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Diffstat (limited to 'libjava/classpath/gnu/java/awt/font/opentype/truetype/GlyphMeasurer.java')
-rw-r--r-- | libjava/classpath/gnu/java/awt/font/opentype/truetype/GlyphMeasurer.java | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/awt/font/opentype/truetype/GlyphMeasurer.java b/libjava/classpath/gnu/java/awt/font/opentype/truetype/GlyphMeasurer.java new file mode 100644 index 00000000000..bbd0b9bffbc --- /dev/null +++ b/libjava/classpath/gnu/java/awt/font/opentype/truetype/GlyphMeasurer.java @@ -0,0 +1,228 @@ +/* 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); + } +} |