private boolean checkJpeg() throws IOException {
byte[] data = new byte[12];
while (true) {
if (read(data, 0, 4) != 4) {
return false;
}
int marker = getShortBigEndian(data, 0);
int size = getShortBigEndian(data, 2);
if ((marker & 0xff00) != 0xff00) {
return false; // not a valid marker
}
if (marker == 0xffe0) { // APPx
if (size < 14) {
return false; // APPx header must be >= 14 bytes
}
if (read(data, 0, 12) != 12) {
return false;
}
final byte[] APP0_ID = {0x4a, 0x46, 0x49, 0x46, 0x00};
if (equals(APP0_ID, 0, data, 0, 5)) {
// System.out.println("data 7=" + data[7]);
if (data[7] == 1) {
setPhysicalWidthDpi(getShortBigEndian(data, 8));
setPhysicalHeightDpi(getShortBigEndian(data, 10));
} else if (data[7] == 2) {
int x = getShortBigEndian(data, 8);
int y = getShortBigEndian(data, 10);
setPhysicalWidthDpi((int) (x * 2.54f));
setPhysicalHeightDpi((int) (y * 2.54f));
}
}
skip(size - 14);
} else if (this.collectComments && size > 2 && marker == 0xfffe) { // comment
size -= 2;
byte[] chars = new byte[size];
if (read(chars, 0, size) != size) {
return false;
}
String comment = new String(chars, "iso-8859-1"); // $NON-NLS-1$
comment = comment.trim();
addComment(comment);
} else if (marker >= 0xffc0 && marker <= 0xffcf && marker != 0xffc4 && marker != 0xffc8) {
if (read(data, 0, 6) != 6) {
return false;
}
this.format = FORMAT_JPEG;
this.bitsPerPixel = (data[0] & 0xff) * (data[5] & 0xff);
this.progressive =
marker == 0xffc2 || marker == 0xffc6 || marker == 0xffca || marker == 0xffce;
this.width = getShortBigEndian(data, 3);
this.height = getShortBigEndian(data, 1);
return true;
} else {
skip(size - 2);
}
}
}
private boolean checkIff() throws IOException {
byte[] a = new byte[10];
// read remaining 2 bytes of file id, 4 bytes file size
// and 4 bytes IFF subformat
if (read(a, 0, 10) != 10) {
return false;
}
final byte[] IFF_RM = {0x52, 0x4d};
if (!equals(a, 0, IFF_RM, 0, 2)) {
return false;
}
int type = getIntBigEndian(a, 6);
if (type != 0x494c424d
&& // type must be ILBM...
type != 0x50424d20) { // ...or PBM
return false;
}
// loop chunks to find BMHD chunk
do {
if (read(a, 0, 8) != 8) {
return false;
}
int chunkId = getIntBigEndian(a, 0);
int size = getIntBigEndian(a, 4);
if ((size & 1) == 1) {
size++;
}
if (chunkId == 0x424d4844) { // BMHD chunk
if (read(a, 0, 9) != 9) {
return false;
}
this.format = FORMAT_IFF;
this.width = getShortBigEndian(a, 0);
this.height = getShortBigEndian(a, 2);
this.bitsPerPixel = a[8] & 0xff;
return (this.width > 0
&& this.height > 0
&& this.bitsPerPixel > 0
&& this.bitsPerPixel < 33);
}
skip(size);
} while (true);
}
private boolean checkGif() throws IOException {
final byte[] GIF_MAGIC_87A = {0x46, 0x38, 0x37, 0x61};
final byte[] GIF_MAGIC_89A = {0x46, 0x38, 0x39, 0x61};
byte[] a = new byte[11]; // 4 from the GIF signature + 7 from the global header
if (read(a) != 11) {
return false;
}
if ((!equals(a, 0, GIF_MAGIC_89A, 0, 4)) && (!equals(a, 0, GIF_MAGIC_87A, 0, 4))) {
return false;
}
this.format = FORMAT_GIF;
this.width = getShortLittleEndian(a, 4);
this.height = getShortLittleEndian(a, 6);
int flags = a[8] & 0xff;
this.bitsPerPixel = ((flags >> 4) & 0x07) + 1;
this.progressive = (flags & 0x02) != 0;
// skip global color palette
if ((flags & 0x80) != 0) {
this.numColors = (1 << ((flags & 7) + 1));
skip(this.numColors * 3);
}
if (!this.determineNumberOfImages) {
return true;
}
this.numberOfImages = 0;
int blockType;
do {
blockType = read();
switch (blockType) {
case (0x2c): // image separator
{
if (read(a, 0, 9) != 9) {
return false;
}
flags = a[8] & 0xff;
int localBitsPerPixel = (flags & 0x07) + 1;
if (localBitsPerPixel > this.bitsPerPixel) {
this.bitsPerPixel = localBitsPerPixel;
}
if ((flags & 0x80) != 0) {
int localNumColors = 1 << localBitsPerPixel;
skip(localNumColors * 3);
if (localNumColors > this.numColors) {
this.numColors = localNumColors;
}
}
skip(1); // initial code length
int n;
do {
n = read();
if (n > 0) {
skip(n);
} else if (n == -1) {
return false;
}
} while (n > 0);
this.numberOfImages++;
break;
}
case (0x21): // extension
{
int extensionType = read();
if (this.collectComments && extensionType == 0xfe) {
StringBuffer sb = new StringBuffer();
int n;
do {
n = read();
if (n == -1) {
return false;
}
if (n > 0) {
for (int i = 0; i < n; i++) {
int ch = read();
if (ch == -1) {
return false;
}
sb.append((char) ch);
}
}
} while (n > 0);
} else {
int n;
do {
n = read();
if (n > 0) {
skip(n);
} else if (n == -1) {
return false;
}
} while (n > 0);
}
break;
}
case (0x3b): // end of file
{
break;
}
default:
{
return false;
}
}
} while (blockType != 0x3b);
return true;
}