[OpenJDK 2D-Dev] RFR: 4497648: TextLayout equals method is not implemented

[Sergey Bylokhov]

Looks fine.

On 20.06.16 15:11, Prasanta Sadhukhan wrote:
> Looks ok to me.
>
> Regards
> Prasanta
> On 6/19/2016 4:46 AM, Philip Race wrote:
>> Bug: https://bugs.openjdk.java.net/browse/JDK-4497648
>> Webrev : http://cr.openjdk.java.net/~prr/4497648/
>>
>> TextLayout is a final class that derives directly from Object.
>> It defines
>> boolean equals(TextLayout)
>> and over-rides
>> boolean equals(Object)
>> int hashCode();
>>
>> The hashCode() delegates to the implementation class TextLine().
>> TextLine is also a final class that directly derives from Object
>> It does over-ride Object.hashCode() but *does not* over-ride
>> Object.equals(Object).
>>
>> Aside from this breaking the rule that you should over-ride neither or
>> both -
>> migitated only by the fact that this is a non-API class -
>> the equals(..) methods on TextLayout() delegate to this class.
>>
>> The result of all this is that TextLayout.equals(..) is really
>> Object.equals(),
>> whilst TextLayout.hashCode() is not Object.hashCode().
>>
>> Further the javadoc on TextLayout.equals(TextLayout) says that the
>> compared instances are equal if they contain the same glyph vectors.
>> Note that whilst there is this and other commentary on the class
>> mentioning glyph vectors, the GlyphVector class is not exposed
>> anywhere in the API of TextLayout and we can take this only to
>> infer that it is implying that the laid out text is equivalent.
>> But as already noted there is no implementation to support
>> comparing the internal state.
>>
>> Since this state of affairs goes back to 1.2 and it is neither easy,
>> nor obviously valuable to be able to make such comparisons, we
>> should make the spec. match the long standing implementation.
>>
>> So this fix removes the over-rides that add no value, and removes
>> the wording about equal glyph vectors in favour of text that cannot
>> be used to interpret that there is anything other than the minimal
>> equivalence of equals. It would have been better if equals(TextLayout)
>> had not been added at all but that ship has sailed.
>>
>> FYI .. I have already discussed this proposal off-line with the JCK team
>> and they are happy so long as the spec. matches the implementation.
>> CCC will be filed once this is reviewed - and I also had an off-line
>> conversation with Joe Darcy.
>>
>> -phil.
>>
>


-- 
Best regards, Sergey.