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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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package javax.swing.text.html;

import java.awt.*;
import javax.swing.SizeRequirements;
import javax.swing.event.DocumentEvent;
import javax.swing.text.Document;
import javax.swing.text.Element;
import javax.swing.text.AttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.View;
import javax.swing.text.ViewFactory;
import javax.swing.text.BadLocationException;
import javax.swing.text.JTextComponent;


Displays the a paragraph, and uses css attributes for its
configuration.

Author: Timothy Prinzing
/**
 * Displays the a paragraph, and uses css attributes for its
 * configuration.
 *
 * @author  Timothy Prinzing
 */

public class ParagraphView extends javax.swing.text.ParagraphView {

    
Constructs a ParagraphView for the given element.

Params:
  • elem – the element that this view is responsible for
/**
     * Constructs a ParagraphView for the given element.
     *
     * @param elem the element that this view is responsible for
     */
    public ParagraphView(Element elem) {
        super(elem);
    }

    
Establishes the parent view for this view.  This is
guaranteed to be called before any other methods if the
parent view is functioning properly.

 This is implemented to forward to the superclass as well as call the setPropertiesFromAttributes method to set the paragraph properties from the css attributes. The call is made at this time to ensure the ability to resolve upward through the parents view attributes. 
Params:
  • parent – the new parent, or null if the view is
 being removed from a parent it was previously added
 to
/**
     * Establishes the parent view for this view.  This is
     * guaranteed to be called before any other methods if the
     * parent view is functioning properly.
     * <p>
     * This is implemented
     * to forward to the superclass as well as call the
     * {@link #setPropertiesFromAttributes setPropertiesFromAttributes}
     * method to set the paragraph properties from the css
     * attributes.  The call is made at this time to ensure
     * the ability to resolve upward through the parents
     * view attributes.
     *
     * @param parent the new parent, or null if the view is
     *  being removed from a parent it was previously added
     *  to
     */
    public void setParent(View parent) {
        super.setParent(parent);
        if (parent != null) {
            setPropertiesFromAttributes();
        }
    }

    
Fetches the attributes to use when rendering.  This is
implemented to multiplex the attributes specified in the
model with a StyleSheet.

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

    
Sets up the paragraph from css attributes instead of
the values found in StyleConstants (i.e. which are used
by the superclass).  Since

/**
     * Sets up the paragraph from css attributes instead of
     * the values found in StyleConstants (i.e. which are used
     * by the superclass).  Since
     */
    protected void setPropertiesFromAttributes() {
        StyleSheet sheet = getStyleSheet();
        attr = sheet.getViewAttributes(this);
        painter = sheet.getBoxPainter(attr);
        if (attr != null) {
            super.setPropertiesFromAttributes();
            setInsets((short) painter.getInset(TOP, this),
                      (short) painter.getInset(LEFT, this),
                      (short) painter.getInset(BOTTOM, this),
                      (short) painter.getInset(RIGHT, this));
            Object o = attr.getAttribute(CSS.Attribute.TEXT_ALIGN);
            if (o != null) {
                // set horizontal alignment
                String ta = o.toString();
                if (ta.equals("left")) {
                    setJustification(StyleConstants.ALIGN_LEFT);
                } else if (ta.equals("center")) {
                    setJustification(StyleConstants.ALIGN_CENTER);
                } else if (ta.equals("right")) {
                    setJustification(StyleConstants.ALIGN_RIGHT);
                } else if (ta.equals("justify")) {
                    setJustification(StyleConstants.ALIGN_JUSTIFIED);
                }
            }
            // Get the width/height
            cssWidth = (CSS.LengthValue)attr.getAttribute(
                                        CSS.Attribute.WIDTH);
            cssHeight = (CSS.LengthValue)attr.getAttribute(
                                         CSS.Attribute.HEIGHT);
        }
    }

    
Convenient method to get the StyleSheet.

Returns:the StyleSheet
/**
     * Convenient method to get the StyleSheet.
     *
     * @return the StyleSheet
     */
    protected StyleSheet getStyleSheet() {
        HTMLDocument doc = (HTMLDocument) getDocument();
        return doc.getStyleSheet();
    }


    
Calculate the needs for the paragraph along the minor axis.

If size requirements are explicitly specified for the paragraph, use that requirements. Otherwise, use the requirements of the superclass ParagraphView.


If the axis parameter is neither View.X_AXIS nor View.Y_AXIS, IllegalArgumentException is thrown. If the r parameter is null, a new SizeRequirements object is created, otherwise the supplied SizeRequirements object is returned.


Params:
  • axis –  the minor axis
  • r –  the input SizeRequirements object
Throws:
Returns: the new or adjusted SizeRequirements object
/**
     * Calculate the needs for the paragraph along the minor axis.
     *
     * <p>If size requirements are explicitly specified for the paragraph,
     * use that requirements.  Otherwise, use the requirements of the
     * superclass {@link javax.swing.text.ParagraphView}.</p>
     *
     * <p>If the {@code axis} parameter is neither {@code View.X_AXIS} nor
     * {@code View.Y_AXIS}, {@link IllegalArgumentException} is thrown.  If the
     * {@code r} parameter is {@code null,} a new {@code SizeRequirements}
     * object is created, otherwise the supplied {@code SizeRequirements}
     * object is returned.</p>
     *
     * @param axis  the minor axis
     * @param r     the input {@code SizeRequirements} object
     * @return      the new or adjusted {@code SizeRequirements} object
     * @throws IllegalArgumentException  if the {@code axis} parameter is invalid
     */
    protected SizeRequirements calculateMinorAxisRequirements(
                                                int axis, SizeRequirements r) {
        r = super.calculateMinorAxisRequirements(axis, r);

        if (BlockView.spanSetFromAttributes(axis, r, cssWidth, cssHeight)) {
            // Offset by the margins so that pref/min/max return the
            // right value.
            int margin = (axis == X_AXIS) ? getLeftInset() + getRightInset() :
                                            getTopInset() + getBottomInset();
            r.minimum -= margin;
            r.preferred -= margin;
            r.maximum -= margin;
        }
        return r;
    }


    
Indicates whether or not this view should be
displayed.  If none of the children wish to be
displayed and the only visible child is the
break that ends the paragraph, the paragraph
will not be considered visible.  Otherwise,
it will be considered visible and return true.

Returns:true if the paragraph should be displayed
/**
     * Indicates whether or not this view should be
     * displayed.  If none of the children wish to be
     * displayed and the only visible child is the
     * break that ends the paragraph, the paragraph
     * will not be considered visible.  Otherwise,
     * it will be considered visible and return true.
     *
     * @return true if the paragraph should be displayed
     */
    public boolean isVisible() {

        int n = getLayoutViewCount() - 1;
        for (int i = 0; i < n; i++) {
            View v = getLayoutView(i);
            if (v.isVisible()) {
                return true;
            }
        }
        if (n > 0) {
            View v = getLayoutView(n);
            if ((v.getEndOffset() - v.getStartOffset()) == 1) {
                return false;
            }
        }
        // If it's the last paragraph and not editable, it shouldn't
        // be visible.
        if (getStartOffset() == getDocument().getLength()) {
            boolean editable = false;
            Component c = getContainer();
            if (c instanceof JTextComponent) {
                editable = ((JTextComponent)c).isEditable();
            }
            if (!editable) {
                return false;
            }
        }
        return true;
    }

    
Renders using the given rendering surface and area on that
surface.  This is implemented to delegate to the superclass
after stashing the base coordinate for tab calculations.

Params:
  • g – the rendering surface to use
  • a – the allocated region to render into
See Also:
/**
     * Renders using the given rendering surface and area on that
     * surface.  This is implemented to delegate to the superclass
     * after stashing the base coordinate for tab calculations.
     *
     * @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) {
        if (a == null) {
            return;
        }

        Rectangle r;
        if (a instanceof Rectangle) {
            r = (Rectangle) a;
        } else {
            r = a.getBounds();
        }
        painter.paint(g, r.x, r.y, r.width, r.height, this);
        super.paint(g, a);
    }

    
Determines the preferred span for this view.  Returns
0 if the view is not visible, otherwise it calls the
superclass method to get the preferred span.
axis.

Params:
  • axis – may be either View.X_AXIS or View.Y_AXIS
See Also:
Returns:  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
/**
     * Determines the preferred span for this view.  Returns
     * 0 if the view is not visible, otherwise it calls the
     * superclass method to get the preferred span.
     * 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
     * @see javax.swing.text.ParagraphView#getPreferredSpan
     */
    public float getPreferredSpan(int axis) {
        if (!isVisible()) {
            return 0;
        }
        return super.getPreferredSpan(axis);
    }

    
Determines the minimum span for this view along an
axis.  Returns 0 if the view is not visible, otherwise
it calls the superclass method to get the minimum span.

Params:
  • axis – may be either View.X_AXIS or
 View.Y_AXIS
See Also:
Returns: the minimum span the view can be rendered into
/**
     * Determines the minimum span for this view along an
     * axis.  Returns 0 if the view is not visible, otherwise
     * it calls the superclass method to get the minimum span.
     *
     * @param axis may be either <code>View.X_AXIS</code> or
     *  <code>View.Y_AXIS</code>
     * @return  the minimum span the view can be rendered into
     * @see javax.swing.text.ParagraphView#getMinimumSpan
     */
    public float getMinimumSpan(int axis) {
        if (!isVisible()) {
            return 0;
        }
        return super.getMinimumSpan(axis);
    }

    
Determines the maximum span for this view along an
axis.  Returns 0 if the view is not visible, otherwise
it calls the superclass method ot get the maximum span.

Params:
  • axis – may be either View.X_AXIS or
 View.Y_AXIS
See Also:
Returns: the maximum span the view can be rendered into
/**
     * Determines the maximum span for this view along an
     * axis.  Returns 0 if the view is not visible, otherwise
     * it calls the superclass method ot get the maximum span.
     *
     * @param axis may be either <code>View.X_AXIS</code> or
     *  <code>View.Y_AXIS</code>
     * @return  the maximum span the view can be rendered into
     * @see javax.swing.text.ParagraphView#getMaximumSpan
     */
    public float getMaximumSpan(int axis) {
        if (!isVisible()) {
            return 0;
        }
        return super.getMaximumSpan(axis);
    }

    private AttributeSet attr;
    private StyleSheet.BoxPainter painter;
    private CSS.LengthValue cssWidth;
    private CSS.LengthValue cssHeight;
}