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A library jar that provides APIs for Applications written for the Google Android Platform.
/*
* Copyright 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.graphics.fonts;
import android.annotation.IntRange;
import android.annotation.NonNull;
import android.annotation.Nullable;
import dalvik.annotation.optimization.FastNative;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
/**
* Provides a utility for font file operations.
* @hide
*/
public class FontFileUtil {
private FontFileUtil() {} // Do not instanciate
/**
* Unpack the weight value from packed integer.
*/
public static int unpackWeight(int packed) {
return packed & 0xFFFF;
}
/**
* Unpack the italic value from packed integer.
*/
public static boolean unpackItalic(int packed) {
return (packed & 0x10000) != 0;
}
/**
* Returns true if the analyzeStyle succeeded
*/
public static boolean isSuccess(int packed) {
return packed != ANALYZE_ERROR;
}
private static int pack(@IntRange(from = 0, to = 1000) int weight, boolean italic) {
return weight | (italic ? 0x10000 : 0);
}
private static final int SFNT_VERSION_1 = 0x00010000;
private static final int SFNT_VERSION_OTTO = 0x4F54544F;
private static final int TTC_TAG = 0x74746366;
private static final int OS2_TABLE_TAG = 0x4F532F32;
private static final int ANALYZE_ERROR = 0xFFFFFFFF;
/**
* Analyze the font file returns packed style info
*/
public static final int analyzeStyle(@NonNull ByteBuffer buffer,
@IntRange(from = 0) int ttcIndex, @Nullable FontVariationAxis[] varSettings) {
int weight = -1;
int italic = -1;
if (varSettings != null) {
for (FontVariationAxis axis :varSettings) {
if ("wght".equals(axis.getTag())) {
weight = (int) axis.getStyleValue();
} else if ("ital".equals(axis.getTag())) {
italic = (axis.getStyleValue() == 1.0f) ? 1 : 0;
}
}
}
if (weight != -1 && italic != -1) {
// Both weight/italic style are specifeid by variation settings.
// No need to look into OS/2 table.
// TODO: Good to look HVAR table to check if this font supports wght/ital axes.
return pack(weight, italic == 1);
}
ByteOrder originalOrder = buffer.order();
buffer.order(ByteOrder.BIG_ENDIAN);
try {
int fontFileOffset = 0;
int magicNumber = buffer.getInt(0);
if (magicNumber == TTC_TAG) {
// TTC file.
if (ttcIndex >= buffer.getInt(8 /* offset to number of fonts in TTC */)) {
return ANALYZE_ERROR;
}
fontFileOffset = buffer.getInt(
12 /* offset to array of offsets of font files */ + 4 * ttcIndex);
}
int sfntVersion = buffer.getInt(fontFileOffset);
if (sfntVersion != SFNT_VERSION_1 && sfntVersion != SFNT_VERSION_OTTO) {
return ANALYZE_ERROR;
}
int numTables = buffer.getShort(fontFileOffset + 4 /* offset to number of tables */);
int os2TableOffset = -1;
for (int i = 0; i < numTables; ++i) {
int tableOffset = fontFileOffset + 12 /* size of offset table */
+ i * 16 /* size of table record */;
if (buffer.getInt(tableOffset) == OS2_TABLE_TAG) {
os2TableOffset = buffer.getInt(tableOffset + 8 /* offset to the table */);
break;
}
}
if (os2TableOffset == -1) {
// Couldn't find OS/2 table. use regular style
return pack(400, false);
}
int weightFromOS2 = buffer.getShort(os2TableOffset + 4 /* offset to weight class */);
boolean italicFromOS2 =
(buffer.getShort(os2TableOffset + 62 /* offset to fsSelection */) & 1) != 0;
return pack(weight == -1 ? weightFromOS2 : weight,
italic == -1 ? italicFromOS2 : italic == 1);
} finally {
buffer.order(originalOrder);
}
}
/**
* Analyze head OpenType table and return fontRevision value as 32bit integer.
*
* The font revision is stored in 16.16 bit fixed point value. This function returns this fixed
* point value as 32 bit integer, i.e. the value multiplied with 65536.
*
* IllegalArgumentException will be thrown for invalid font data.
* If the font file is invalid, returns -1L.
*
* @param buffer a buffer of OpenType font
* @param index a font index
* @return font revision that shifted 16 bits left.
*/
public static long getRevision(@NonNull ByteBuffer buffer, @IntRange(from = 0) int index) {
return nGetFontRevision(buffer, index);
}
/**
* Analyze name OpenType table and return PostScript name.
*
* IllegalArgumentException will be thrown for invalid font data.
* null will be returned if not found or the PostScript name is invalid.
*
* @param buffer a buffer of OpenType font
* @param index a font index
* @return a post script name or null if it is invalid or not found.
*/
public static String getPostScriptName(@NonNull ByteBuffer buffer,
@IntRange(from = 0) int index) {
return nGetFontPostScriptName(buffer, index);
}
/**
* Analyze name OpenType table and return true if the font has PostScript Type 1 glyphs.
*
* IllegalArgumentException will be thrown for invalid font data.
* -1 will be returned if the byte buffer is not a OpenType font data.
* 0 will be returned if the font file doesn't have PostScript Type 1 glyphs, i.e. ttf file.
* 1 will be returned if the font file has PostScript Type 1 glyphs, i.e. otf file.
*
* @param buffer a buffer of OpenType font
* @param index a font index
* @return a post script name or null if it is invalid or not found.
*/
public static int isPostScriptType1Font(@NonNull ByteBuffer buffer,
@IntRange(from = 0) int index) {
return nIsPostScriptType1Font(buffer, index);
}
/**
* Analyze the file content and returns 1 if the font file is an OpenType collection file, 0 if
* the font file is a OpenType font file, -1 otherwise.
*/
public static int isCollectionFont(@NonNull ByteBuffer buffer) {
ByteBuffer copied = buffer.slice();
copied.order(ByteOrder.BIG_ENDIAN);
int magicNumber = copied.getInt(0);
if (magicNumber == TTC_TAG) {
return 1;
} else if (magicNumber == SFNT_VERSION_1 || magicNumber == SFNT_VERSION_OTTO) {
return 0;
} else {
return -1;
}
}
@FastNative
private static native long nGetFontRevision(@NonNull ByteBuffer buffer,
@IntRange(from = 0) int index);
@FastNative
private static native String nGetFontPostScriptName(@NonNull ByteBuffer buffer,
@IntRange(from = 0) int index);
@FastNative
private static native int nIsPostScriptType1Font(@NonNull ByteBuffer buffer,
@IntRange(from = 0) int index);
}
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