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docs(disp): LV_COLOR_SCREEN_TRANSP remove dependency on LV_COLOR_DEPTH_32 as transparency is supported across all color depths (#3556)

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* Kconfig - LV_COLOR_SCREEN_TRANSP remove dependency on LV_COLOR_DEPTH_32 as transparency is supported across all color depths

* display.md - LV_COLOR_SCREEN_TRANSP remove mention of 32bpp requirement that is no longer necessary
This commit is contained in:
Chris Morgan
2022-08-10 08:00:14 -04:00
committed by GitHub
parent d59bba12db
commit f58dcd94fc
2 changed files with 2 additions and 5 deletions
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docs/overview/display.md
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@@ -63,11 +63,10 @@ See the [Display background](#display-background) section for more details. If t
This configuration (transparent screen and display) could be used to create for example OSD menus where a video is played on a lower layer, and a menu is overlayed on an upper layer.
To handle transparent displays, special (slower) color mixing algorithms need to be used by LVGL so this feature needs to enabled with `LV_COLOR_SCREEN_TRANSP` in `lv_conf.h`.
As this mode operates on the Alpha channel of the pixels `LV_COLOR_DEPTH = 32` is also required. The Alpha channel of 32-bit colors will be 0 where there are no objects and 255 where there are solid objects.
The Alpha channel of 32-bit colors will be 0 where there are no objects and 255 where there are solid objects.
In summary, to enable transparent screens and displays for OSD menu-like UIs:
- Enable `LV_COLOR_SCREEN_TRANSP` in `lv_conf.h`
- Be sure to use `LV_COLOR_DEPTH 32`
- Set the screen's opacity to `LV_OPA_TRANSP` e.g. with `lv_obj_set_style_local_bg_opa(lv_scr_act(), LV_OBJMASK_PART_MAIN, LV_STATE_DEFAULT, LV_OPA_TRANSP)`
- Set the display opacity to `LV_OPA_TRANSP` with `lv_disp_set_bg_opa(NULL, LV_OPA_TRANSP);`