Awesome! Just what I needed to help me with 8-bit bitmaps (and maybe lower).
Right now I am using the color table that is in the bitmap (I need to add
mapping support though if the bitmap does not have a color table).
I am using this to lookup the index on the table and output it:
grey = (*imageData++);
if (gotIndex) {
r = colors[grey].r >> 3;
g = colors[grey].g >> 2;
b = colors[grey].b >> 3;
*winData++ = (r<<11) + (g<<5) + b;
} else {
*winData++ = grey;
}
It gets all of the correct mappings, but the first half of the image is a
big black chunk (but the second half is the full image sqeezed into the
second half of the destination. Does this half to do with the conversion
above, or some alignment?
Thanks,
Donald
"David Birdsall" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> Chinmaya,
>
> You can roll your own BMP reading function(s) using the file format given
here:
>
> http://astronomy.swin.edu.au/~pbourke/dataformats/bmp/
> http://www.javaworld.com/javatips/jw-javatip43_p.html
>
> You'll have to convert 24-bit images to Palm OS's hi-colour (565) format
to take each byte as a percentage of 0x3f (6 bits) or 0x1f (5 bits) and bit
shift, like R = (((RGB >> 16) & 0xff) * 0x1f >> 8) and you may also have to
map 8-bit BMP palettes to Palm's system palette (or some other palette) by
calculating each colour's relative difference using a colour distance
function given below:
>
> http://www.compuphase.com/cmetric.htm
>
> I think you can get the system palette using the function WinPalette. It
says in the Palm OS developer docs: "You can attach a custom color table to
a bitmap, and if you do, the bitmap is drawn using that color table.
However, this is a performance drain." So palette mapping speeds things up a
bit.
>
> To speed up the colour mapping when you load an 8-bit image, you can
create an index-lookup table, to map the BMP's palette indexes to indexes
pointing to the closest matching colours in the target palette, using that
colour distance function.
>
> It's then a case of setting the data for the Palm Bitmap, using
BmpGetBits(BitmapType*), casting the void* to UInt8* or UInt16* depending on
the colour depth and setting the values.
>
> A word of warning; if you attempt to use WinGetBitmap with
WinCreateOffscreenWindow and nativeFormat, you may find your 565 data won't
be in RGB format! I had a go on a Treo Sim and found it was in BGR (I think
this is platform/device-specific)
>
> Hope that helps you. It's a start at least, if nothing else.
>
> Regards,
> David
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Behalf Of Chinmaya
> Sent: 20 January 2006 07:17
> To: Palm Developer Forum
> Subject: Bitmap format
>
>
> Hi All Developers,
>
> I have a lot of basic queries on PalmOS, as I want to know a lot on
it.Palm developers please help me and tell me the best answers to my
questions , so that my basic fundas on Palm will be clear.
> I will send queries one by one in Palm Forum site.
>
> 1. I have a question on BMP format,
> i.e.
> "What's difference between Windows bitmap and Palmos bitmap?"
> If both are same then OK.
> As I know, both are not same(Bcoz, palmos bmp size is different from
windows bmp format.).
> If both differ,then how palm converts the window bmp to a palm bmp ?
>
> Thanks in Advance!.............
> Regards,
> Chinmaya
> (India)
>
>
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