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PostPosted: Fri Aug 17, 2001 3:25 am
by artosoft

I found the compression did not work for RLE in visor prism. PalmOS v3.52rev1.4.

The Line compression method work on it, but not RLE compression.
If I save with RLE compression, next time I read it with BmpInfo(), it will report as no compression (0).

Did visor prism OS support RLE compression?

Best regards, Dian Suharto.

PostPosted: Sat Aug 18, 2001 1:23 am
by jstadolnik
Odd, I don't see this problem when running on a OS3.5.2H1 emulator rom. It's probably the patch you're running.

The 3.5.2 v.1.4 Handspring patch has been pulled from the market due to a bug in it. I don't know if it could be causing a problem with RLE compression though.

What are you getting as a return value from SaveBmp() when using RLE compression?


PostPosted: Sat Aug 18, 2001 10:46 pm
by artosoft
It is not save compression (Line or RLE) for bitmap less than 16x5. And for 4bps and 8bss also different.

It is known issue? Anything to know if it is fail to save small bitmap?

Dian Suharto

PostPosted: Sun Aug 19, 2001 12:51 am
by jstadolnik
It turns out the PalmOS will not compress bitmaps under a certain size because compressing them provides little to no benefit. Essentially, compression was intended for use with large bitmaps where the memory savings are significant.

I suspect that the threshold is a based on the number of bytes in the bitmap, which varies for different screen depths. For example if the cutoff is 256 bytes, it will take a larger 4 bit gray bitmap to hit this threshold than it will for an 8 bit color one.

I recently learned something interesting about huge bitmaps. The largest size of any single palm resource (including bitmaps) is 65k. This is why very large bitmaps (e.g. 160 by 160 with 8 bit color) cannot be created. However, if a bitmap is compressed it can usually have larger dimensions because it will still fit within the 65k limit!