001    /* ParagraphView.java -- Renders a paragraph in HTML
002       Copyright (C) 2006 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package javax.swing.text.html;
040    
041    import gnu.javax.swing.text.html.css.Length;
042    
043    import java.awt.Graphics;
044    import java.awt.Rectangle;
045    import java.awt.Shape;
046    
047    import javax.swing.SizeRequirements;
048    import javax.swing.text.AttributeSet;
049    import javax.swing.text.Document;
050    import javax.swing.text.Element;
051    import javax.swing.text.StyleConstants;
052    import javax.swing.text.View;
053    
054    /**
055     * Renders a paragraph in HTML. This is a subclass of
056     * {@link javax.swing.text.ParagraphView} with some adjustments for
057     * understanding stylesheets.
058     *
059     * @author Roman Kennke (kennke@aicas.com)
060     */
061    public class ParagraphView
062      extends javax.swing.text.ParagraphView
063    {
064    
065      /**
066       * The attributes used by this view.
067       */
068      private AttributeSet attributes;
069    
070      /**
071       * The stylesheet's box painter.
072       */
073      private StyleSheet.BoxPainter painter;
074    
075      /**
076       * The width as specified in the stylesheet or null if not specified.
077       */
078      private Length cssWidth;
079    
080      /**
081       * The height as specified in the stylesheet or null if not specified.
082       */
083      private Length cssHeight;
084    
085      /**
086       * Creates a new ParagraphView for the specified element.
087       *
088       * @param element the element
089       */
090      public ParagraphView(Element element)
091      {
092        super(element);
093      }
094    
095      /**
096       * Sets the parent of this view. This is implemented to call the parent
097       * functionality and then trigger {@link #setPropertiesFromAttributes} in
098       * order to load the stylesheet attributes.
099       *
100       * @param parent the parent view to set
101       */
102      public void setParent(View parent)
103      {
104        super.setParent(parent);
105        if (parent != null)
106          setPropertiesFromAttributes();
107      }
108    
109      /**
110       * Returns the attributes used by this view. This is implemented to multiplex
111       * the attributes of the model with the attributes of the stylesheet.
112       */
113      public AttributeSet getAttributes()
114      {
115        if (attributes == null)
116          {
117            attributes = getStyleSheet().getViewAttributes(this);
118          }
119        return attributes;
120      }
121    
122      /**
123       * Loads the visual properties of the ParagraphView from the element's
124       * attributes and the stylesheet of the HTML document.
125       */
126      protected void setPropertiesFromAttributes()
127      {
128        super.setPropertiesFromAttributes();
129    
130        // Fetch CSS attributes.
131        attributes = getAttributes();
132        if (attributes != null)
133          {
134            super.setPropertiesFromAttributes();
135            Object o = attributes.getAttribute(CSS.Attribute.TEXT_ALIGN);
136            if (o != null)
137              {
138                String align = o.toString();
139                if (align.equals("left"))
140                  setJustification(StyleConstants.ALIGN_LEFT);
141                else if (align.equals("right"))
142                  setJustification(StyleConstants.ALIGN_RIGHT);
143                else if (align.equals("center"))
144                  setJustification(StyleConstants.ALIGN_CENTER);
145                else if (align.equals("justify"))
146                  setJustification(StyleConstants.ALIGN_JUSTIFIED);
147              }
148    
149            // Fetch StyleSheet's box painter.
150            painter = getStyleSheet().getBoxPainter(attributes);
151            setInsets((short) painter.getInset(TOP, this),
152                      (short) painter.getInset(LEFT, this),
153                      (short) painter.getInset(BOTTOM, this),
154                      (short) painter.getInset(RIGHT, this));
155    
156            StyleSheet ss = getStyleSheet();
157            float emBase = ss.getEMBase(attributes);
158            float exBase = ss.getEXBase(attributes);
159            cssWidth = (Length) attributes.getAttribute(CSS.Attribute.WIDTH);
160            if (cssWidth != null)
161              cssWidth.setFontBases(emBase, exBase);
162            cssHeight = (Length) attributes.getAttribute(CSS.Attribute.WIDTH);
163            if (cssHeight != null)
164              cssHeight.setFontBases(emBase, exBase);
165          }
166      }
167    
168      /**
169       * Returns the stylesheet used by this view.
170       *
171       * @return the stylesheet used by this view
172       */
173      protected StyleSheet getStyleSheet()
174      {
175        Document doc = getDocument();
176        StyleSheet styleSheet = null;
177        if (doc instanceof HTMLDocument)
178          styleSheet = ((HTMLDocument) doc).getStyleSheet();
179        return styleSheet;
180      }
181    
182      /**
183       * Calculates the minor axis requirements of this view. This is implemented
184       * to return the super class'es requirements and modifies the minimumSpan
185       * slightly so that it is not smaller than the length of the longest word.
186       *
187       * @param axis the axis
188       * @param r the SizeRequirements object to be used as return parameter;
189       *        if <code>null</code> a new one will be created
190       *
191       * @return the requirements along the minor layout axis
192       */
193      protected SizeRequirements calculateMinorAxisRequirements(int axis,
194                                                                SizeRequirements r)
195      {
196        r = super.calculateMinorAxisRequirements(axis, r);
197        if (! setCSSSpan(r, axis))
198          {
199            int margin = axis == X_AXIS ? getLeftInset() + getRightInset()
200                                        : getTopInset() + getBottomInset();
201            r.minimum -= margin;
202            r.preferred -= margin;
203            r.maximum -= margin;
204          }
205        return r;
206      }
207    
208      /**
209       * Sets the span on the SizeRequirements object according to the
210       * according CSS span value, when it is set.
211       * 
212       * @param r the size requirements
213       * @param axis the axis
214       *
215       * @return <code>true</code> when the CSS span has been set,
216       *         <code>false</code> otherwise
217       */
218      private boolean setCSSSpan(SizeRequirements r, int axis)
219      {
220        boolean ret = false;
221        if (axis == X_AXIS)
222          {
223            if (cssWidth != null && ! cssWidth.isPercentage())
224              {
225                r.minimum = (int) cssWidth.getValue();
226                r.preferred = (int) cssWidth.getValue();
227                r.maximum = (int) cssWidth.getValue();
228                ret = true;
229              }
230          }
231        else
232          {
233            if (cssHeight != null && ! cssWidth.isPercentage())
234              {
235                r.minimum = (int) cssHeight.getValue();
236                r.preferred = (int) cssHeight.getValue();
237                r.maximum = (int) cssHeight.getValue();
238                ret = true;
239              }
240          }
241        return ret;
242      }
243    
244      /**
245       * Determines if this view is visible or not. If none of the children is
246       * visible and the only visible child is the break that ends the paragraph,
247       * this paragraph is not considered to be visible.
248       *
249       * @return the visibility of this paragraph
250       */
251      public boolean isVisible()
252      {
253        // FIXME: Implement the above specified behaviour.
254        return super.isVisible();
255      }
256    
257      /**
258       * Paints this view. This paints the box using the stylesheet's
259       * box painter for this view and delegates to the super class paint()
260       * afterwards.
261       *
262       * @param g the graphics object
263       * @param a the current allocation of this view
264       */
265      public void paint(Graphics g, Shape a)
266      {
267        if (a != null)
268          {
269            Rectangle r = a instanceof Rectangle ? (Rectangle) a : a.getBounds();
270            painter.paint(g, r.x, r.y, r.width, r.height, this);
271          }
272        super.paint(g, a);
273      }
274    
275      /**
276       * Returns the preferred span of this view. If this view is not visible,
277       * we return <code>0</code>, otherwise the super class is called.
278       *
279       * @param axis the axis
280       *
281       * @return the preferred span of this view
282       */
283      public float getPreferredSpan(int axis)
284      {
285        float span = 0;
286        if (isVisible())
287          span = super.getPreferredSpan(axis);
288        return span;
289      }
290    
291      /**
292       * Returns the minimum span of this view. If this view is not visible,
293       * we return <code>0</code>, otherwise the super class is called.
294       *
295       * @param axis the axis
296       *
297       * @return the minimum span of this view
298       */
299      public float getMinimumSpan(int axis)
300      {
301        float span = 0;
302        if (isVisible())
303          span = super.getMinimumSpan(axis);
304        return span;
305      }
306    
307      /**
308       * Returns the maximum span of this view. If this view is not visible,
309       * we return <code>0</code>, otherwise the super class is called.
310       *
311       * @param axis the axis
312       *
313       * @return the maximum span of this view
314       */
315      public float getMaximumSpan(int axis)
316      {
317        float span = 0;
318        if (isVisible())
319          span = super.getMaximumSpan(axis);
320        return span;
321      }
322    }