[OpenJDK 2D-Dev] [9] Review Request: 8059942 Default implementation of DrawImage.renderImageXform() should be improved for d3d/ogl

Sergey Bylokhov Sergey.Bylokhov at oracle.com
Thu Nov 13 16:35:39 UTC 2014

Hi, Jim.
Please review an updated version of the fix:
The new method in Region class was added.

On 11.11.2014 5:43, Jim Graham wrote:
> On 11/10/14 2:52 PM, Sergey Bylokhov wrote:
>> Hi, Jim.
>> To simply fill a span in the Region, I'll need to open 
>> Region.appendSpan() method,
>>  but I do not want to do it.
> No, that method should remain private.  All region objects should be 
> fully constructed at all times when in the hands of calling code.
>>  So I need to create my own EdgesSpanIterator, or totally eliminate 
> this loop and
>>  return Region object from the TransformHelper directly.
> No, all you need is a method:
> /**
>  * (describe edges array - 0,1 are y range, 2N,2N+1 are x ranges, 1 
> per y range)
>  * (dxoff, dyoff are offsets that the edges array values are relative to)
>  */
> static Region getInstance(int dxoff, int dyoff, int edges[]) {
>     // copy loop from DrawImage.java here, but use direct manipulation
>     // of the spans array instead of union operations.
>     // You should be able to pre-allocate the spans array as well to
>     // save on growth using appendSpan() et al.
> }
> That should take only a few minutes to write, then DrawImage simply does:
> Region blitclip = Region.getInstance(dx1, dy1, edges);
>> Probably some logic can be moved from TransformHelper to the java level
>> (at least generation of edges array). Additionally it will be simpler to
>>  check a performance improvement, because now it is not so obvious 
> comparing
>>  to the current percents improvement.
> Unfortunately the exact calculations to compute the edges array depend 
> on a lot of calculations done at the native level.  This would be a 
> major repartitioning of the code...
>         ...jim

Best regards, Sergey.

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