Parameters
- pageIndex
- The zero based page index.
Return Value
An image grid as array of rectangles.
Method must return null if decoder cannot set image by parts.
Target Platforms: .NET 10; .NET 9; .NET 8; .NET 7; .NET 6; .NET Framework 4.8, 4.7, 4.6, 4.5, 4.0, 3.5