ej.microui.display.transform

Class ImageRotation

java.lang.Object

ej.microui.display.transform.AbstractTransform

ej.microui.display.transform.ImageRotation

public class ImageRotation
extends AbstractTransform

This class holds a context in order to perform a free rotation (0 to 360 degrees) on images. The rotation is specified by the center and the angle. The reference point is the image top-left corner. The rotation point is relative to the current translation of the graphics context where the image will be drawn. The image anchor point is relative to the same translation and to the given alignment.

To rotate an image on itself, use the following lines:

ImageRotation rotation = new ImageRotation();
int imageWidth = image.getWidth();
int imageHeight = image.getHeight();
int rx = x + imageWidth / 2;
int ry = y + imageHeight / 2;
rotation.setRotationCenter(rx, ry);
rotation.setAngle(78);
rotation.drawNearestNeighbor(gc, image, rx, ry, GraphicsContext.HCENTER | GraphicsContext.VCENTER);


To rotate an image around a circle, use the following lines:

ImageRotation rotation = new ImageRotation();
rotation.setRotationCenter(rx, ry);
for (int i = 0; i < 360; i += 45) {
rotation.setAngle(i);
rotation.drawBilinear(gc, image, rx - diameter / 2, ry - diameter / 2,
GraphicsContext.TOP | GraphicsContext.LEFT);
}


An image rotation instance holds a global state for all drawings. Several instances can be created at same time. However a default instance is created on MicroUI framework startup and it always available.

Since:

2.0

Field Summary

Fields

Modifier and Type	Field and Description
static ImageRotation	Singleton Default instance created on MicroUI framework startup.

Constructor Summary

Constructors

Constructor and Description
ImageRotation()

Method Summary

Modifier and Type	Method and Description
void	drawBilinear(GraphicsContext gc, Image image, int x, int y, int anchor) Draws the given Image applying the current rotation.
void	drawNearestNeighbor(GraphicsContext gc, Image image, int x, int y, int anchor) Draws the given Image applying the current rotation.
int	getAngle() Returns the current rotation angle.
int	getRotationX() Returns the current X coordinate.
int	getRotationY() Returns the current Y coordinate.
void	setAngle(int angle) Set the new rotation angle.
void	setRotationCenter(int x, int y) Set the new rotation center coordinates.

Methods inherited from class ej.microui.display.transform.AbstractTransform

getAlpha, getTranslateX, getTranslateY, isMirrored, resetAlpha, resetTranslate, setAlpha, setMirror, translate

Methods inherited from class java.lang.Object

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

Field Detail

Singleton

public static final ImageRotation Singleton

Default instance created on MicroUI framework startup.

Constructor Detail

ImageRotation

public ImageRotation()

Method Detail

getAngle

public int getAngle()

Returns the current rotation angle.

Returns:

the current rotation angle.

setAngle

public void setAngle(int angle)

Set the new rotation angle.

Parameters:

angle - the new rotation angle

setRotationCenter

public void setRotationCenter(int x,
                              int y)

Set the new rotation center coordinates.

Parameters:

x - the x coordinate

y - the y coordinate

getRotationX

public int getRotationX()

Returns the current X coordinate.

Returns:

the current X coordinate.

getRotationY

public int getRotationY()

Returns the current Y coordinate.

Returns:

the current Y coordinate.

drawBilinear

public void drawBilinear(GraphicsContext gc,
                         Image image,
                         int x,
                         int y,
                         int anchor)

Draws the given Image applying the current rotation. This method uses the bilinear algorithm to render the image. This algorithm performs better rendering than nearest neighbor algorithm but it is slower to apply.

Parameters:

gc - the GraphicsContext where render the drawing.

image - the Image to draw

x - the x coordinate of the image reference anchor point

y - the y coordinate of the image reference anchor point

anchor - position of the image reference point around the anchor point

Throws:

java.lang.NullPointerException - if @{code image} or @{code gc} is @{code null}

java.lang.IllegalArgumentException - if anchor is not a valid value (BASELINE is illegal).

See Also:

drawNearestNeighbor(GraphicsContext, Image, int, int, int)

drawNearestNeighbor

public void drawNearestNeighbor(GraphicsContext gc,
                                Image image,
                                int x,
                                int y,
                                int anchor)

Draws the given Image applying the current rotation. This method uses the nearest neighbor algorithm to render the image. This algorithm is faster than bilinear algorithm but its rendering is more simple.

Parameters:

gc - the GraphicsContext where render the drawing.

image - the Image to draw

x - the x coordinate of the image reference anchor point

y - the y coordinate of the image reference anchor point

anchor - position of the image reference point around the anchor point

Throws:

java.lang.NullPointerException - if @{code image} or @{code gc} is @{code null}

java.lang.IllegalArgumentException - if anchor is not a valid value (BASELINE is illegal).

See Also:

drawBilinear(GraphicsContext, Image, int, int, int)