guiutils.java

java高级使用教程 全书一共分六章

// GuiUtils - some static GUI utilities
//
// Copyright (C)1996,1998 by Jef Poskanzer <[e-mail]>.  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/

package Acme;

import java.awt.*;
import java.awt.image.*;
import java.applet.*;

/// Some static GUI utilities.
// <P>
// <A HREF="/resources/classes/Acme/GuiUtils.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>

public class GuiUtils
    {

    /// Returns the top available parent of a component.
    public static Component getTopParent( Component comp )
	{
	Component parent;
	while ( ( parent = comp.getParent() ) != null )
	    comp = parent;
	return comp;
	}

    /// Calls pack() on the nearest parent that's a Window.
    public static void packWindow( Component comp )
	{
	while ( comp != null )
	    {
	    if ( comp instanceof Window )
		{
		((Window) comp).pack();
		return;
		}
	    comp = comp.getParent();
	    }
	}


    private static final int SPLINE_THRESH = 3;

    /// Draw a three-point spline.
    public static void drawSpline( Graphics graphics, int x1, int y1, int x2, int y2, int x3, int y3 )
	{
	int xa, ya, xb, yb, xc, yc, xp, yp;

	xa = ( x1 + x2 ) / 2;
	ya = ( y1 + y2 ) / 2;
	xc = ( x2 + x3 ) / 2;
	yc = ( y2 + y3 ) / 2;
	xb = ( xa + xc ) / 2;
	yb = ( ya + yc ) / 2;

	xp = ( x1 + xb ) / 2;
	yp = ( y1 + yb ) / 2;
	if ( Math.abs( xa - xp ) + Math.abs( ya - yp ) > SPLINE_THRESH )
	    drawSpline( graphics, x1, y1, xa, ya, xb, yb );
	else
	    graphics.drawLine( x1, y1, xb, yb );

	xp = ( x3 + xb ) / 2;
	yp = ( y3 + yb ) / 2;
	if ( Math.abs( xc - xp ) + Math.abs( yc - yp ) > SPLINE_THRESH )
	    drawSpline( graphics, xb, yb, xc, yc, x3, y3 );
	else
	    graphics.drawLine( xb, yb, x3, y3 );
	}


    private static final int DDA_SCALE = 8192;

    /// Draw a thick line.
    public static void drawThickLine( Graphics graphics, int x1, int y1, int x2, int y2, int linewidth )
	{
	// Draw the starting point filled.
	graphics.fillOval(
	    x1 - linewidth / 2, y1 - linewidth / 2, linewidth, linewidth );

	// Short-circuit zero-length lines.
	if ( x1 == x2 && y1 == y2 )
	    return;

	/* Draw, using a simple DDA. */
	if ( Math.abs( x2 - x1 ) > Math.abs( y2 - y1 ) )
	    {
	    // Loop over X domain.
	    int dy, srow;
	    int dx, col, row, prevrow;

	    if ( x2 > x1 )
		dx = 1;
	    else
		dx = -1;
	    dy = ( y2 - y1 ) * DDA_SCALE / Math.abs( x2 - x1 );
	    prevrow = row = y1;
	    srow = row * DDA_SCALE + DDA_SCALE / 2;
	    col = x1;
	    for (;;)
		{
		if ( row != prevrow )
		    {
		    graphics.drawOval(
			col - linewidth / 2, prevrow - linewidth / 2,
			linewidth, linewidth );
		    prevrow = row;
		    }
		graphics.drawOval(
		    col - linewidth / 2, row - linewidth / 2,
		    linewidth, linewidth );
		if ( col == x2 )
		    break;
		srow += dy;
		row = srow / DDA_SCALE;
		col += dx;
		}
	    }
	else
	    {
	    // Loop over Y domain.
	    int dx, scol;
	    int dy, col, row, prevcol;

	    if ( y2 > y1 )
		dy = 1;
	    else
		dy = -1;
	    dx = ( x2 - x1 ) * DDA_SCALE / Math.abs( y2 - y1 );
	    row = y1;
	    prevcol = col = x1;
	    scol = col * DDA_SCALE + DDA_SCALE / 2;
	    for ( ; ; )
		{
		if ( col != prevcol )
		    {
		    graphics.drawOval(
			prevcol - linewidth / 2, row - linewidth / 2,
			linewidth, linewidth );
		    prevcol = col;
		    }
		graphics.drawOval(
		    col - linewidth / 2, row - linewidth / 2,
		    linewidth, linewidth );
		if ( row == y2 )
		    break;
		row += dy;
		scol += dx;
		col = scol / DDA_SCALE;
		}
	    }
	}


    /// Parse a color string into a Color.  The color can be specified
    // by name as one of:
    // <BLOCKQUOTE>
    // black blue cyan darkGray gray green lightGray
    // magenta orange pink red white yellow
    // </BLOCKQUOTE>
    // Or, as an #rrggbb hex number, like in Netscape.
    public static Color parseColor( String str )
	{
	if ( str.startsWith( "#" ) )
	    {
	    try
		{
		int h = Integer.parseInt( str.substring( 1 ), 16 );
		return new Color(
		    ( h >>> 16 ) & 0xff, ( h >>> 8 ) & 0xff, h & 0xff );
		}
	    catch ( NumberFormatException e )
		{
		return null;
		}
	    }
	Color color;
	color = parseNamedColor( str );
	if ( color != null )
	    return color;
	if ( str.substring( 0, 4 ).equalsIgnoreCase( "dark" ) )
	    {
	    color = parseNamedColor( str.substring( 4 ) );
	    if ( color != null )
		return color.darker();
	    }
	if ( str.substring( 0, 5 ).equalsIgnoreCase( "light" ) )
	    {
	    color = parseNamedColor( str.substring( 5 ) );
	    if ( color != null )
		return color.brighter();
	    }
	if ( str.substring( 0, 6 ).equalsIgnoreCase( "bright" ) )
	    {
	    color = parseNamedColor( str.substring( 6 ) );
	    if ( color != null )
		return color.brighter();
	    }
	return null;
	}

    private static Color parseNamedColor( String str )
	{
	if ( str.equalsIgnoreCase( "black" ) )
	    return Color.black;
	if ( str.equalsIgnoreCase( "blue" ) )
	    return Color.blue;
	if ( str.equalsIgnoreCase( "cyan" ) )
	    return Color.cyan;
	if ( str.equalsIgnoreCase( "darkGray" ) )
	    return Color.darkGray;
	if ( str.equalsIgnoreCase( "gray" ) )
	    return Color.gray;
	if ( str.equalsIgnoreCase( "green" ) )
	    return Color.green;
	if ( str.equalsIgnoreCase( "lightGray" ) )
	    return Color.lightGray;
	if ( str.equalsIgnoreCase( "magenta" ) )
	    return Color.magenta;
	if ( str.equalsIgnoreCase( "orange" ) )
	    return Color.orange;
	if ( str.equalsIgnoreCase( "pink" ) )
	    return Color.pink;
	if ( str.equalsIgnoreCase( "red" ) )
	    return Color.red;
	if ( str.equalsIgnoreCase( "white" ) )
	    return Color.white;
	if ( str.equalsIgnoreCase( "yellow" ) )
	    return Color.yellow;
	return null;
	}