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) {
// not an APPx header as we know it, skip
skip(size - 2);
continue;
}
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 (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");
comment = comment.trim();
addComment(comment);
} else if (marker >= 0xffc0 && marker <= 0xffcf && marker != 0xffc4 && marker != 0xffc8) {
if (read(data, 0, 6) != 6) {
return false;
}
format = FORMAT_JPEG;
bitsPerPixel = (data[0] & 0xff) * (data[5] & 0xff);
progressive = marker == 0xffc2 || marker == 0xffc6 || marker == 0xffca || marker == 0xffce;
width = getShortBigEndian(data, 3);
height = getShortBigEndian(data, 1);
return true;
} else {
skip(size - 2);
}
}
}
private boolean checkPcx() throws IOException {
byte[] a = new byte[64];
if (read(a) != a.length) {
return false;
}
if (a[0] != 1) { // encoding, 1=RLE is only valid value
return false;
}
// width / height
int x1 = getShortLittleEndian(a, 2);
int y1 = getShortLittleEndian(a, 4);
int x2 = getShortLittleEndian(a, 6);
int y2 = getShortLittleEndian(a, 8);
if (x1 < 0 || x2 < x1 || y1 < 0 || y2 < y1) {
return false;
}
width = x2 - x1 + 1;
height = y2 - y1 + 1;
// color depth
int bits = a[1];
int planes = a[63];
if (planes == 1 && (bits == 1 || bits == 2 || bits == 4 || bits == 8)) {
// paletted
bitsPerPixel = bits;
} else if (planes == 3 && bits == 8) {
// RGB truecolor
bitsPerPixel = 24;
} else {
return false;
}
setPhysicalWidthDpi(getShortLittleEndian(a, 10));
setPhysicalHeightDpi(getShortLittleEndian(a, 10));
format = FORMAT_PCX;
return true;
}
private boolean checkBmp() throws IOException {
byte[] a = new byte[44];
if (read(a) != a.length) {
return false;
}
width = getIntLittleEndian(a, 16);
height = getIntLittleEndian(a, 20);
if (width < 1 || height < 1) {
return false;
}
bitsPerPixel = getShortLittleEndian(a, 26);
if (bitsPerPixel != 1
&& bitsPerPixel != 4
&& bitsPerPixel != 8
&& bitsPerPixel != 16
&& bitsPerPixel != 24
&& bitsPerPixel != 32) {
return false;
}
int x = (int) (getIntLittleEndian(a, 36) * 0.0254);
if (x > 0) {
setPhysicalWidthDpi(x);
}
int y = (int) (getIntLittleEndian(a, 40) * 0.0254);
if (y > 0) {
setPhysicalHeightDpi(y);
}
format = FORMAT_BMP;
return true;
}