add Image.SubImageInto method #2903
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Instead of allocating the result on heap for the user, allow the caller side to decide whether it should be heap-allocated or stack-allocated. This new method allows us to have a zero-alloc SubImage routine for the use cases where we don't want to make an extra allocation. The performance difference is measurable (comparison is done with benchstat): name old time/op new time/op delta SubImage-12 203ns ± 2% 33ns ± 2% -83.91% (p=0.000 n=20+19) name old alloc/op new alloc/op delta SubImage-12 112B ± 0% 0B -100.00% (p=0.000 n=20+20) Using SubImage is `~203ns`, SubImageInto is `~33ns`. SubImage does 1 allocation, SubImageInto does none. SubImage is rewritten in a way to avoid the code duplication. It should work identically to the previous contract (it returns nil if `i` is disposed, etc.) Fixes hajimehoshi#2902
hajimehoshi
requested changes
Feb 4, 2024
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Instead of allocating the result on heap for the user, allow the caller side to decide whether it should be heap-allocated or stack-allocated.
This new method allows us to have a zero-alloc SubImage routine for the use cases where we don't want to make an extra allocation.
The performance difference is measurable (comparison is done with benchstat):
Using SubImage is
~203ns, SubImageInto is~33ns. SubImage does 1 allocation, SubImageInto does none.SubImage is rewritten in a way to avoid the code duplication. It should work identically to the previous contract (it returns nil if
iis disposed, etc.)Fixes #2902
What issue is this addressing?
#2902
What type of issue is this addressing?
Feature.
What this PR does | solves
It introduces a more efficient way of making subimages.