/*******************************************************************************
 * 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
 *     
 * Port to the D programming language:
 *     Jacob Carlborg <jacob.carlborg@gmail.com>
 *******************************************************************************/
module dwt.custom.ControlEditor;

import Math = tango.math.Math;

import dwt.DWT;
import dwt.graphics.Rectangle;
import dwt.widgets.Composite;
import dwt.widgets.Control;
import dwt.widgets.Event;
import dwt.widgets.Listener;
import dwt.widgets.ScrollBar;

/**
 *
 * A ControlEditor is a manager for a Control that appears above a composite and tracks with the
 * moving and resizing of that composite.  It can be used to display one control above 
 * another control.  This could be used when editing a control that does not have editing 
 * capabilities by using a text editor or for launching a dialog by placing a button 
 * above a control.
 *
 * <p> Here is an example of using a ControlEditor:
 *
 * <code><pre>
 * Canvas canvas = new Canvas(shell, DWT.BORDER);
 * canvas.setBounds(10, 10, 300, 300);  
 * Color color = new Color(null, 255, 0, 0);
 * canvas.setBackground(color);
 * ControlEditor editor = new ControlEditor (canvas);
 * // The editor will be a button in the bottom right corner of the canvas.
 * // When selected, it will launch a Color dialog that will change the background 
 * // of the canvas.
 * Button button = new Button(canvas, DWT.PUSH);
 * button.setText("Select Color...");
 * button.addSelectionListener (new SelectionAdapter() {
 *  public void widgetSelected(SelectionEvent e) {
 *      ColorDialog dialog = new ColorDialog(shell);
 *      dialog.open();
 *      RGB rgb = dialog.getRGB();
 *      if (rgb !is null) {
 *          if (color !is null) color.dispose();
 *          color = new Color(null, rgb);
 *          canvas.setBackground(color);
 *      }
 *      
 *  }
 * });
 *
 * editor.horizontalAlignment = DWT.RIGHT;
 * editor.verticalAlignment = DWT.BOTTOM;
 * editor.grabHorizontal = false;
 * editor.grabVertical = false;
 * Point size = button.computeSize(DWT.DEFAULT, DWT.DEFAULT);
 * editor.minimumWidth = size.x;
 * editor.minimumHeight = size.y;
 * editor.setEditor (button);
 * </pre></code>
 */
public class ControlEditor {

    /**
     * Specifies how the editor should be aligned relative to the control.  Allowed values
     * are DWT.LEFT, DWT.RIGHT and DWT.CENTER.  The default value is DWT.CENTER.
     */
    public int horizontalAlignment = DWT.CENTER;

    /**
     * Specifies whether the editor should be sized to use the entire width of the control.
     * True means resize the editor to the same width as the cell.  False means do not adjust 
     * the width of the editor. The default value is false.
     */
    public bool grabHorizontal = false;

    /**
     * Specifies the minimum width the editor can have.  This is used in association with
     * a true value of grabHorizontal.  If the cell becomes smaller than the minimumWidth, the 
     * editor will not made smaller than the minimum width value.  The default value is 0.
     */
    public int minimumWidth = 0;

    /**
     * Specifies how the editor should be aligned relative to the control.  Allowed values
     * are DWT.TOP, DWT.BOTTOM and DWT.CENTER.  The default value is DWT.CENTER.
     */
    public int verticalAlignment = DWT.CENTER;

    /**
     * Specifies whether the editor should be sized to use the entire height of the control.
     * True means resize the editor to the same height as the underlying control.  False means do not adjust 
     * the height of the editor.    The default value is false.
     */
    public bool grabVertical = false;

    /**
     * Specifies the minimum height the editor can have.  This is used in association with
     * a true value of grabVertical.  If the control becomes smaller than the minimumHeight, the 
     * editor will not made smaller than the minimum height value.  The default value is 0.
     */
    public int minimumHeight = 0;

    Composite parent;
    Control editor;
    private bool hadFocus;
    private Listener controlListener;
    private Listener scrollbarListener;

    private const static int[] EVENTS = [DWT.KeyDown, DWT.KeyUp, DWT.MouseDown, DWT.MouseUp, DWT.Resize];

    /**
     * Creates a ControlEditor for the specified Composite.
     *
     * @param parent the Composite above which this editor will be displayed
     *
     */
    public this (Composite parent) {
        this.parent = parent;

        controlListener = new class Listener {
            public void handleEvent (Event e) {
                layout();
            }
        };
        for (int i = 0; i < EVENTS.length; i++) {
            parent.addListener(EVENTS[i], controlListener);
        }

        scrollbarListener = new class Listener {
            public void handleEvent (Event e) {
                scroll(e);
            }
        };
        ScrollBar hBar = parent.getHorizontalBar();
        if (hBar !is null)
            hBar.addListener(DWT.Selection, scrollbarListener);
        ScrollBar vBar = parent.getVerticalBar();
        if (vBar !is null)
            vBar.addListener(DWT.Selection, scrollbarListener);
    }

    Rectangle computeBounds () {
        Rectangle clientArea = parent.getClientArea();
        Rectangle editorRect = new Rectangle(clientArea.x, clientArea.y, minimumWidth, minimumHeight);

        if (grabHorizontal)
            editorRect.width = Math.max(clientArea.width, minimumWidth);

        if (grabVertical)
            editorRect.height = Math.max(clientArea.height, minimumHeight);

        switch (horizontalAlignment) {
            case DWT.RIGHT:
                editorRect.x += clientArea.width - editorRect.width;
            break;
            case DWT.LEFT:
            // do nothing - clientArea.x is the right answer
            break;
            default:
                // default is CENTER
                editorRect.x += (clientArea.width - editorRect.width) / 2;
        }

        switch (verticalAlignment) {
            case DWT.BOTTOM:
                editorRect.y += clientArea.height - editorRect.height;
            break;
            case DWT.TOP:
            // do nothing - clientArea.y is the right answer
            break;
            default:
                // default is CENTER
                editorRect.y += (clientArea.height - editorRect.height) / 2;
        }

        return editorRect;

    }

    /**
     * Removes all associations between the Editor and the underlying composite.  The
     * composite and the editor Control are <b>not</b> disposed.
     */
    public void dispose () {
        if (parent !is null && !parent.isDisposed()) {
            for (int i = 0; i < EVENTS.length; i++) {
                parent.removeListener(EVENTS[i], controlListener);
            }
            ScrollBar hBar = parent.getHorizontalBar();
            if (hBar !is null)
                hBar.removeListener(DWT.Selection, scrollbarListener);
            ScrollBar vBar = parent.getVerticalBar();
            if (vBar !is null)
                vBar.removeListener(DWT.Selection, scrollbarListener);
        }

        parent = null;
        editor = null;
        hadFocus = false;
        controlListener = null;
        scrollbarListener = null;
    }

    /**
     * Returns the Control that is displayed above the composite being edited.
     *
     * @return the Control that is displayed above the composite being edited
     */
    public Control getEditor () {
        return editor;
    }

    /**
     * Lays out the control within the underlying composite.  This
     * method should be called after changing one or more fields to
     * force the Editor to resize.
     * 
     * @since 2.1
     */
    public void layout () {
        if (editor is null || editor.isDisposed())
            return;
        if (editor.getVisible()) {
            hadFocus = editor.isFocusControl();
        } // this doesn't work because
        // resizing the column takes the focus away
        // before we get here
        editor.setBounds(computeBounds());
        if (hadFocus) {
            if (editor is null || editor.isDisposed())
                return;
            editor.setFocus();
        }
    }

    void scroll (Event e) {
        if (editor is null || editor.isDisposed())
            return;
        layout();
    }

    /**
     * Specify the Control that is to be displayed.
     *
     * <p>Note: The Control provided as the editor <b>must</b> be created with its parent 
     * being the Composite specified in the ControlEditor constructor.
     * 
     * @param editor the Control that is displayed above the composite being edited
     */
    public void setEditor (Control editor) {

        if (editor is null) {
            // this is the case where the caller is setting the editor to be blank
            // set all the values accordingly
            this.editor = null;
            return;
        }

        this.editor = editor;
        layout();
        if (this.editor is null || this.editor.isDisposed())
            return;
        editor.setVisible(true);
    }
}