| /* GlyphMeasurer.java -- Helper for measuring TrueType glyphs. |
| Copyright (C) 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 gnu.java.awt.font.opentype.truetype; |
| |
| import java.awt.FontFormatException; |
| import java.nio.ByteBuffer; |
| import java.nio.ShortBuffer; |
| |
| |
| /** |
| * A class for measuring TrueType and OpenType glyphs. |
| * |
| * <p><b>Lack of Thread Safety:</b> Glyph measurers are intentionally |
| * <i>not</i> safe to access from multiple concurrent |
| * threads. Synchronization needs to be performed externally. Usually, |
| * the font has already obtained a lock before calling the scaler, |
| * which in turn calls the GlyphMeasurer. It would thus be wasteful to |
| * acquire additional locks for the GlyphMeasurer. |
| * |
| * @author Sascha Brawer (brawer@dandelis.ch) |
| */ |
| final class GlyphMeasurer |
| { |
| /** |
| * A view buffer that allows accessing the contents of the |
| * font’s <code>hmtx</code> table as shorts. |
| */ |
| private final ShortBuffer horizontalGlyphMetrics; |
| |
| |
| /** |
| * A view buffer that allows accessing the contents of the |
| * font’s <code>vmtx</code> table as shorts. |
| */ |
| private final ShortBuffer verticalGlyphMetrics; |
| |
| |
| private final int numLongHorizontalMetricsEntries; |
| private final int numLongVerticalMetricsEntries; |
| |
| private final int horizontalAscent; |
| private final int verticalAscent; |
| |
| private final int horizontalDescent; |
| private final int verticalDescent; |
| |
| private final int horizontalLineGap; |
| |
| |
| /** |
| * Constructs a GlyphMeasurer from TrueType/OpenType font tables. |
| * |
| * @param hhea the <code>hhea</code> table, which contains |
| * information about horizontal metrics that is common to all |
| * glyphs. |
| * |
| * @param hmtx the <code>hmtx</code> table, which contains |
| * glyph-specific information about horizontal metrics. |
| * |
| * @param vhea the <code>vhea</code> table, which contains |
| * information about vertical metrics that is common to all |
| * glyphs. If a font does not provide such a table, pass |
| * <code>null</code>. |
| * |
| * @param vmtx the <code>vmtx</code> table, which contains |
| * glyph-specific information about vertical metrics. If a font |
| * does not provide such a table, pass <code>null</code>. |
| */ |
| GlyphMeasurer(ByteBuffer hhea, ByteBuffer hmtx, |
| ByteBuffer vhea, ByteBuffer vmtx) |
| throws FontFormatException |
| { |
| if ((hhea.getInt(0) != 0x00010000) || (hhea.getInt(30) != 0)) |
| throw new FontFormatException("unsupported hhea format"); |
| |
| horizontalAscent = hhea.getShort(4); |
| horizontalDescent = hhea.getShort(6); |
| horizontalLineGap = hhea.getShort(8); |
| |
| numLongHorizontalMetricsEntries = hhea.getChar(34); |
| horizontalGlyphMetrics = hmtx.asShortBuffer(); |
| |
| if (vhea != null) |
| { |
| verticalAscent = vhea.getShort(4); |
| verticalDescent = vhea.getShort(6); |
| numLongVerticalMetricsEntries = vhea.getChar(34); |
| verticalGlyphMetrics = vmtx.asShortBuffer(); |
| } |
| else |
| { |
| verticalAscent = /* advanceWidthMax */ hhea.getChar(10) / 2; |
| verticalDescent = -verticalAscent; |
| numLongVerticalMetricsEntries = 0; |
| verticalGlyphMetrics = null; |
| } |
| } |
| |
| |
| /** |
| * Returns the distance from the baseline to the highest ascender. |
| * |
| * @param horizontal <code>true</code> for horizontal line layout, |
| * <code>false</code> for vertical line layout. |
| * |
| * @return the maximal ascent, in font units. |
| */ |
| public int getAscent(boolean horizontal) |
| { |
| return horizontal ? horizontalAscent : verticalAscent; |
| } |
| |
| |
| /** |
| * Returns the distance from the baseline to the lowest descender. |
| * |
| * @param horizontal <code>true</code> for horizontal line layout, |
| * <code>false</code> for vertical line layout. |
| * |
| * @return the maximal descent, in font units. |
| */ |
| public int getDescent(boolean horizontal) |
| { |
| return horizontal ? horizontalDescent : verticalDescent; |
| } |
| |
| |
| /** |
| * Returns the typographic line gap. |
| * |
| * @param horizontal <code>true</code> for horizontal line layout, |
| * <code>false</code> for vertical line layout. |
| * |
| * @return the line gap, in font units. |
| */ |
| public int getLineGap(boolean horizontal) |
| { |
| return horizontalLineGap; |
| } |
| |
| |
| /** |
| * Determines the advance width of a glyph, without considering |
| * hinting. |
| * |
| * @param glyphIndex the index of the glyph whose advance width is |
| * to be determined. |
| * |
| * @param horizontal <code>true</code> for horizontal line layout, |
| * <code>false</code> for vertical line layout. |
| * |
| * @return the advance width, in font units. |
| */ |
| public int getAdvanceWidth(int glyphIndex, boolean horizontal) |
| { |
| if (!horizontal) |
| return 0; |
| |
| glyphIndex = Math.min(glyphIndex, |
| numLongHorizontalMetricsEntries - 1); |
| return horizontalGlyphMetrics.get(glyphIndex << 1); |
| } |
| |
| |
| /** |
| * Determines the advance width of a glyph, without considering |
| * hinting. |
| * |
| * @param glyphIndex the index of the glyph whose advance width is |
| * to be determined. |
| * |
| * @param horizontal <code>true</code> for horizontal line layout, |
| * <code>false</code> for vertical line layout. |
| * |
| * @return the advance width, in font units. |
| */ |
| public int getAdvanceHeight(int glyphIndex, boolean horizontal) |
| { |
| if (horizontal) |
| return 0; |
| |
| /* If a font does not provide vertical glyph metrics, advance |
| * by the height of one horizontal line. |
| */ |
| if (verticalGlyphMetrics == null) |
| return horizontalAscent - horizontalDescent + horizontalLineGap; |
| |
| glyphIndex = Math.min(glyphIndex, |
| numLongVerticalMetricsEntries - 1); |
| return verticalGlyphMetrics.get(glyphIndex << 1); |
| } |
| } |