| public java.lang.CharSequence | filter(java.lang.CharSequence source, int start, int end, Spanned dest, int dstart, int dend)This method is called when the buffer is going to replace the
range dstart … dend of dest
with the new text from the range start … end
of source. Returns the CharSequence that we want
placed there instead, including an empty string
if appropriate, or null to accept the original
replacement. Be careful to not to reject 0-length replacements,
as this is what happens when you delete text.
char[] out = new char[end - start]; // reserve enough space for whole string
int outidx = 0;
boolean changed = false;
onStart();
// Scan through beginning characters in dest, calling onInvalidCharacter()
// for each invalid character.
for (int i = 0; i < dstart; i++) {
char c = dest.charAt(i);
if (!isAllowed(c)) onInvalidCharacter(c);
}
// Scan through changed characters rejecting disallowed chars
for (int i = start; i < end; i++) {
char c = source.charAt(i);
if (isAllowed(c)) {
// Character allowed. Add it to the sequence.
out[outidx++] = c;
} else {
if (mAppendInvalid) out[outidx++] = c;
else changed = true; // we changed the original string
onInvalidCharacter(c);
}
}
// Scan through remaining characters in dest, calling onInvalidCharacter()
// for each invalid character.
for (int i = dend; i < dest.length(); i++) {
char c = dest.charAt(i);
if (!isAllowed(c)) onInvalidCharacter(c);
}
onStop();
if (!changed) {
return null;
}
String s = new String(out, 0, outidx);
if (source instanceof Spanned) {
SpannableString sp = new SpannableString(s);
TextUtils.copySpansFrom((Spanned) source,
start, end, null, sp, 0);
return sp;
} else {
return s;
}
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