Palette

The 16 colours the framebuffer's indices stand for, and a fade applied on top of them. More...

Functions
void	gfx_setPalette (const uint16_t *rgb565, uint8_t count)
	Sets the first count palette entries.
void	gfx_setPaletteEntry (uint8_t index, uint16_t rgb565)
	Sets one palette entry.
void	gfx_setFade (uint8_t amount, uint16_t rgb565=0x0000)
	Fades every colour toward one colour (black by default).
uint8_t	gfx_fade (void)
	The current fade amount.
uint16_t	gfx_paletteOut (uint8_t index)
	The colour a palette index actually reaches the panel as, fade included.
static uint16_t	gfx_rgb (uint8_t r, uint8_t g, uint8_t b)
	Packs an 8-bit-per-channel colour into RGB565.
uint8_t	gfx_nearest (uint16_t rgb565)
	Nearest palette index for a full RGB565 colour.

Variables
uint16_t	gfx_pal [16]
	The 16 palette colours as set, in RGB565.

Detailed Description

The 16 colours the framebuffer's indices stand for, and a fade applied on top of them.

Palette changes are STAGED: they take effect when the next flush starts, never part-way through one in flight, so these are safe to call at any time - including between gfx_flushAsync() and gfx_wait(). Every frame is re-sent through the palette, so animating it (cycling a slot, pulsing a highlight, a fade) costs a 256-entry table rebuild per frame and no drawing at all.

Function Documentation

gfx_setPalette()

void gfx_setPalette	(	const uint16_t *	rgb565,
		uint8_t	count
	)

Sets the first count palette entries.

Parameters

rgb565	The colours, in RGB565 (see gfx_rgb()). Passing gfx_pal itself just re-stages the palette.
count	How many entries to set, from index 0; at most 16 are used.

gfx_setPaletteEntry()

void gfx_setPaletteEntry	(	uint8_t	index,
		uint16_t	rgb565
	)

Sets one palette entry.

Parameters

index	Palette index, 0..15 (only the low 4 bits are used).
rgb565	The colour, in RGB565.

gfx_setFade()

void gfx_setFade	(	uint8_t	amount,
		uint16_t	rgb565 = 0x0000
	)

Fades every colour toward one colour (black by default).

Applied while the expansion table is built, so gfx_pal[] keeps the true colours and gfx_nearest() still matches against them. Staged like the palette.

Parameters

amount	0 = the palette as set, 255 = solid rgb565.
rgb565	The colour faded toward, in RGB565 (default black).

gfx_fade()

uint8_t gfx_fade

(

void

)

The current fade amount.

Returns

0 (no fade) to 255 (every colour is the fade colour).

gfx_paletteOut()

uint16_t gfx_paletteOut

(

uint8_t

index

)

The colour a palette index actually reaches the panel as, fade included.

Parameters

index

Palette index, 0..15.

Returns

The colour in RGB565.

gfx_rgb()

static uint16_t gfx_rgb ( uint8_t  r, uint8_t  g, uint8_t  b  )

inlinestatic

Packs an 8-bit-per-channel colour into RGB565.

Parameters

r	Red, 0..255 (the top 5 bits are kept).
g	Green, 0..255 (the top 6 bits are kept).
b	Blue, 0..255 (the top 5 bits are kept).

Returns

The colour in RGB565, for gfx_setPalette() and the like.

gfx_nearest()

uint8_t gfx_nearest

(

uint16_t

rgb565

)

Nearest palette index for a full RGB565 colour.

Linear search over 16 entries, by weighted distance, against the palette as set (not as faded) - fine at setup time to build named constants, far too slow to call per pixel.

Parameters

rgb565

The colour, in RGB565.

Returns

The palette index, 0..15, closest to it.

Variable Documentation

gfx_pal

uint16_t gfx_pal[16]

extern

The 16 palette colours as set, in RGB565.

Read it freely; change it with gfx_setPalette() or gfx_setPaletteEntry(), which stage the change for the next flush. The fade (gfx_setFade()) is not applied here: gfx_paletteOut() gives the colour the panel actually receives.