JDK8/Java8源码在线阅读

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package javax.swing.text;

import java.awt.*;
import javax.swing.Icon;
import javax.swing.event.*;

/**
 * Icon decorator that implements the view interface.  The
 * entire element is used to represent the icon.  This acts
 * as a gateway from the display-only View implementations to
 * interactive lightweight icons (that is, it allows icons
 * to be embedded into the View hierarchy.  The parent of the icon
 * is the container that is handed out by the associated view
 * factory.
 *
 * @author Timothy Prinzing
 */
public class IconView extends View  {

    /**
     * Creates a new icon view that represents an element.
     *
     * @param elem the element to create a view for
     */
    public IconView(Element elem) {
        super(elem);
        AttributeSet attr = elem.getAttributes();
        c = StyleConstants.getIcon(attr);
    }

    // --- View methods ---------------------------------------------

    /**
     * Paints the icon.
     * The real paint behavior occurs naturally from the association
     * that the icon has with its parent container (the same
     * container hosting this view), so this simply allows us to
     * position the icon properly relative to the view.  Since
     * the coordinate system for the view is simply the parent
     * containers, positioning the child icon is easy.
     *
     * @param g the rendering surface to use
     * @param a the allocated region to render into
     * @see View#paint
     */
    public void paint(Graphics g, Shape a) {
        Rectangle alloc = a.getBounds();
        c.paintIcon(getContainer(), g, alloc.x, alloc.y);
    }

    /**
     * Determines the preferred span for this view along an
     * axis.
     *
     * @param axis may be either View.X_AXIS or View.Y_AXIS
     * @return  the span the view would like to be rendered into
     *           Typically the view is told to render into the span
     *           that is returned, although there is no guarantee.
     *           The parent may choose to resize or break the view.
     * @exception IllegalArgumentException for an invalid axis
     */
    public float getPreferredSpan(int axis) {
        switch (axis) {
        case View.X_AXIS:
            return c.getIconWidth();
        case View.Y_AXIS:
            return c.getIconHeight();
        default:
            throw new IllegalArgumentException("Invalid axis: " + axis);
        }
    }

    /**
     * Determines the desired alignment for this view along an
     * axis.  This is implemented to give the alignment to the
     * bottom of the icon along the y axis, and the default
     * along the x axis.
     *
     * @param axis may be either View.X_AXIS or View.Y_AXIS
     * @return the desired alignment >= 0.0f && <= 1.0f.  This should be
     *   a value between 0.0 and 1.0 where 0 indicates alignment at the
     *   origin and 1.0 indicates alignment to the full span
     *   away from the origin.  An alignment of 0.5 would be the
     *   center of the view.
     */
    public float getAlignment(int axis) {
        switch (axis) {
        case View.Y_AXIS:
            return 1;
        default:
            return super.getAlignment(axis);
        }
    }

    /**
     * Provides a mapping from the document model coordinate space
     * to the coordinate space of the view mapped to it.
     *
     * @param pos the position to convert >= 0
     * @param a the allocated region to render into
     * @return the bounding box of the given position
     * @exception BadLocationException  if the given position does not
     *   represent a valid location in the associated document
     * @see View#modelToView
     */
    public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {
        int p0 = getStartOffset();
        int p1 = getEndOffset();
        if ((pos >= p0) && (pos <= p1)) {
            Rectangle r = a.getBounds();
            if (pos == p1) {
                r.x += r.width;
            }
            r.width = 0;
            return r;
        }
        throw new BadLocationException(pos + " not in range " + p0 + "," + p1, pos);
    }

    /**
     * Provides a mapping from the view coordinate space to the logical
     * coordinate space of the model.
     *
     * @param x the X coordinate &gt;= 0
     * @param y the Y coordinate &gt;= 0

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