PiBox » MusicFE

This isn't as easy at it seems. Consider

1. If there are 1000's of images, that could take 100's of MB of memory to pre-allocate the images.
2. If we only allocate a few, which few do we allocate?
   1. What if the user searches for albums/artists - do we redo the preallocations? Won't that just slow things down too?

The way it works now is that 5 images are selected with 2 on either side of the active selection. Those five are loaded each time. It's relatively fast but could benefit from 2D acceleration (re: OpenGL again).

A short term alternative would be to cache the images and only load new ones on either end as the carousel spins. And don't allow the user to hit next/prev too fast - disable key presses while drawing. That may give the appearance of better performance.

For more help with OpenGL/etc, see the Adding OpenGL to Cairo issue. In particular, this discussion suggests that an X program can just create an empty window and provide the size and offsets to DispmanX to do the rendering. DispmanX will be displayed above the X window, which means you could interleave the two windows.

Side note: The cover art database is made up of png files because the genid3db.sh outputs them as png files. So I only need a PNG loader

Another side note: All HDMI connected boards have /dev/dri/card0. The RPi LCD and TFT displays do not have this device file. /dev/dri/card0 is the DRM interface. The reason it's missing on RPi LCD and TFT's is because either firstboot or lcdshow removes the dtoverlays for vc4-fkms-v3d*.

Code is ported and ready to test. If I understand this correctly, the EGL will be displayed under the X, but I think that only works if I set the layer the EGL should be on with DispmanX.

Need a step-by-step plan for this.

1. Update demo to accept GTK+ window size and offset instead of using full screen.
2. Refactor do_carousel_drawing()
   1. Get 5 images
      1. Only parse JSON data.
      2. pointer to data struct array
   2. Allocate Cairo images vs DispmanX resources
   3. Compute scaling and positioning
   4. Draw Cairo vs DispmanX
3. Free/cleanup data struct array

Some things I'm learning while working on that plan.

• dispmanx has no native file loading.
  • Will need to incorporate a png reader
• Each image in the carousel is a dispmanx resource
• Only create 1 new resource, no matter the direction the carousel moves
  • vc_dispmanx_element_change_source() can swap sources, just remember are we moving down or up in the carousel.

This would really be better done with OpenGL but I couldn't get that to integrate - maybe I need to make sure I'm linking against -lbrcmGLESv2 -lbrcmEGL? But OpenGL doesn't load PNG files natively either.