/*******************************************************************************
 * Copyright (c) 2000, 2008 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:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.jface.text.MarginPainter;

import dwt.dwthelper.utils;


import dwt.DWT;
import dwt.custom.StyledText;
import dwt.events.PaintEvent;
import dwt.events.PaintListener;
import dwt.graphics.Color;
import dwt.graphics.GC;
import dwt.graphics.Rectangle;


/**
 * Paints a vertical line (margin line) after a given column respecting the text
 * viewer's font.
 * <p>
 * Clients usually instantiate and configure objects of this class.</p>
 * <p>
 * This class is not intended to be subclassed.</p>
 *
 * @since 2.1
 * @noextend This class is not intended to be subclassed by clients.
 */
public class MarginPainter : IPainter, PaintListener {

    /** The widget of the text viewer */
    private StyledText fTextWidget;

    /** The column after which to paint the line, default value <code>80</code> */
    private int fMarginWidth= 80;
    /** The color in which to paint the line */
    private Color fColor;
    /** The line style of the line to be painted, default value <code>DWT.LINE_SOLID</code> */
    private int fLineStyle= DWT.LINE_SOLID;
    /** The line width of the line to be painted, default value <code>1</code> */
    private int fLineWidth= 0; // NOTE: 0 means width is 1 but with optimized performance
    /** The cached x-offset of the <code>fMarginWidth</code> for the current font */
    private int fCachedWidgetX= -1;
    /** The active state of this painter */
    private bool fIsActive= false;

    /**
     * Creates a new painter for the given text viewer.
     *
     * @param textViewer the text viewer
     */
    public MarginPainter(ITextViewer textViewer) {
        fTextWidget= textViewer.getTextWidget();
    }

    /**
     * Sets the column after which to draw the margin line.
     *
     * @param width the column
     */
    public void setMarginRulerColumn(int width) {
        fMarginWidth= width;
        initialize();
    }

    /**
     * Sets the line style of the margin line.
     *
     * @param lineStyle a <code>DWT</code> style constant describing the line style
     */
    public void setMarginRulerStyle(int lineStyle) {
        fLineStyle= lineStyle;
    }

    /**
     * Sets the line width of the margin line.
     *
     * @param lineWidth the line width
     */
    public void setMarginRulerWidth(int lineWidth) {
        if (lineWidth is 1)
            lineWidth= 0; // NOTE: 0 means width is 1 but with optimized performance
        fLineWidth= lineWidth;
    }

    /**
     * Sets the color of the margin line. Must be called before <code>paint</code> is called the first time.
     *
     * @param color the color
     */
    public void setMarginRulerColor(Color color) {
        fColor= color;
    }

    /**
     * Initializes this painter, by flushing and recomputing all caches and causing
     * the widget to be redrawn. Must be called explicitly when font of text widget changes.
     */
    public void initialize() {
        computeWidgetX();
        fTextWidget.redraw();
    }

    /**
     * Computes and remembers the x-offset of the margin column for the
     * current widget font.
     */
    private void computeWidgetX() {
        GC gc= new GC(fTextWidget);
        int pixels= gc.getFontMetrics().getAverageCharWidth();
        gc.dispose();

        fCachedWidgetX= pixels * fMarginWidth;
    }

    /*
     * @see IPainter#deactivate(bool)
     */
    public void deactivate(bool redraw) {
        if (fIsActive) {
            fIsActive= false;
            fCachedWidgetX= -1;
            fTextWidget.removePaintListener(this);
            if (redraw)
                fTextWidget.redraw();
        }
    }

    /*
     * @see IPainter#dispose()
     */
    public void dispose() {
        fTextWidget= null;
    }

    /*
     * @see IPainter#paint(int)
     */
    public void paint(int reason) {
        if (!fIsActive) {
            fIsActive= true;
            fTextWidget.addPaintListener(this);
            if (fCachedWidgetX is -1)
                computeWidgetX();
            fTextWidget.redraw();
        } else if (CONFIGURATION is reason || INTERNAL is reason)
            fTextWidget.redraw();
    }

    /*
     * @see dwt.events.PaintListener#paintControl(dwt.events.PaintEvent)
     */
    public void paintControl(PaintEvent e) {
        if (fTextWidget !is null) {
            int x= fCachedWidgetX - fTextWidget.getHorizontalPixel();
            if (x >= 0) {
                Rectangle area= fTextWidget.getClientArea();
                e.gc.setForeground(fColor);
                e.gc.setLineStyle(fLineStyle);
                e.gc.setLineWidth(fLineWidth);
                e.gc.drawLine(x, 0, x, area.height);
            }
        }
    }

    /*
     * @see dwtx.jface.text.IPainter#setPositionManager(dwtx.jface.text.IPaintPositionManager)
     */
    public void setPositionManager(IPaintPositionManager manager) {
    }
}