Rodolfo Giometti wrote:
On Wed, Jul 18, 2007 at 09:40:28AM -0400, Joey Oravec wrote:
"Rodolfo Giometti" giometti@enneenne.com wrote in message news:20070718083012.GE4836@enneenne.com...
I'm planning to review the splash image support and in order to do that my next steps should be:
- Remove the logo support.
As long as it's modular, I agreed because the two functions are nearly identical. It's important to add/remove code to keep the size down. Probably should test for a pointer to a compressed (gzip) image, uncompress, then call the bmp_display.
I think we should remove it definitely... it's just doubled code.
- Rewrite the lcd_display_bitmap() in order to be more portable
across several BPP values.
Keep it modular; have a bitmap_display(addr, x, y) robust to bpp that is called from an lcd_display_splash_screen(). Account for 24-bit LCDs and files. The bit-per-pixel data structure was a poor-fit with 24-bit, and I didn't even try to support colormapped files on a truecolor display. Great idea because it might save a ton of flash to display an 8bpp image on a 24bpp display.
- If there's an overall flash savings, it would be nice to support GIF,
PNG, or some other format smaller than a BMP. How complex is the parsing, and would it be a net savings on flash?
I think we should support just one format for two reasons:
Supporting just one format keep the code smallest.
We have "convert". :)
- Account for text overlay on splash screen. There are callbacks for bootup
progress, and it's nice to lcd_printf() the status to some rectangle on the screen. Even better if it scrolls or clears nicely.
- Document and improve the videolfb ATAG. I hardcode my framebuffer to the
end of RAM, don't tell linux to use that memory, and pass the info to linux. The display still flickers until you remove the re-initialization, but at least Linux won't move and therefore clobber the contents of the framebuffer.
I dislike this feature. :) IMHO I think it introduces several problems and complications whose can be avoided just defining a boot logo into Linux... however it could be keep into some consideration.
Thanks for your suggestions,
Rodolfo
FWIIW, I took a screenshot, saved it as a 16 bit BMP, then converted the BMP as a GIF, JPEG, and a PNG. While very unscientific, this says BMP with gzip is a winner for two reasons: 1) It is similar in compression ratios to PNG and GIF 2) We already know how to gunzip and BMP.
Benchmark: 495410 screenshot-16.bmp
25411 screenshot-16.bmp.gz 25875 screenshot-16.PNG 37727 screenshot-16.GIF 148854 screenshot-16.JPG
(Trivia: I did JPEG because it was there. It is generally a poor choice for splash screens because it has artifacts on sharp transitions, which splash screens tend to have.)
gvb