com.sharkysoft.fig.core

Class FigureTransform

java.lang.Object

com.sharkysoft.fig.core.FigureTransform

public class FigureTransform
extends Object

Manages view transformation.

Details: FigureTransform manages the conversion of coordinates between the physical view and the logical figure. The transformation is based on a focus, scale, and rotation. The focus is the logical figure coordinate displayed at the center of the physical view. The scale controls the magnification of the figure in the view. The rotation controls the viewing angle. Each of these properties can be independently configured, and adjustments to these properties result in live changes to the view.

Author:

Sharky

Field Summary

Fields

Modifier and Type	Field and Description
static double	MAX_SCALE Maximum supported scale.
static double	MIN_SCALE Minimum supported scale.

Constructor Summary

Constructors

Constructor and Description
FigureTransform(FigureView iDrawPanel)

Method Summary

Methods

Modifier and Type	Method and Description
void	componentResized()
Point2D	getFocus() Returns view's focus.
double	getPixelSize() Returns logical size of pixel.
double	getRotation() Returns viewing angle.
int	getRotationStep() Returns current rotation value.
double	getScale() Returns current viewing scale.
int	getScaleStep() Returns current viewing scale step.
AffineTransform	getTransform()
void	interactiveRotate(int iTicks)
void	interactiveScale(int iTicks)
void	interactiveTranslate(Point iFrom, Point iTo) Translates view.
void	resumeRepainting() Enables repaint events.
void	rotateGestured(int iTicks) Deprecated. Use interactiveRotate.
void	scaleGestured(int iTicks) Deprecated. Use interactiveScale.
void	setFocus(Point2D iPoint) Centers view on point.
void	setRotation(double iRotation) Sets viewing angle.
void	setRotationStep(int iRotation) Sets new rotation value.
void	setScale(double iScale) Sets viewing scale.
void	setScaleStep(int iStep) Sets viewing scale step.
void	suspendRepainting() Temporarily suspends repaint events.
void	transformToLogical(Point2D ioPoint) Changes physical point to logical point.
void	translateGestured(Point iFrom, Point iTo) Deprecated. Use interactiveTranslate.
void	viewArea(Area iArea)

Methods inherited from class java.lang.Object

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

Field Detail

MIN_SCALE

public static final double MIN_SCALE

Minimum supported scale.

Details: MIN_SCALE is the minimum scale allowed in setScale(double).

See Also:

Constant Field Values

MAX_SCALE

public static final double MAX_SCALE

Maximum supported scale.

Details: MAX_SCALE is the maximum scale allowed in setScale(double).

See Also:

Constant Field Values

Constructor Detail

FigureTransform

public FigureTransform(FigureView iDrawPanel)

Method Detail

suspendRepainting

public void suspendRepainting()

Temporarily suspends repaint events.

Details: Normally, when the transform is changed, this class will generate a repaint event so the view can redraw the figure according to the new transform. There are some instances, however, where you may wish to temporarily disable repaint events. This is useful, for instance, when you need to make multiple transform changes and you would like the repaint event to occur after the final change. Use this method to temporarily suspend repainting. Don't forget to resume repainting with resumeRepainting().

resumeRepainting

public void resumeRepainting()

Enables repaint events.

Details: Use this method to resume painting after suspending it with suspendRepainting(). Calling this method generates a "catch up" repaint event, whether one is actually needed or not.

getFocus

public Point2D getFocus()

Returns view's focus.

Details: By default, the view is centered, or focused, on the figure's origin (i.e., point (0, 0)). However, views can focus on any position in the figure. getFocus returns the logical point in the figure on which the view is focused, or in other words, the logical point displayed at the center of the view.

Returns:

the current focus

See Also:

setFocus(Point2D)

setFocus

public void setFocus(Point2D iPoint)

Centers view on point.

Details: setFocus centers the view on the given logical point in the figure. The display is refreshed automatically.

Parameters:

iPoint - the new focus

See Also:

getFocus()

getRotation

public double getRotation()

Returns viewing angle.

Details: getRotation returns the viewing angle. The value returned is expressed in radians, between -pi and +pi.

Returns:

current viewing angle

setRotation

public void setRotation(double iRotation)

Sets viewing angle.

Details: setRotation sets the current viewing angle to the supplied value, expressed in radians. The display is updated.

The new angle may be expressed in values outside of the -pi to +pi range. However, the farther away from this range the angle is, the less accurate the result. In any case, the angle is normalized before it is used.

Parameters:

iRotation - new viewing angle

getRotationStep

public int getRotationStep()

Returns current rotation value.

Details: In order to avoid rounding error, it may be desirable to process the viewing angle using discrete values. getRotationStep returns the current viewing angle in degrees, rounded to the nearest whole number. The value returned is normalized so that it falls between -180 and +180.

Returns:

current rotation value

See Also:

setRotationStep(int)

setRotationStep

public void setRotationStep(int iRotation)

Sets new rotation value.

Details: In order to avoid rounding errors, it may be desirable to process the viewing angle using discrete values. setRotationStep sets the current viewing angle to the given value, which is expressed in degrees.

Parameters:

iRotation - new rotation value

See Also:

getRotationStep()

getScale

public double getScale()

Returns current viewing scale.

Details: getScale returns the current viewing scale. This value is the ratio of physical viewing units to logical figure units. The value 1.0 indicates that the view is displaying the figure exactly to scale. Values greater than 1 indicate that the view is "zoomed in." Values smaller than 1 indicate that the view is "zoomed out."

Returns:

current scale value

setScale

public void setScale(double iScale)

Sets viewing scale.

Details: setScale sets the current viewing scale to the given value. (See getScale() for the interpretation of scale values.) The view is immediately refreshed.

Parameters:

iScale - new scale value

getScaleStep

public int getScaleStep()

Returns current viewing scale step.

Details: Using setScale(double), the view can be configured to display the figure at any scale. However, to avoid cumulative floating point rounding error, it may be desirable to process the scale value using discrete values. The "scale steps" map discrete integer values to a subset of all available viewing scales. The map is defined as follows:

scale = 2^{step / 10}

In particular, observe that step 0 sets the scale to 1.0. Positive steps magnify, and negative steps reduce.

getScaleStep returns the closest step to the current scale.

Returns:

the current scale step

See Also:

setScaleStep(int)

setScaleStep

public void setScaleStep(int iStep)

Sets viewing scale step.

Details: setScaleStep sets the viewing scale step to the given value. See getScaleStep() for an explanation of scale steps.

Parameters:

iStep - the new scale step

See Also:

getScaleStep()

getPixelSize

public double getPixelSize()

Returns logical size of pixel.

Details: getPixelSize returns the logical size (width or height) of one physical pixel in the view.

Returns:

the logical size

componentResized

public void componentResized()

getTransform

public AffineTransform getTransform()

transformToLogical

public void transformToLogical(Point2D ioPoint)

Changes physical point to logical point.

Details: This method transforms the given point from the physical coordinate system of the view to the logical coordinate system of the figure. The fields of the original point are overwritten with the transformed values.

Parameters:

ioPoint - point to transform

viewArea

public void viewArea(Area iArea)

translateGestured

public void translateGestured(Point iFrom,
                     Point iTo)

Deprecated. Use interactiveTranslate.

Translates view.

Details: translateGestured translates the current figure view in both the X and Y directions, according to the mouse gesture reflected in the parameters. This method supports only the drag style of translate gesture. Thus, when this method is called with iFrom and iTo set to the physical coordinates of the mouse gesture, it will convert the the drag gesture into a corresponding logical translation of the view, regardless of the current view transform. A repaint notice will also be sent to the widget so that the figure can be redrawn in the new position.

Parameters:

iFrom - the beginning drag point

iTo - the ending drag point

interactiveTranslate

public void interactiveTranslate(Point iFrom,
                        Point iTo)

Translates view.

Details: This method translates the current view in both the X and Y directions, according to the user interaction reflected in the parameters. The two points given are interpreted as if they are the beginning and ending mouse coordinates of a drag event that took place in the view. These points are converted into logical coordinates in order to determine the direction and amount of view translation that has been commanded. A repaint notice is automatically sent to the view so the the figure will be redrawn in the new position.

Parameters:

iFrom - the beginning drag point

iTo - the ending drag point

scaleGestured

public void scaleGestured(int iTicks)

Deprecated. Use interactiveScale.

interactiveScale

public void interactiveScale(int iTicks)

rotateGestured

public void rotateGestured(int iTicks)

Deprecated. Use interactiveRotate.

interactiveRotate

public void interactiveRotate(int iTicks)