Add GDT_Int8 support (RFC 87)

[rouault]

On reading, PIXELTYPE=SIGNEDBYTE in IMAGE_STRUCTURE metadata domain is no longer reported in drivers that used to do it.

On writing, the PIXELTYPE=SIGNEDBYTE creation option is preserved in drivers that used to support it, but is deprecated.

[mgoacolou]

for consistency purpose it should be great to have the GDT_UInt8 as an alias of GDT_Byte witch is still ambiguous, isn't it?

[rouault]

for consistency purpose it should be great to have the GDT_UInt8 as an alias of GDT_Byte witch is still ambiguous, isn't it?

I had indeed pondered about that. GDT_Byte is not strictly speaking ambiguous as it has always been documented as a unsigned 8-bit integer (if one excludes the PIXELTYPE=SIGNEDBYTE hint that amends it). If we were to provide GDT_UInt8, this should by as a #define GDT_UInt8 GDT_Byte rather than as a proper enumeration value of GDALDataType, so that people who swith( eDataType ) don't have to include case statements for both GDT_Byte and GDT_UInt8.

[sgillies]

Can we adhere to the example of numpy? Ubyte (same as uint8) vs byte?

…

On Tue, Nov 8, 2022, 6:04 AM Even Rouault ***@***.***> wrote: for consistency purpose it should be great to have the GDT_UInt8 as an alias of GDT_Byte witch is still ambiguous, isn't it? I had indeed pondered about that. GDT_Byte is not strictly speaking ambiguous as it has always been documented as a unsigned 8-bit integer (if one expects the PIXELTYPE=SIGNEDBYTE hint that amends it). If we were to provide GDT_UInt8, this should by as a #define GDT_UInt8 GDT_Byte rather than as a proper enumeration value of GDALDataType, so that people who swith( eDataType ) don't have to include case statements for both GDT_Byte and GDT_UInt8. — Reply to this email directly, view it on GitHub <#6633 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAIHINGJAEBYMJMDZXNHA3WHJFUPANCNFSM6AAAAAAR2E6MJY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[rouault]

Ubyte (same as uint8) vs byte?

what do you suggest exactly: keep GDT_Byte in the enumeration and add #define GDT_UByte GDT_Byte to create the alias ?