/*******************************************************************************
 * Copyright (c) 2000, 2007 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
module dwt.graphics.Transform;

import dwt.dwthelper.utils;

import dwt.DWT;
import dwt.DWTError;
import dwt.DWTException;
import dwt.internal.cocoa.NSAffineTransform;
import dwt.internal.cocoa.NSAffineTransformStruct;
import dwt.internal.cocoa.NSPoint;

/**
 * Instances of this class represent transformation matrices for 
 * points expressed as (x, y) pairs of floating point numbers.
 * <p>
 * Application code must explicitly invoke the <code>Transform.dispose()</code> 
 * method to release the operating system resources managed by each instance
 * when those instances are no longer required.
 * </p>
 * <p>
 * This class requires the operating system's advanced graphics subsystem
 * which may not be available on some platforms.
 * </p>
 * 
 * @since 3.1
 */
public class Transform : Resource {
    /**
     * the OS resource for the Transform
     * (Warning: This field is platform dependent)
     * <p>
     * <b>IMPORTANT:</b> This field is <em>not</em> part of the DWT
     * public API. It is marked public only so that it can be shared
     * within the packages provided by DWT. It is not available on all
     * platforms and should never be accessed from application code.
     * </p>
     */
    public NSAffineTransform handle;
    
/**
 * Constructs a new identity Transform.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 * 
 * @param device the device on which to allocate the Transform
 * 
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
 * </ul>
 * @exception DWTException <ul>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 * @exception DWTError <ul>
 *    <li>ERROR_NO_HANDLES if a handle for the Transform could not be obtained</li>
 * </ul>
 * 
 * @see #dispose()
 */
public Transform (Device device) {
    this(device, 1, 0, 0, 1, 0, 0);
}

/**
 * Constructs a new Transform given an array of elements that represent the 
 * matrix that describes the transformation.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 * 
 * @param device the device on which to allocate the Transform
 * @param elements an array of floats that describe the transformation matrix
 * 
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device, or the elements array is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the elements array is too small to hold the matrix values</li>
 * </ul>
 * @exception DWTException <ul>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 * @exception DWTError <ul>
 *    <li>ERROR_NO_HANDLES if a handle for the Transform could not be obtained</li>
 * </ul>
 * 
 * @see #dispose()
 */
public Transform(Device device, float[] elements) {
    this (device, checkTransform(elements)[0], elements[1], elements[2], elements[3], elements[4], elements[5]);
}

/**
 * Constructs a new Transform given all of the elements that represent the 
 * matrix that describes the transformation.
 * <p>
 * This operation requires the operating system's advanced
 * graphics subsystem which may not be available on some
 * platforms.
 * </p>
 * 
 * @param device the device on which to allocate the Transform
 * @param m11 the first element of the first row of the matrix
 * @param m12 the second element of the first row of the matrix
 * @param m21 the first element of the second row of the matrix
 * @param m22 the second element of the second row of the matrix
 * @param dx the third element of the first row of the matrix
 * @param dy the third element of the second row of the matrix
 * 
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li>
 * </ul>
 * @exception DWTException <ul>
 *    <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li>
 * </ul>
 * @exception DWTError <ul>
 *    <li>ERROR_NO_HANDLES if a handle for the Transform could not be obtained</li>
 * </ul>
 * 
 * @see #dispose()
 */
public Transform (Device device, float m11, float m12, float m21, float m22, float dx, float dy) {
    super(device);
    handle = NSAffineTransform.transform();
    if (handle is null) DWT.error(DWT.ERROR_NO_HANDLES);
    handle.retain();
    setElements(m11, m12, m21, m22, dx, dy);
    init();
}

static float[] checkTransform(float[] elements) {
    if (elements is null) DWT.error(DWT.ERROR_NULL_ARGUMENT);
    if (elements.length < 6) DWT.error(DWT.ERROR_INVALID_ARGUMENT);
    return elements;
}

void destroy() {
    handle.release();
    handle = null;
}

/**
 * Fills the parameter with the values of the transformation matrix
 * that the receiver represents, in the order {m11, m12, m21, m22, dx, dy}.
 *
 * @param elements array to hold the matrix values
 *
 * @exception DWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parameter is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter is too small to hold the matrix values</li>
 * </ul>
 */
public void getElements(float[] elements) {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    if (elements is null) DWT.error(DWT.ERROR_NULL_ARGUMENT);
    if (elements.length < 6) DWT.error(DWT.ERROR_INVALID_ARGUMENT);
    NSAffineTransformStruct struct = handle.transformStruct();
    elements[0] = struct.m11;
    elements[1] = struct.m12;
    elements[2] = struct.m21;
    elements[3] = struct.m22;
    elements[4] = struct.tX;
    elements[5] = struct.tY;
}

public void identity() {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    NSAffineTransformStruct struct = new NSAffineTransformStruct();
    struct.m11 = 1;
    struct.m22 = 1;
    handle.setTransformStruct(struct);
}

/**
 * Modifies the receiver such that the matrix it represents becomes the
 * the mathematical inverse of the matrix it previously represented. 
 *
 * @exception DWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_CANNOT_INVERT_MATRIX - if the matrix is not invertible</li>
 * </ul>
 */
public void invert() {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    NSAffineTransformStruct struct = handle.transformStruct();
    if ((struct.m11 * struct.m22 - struct.m12 * struct.m21) is 0) {
        DWT.error(DWT.ERROR_CANNOT_INVERT_MATRIX);
    }
    handle.invert();
}

/**
 * Returns <code>true</code> if the Transform has been disposed,
 * and <code>false</code> otherwise.
 * <p>
 * This method gets the dispose state for the Transform.
 * When a Transform has been disposed, it is an error to
 * invoke any other method using the Transform.
 *
 * @return <code>true</code> when the Transform is disposed, and <code>false</code> otherwise
 */
public bool isDisposed() {
    return handle is null;
}

/**
 * Returns <code>true</code> if the Transform represents the identity matrix
 * and false otherwise.
 *
 * @return <code>true</code> if the receiver is an identity Transform, and <code>false</code> otherwise
 */
public bool isIdentity() {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    NSAffineTransformStruct struct = handle.transformStruct();
    return struct.m11 is 1 && struct.m12 is 0 && struct.m21 is 0 && struct.m22 is 1 && struct.tX is 0 && struct.tY is 0;
}

/**
 * Modifies the receiver such that the matrix it represents becomes the
 * the result of multiplying the matrix it previously represented by the
 * argument. 
 *
 * @param matrix the matrix to multiply the receiver by
 * 
 * @exception DWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parameter is null</li>
 *    <li>ERROR_INVALID_ARGUMENT - if the parameter has been disposed</li>
 * </ul>
 */
public void multiply(Transform matrix) {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    if (matrix is null) DWT.error(DWT.ERROR_NULL_ARGUMENT);
    if (matrix.isDisposed()) DWT.error(DWT.ERROR_INVALID_ARGUMENT);
    handle.prependTransform(matrix.handle);
}

/**
 * Modifies the receiver so that it represents a transformation that is
 * equivalent to its previous transformation rotated by the specified angle.
 * The angle is specified in degrees and for the identity transform 0 degrees
 * is at the 3 o'clock position. A positive value indicates a clockwise rotation
 * while a negative value indicates a counter-clockwise rotation.
 *
 * @param angle the angle to rotate the transformation by
 * 
 * @exception DWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void rotate(float angle) {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    handle.rotateByDegrees(angle);
}

/**
 * Modifies the receiver so that it represents a transformation that is
 * equivalent to its previous transformation scaled by (scaleX, scaleY).
 * 
 * @param scaleX the amount to scale in the X direction
 * @param scaleY the amount to scale in the Y direction
 * 
 * @exception DWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void scale(float scaleX, float scaleY) {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    handle.scaleXBy(scaleX, scaleY);
}

/**
 * Modifies the receiver to represent a new transformation given all of
 * the elements that represent the matrix that describes that transformation.
 * 
 * @param m11 the first element of the first row of the matrix
 * @param m12 the second element of the first row of the matrix
 * @param m21 the first element of the second row of the matrix
 * @param m22 the second element of the second row of the matrix
 * @param dx the third element of the first row of the matrix
 * @param dy the third element of the second row of the matrix
 * 
 * @exception DWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void setElements(float m11, float m12, float m21, float m22, float dx, float dy) {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    NSAffineTransformStruct struct = new NSAffineTransformStruct();
    struct.m11 = m11;
    struct.m12 = m12;
    struct.m21 = m21;
    struct.m22 = m22;
    struct.tX = dx;
    struct.tY = dy;
    handle.setTransformStruct(struct);
}

public void shear(float shearX, float shearY) {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    NSAffineTransformStruct struct = new NSAffineTransformStruct();
    struct.m11 = 1;
    struct.m12 = shearX;
    struct.m21 = shearY;
    struct.m22 = 1;
    NSAffineTransform matrix = NSAffineTransform.transform();
    matrix.setTransformStruct(struct);
    handle.prependTransform(matrix);
}

/** 
 * Given an array containing points described by alternating x and y values,
 * modify that array such that each point has been replaced with the result of
 * applying the transformation represented by the receiver to that point.
 *
 * @param pointArray an array of alternating x and y values to be transformed
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the point array is null</li>
 * </ul>    
 * @exception DWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void transform(float[] pointArray) {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    if (pointArray is null) DWT.error(DWT.ERROR_NULL_ARGUMENT);
    NSPoint point = new NSPoint();
    int length = pointArray.length / 2;
    for (int i = 0, j = 0; i < length; i++, j += 2) {
        point.x = pointArray[j];
        point.y = pointArray[j + 1];
        point = handle.transformPoint(point);
        pointArray[j] = point.x;                
        pointArray[j + 1] = point.y;                
    }
}

/**
 * Modifies the receiver so that it represents a transformation that is
 * equivalent to its previous transformation translated by (offsetX, offsetY).
 * 
 * @param offsetX the distance to translate in the X direction
 * @param offsetY the distance to translate in the Y direction
 * 
 * @exception DWTException <ul>
 *    <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
 * </ul>
 */
public void translate(float offsetX, float offsetY) {
    if (isDisposed()) DWT.error(DWT.ERROR_GRAPHIC_DISPOSED);
    handle.translateXBy(offsetX, offsetY);
}

/**
 * Returns a string containing a concise, human-readable
 * description of the receiver.
 *
 * @return a string representation of the receiver
 */
public String toString() {
    if (isDisposed()) return "Transform {*DISPOSED*}";
    float[] elements = new float[6];
    getElements(elements);
    return "Transform {" + elements [0] + ", " + elements [1] + ", " +elements [2] + ", " +elements [3] + ", " +elements [4] + ", " +elements [5] + "}";
}

}