Baixar SageThumbs 2K 2.2.0 per a Windows

## What's changed

### Fixed

- **A handful of registered formats could never show a thumbnail, on any version.**
Wavefront RLA, PlayStation TIM, MacPaint, Dr Halo CUT, Alias PIX, Garmin JNX and ZX Spectrum
SCREEN$ were all listed as supported and none of them ever worked.

The reason is the same for all of them. Most image formats begin with a few bytes that
identify them, so a decoder handed anonymous bytes can work out what it is looking at. These
formats do not. The only thing that says what they are is the file name, and the stage of our
pipeline that handles the obscure long tail was being given the bytes without the name, so it
always answered "I do not recognise this". Camera RAW files were caught by the same wall
whenever the camera had not stored a preview picture inside the file, which is why the
Minolta test file produced nothing at all.

When every other stage has already given up, that stage is now told the file's name too. All
seven formats decode, and a Minolta RAW with no built-in preview now gets a thumbnail
developed from the sensor data instead of nothing.

Formats that identify themselves are deliberately left alone, so nothing that worked before
can be pushed down a different path by a misleading file name.

- **Layered GIMP files lost their upper layers, and some stopped showing a thumbnail at all.**
Reported on 2026-08-17 as "xcf don't work anymore with new versions for big files", and that
is exactly what was happening.

2.0.0 added a limit on how much layer data a `.xcf` may be worth decoding, so that a
deliberately malformed file cannot claim thousands of full-size layers and tie up your
machine drawing them. The limit was sound. The order it was spent in was not: layers were
paid for from the bottom of the stack upward, so a file with more layers than the allowance
covers spent everything on the layers underneath and then quietly skipped the ones on top,
the only ones you can actually see. The thumbnail that came out looked completely normal and
was a picture of a half-finished image.

How big is "big"? Any file whose layers add up to more than a 16384 x 16384 image: twelve
full-canvas layers of a 6000 x 4000 picture, twenty-three of a 4000 x 3000 one, or just two
layers of a 12000 x 12000 canvas. Where the lower layers happened to be transparent (an
erased background, an empty base), everything drawn was invisible, the result was a blank
image, and the file fell back to the plain document icon. That is the "no thumbnail" half of
the report.

Layers are now paid for from the top down, so a file too big for the allowance gives up the
layers underneath whatever is covering them instead of the ones on top. Hidden layers, fully
transparent ones and layers parked off the edge of the canvas are no longer charged at all.
They cannot change the picture, so they now cost nothing, which leaves the whole allowance
for layers that are actually visible. Large layered files are also faster as a result: a
12000 x 12000 two-layer file went from 11.8 to 5.4 seconds, and now shows the right image.

- **GIMP files over 256 MB now get a thumbnail. They never have before, on any version.**

There was a ceiling on how much of a file we will read into memory at once, and a `.xcf`
past it was simply refused. Most formats have a way around that: a photo has a small preview
baked into its header, and Windows can open a huge PNG or TIFF itself and shrink it while it
reads. A GIMP file has neither. It stores no preview at all, and Windows has no idea what an
`.xcf` is, so every one of those escape routes declined and the file kept the plain document
icon. Layered artwork is exactly the kind of file that gets that big, so this hit the people
most likely to have installed SageThumbs for GIMP support in the first place.

It now reads a `.xcf` the way the format is actually built: as a map of positions, jumping
to the layers it needs and pulling one 64-pixel tile at a time, so nothing is ever held in
memory but the piece being looked at. A 305 MB file that produced nothing now thumbnails in
3.2 seconds. Files under the old ceiling take the same route and produce the identical
picture, verified across the whole test corpus.