Class ViewTransform

java.lang.Object

it.univr.di.cstnu.gui.ViewTransform

public final class ViewTransform
extends Object

Affine pan+zoom transform between model and view coordinates.

Scale is limited to [0.01, 50.0]. No rotation or shear is supported: the transform only scales and translates.

Author:

posenato

Field Summary

Fields

Modifier and Type	Field	Description
static final double	DEFAULT_SCALE	Default scale (1:1).
static final double	MAX_SCALE	Maximum allowed scale factor.
static final double	MIN_SCALE	Minimum allowed scale factor.

Constructor Summary

Constructors

Constructor	Description
ViewTransform()	Creates a new transform initialized to identity (scale 1, no translation).

Method Summary

Modifier and Type	Method	Description
void	fitTo(Rectangle2D modelBounds, Dimension viewSize, double marginPx)	Fit modelBounds into viewSize with marginPx margin on each side.
double	getScale()
void	panBy(double viewDx, double viewDy)	Pan by (viewDx, viewDy) in view space.
void	reset()	Reset to identity (scale=1, no translation).
AffineTransform	toAffineTransform()
Point2D	toModel(Point2D viewPoint)	Convert view coordinates to model coordinates.
Point2D	toView(Point2D modelPoint)	Convert model coordinates to view coordinates.
void	zoomBy(double factor, Point2D pivotInView)	Zoom by factor keeping pivotInView stationary.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DEFAULT_SCALE

public static final double DEFAULT_SCALE

Default scale (1:1).

See Also:

• Constant Field Values

MAX_SCALE

public static final double MAX_SCALE

Maximum allowed scale factor.

See Also:

• Constant Field Values

MIN_SCALE

public static final double MIN_SCALE

Minimum allowed scale factor.

See Also:

• Constant Field Values

Constructor Details

ViewTransform

public ViewTransform()

Creates a new transform initialized to identity (scale 1, no translation).

Method Details

fitTo

public void fitTo(@Nonnull
 Rectangle2D modelBounds,
 @Nonnull
 Dimension viewSize,
 double marginPx)

Fit modelBounds into viewSize with marginPx margin on each side.

Parameters:

modelBounds - the bounding box in model space to fit, not null

viewSize - the size of the view in pixels, not null

marginPx - margin, in pixels, to leave on each side

getScale

public double getScale()

Returns:

the current scale factor

panBy

public void panBy(double viewDx,
 double viewDy)

Pan by (viewDx, viewDy) in view space.

Parameters:

viewDx - horizontal displacement in view coordinates

viewDy - vertical displacement in view coordinates

reset

public void reset()

Reset to identity (scale=1, no translation).

toAffineTransform

@Nonnull
public AffineTransform toAffineTransform()

Returns:

an AffineTransform equivalent to this transform

toModel

@Nonnull
public Point2D toModel(@Nonnull
 Point2D viewPoint)

Convert view coordinates to model coordinates.

Parameters:

viewPoint - a point in view space, not null

Returns:

the corresponding point in model space

toView

@Nonnull
public Point2D toView(@Nonnull
 Point2D modelPoint)

Convert model coordinates to view coordinates.

Parameters:

modelPoint - a point in model space, not null

Returns:

the corresponding point in view space

zoomBy

public void zoomBy(double factor,
 @Nonnull
 Point2D pivotInView)

Zoom by factor keeping pivotInView stationary. The model point that was under pivotInView before the call stays under pivotInView after the call.

Parameters:

factor - the multiplicative zoom factor (> 1 zooms in, < 1 zooms out)

pivotInView - the pivot point in view coordinates, not null