RFR: 8369129: Raster createPackedRaster methods specification clean up [v4]

[Phil Race]

On Tue, 4 Nov 2025 01:12:07 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> I've played around a bit.
>> Commenting specifically about the one createInterleavedRaster factory method which accepts, width, height and the strides, I don't think such cases of zero pixel stride have ever been useful.
>> I've written a small test (which I'll paste below) and as far as I've found so far, a zero pixel or scan line stride always results in an exception
>> from somewhere. And the exceptions are the same for each case. I've tried JDK 8, JDK 24 and a build of the current proposed fix.
>> 
>> So I think we could explicitly disallow 0 for these strides on this method although rather than a mix
>> of  RasterFormatException and IllegalArgumentException, they'd all become IllegalArgumentException
>> 
>> For the  other public factory method createInterleavedRaster that accepts a DataBuffer,  even if the app makes it large enough,
>> there's still an exception in most cases. The sole "working" case I've found is if bandoffsets are also all zero.
>> 
>>  Raster.createInterleavedRaster(new DataBufferByte(100), 1, 1, 0, 0, new int[] { 0 });
>> 
>> To continue to allow that we'd need to still allow zero strides on that method and use words about the bandoffsets.
>> 
>> The words about the bandOffsets should in fact go on both methods. They apply more broadly than a zero stride.
>> 
>> I'll proceed accordingly unless you spot an issue. Also I'll need to run all our tests which I've not done yet.
>> 
>> I don't intend to look at the allowability of zero in other APIs as part of this change.
>> 
>> BTW negative strides was asked for here : https://bugs.openjdk.org/browse/JDK-4296691
>>  
>> I don't think we'll ever do that.
>> 
>> test program :
>> import static java.awt.image.DataBuffer.TYPE_BYTE ;
>> import java.awt.image.Raster;
>> 
>> public class ZeroStride {
>>     public static void main(String[] args) {
>>         //   w  h  ss ps           bandoffsets
>>         test(1, 1, 0, 0, new int[] { 0, 0, 0});
>>         test(1, 1, 0, 0, new int[] { 0, 1, 2});
>>         test(1, 1, 0, 1, new int[] { 0, 0, 0});
>>         test(1, 1, 3, 0, new int[] { 0, 0, 0});
>>         test(1, 1, 3, 0, new int[] { 0, 1, 2});
>>     }
>> 
>>     static void test(int w, int h, int scanlineStride, int pixelStride, int[] offsets) {
>>         try {
>>              System.err.println("w="+w+" h=" + h + " scanlineStride=" + scanlineStride +
>>                                 " pixelStride = " + pixelStride +
>>                                 ((offsets[1] == 0) ? " bands={0,0,0}" : " bands={0,1,2}"));
>>              ...
>
>>I'll proceed accordingly unless you spot an issue. Also I'll need to run all our tests which I've not done yet.
> 
> all tests are green?

Yes all tests are green.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27627#discussion_r2547806650