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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
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tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/javax/swing/text/Utilities.java
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+/* Utilities.java --
+ Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package javax.swing.text;
+
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Point;
+import java.text.BreakIterator;
+
+import javax.swing.text.Position.Bias;
+
+/**
+ * A set of utilities to deal with text. This is used by several other classes
+ * inside this package.
+ *
+ * @author Roman Kennke (roman@ontographics.com)
+ * @author Robert Schuster (robertschuster@fsfe.org)
+ */
+public class Utilities
+{
+
+ /**
+ * Creates a new <code>Utilities</code> object.
+ */
+ public Utilities()
+ {
+ // Nothing to be done here.
+ }
+
+ /**
+ * Draws the given text segment. Contained tabs and newline characters
+ * are taken into account. Tabs are expanded using the
+ * specified {@link TabExpander}.
+ *
+ *
+ * The X and Y coordinates denote the start of the <em>baseline</em> where
+ * the text should be drawn.
+ *
+ * @param s the text fragment to be drawn.
+ * @param x the x position for drawing.
+ * @param y the y position for drawing.
+ * @param g the {@link Graphics} context for drawing.
+ * @param e the {@link TabExpander} which specifies the Tab-expanding
+ * technique.
+ * @param startOffset starting offset in the text.
+ * @return the x coordinate at the end of the drawn text.
+ */
+ public static final int drawTabbedText(Segment s, int x, int y, Graphics g,
+ TabExpander e, int startOffset)
+ {
+ // This buffers the chars to be drawn.
+ char[] buffer = s.array;
+
+ // The font metrics of the current selected font.
+ FontMetrics metrics = g.getFontMetrics();
+
+ int ascent = metrics.getAscent();
+
+ // The current x and y pixel coordinates.
+ int pixelX = x;
+
+ int pos = s.offset;
+ int len = 0;
+
+ int end = s.offset + s.count;
+
+ for (int offset = s.offset; offset < end; ++offset)
+ {
+ char c = buffer[offset];
+ switch (c)
+ {
+ case '\t':
+ if (len > 0) {
+ g.drawChars(buffer, pos, len, pixelX, y);
+ pixelX += metrics.charsWidth(buffer, pos, len);
+ len = 0;
+ }
+ pos = offset+1;
+ if (e != null)
+ pixelX = (int) e.nextTabStop((float) pixelX, startOffset + offset
+ - s.offset);
+ else
+ pixelX += metrics.charWidth(' ');
+ x = pixelX;
+ break;
+ case '\n':
+ case '\r':
+ if (len > 0) {
+ g.drawChars(buffer, pos, len, pixelX, y);
+ pixelX += metrics.charsWidth(buffer, pos, len);
+ len = 0;
+ }
+ x = pixelX;
+ break;
+ default:
+ len += 1;
+ }
+ }
+
+ if (len > 0)
+ {
+ g.drawChars(buffer, pos, len, pixelX, y);
+ pixelX += metrics.charsWidth(buffer, pos, len);
+ }
+
+ return pixelX;
+ }
+
+ /**
+ * Determines the width, that the given text <code>s</code> would take
+ * if it was printed with the given {@link java.awt.FontMetrics} on the
+ * specified screen position.
+ * @param s the text fragment
+ * @param metrics the font metrics of the font to be used
+ * @param x the x coordinate of the point at which drawing should be done
+ * @param e the {@link TabExpander} to be used
+ * @param startOffset the index in <code>s</code> where to start
+ * @returns the width of the given text s. This takes tabs and newlines
+ * into account.
+ */
+ public static final int getTabbedTextWidth(Segment s, FontMetrics metrics,
+ int x, TabExpander e,
+ int startOffset)
+ {
+ // This buffers the chars to be drawn.
+ char[] buffer = s.array;
+
+ // The current x coordinate.
+ int pixelX = x;
+
+ // The current maximum width.
+ int maxWidth = 0;
+
+ int end = s.offset + s.count;
+ int count = 0;
+ for (int offset = s.offset; offset < end; offset++)
+ {
+ switch (buffer[offset])
+ {
+ case '\t':
+ // In case we have a tab, we just 'jump' over the tab.
+ // When we have no tab expander we just use the width of 'm'.
+ if (e != null)
+ pixelX = (int) e.nextTabStop(pixelX,
+ startOffset + offset - s.offset);
+ else
+ pixelX += metrics.charWidth(' ');
+ break;
+ case '\n':
+ // In case we have a newline, we must 'draw'
+ // the buffer and jump on the next line.
+ pixelX += metrics.charsWidth(buffer, offset - count, count);
+ count = 0;
+ break;
+ default:
+ count++;
+ }
+ }
+
+ // Take the last line into account.
+ pixelX += metrics.charsWidth(buffer, end - count, count);
+
+ return pixelX - x;
+ }
+
+ /**
+ * Provides a facility to map screen coordinates into a model location. For a
+ * given text fragment and start location within this fragment, this method
+ * determines the model location so that the resulting fragment fits best
+ * into the span <code>[x0, x]</code>.
+ *
+ * The parameter <code>round</code> controls which model location is returned
+ * if the view coordinates are on a character: If <code>round</code> is
+ * <code>true</code>, then the result is rounded up to the next character, so
+ * that the resulting fragment is the smallest fragment that is larger than
+ * the specified span. If <code>round</code> is <code>false</code>, then the
+ * resulting fragment is the largest fragment that is smaller than the
+ * specified span.
+ *
+ * @param s the text segment
+ * @param fm the font metrics to use
+ * @param x0 the starting screen location
+ * @param x the target screen location at which the requested fragment should
+ * end
+ * @param te the tab expander to use; if this is <code>null</code>, TABs are
+ * expanded to one space character
+ * @param p0 the starting model location
+ * @param round if <code>true</code> round up to the next location, otherwise
+ * round down to the current location
+ *
+ * @return the model location, so that the resulting fragment fits within the
+ * specified span
+ */
+ public static final int getTabbedTextOffset(Segment s, FontMetrics fm, int x0,
+ int x, TabExpander te, int p0,
+ boolean round)
+ {
+ int found = s.count;
+ int currentX = x0;
+ int nextX = currentX;
+
+ int end = s.offset + s.count;
+ for (int pos = s.offset; pos < end && found == s.count; pos++)
+ {
+ char nextChar = s.array[pos];
+
+ if (nextChar != '\t')
+ nextX += fm.charWidth(nextChar);
+ else
+ {
+ if (te == null)
+ nextX += fm.charWidth(' ');
+ else
+ nextX += ((int) te.nextTabStop(nextX, p0 + pos - s.offset));
+ }
+
+ if (x >= currentX && x < nextX)
+ {
+ // Found position.
+ if ((! round) || ((x - currentX) < (nextX - x)))
+ {
+ found = pos - s.offset;
+ }
+ else
+ {
+ found = pos + 1 - s.offset;
+ }
+ }
+ currentX = nextX;
+ }
+
+ return found;
+ }
+
+ /**
+ * Provides a facility to map screen coordinates into a model location. For a
+ * given text fragment and start location within this fragment, this method
+ * determines the model location so that the resulting fragment fits best
+ * into the span <code>[x0, x]</code>.
+ *
+ * This method rounds up to the next location, so that the resulting fragment
+ * will be the smallest fragment of the text, that is greater than the
+ * specified span.
+ *
+ * @param s the text segment
+ * @param fm the font metrics to use
+ * @param x0 the starting screen location
+ * @param x the target screen location at which the requested fragment should
+ * end
+ * @param te the tab expander to use; if this is <code>null</code>, TABs are
+ * expanded to one space character
+ * @param p0 the starting model location
+ *
+ * @return the model location, so that the resulting fragment fits within the
+ * specified span
+ */
+ public static final int getTabbedTextOffset(Segment s, FontMetrics fm, int x0,
+ int x, TabExpander te, int p0)
+ {
+ return getTabbedTextOffset(s, fm, x0, x, te, p0, true);
+ }
+
+ /**
+ * Finds the start of the next word for the given offset.
+ *
+ * @param c
+ * the text component
+ * @param offs
+ * the offset in the document
+ * @return the location in the model of the start of the next word.
+ * @throws BadLocationException
+ * if the offset is invalid.
+ */
+ public static final int getNextWord(JTextComponent c, int offs)
+ throws BadLocationException
+ {
+ if (offs < 0 || offs > (c.getText().length() - 1))
+ throw new BadLocationException("invalid offset specified", offs);
+ String text = c.getText();
+ BreakIterator wb = BreakIterator.getWordInstance();
+ wb.setText(text);
+
+ int last = wb.following(offs);
+ int current = wb.next();
+ int cp;
+
+ while (current != BreakIterator.DONE)
+ {
+ for (int i = last; i < current; i++)
+ {
+ cp = text.codePointAt(i);
+
+ // Return the last found bound if there is a letter at the current
+ // location or is not whitespace (meaning it is a number or
+ // punctuation). The first case means that 'last' denotes the
+ // beginning of a word while the second case means it is the start
+ // of something else.
+ if (Character.isLetter(cp)
+ || !Character.isWhitespace(cp))
+ return last;
+ }
+ last = current;
+ current = wb.next();
+ }
+
+ throw new BadLocationException("no more words", offs);
+ }
+
+ /**
+ * Finds the start of the previous word for the given offset.
+ *
+ * @param c
+ * the text component
+ * @param offs
+ * the offset in the document
+ * @return the location in the model of the start of the previous word.
+ * @throws BadLocationException
+ * if the offset is invalid.
+ */
+ public static final int getPreviousWord(JTextComponent c, int offs)
+ throws BadLocationException
+ {
+ String text = c.getText();
+
+ if (offs <= 0 || offs > text.length())
+ throw new BadLocationException("invalid offset specified", offs);
+
+ BreakIterator wb = BreakIterator.getWordInstance();
+ wb.setText(text);
+ int last = wb.preceding(offs);
+ int current = wb.previous();
+ int cp;
+
+ while (current != BreakIterator.DONE)
+ {
+ for (int i = last; i < offs; i++)
+ {
+ cp = text.codePointAt(i);
+
+ // Return the last found bound if there is a letter at the current
+ // location or is not whitespace (meaning it is a number or
+ // punctuation). The first case means that 'last' denotes the
+ // beginning of a word while the second case means it is the start
+ // of some else.
+ if (Character.isLetter(cp)
+ || !Character.isWhitespace(cp))
+ return last;
+ }
+ last = current;
+ current = wb.previous();
+ }
+
+ return 0;
+ }
+
+ /**
+ * Finds the start of a word for the given location.
+ * @param c the text component
+ * @param offs the offset location
+ * @return the location of the word beginning
+ * @throws BadLocationException if the offset location is invalid
+ */
+ public static final int getWordStart(JTextComponent c, int offs)
+ throws BadLocationException
+ {
+ String text = c.getText();
+
+ if (offs < 0 || offs > text.length())
+ throw new BadLocationException("invalid offset specified", offs);
+
+ BreakIterator wb = BreakIterator.getWordInstance();
+ wb.setText(text);
+
+ if (wb.isBoundary(offs))
+ return offs;
+
+ return wb.preceding(offs);
+ }
+
+ /**
+ * Finds the end of a word for the given location.
+ * @param c the text component
+ * @param offs the offset location
+ * @return the location of the word end
+ * @throws BadLocationException if the offset location is invalid
+ */
+ public static final int getWordEnd(JTextComponent c, int offs)
+ throws BadLocationException
+ {
+ if (offs < 0 || offs >= c.getText().length())
+ throw new BadLocationException("invalid offset specified", offs);
+
+ String text = c.getText();
+ BreakIterator wb = BreakIterator.getWordInstance();
+ wb.setText(text);
+ return wb.following(offs);
+ }
+
+ /**
+ * Get the model position of the end of the row that contains the
+ * specified model position. Return null if the given JTextComponent
+ * does not have a size.
+ * @param c the JTextComponent
+ * @param offs the model position
+ * @return the model position of the end of the row containing the given
+ * offset
+ * @throws BadLocationException if the offset is invalid
+ */
+ public static final int getRowEnd(JTextComponent c, int offs)
+ throws BadLocationException
+ {
+ String text = c.getText();
+ if (text == null)
+ return -1;
+
+ // Do a binary search for the smallest position X > offs
+ // such that that character at positino X is not on the same
+ // line as the character at position offs
+ int high = offs + ((text.length() - 1 - offs) / 2);
+ int low = offs;
+ int oldHigh = text.length() + 1;
+ while (true)
+ {
+ if (c.modelToView(high).y != c.modelToView(offs).y)
+ {
+ oldHigh = high;
+ high = low + ((high + 1 - low) / 2);
+ if (oldHigh == high)
+ return high - 1;
+ }
+ else
+ {
+ low = high;
+ high += ((oldHigh - high) / 2);
+ if (low == high)
+ return low;
+ }
+ }
+ }
+
+ /**
+ * Get the model position of the start of the row that contains the specified
+ * model position. Return null if the given JTextComponent does not have a
+ * size.
+ *
+ * @param c the JTextComponent
+ * @param offs the model position
+ * @return the model position of the start of the row containing the given
+ * offset
+ * @throws BadLocationException if the offset is invalid
+ */
+ public static final int getRowStart(JTextComponent c, int offs)
+ throws BadLocationException
+ {
+ String text = c.getText();
+ if (text == null)
+ return -1;
+
+ // Do a binary search for the greatest position X < offs
+ // such that the character at position X is not on the same
+ // row as the character at position offs
+ int high = offs;
+ int low = 0;
+ int oldLow = 0;
+ while (true)
+ {
+ if (c.modelToView(low).y != c.modelToView(offs).y)
+ {
+ oldLow = low;
+ low = high - ((high + 1 - low) / 2);
+ if (oldLow == low)
+ return low + 1;
+ }
+ else
+ {
+ high = low;
+ low -= ((low - oldLow) / 2);
+ if (low == high)
+ return low;
+ }
+ }
+ }
+
+ /**
+ * Determine where to break the text in the given Segment, attempting to find
+ * a word boundary.
+ * @param s the Segment that holds the text
+ * @param metrics the font metrics used for calculating the break point
+ * @param x0 starting view location representing the start of the text
+ * @param x the target view location
+ * @param e the TabExpander used for expanding tabs (if this is null tabs
+ * are expanded to 1 space)
+ * @param startOffset the offset in the Document of the start of the text
+ * @return the offset at which we should break the text
+ */
+ public static final int getBreakLocation(Segment s, FontMetrics metrics,
+ int x0, int x, TabExpander e,
+ int startOffset)
+ {
+ int mark = Utilities.getTabbedTextOffset(s, metrics, x0, x, e, startOffset,
+ false);
+ int breakLoc = mark;
+ // If mark is equal to the end of the string, just use that position.
+ if (mark < s.count - 1)
+ {
+ for (int i = s.offset + mark; i >= s.offset; i--)
+ {
+ char ch = s.array[i];
+ if (ch < 256)
+ {
+ // For ASCII simply scan backwards for whitespace.
+ if (Character.isWhitespace(ch))
+ {
+ breakLoc = i - s.offset + 1;
+ break;
+ }
+ }
+ else
+ {
+ // Only query BreakIterator for complex chars.
+ BreakIterator bi = BreakIterator.getLineInstance();
+ bi.setText(s);
+ int pos = bi.preceding(i + 1);
+ if (pos > s.offset)
+ {
+ breakLoc = breakLoc - s.offset;
+ }
+ break;
+ }
+ }
+ }
+ return breakLoc;
+ }
+
+ /**
+ * Returns the paragraph element in the text component <code>c</code> at
+ * the specified location <code>offset</code>.
+ *
+ * @param c the text component
+ * @param offset the offset of the paragraph element to return
+ *
+ * @return the paragraph element at <code>offset</code>
+ */
+ public static final Element getParagraphElement(JTextComponent c, int offset)
+ {
+ Document doc = c.getDocument();
+ Element par = null;
+ if (doc instanceof StyledDocument)
+ {
+ StyledDocument styledDoc = (StyledDocument) doc;
+ par = styledDoc.getParagraphElement(offset);
+ }
+ else
+ {
+ Element root = c.getDocument().getDefaultRootElement();
+ int parIndex = root.getElementIndex(offset);
+ par = root.getElement(parIndex);
+ }
+ return par;
+ }
+
+ /**
+ * Returns the document position that is closest above to the specified x
+ * coordinate in the row containing <code>offset</code>.
+ *
+ * @param c the text component
+ * @param offset the offset
+ * @param x the x coordinate
+ *
+ * @return the document position that is closest above to the specified x
+ * coordinate in the row containing <code>offset</code>
+ *
+ * @throws BadLocationException if <code>offset</code> is not a valid offset
+ */
+ public static final int getPositionAbove(JTextComponent c, int offset, int x)
+ throws BadLocationException
+ {
+ int offs = getRowStart(c, offset);
+
+ if(offs == -1)
+ return -1;
+
+ // Effectively calculates the y value of the previous line.
+ Point pt = c.modelToView(offs-1).getLocation();
+
+ pt.x = x;
+
+ // Calculate a simple fitting offset.
+ offs = c.viewToModel(pt);
+
+ // Find out the real x positions of the calculated character and its
+ // neighbour.
+ int offsX = c.modelToView(offs).getLocation().x;
+ int offsXNext = c.modelToView(offs+1).getLocation().x;
+
+ // Chose the one which is nearer to us and return its offset.
+ if (Math.abs(offsX-x) <= Math.abs(offsXNext-x))
+ return offs;
+ else
+ return offs+1;
+ }
+
+ /**
+ * Returns the document position that is closest below to the specified x
+ * coordinate in the row containing <code>offset</code>.
+ *
+ * @param c the text component
+ * @param offset the offset
+ * @param x the x coordinate
+ *
+ * @return the document position that is closest above to the specified x
+ * coordinate in the row containing <code>offset</code>
+ *
+ * @throws BadLocationException if <code>offset</code> is not a valid offset
+ */
+ public static final int getPositionBelow(JTextComponent c, int offset, int x)
+ throws BadLocationException
+ {
+ int offs = getRowEnd(c, offset);
+
+ if(offs == -1)
+ return -1;
+
+ Point pt = null;
+
+ // Note: Some views represent the position after the last
+ // typed character others do not. Converting offset 3 in "a\nb"
+ // in a PlainView will return a valid rectangle while in a
+ // WrappedPlainView this will throw a BadLocationException.
+ // This behavior has been observed in the RI.
+ try
+ {
+ // Effectively calculates the y value of the next line.
+ pt = c.modelToView(offs+1).getLocation();
+ }
+ catch(BadLocationException ble)
+ {
+ return offset;
+ }
+
+ pt.x = x;
+
+ // Calculate a simple fitting offset.
+ offs = c.viewToModel(pt);
+
+ if (offs == c.getDocument().getLength())
+ return offs;
+
+ // Find out the real x positions of the calculated character and its
+ // neighbour.
+ int offsX = c.modelToView(offs).getLocation().x;
+ int offsXNext = c.modelToView(offs+1).getLocation().x;
+
+ // Chose the one which is nearer to us and return its offset.
+ if (Math.abs(offsX-x) <= Math.abs(offsXNext-x))
+ return offs;
+ else
+ return offs+1;
+ }
+
+ /** This is an internal helper method which is used by the
+ * <code>javax.swing.text</code> package. It simply delegates the
+ * call to a method with the same name on the <code>NavigationFilter</code>
+ * of the provided <code>JTextComponent</code> (if it has one) or its UI.
+ *
+ * If the underlying method throws a <code>BadLocationException</code> it
+ * will be swallowed and the initial offset is returned.
+ */
+ static int getNextVisualPositionFrom(JTextComponent t, int offset, int direction)
+ {
+ NavigationFilter nf = t.getNavigationFilter();
+
+ try
+ {
+ return (nf != null)
+ ? nf.getNextVisualPositionFrom(t,
+ offset,
+ Bias.Forward,
+ direction,
+ new Position.Bias[1])
+ : t.getUI().getNextVisualPositionFrom(t,
+ offset,
+ Bias.Forward,
+ direction,
+ new Position.Bias[1]);
+ }
+ catch (BadLocationException ble)
+ {
+ return offset;
+ }
+
+ }
+
+}