is the composition of the receiver and aTransformation. The effect of applying the resulting WindowingTransformation to an object is the same as that of first applying aTransformation to the object and then applying the receiver to its result.

	printing	top
	printOn: Refer to the comment in Object|printOn:.

	private	top
	checkScale: Convert aScale to the internal format of a floating-point Point.
	setScale:translation: Sets the scale to aScale and the translation to aTranslation.

	scrolling	top
	scrollBy: Answer a WindowingTransformation with the same scale as the receiver and with a translation of the current translation plus aPoint scaled by the current scale. It is used when the translation is known in source coordinates, rather than scaled source coordinates (see WindowingTransformation|translateBy:). An example is that of scrolling objects with respect to a stationary window in the source coordinate system. If no scaling is in effect (scale = nil), then WindowingTransformation|translateBy: and WindowingTransformation|scrollBy: are equivalent.

	transforming	top
	align:with: Answer a WindowingTransformation with the same scale as the receiver and with a translation of (aPoint2 - aPoint1). It is normally used when the source and destination coordinate systems are scaled the same (that is, there is no scaling between them), and is then a convenient way of specifying a translation, given two points that are intended to coincide.
	noScale Answer true if the identity scale is in effect; answer false, otherwise.
	scale Answer a copy of the point that represents the current scale of the receiver.
	scaleBy: Answer a WindowingTransformation with the scale and translation of the receiver both scaled by aScale.
	translateBy: Answer a WindowingTransformation with the same scale as the receiver and with a translation of the current translation plus aPoint. It is used when the translation is known in scaled source coordinates, rather than source coordinates (see WindowingTransformation|scrollBy:). If no scaling is in effect (scale = nil), then WindowingTransformation|translateBy: and WindowingTransformation|scrollBy: are equivalent.
	translation Answer a copy of the receiver's translation.

	instance creation	top
	identity Answer an instance of me with no scaling (nil) and no translation (0@0).
	scale:translation: Answer an instance of me with a scale factor of aScale and a translation offset of aTranslation. When the transformation is applied (see WindowingTransformation|apply:), the scale is applied first, followed by the translation.
	window:viewport: Answer an instance of me with a scale and translation based on aWindow and aViewport. The scale and translation are computed such that aWindow, when transformed, coincides with aViewport.