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package jogamp.opengl.util.pngj;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.charset.Charset;
import java.util.HashSet;
import java.util.Set;
import java.util.zip.CRC32;
/**
* Some utility static methods.
* <p>
* See also <code>FileHelper</code> (if not sandboxed).
* <p>
* Client code should rarely need these methods.
*/
public class PngHelper {
/**
* Default charset, used internally by PNG for several things
*/
public static Charset charsetLatin1 = Charset.forName("ISO-8859-1");
public static Charset charsetUTF8 = Charset.forName("UTF-8"); // only for some chunks
static boolean DEBUG = false;
public static int readByte(InputStream is) {
try {
return is.read();
} catch (IOException e) {
throw new PngjOutputException(e);
}
}
/**
* -1 if eof
*
* PNG uses "network byte order"
*/
public static int readInt2(InputStream is) {
try {
int b1 = is.read();
int b2 = is.read();
if (b1 == -1 || b2 == -1)
return -1;
return (b1 << 8) + b2;
} catch (IOException e) {
throw new PngjInputException("error reading readInt2", e);
}
}
/**
* -1 if eof
*/
public static int readInt4(InputStream is) {
try {
int b1 = is.read();
int b2 = is.read();
int b3 = is.read();
int b4 = is.read();
if (b1 == -1 || b2 == -1 || b3 == -1 || b4 == -1)
return -1;
return (b1 << 24) + (b2 << 16) + (b3 << 8) + b4;
} catch (IOException e) {
throw new PngjInputException("error reading readInt4", e);
}
}
public static int readInt1fromByte(byte[] b, int offset) {
return (b[offset] & 0xff);
}
public static int readInt2fromBytes(byte[] b, int offset) {
return ((b[offset] & 0xff) << 16) | ((b[offset + 1] & 0xff));
}
public static int readInt4fromBytes(byte[] b, int offset) {
return ((b[offset] & 0xff) << 24) | ((b[offset + 1] & 0xff) << 16) | ((b[offset + 2] & 0xff) << 8)
| (b[offset + 3] & 0xff);
}
public static void writeByte(OutputStream os, byte b) {
try {
os.write(b);
} catch (IOException e) {
throw new PngjOutputException(e);
}
}
public static void writeInt2(OutputStream os, int n) {
byte[] temp = { (byte) ((n >> 8) & 0xff), (byte) (n & 0xff) };
writeBytes(os, temp);
}
public static void writeInt4(OutputStream os, int n) {
byte[] temp = new byte[4];
writeInt4tobytes(n, temp, 0);
writeBytes(os, temp);
}
public static void writeInt2tobytes(int n, byte[] b, int offset) {
b[offset] = (byte) ((n >> 8) & 0xff);
b[offset + 1] = (byte) (n & 0xff);
}
public static void writeInt4tobytes(int n, byte[] b, int offset) {
b[offset] = (byte) ((n >> 24) & 0xff);
b[offset + 1] = (byte) ((n >> 16) & 0xff);
b[offset + 2] = (byte) ((n >> 8) & 0xff);
b[offset + 3] = (byte) (n & 0xff);
}
/**
* guaranteed to read exactly len bytes. throws error if it cant
*/
public static void readBytes(InputStream is, byte[] b, int offset, int len) {
if (len == 0)
return;
try {
int read = 0;
while (read < len) {
int n = is.read(b, offset + read, len - read);
if (n < 1)
throw new RuntimeException("error reading bytes, " + n + " !=" + len);
read += n;
}
} catch (IOException e) {
throw new PngjInputException("error reading", e);
}
}
public static void writeBytes(OutputStream os, byte[] b) {
try {
os.write(b);
} catch (IOException e) {
throw new PngjOutputException(e);
}
}
public static void writeBytes(OutputStream os, byte[] b, int offset, int n) {
try {
os.write(b, offset, n);
} catch (IOException e) {
throw new PngjOutputException(e);
}
}
public static void logdebug(String msg) {
if (DEBUG)
System.out.println(msg);
}
public static Set<String> asSet(String... values) {
return new HashSet<String>(java.util.Arrays.asList(values));
}
public static Set<String> unionSets(Set<String> set1, Set<String> set2) {
Set<String> s = new HashSet<String>();
s.addAll(set1);
s.addAll(set2);
return s;
}
public static Set<String> unionSets(Set<String> set1, Set<String> set2, Set<String> set3) {
Set<String> s = new HashSet<String>();
s.addAll(set1);
s.addAll(set2);
s.addAll(set3);
return s;
}
private static final ThreadLocal<CRC32> crcProvider = new ThreadLocal<CRC32>() {
protected CRC32 initialValue() {
return new CRC32();
}
};
/** thread-singleton crc engine */
public static CRC32 getCRC() {
return crcProvider.get();
}
static final byte[] pngIdBytes = { -119, 80, 78, 71, 13, 10, 26, 10 }; // png magic
public static double resMetersToDpi(long res) {
return (double) res * 0.0254;
}
public static long resDpiToMeters(double dpi) {
return (long) (dpi / 0.0254 + 0.5);
}
public static int doubleToInt100000(double d) {
return (int) (d * 100000.0 + 0.5);
}
public static double intToDouble100000(int i) {
return i / 100000.0;
}
public static int clampTo_0_255(int i) {
return i > 255 ? 255 : (i < 0 ? 0 : i);
}
public static int clampTo_0_65535(int i) {
return i > 65535 ? 65535 : (i < 0 ? 0 : i);
}
public static int clampTo_128_127(int x) {
return x > 127 ? 127 : (x < -128 ? -128 : x);
}
}
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