mtPaint 2.02 now available

Under development: PCMCIA, wireless, etc.
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Mark Tyler

mtPaint 2.02 now available

#1 Post by Mark Tyler »

Here is the latest mtPaint:

http://www.btinternet.com/~mark.tyler4/ ... 02.tar.bz2

This release adds support for loading and saving PNG files with a transparency index. An optional zoom grid has been added. The save image window has been improved. Partial French and Portuguese translations have been added. A bug with the painting tool has been fixed.

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BarryK
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#2 Post by BarryK »

Hi Mark,
I was just thinking about transparency in mtPaint a few days ago.

back in the days when I used Windows, I used to like the Software602
shareware office suite.
It has a paint program, and in the menu it had an entry "Choose color for transparency" -- then a little pointer icon would appear, and I would click over
the color that I wanted to be transparent, and that was it.

That works for GIF.
But PNG, does it assign an actual color as transparent, or is it a different
mechanism?

Transparency in mtPaint has not been so seamless.
For example, I opened a XPM image with one transparent "color" (a "None"
entry), did nothing, just saved it as a GIF, thinking that the transparency
would be preserved, but it wasn't.
... I guess this is because they are two different things? The XPM transparency
is not one of the colors?

Note, Puppy uses the full GIF library with LZW compression.
I thought that the LZW patent had expired, maybe it has in most places in
the world, but I recently read something about it fully expiring in
August 2006. Anyway we are using LZW!

Mark Tyler

#3 Post by Mark Tyler »

Barry,

Until version 2.02 transparency was only available with XPM files. The transparency in 2.02 is just for PNG files - I haven't spent any time working on GIF transparency as I feel its a less important file format than PNG these days.

The system of transparency I have used for PNG files in v2.02 is a very basic colour indexing system where a single colour is treated as transparent (RGB images or indexed palette images). The PNG format also allows for multiple colour transparencies and even full alpha channel transparency but I feel this is a little complex for a program like mtPaint (it would require a lot of new code and changes to the UI).

You can load a PNG file with an alpha channel but mtPaint regards a pixel as either fully transparent or fully opaque (it chops it at 50%).

If you load an XPM file into mtPaint and then save it as a PNG it should retain the transparency, as should doing this in reverse with an indexed palette PNG file saved as XPM.

You can pick the colour via the Preferences->Files section or by using the 'Save as' window.

I hope this new feature is helpful - let me know if there are any problems.

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