RFR: JDK-8297413: Remove easy warnings in javafx.graphics

[John Hendrikx]

On Tue, 22 Nov 2022 22:21:11 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> good catch - I think the change is not equivalent.  It should be either
>> 
>> 4L * physicalWidth * physicalHeight;
>> 
>> 
>> or
>> 
>> 
>> ((long)physicalWidth) * physicalHeight * 4L;
>> 
>> 
>> the proposed change might result in overflow bc the first intermediate result is likely to be int.
>
> Actually, I think the new code correct, though less clear, since `(long)` is applied to `physicalWidth` before the multiplication. The fact that we had to scratch our head and discuss it highlights the point I was trying to make. I do think this is one place where reverting the code back would be best. Then it's obvious that all of the intermediate calculations are in long.

The cast has precedence and Java will not downcast mid calculation and lose precision, so all examples here are correct.

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PR: https://git.openjdk.org/jfx/pull/960