src/java.desktop/share/classes/javax/swing/text/html/HRuleView.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * 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.html;

import java.awt.*;
import javax.swing.event.DocumentEvent;
import javax.swing.text.*;
import java.util.Enumeration;
import java.lang.Integer;

/**
 * A view implementation to display an html horizontal
 * rule.
 *
 * @author  Timothy Prinzing
 * @author  Sara Swanson
 */
class HRuleView extends View  {

    /**
     * Creates a new view that represents an <hr> element.
     *
     * @param elem the element to create a view for
     */
    public HRuleView(Element elem) {
        super(elem);
        setPropertiesFromAttributes();
    }

    /**
     * Update any cached values that come from attributes.
     */
    protected void setPropertiesFromAttributes() {
        StyleSheet sheet = ((HTMLDocument)getDocument()).getStyleSheet();
        AttributeSet eAttr = getElement().getAttributes();
        attr = sheet.getViewAttributes(this);

        alignment = StyleConstants.ALIGN_CENTER;
        size = 0;
        noshade = null;
        widthValue = null;

        if (attr != null) {
            // getAlignment() returns ALIGN_LEFT by default, and HR should
            // use ALIGN_CENTER by default, so we check if the alignment
            // attribute is actually defined
            if (attr.getAttribute(StyleConstants.Alignment) != null) {
                alignment = StyleConstants.getAlignment(attr);
            }

            noshade = (String)eAttr.getAttribute(HTML.Attribute.NOSHADE);
            Object value = eAttr.getAttribute(HTML.Attribute.SIZE);
            if (value instanceof String s) {
                try {
                    size = Integer.parseInt(s);
                } catch (NumberFormatException e) {
                    size = 1;
                }
            }
            value = attr.getAttribute(CSS.Attribute.WIDTH);
            if (value instanceof CSS.LengthValue lv) {
                widthValue = lv;
            }
            topMargin = getLength(CSS.Attribute.MARGIN_TOP, attr);
            bottomMargin = getLength(CSS.Attribute.MARGIN_BOTTOM, attr);
            leftMargin = getLength(CSS.Attribute.MARGIN_LEFT, attr);
            rightMargin = getLength(CSS.Attribute.MARGIN_RIGHT, attr);
        }
        else {
            topMargin = bottomMargin = leftMargin = rightMargin = 0;
        }
        size = Math.max(2, size);
    }

    // This will be removed and centralized at some point, need to unify this
    // and avoid private classes.
    private float getLength(CSS.Attribute key, AttributeSet a) {
        CSS.LengthValue lv = (CSS.LengthValue) a.getAttribute(key);
        float len = (lv != null) ? lv.getValue() : 0;
        return len;
    }

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

    /**
     * Paints the view.
     *
     * @param g the graphics context
     * @param a the allocation region for the view
     * @see View#paint
     */
    public void paint(Graphics g, Shape a) {
        Rectangle alloc = (a instanceof Rectangle) ? (Rectangle)a :
                          a.getBounds();
        int x = 0;
        int y = alloc.y + SPACE_ABOVE + (int)topMargin;
        int width = alloc.width - (int)(leftMargin + rightMargin);
        if (widthValue != null) {
            width = (int)widthValue.getValue((float)width);
        }
        int height = alloc.height - (SPACE_ABOVE + SPACE_BELOW +
                                     (int)topMargin + (int)bottomMargin);
        if (size > 0)
                height = size;

        // Align the rule horizontally.
        switch (alignment) {
        case StyleConstants.ALIGN_CENTER:
            x = alloc.x + (alloc.width / 2) - (width / 2);
            break;
        case StyleConstants.ALIGN_RIGHT:
            x = alloc.x + alloc.width - width - (int)rightMargin;
            break;
        case StyleConstants.ALIGN_LEFT:
        default:
            x = alloc.x + (int)leftMargin;
            break;
        }

        // Paint either a shaded rule or a solid line.
        if (noshade != null) {
            g.setColor(Color.black);
            g.fillRect(x, y, width, height);
        }
        else {
            Color bg = getContainer().getBackground();
            Color bottom, top;
            if (bg == null || bg.equals(Color.white)) {
                top = Color.darkGray;
                bottom = Color.lightGray;
            }
            else {
                top = Color.darkGray;
                bottom = Color.white;
            }
            g.setColor(bottom);
            g.drawLine(x + width - 1, y, x + width - 1, y + height - 1);
            g.drawLine(x, y + height - 1, x + width - 1, y + height - 1);
            g.setColor(top);
            g.drawLine(x, y, x + width - 1, y);
            g.drawLine(x, y, x, y + height - 1);
        }

    }


    /**
     * Calculates the desired shape of the rule... this is
     * basically the preferred size of the border.
     *
     * @param axis may be either X_AXIS or Y_AXIS
     * @return the desired span
     * @see View#getPreferredSpan
     */
    public float getPreferredSpan(int axis) {
        switch (axis) {
        case View.X_AXIS:
            return 1;
        case View.Y_AXIS:
            if (size > 0) {
                return size + SPACE_ABOVE + SPACE_BELOW + topMargin +
                    bottomMargin;
            } else {
                if (noshade != null) {
                    return 2 + SPACE_ABOVE + SPACE_BELOW + topMargin +
                        bottomMargin;
                } else {
                    return SPACE_ABOVE + SPACE_BELOW + topMargin +bottomMargin;
                }
            }
        default:
            throw new IllegalArgumentException("Invalid axis: " + axis);
        }
    }

    /**
     * Gets the resize weight for the axis.
     * The rule is: rigid vertically and flexible horizontally.
     *
     * @param axis may be either X_AXIS or Y_AXIS
     * @return the weight
     */
    public int getResizeWeight(int axis) {
        if (axis == View.X_AXIS) {
                return 1;
        } else if (axis == View.Y_AXIS) {
                return 0;
        } else {
            return 0;
        }
    }

    /**
     * Determines how attractive a break opportunity in
     * this view is.  This is implemented to request a forced break.
     *
     * @param axis may be either View.X_AXIS or View.Y_AXIS
     * @param pos the potential location of the start of the
     *   broken view (greater than or equal to zero).
     *   This may be useful for calculating tab
     *   positions.
     * @param len specifies the relative length from <em>pos</em>
     *   where a potential break is desired. The value must be greater
     *   than or equal to zero.
     * @return the weight, which should be a value between
     *   ForcedBreakWeight and BadBreakWeight.
     */
    public int getBreakWeight(int axis, float pos, float len) {
        if (axis == X_AXIS) {
            return ForcedBreakWeight;
        }
        return BadBreakWeight;
    }

    public View breakView(int axis, int offset, float pos, float len) {
        return null;
    }

    /**
     * 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
     * @param a the allocated region to render into
     * @return the bounding box of the given position
     * @throws 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;
        }
        return null;
    }

    /**
     * Provides a mapping from the view coordinate space to the logical
     * coordinate space of the model.
     *
     * @param x the X coordinate
     * @param y the Y coordinate
     * @param a the allocated region to render into
     * @return the location within the model that best represents the
     *  given point of view
     * @see View#viewToModel
     */
    public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) {
        Rectangle alloc = (Rectangle) a;
        if (x < alloc.x + (alloc.width / 2)) {
            bias[0] = Position.Bias.Forward;
            return getStartOffset();
        }
        bias[0] = Position.Bias.Backward;
        return getEndOffset();
    }

    /**
     * Fetches the attributes to use when rendering.  This is
     * implemented to multiplex the attributes specified in the
     * model with a StyleSheet.
     */
    public AttributeSet getAttributes() {
        return attr;
    }

    public void changedUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
        super.changedUpdate(changes, a, f);
        int pos = changes.getOffset();
        if (pos <= getStartOffset() && (pos + changes.getLength()) >=
            getEndOffset()) {
            setPropertiesFromAttributes();
        }
    }

    // --- variables ------------------------------------------------

    private float topMargin;
    private float bottomMargin;
    private float leftMargin;
    private float rightMargin;
    private int alignment = StyleConstants.ALIGN_CENTER;
    private String noshade = null;
    private int size = 0;
    private CSS.LengthValue widthValue;

    private static final int SPACE_ABOVE = 3;
    private static final int SPACE_BELOW = 3;

    /** View Attributes. */
    private AttributeSet attr;
}