+1
-phil.
On 04/12/2016 01:19 PM, Jim Graham wrote:
On 4/12/2016 12:59 PM, Phil Race wrote:
I am catching up on email here, and "+1" but a couple of comments
- I suppose that we can't learn anything useful from
"cm.validbits.equals(this.validbits)"
since only the bits up to "map_size" should be tested ?
Perhaps if the constructors truncated it at the required size we could
use equals(). I'm not sure that is worthwhile, given how rarely it is
used. I think it is used by default on some platforms (Windows?
X11?) if they have an 8-bit screen with a sparse colormap, but that
should be pretty rare these days since nearly everything we use should
be 24-bits these days.
I have a better idea, though.
But, since the field is assigned the original supplied value from the
constructor, then the likelihood that a non-null value will be ==
identical to another colormap is likely larger than normal, perhaps we
can make it faster by checking for == and then slipping into the
faster test that simply compares the rgb[] values? Something like:
if (validBits == cm.validBits) {
compare rgb[] entries
} else if (validBits == null || cm.validBits == null) {
return false;
} else {
bigger loop that compares rgb[] and validBits() values
}
Note that if the two fields are == and non-null, then the entries in
the rgb[] array for indices that are non-valid should have zeros in
them because of the way that the colormap data is copied internally,
so the rgb[] comparisons should be valid without checking the
associated bits.
Potentially we could also use:
boolean fulltest;
if (validBits == cm.validBits) {
fulltest = false;
} else if (validBits == null || cm.validBits == null) {
return false;
} else if (validBits.equals(cm.validBits)) {
fulltest = false;
} else {
fulltest = true;
}
if (fulltest) {
compare both rgb[] and validBits() values
} else {
compare rgb[] entries alone
}
In this case we are using validBits.equals() to reduce the amount of
testing in the loop, but are not basing a conclusion on whether the
result of the comparison will be true or false. equals() implies we
don't need to compare its values bit by bit, but !equals() doesn't
mean that the ICMs aren't equals()...
...jim
