Bitmap to Array for use in graphics.drawImage()

[espruino-discuss3]

Posted at 2016-09-22 by Bennr

Hello, I've been looking around for a way to generate an array to store images in for use on an OLED, and while there are lots of results on Google, I don't seem to be able to find anything suitable that works for me.

I have a monochrome bitmap that I would like to convert to an array that I can put on the Pico. It feels like it should be very simple, but I am not having much luck getting them to work. Any tips/ideas? I am using ImageMagick on os x if anyone has an idea on how to use that to achieve it.

[espruino-discuss3]

Posted at 2016-09-22 by @gfwilliams

Did you see the docs on the Graphics library? http://www.espruino.com/Graphics

There's some info at the bottom about getting a bitmap in a form Espruino can use - it should work on OSX, but if it doesn't let me know!

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Posted at 2016-09-22 by Wilberforce

The xbm (X bitmap) format might be of use. It's monochrome and is like a declaration in c that you could convert to JavaScript, the output is text:

https://en.m.wikipedia.org/wiki/X_BitMap

#define test_width 16
#define test_height 7
static char test_bits[] = {
0x13, 0x00, 0x15, 0x00, 0x93, 0xcd, 0x55, 0xa5, 0x93, 0xc5, 0x00, 0x80,
0x00, 0x60 };

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Posted at 2016-09-22 by @gfwilliams

Actually I'll just have a go bodging up an online converter - give me a few minutes

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Posted at 2016-09-22 by Bennr

@gfwilliams Argh! Another case of me not reading things properly, sorry! Yes, there is an example down there of course, AND a link to a base64 encoder. Derp!

@wilberforce Thanks for the tip, I'll try that out as I'm getting some noise on my images at the moment.

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Posted at 2016-09-22 by @gfwilliams

Tadaaa! http://www.espruino.com/Image+Converter

(Not tested, but it sure looks ok)

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Posted at 2016-09-22 by Bennr

@gfwilliams Looks good! However, I don't know if it's my setup or something else, but this image:

Which gave this screenshot when uploaded:

Makes this on my display:

What do you think? When I display fonts, etc, it seems to work, and although there is some noise when I base64 encode images they seem to be ok too.

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Posted at 2016-09-22 by @gfwilliams

Ahh, thanks! I got the bit order wrong - have a go now!

That'll teach me for not testing it :)

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Posted at 2016-09-22 by Bennr

Woohoo! Thanks!

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Posted at 2017-02-28 by hygy

@gfwilliams Uh this is really cool! Thanks for it!!!