/** Reads Netscape extenstion to obtain iteration count */
protected void readNetscapeExt() {
do {
readBlock();
if (block[0] == 1) {
// loop count sub-block
final int b1 = (block[1]) & 0xff;
final int b2 = (block[2]) & 0xff;
loopCount = (b2 << 8) | b1;
}
} while ((blockSize > 0) && !err());
}
/** Main file parser. Reads GIF content blocks. */
protected void readContents() {
// read GIF file content blocks
boolean done = false;
while (!(done || err())) {
int code = read();
switch (code) {
case 0x2C: // image separator
readBitmap();
break;
case 0x21: // extension
code = read();
switch (code) {
case 0xf9: // graphics control extension
// Start a new frame
currentFrame = new GifFrame();
readGraphicControlExt();
break;
case 0xff: // application extension
readBlock();
String app = "";
for (int i = 0; i < 11; i++) {
app += (char) block[i];
}
if (app.equals("NETSCAPE2.0")) {
readNetscapeExt();
} else {
skip(); // don't care
}
break;
case 0xfe: // comment extension
skip();
break;
case 0x01: // plain text extension
skip();
break;
default: // uninteresting extension
skip();
}
break;
case 0x3b: // terminator
done = true;
break;
case 0x00: // bad byte, but keep going and see what happens break;
default:
status = STATUS_FORMAT_ERROR;
}
}
}
/** Skips variable length blocks up to and including next zero length block. */
protected void skip() {
do {
readBlock();
} while ((blockSize > 0) && !err());
}
