rasterizeHeadless
Rasterizes portable draw commands into a deterministic physical image.
Commands are snapshotted in their supplied order before pixel allocation or painting. The caller must not mutate the supplied list or command graph concurrently with this call. Each call owns its raster storage and shares no mutable state with another call. Rectangles use the logical origin at the top-left, x increasing rightward, y increasing downward, and half-open edges; the positive viewport and every active nested child clip are intersected before sampling. BlitImage uses nearest pixel-center sampling: for destination-relative coordinate d, source extent S, and destination extent D, the sampled source offset is floor(((2 * d + 1) * S) / (2 * D)); viewport clipping preserves this mapping against the original unclipped destination rectangle. FillRectangle and BlitImage apply the same logical source pixel to every physical pixel in its scale block, while BlitImagePixels applies the same mapping separately to each physical output pixel and the scaled destination extent. SampledImage instead maps final physical pixel centers through its original fractional destination into the source and samples the nearest texel. Its normalized source channels are multiplied by normalized tint channels without intermediate eight-bit rounding, and samples below the command's alpha cutoff are discarded before blending. Every command blends against each existing physical destination pixel independently, preserving image detail beneath later logical overlays. Painting starts with transparent black and uses straight ARGB source-over; integral blending uses Long intermediates. For source alpha sa, destination alpha da, and channel values sc and dc, alphaN = sa * 255 + da * (255 - sa), oa = floor((alphaN + 127) / 255), and when alphaN != 0 each channel is floor((sc * sa * 255 + dc * da * (255 - sa) + floor(alphaN / 2)) / alphaN). When alphaN == 0, the result is exactly 0x00000000. Each channel and alpha is rounded half-up per command, with canonical zero for transparent output. SampledImage uses floating-point normalized source-over and quantizes only the final blended channels and alpha by the same half-up rule. Transparent sources are no-ops, opaque sources replace, and no gamma conversion, interpolation, or saturation is applied.
Return
an immutable physical ARGB image with transparent-black initial pixels. The physical size is the checked viewport width and height multiplied by scale.
Parameters
the core-emitted draw commands in execution order; opaque platform commands are unsupported.
the positive logical viewport.
the positive integer logical-to-physical scale.
Throws
when the viewport or scale is invalid, a command is unsupported or null from Java, or the clip stack is unbalanced.
when checked physical dimensions, pixel area, or derived raster storage exceeds Int.MAX_VALUE.